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  • Elsevier  (5,804,757)
  • Wiley  (1,037,712)
  • Molecular Diversity Preservation International  (495,622)
  • Oxford University Press  (428,980)
Collection
Keywords
Publisher
Language
Years
  • 1
    Electronic Resource
    Electronic Resource
    A measurement of τ polarization in Z^0 decays (1992-8977)
    Amsterdam : Elsevier
    Physics Letters B 294 (1992), S. 466-478 
    Details
    ISSN: 0370-2693
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0370-2693(92)91549-O
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  • 2
    Electronic Resource
    Electronic Resource
    Measurement of the average lifetime of b hadrons (1993-4325)
    Amsterdam : Elsevier
    Physics Letters B 317 (1993), S. 474-484 
    Details
    ISSN: 0370-2693
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0370-2693(93)91027-K
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  • 3
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    Towards a Vigilant Society (2024)
    Oxford University Press
    Details
    Publication Date: 2024-04-11
    Description: Towards a Vigilant Society sheds light on the emergence of a new society of vigilance, in particular the actions of anti-migrant groups around Dover and Calais. Based on field research on both sides of the channel, it studies the dynamics of these groups – midway between a social movement and vigilantism – at these two key points in the international migration route between the European Union and the United Kingdom. In recent years, a series of anti-migrant groups have been mobilising on both sides of the Channel to counter migrations. Their actions range from demonstrations, to violence against migrants. And by staging their actions on social media, which is an extraordinary sounding board, these groups can build an online community and a mass audience, influencing public opinion and even the migration policies of states.
    Keywords: Vigilantism Citizen participation in policing Securitisation Social reaction to migration Anti-migrant groups Far-right social movements Calais Dover Neighbourhood watches ; thema EDItEUR::J Society and Social Sciences::JH Sociology and anthropology::JHB Sociology ; thema EDItEUR::J Society and Social Sciences::JB Society and culture: general::JBF Social and ethical issues::JBFH Migration, immigration and emigration ; thema EDItEUR::5 Interest qualifiers::5P Relating to specific groups and cultures or social and cultural interests::5PB Relating to peoples: ethnic groups, indigenous peoples, cultures and other groupings of people::5PBC Relating to migrant groups / diaspora communities or peoples ; thema EDItEUR::J Society and Social Sciences::JB Society and culture: general::JBF Social and ethical issues::JBFG Refugees and political asylum
    Language: English
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  • 4
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    City of Equals (2024)
    Oxford University Press
    Details
    Publication Date: 2024-04-06
    Description: When we think about equality in the city, we are very likely to think first of the wide and growing divide between rich and poor, in material terms. Yet when we think more about a 'city of equals' it becomes apparent that how people feel treated by the city and those around them, and whether they can live according to their values, are much more central. Accordingly, combining their own reflections, a multi-disciplinary literature review, and, distinctively, more than 180 interviews in 10 cities in 6 countries, Wolff and de Shalit have derived an account of a city of equals based on the idea that it should give each of its city-zens a secure sense of place or belonging. Four underlying values structure this account. First, access to the goods and services of the city should not be based purely on the market. Second, each person should be able to live a life they find meaningful. Third, there should be diversity and wide social mixing. Fourth, there should be 'non-deferential inclusion': each person should be able to get access to what they are entitled to without being treated as less worthy than others. They should be able to enjoy their rights without bowing and scraping, waiting longer than others, or going through special bureaucratic hurdles. In sum, in a city of equals each person is proud of their city and has the (justified) feeling that their city is proud of (people like) them.
    Keywords: cities, equality, inequality, relational equality, equality in the city, inclusion, diversity, social mixing, public reflective equilibrium, urban political philosophy ; thema EDItEUR::J Society and Social Sciences::JP Politics and government::JPA Political science and theory ; thema EDItEUR::Q Philosophy and Religion::QD Philosophy::QDT Topics in philosophy::QDTQ Ethics and moral philosophy ; thema EDItEUR::R Earth Sciences, Geography, Environment, Planning::RG Geography
    Language: English
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  • 5
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    The Ethics of Surveillance in Times of Emergency (2024)
    Oxford University Press
    Details
    Publication Date: 2024-04-08
    Description: The Covid-19 pandemic is arguably the first international emergency of the twenty-first century. In order to respond to this emergency, countries and governments around the world were forced to engage in a range of actions and policies that would not otherwise have been permitted. Looking in particular at the use of surveillance technologies, this book examines the challenge of ethics in emergencies. What can states do to keep their populations safe, what can citizens expect of their governments, and when are those government actions unjustified? By looking at the use of surveillance in times of emergency, this book explores ethical, philosophical, political, and social concepts, challenges them, and offers a set of views on where those concepts may evolve into the future. As a global population, we will be faced with emergencies, and it is possible that these will also be global in their impact. The ethics of surveillance in times of emergency is both of its time, and ongoing; we must learn our lessons from the last emergency, to be prepared for the next ones.
    Keywords: applied ethics, surveillance, emergency ethics, pandemics, public health ; thema EDItEUR::Q Philosophy and Religion::QD Philosophy::QDT Topics in philosophy::QDTQ Ethics and moral philosophy ; thema EDItEUR::Q Philosophy and Religion::QD Philosophy::QDT Topics in philosophy::QDTS Social and political philosophy ; thema EDItEUR::M Medicine and Nursing::MB Medicine: general issues::MBN Public health and preventive medicine ; thema EDItEUR::Q Philosophy and Religion::QD Philosophy::QDT Topics in philosophy::QDTQ Ethics and moral philosophy ; thema EDItEUR::Q Philosophy and Religion::QD Philosophy::QDT Topics in philosophy::QDTS Social and political philosophy ; thema EDItEUR::M Medicine and Nursing::MB Medicine: general issues::MBN Public health and preventive medicine
    Language: English
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  • 6
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    What Is Structural Injustice? (2024)
    Oxford University Press
    Details
    Publication Date: 2024-04-04
    Description: What is Structural Injustice? is the first edited collection to bring together the voices of leading structural injustice scholars from politics, philosophy and law to explore the concept of structural injustice which has now become a central feature of all three disciplines and is considered by many to be a ‘field of study.’ The volume features specially selected original and essential works on structural injustice. The volume provides a range of disciplinary, ontological and epistemological perspectives on what structural injustice is and includes feminist and post-colonial theories to interrogate how structural injustice exacerbates and reproduces existing inequalities and relations of power. This book aims to become a touchstone text for those interested in the different ways we can understand structural injustice, how it manifests, how it relates to other forms of injustice, who is responsible for its redress and the different ways we might go about it. This book will appeal to a wide audience of students, both undergraduate and postgraduate, as well as the general academic population, experts on structural injustice, interested practitioners in politics and members of the public.
    Keywords: " Structural injustice, politics, philosophy, law, ontology, epistemology, feminism, power, historical injustice. " ; thema EDItEUR::J Society and Social Sciences::JP Politics and government::JPA Political science and theory ; thema EDItEUR::Q Philosophy and Religion::QD Philosophy ; thema EDItEUR::J Society and Social Sciences::JP Politics and government
    Language: English
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  • 7
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    Just Prospering? Plato and the Sophistic Debate about Justice (2024)
    Oxford University Press
    Details
    Publication Date: 2024-04-11
    Description: This book argues that Plato’s Republic must be understood as developing out of a 5th Century sophistic debate. In Part One the author presents a new analysis of the sophists and their extant texts addressing the important topics of justice and its value. This part shows that already in the 5th Century there was a robust debate about whether the just or unjust life was better for the self-interested individual, and that multiple sophistic authors made inventive and philosophically sophisticated arguments on both sides of this debate. The Moral Cynics argues that the intelligent individual was better off being unjust, whereas the Friends of Justice defended the idea that the just life was better for human beings. Part Two argues that Plato was very much aware of this debate and that in a number of dialogues—but most importantly in Republic—he engaged with this debate. The immoralist challenge that Glaucon and Adeimantus pose to Socrates early in Republic draws from the arguments of the 5th Century Moral Cynics and moreover identifies problems with the arguments of the 5th Century Friends of Justice. By having Socrates make an argument that overcomes the theoretical weaknesses of the earlier Friends of Justice, Plato is able to pose a new defence of justice that is more effective at responding to the Moral Cynics. The book’s analysis of Republic suggests new readings for certain important passages, such as the division of goods.
    Keywords: Justice Prospering [εὐδαιμονία] Plato The Sophists The History of Moral and Political Philosophy ; thema EDItEUR::Q Philosophy and Religion::QD Philosophy::QDH Philosophical traditions and schools of thought::QDHA Ancient Greek and Roman philosophy ; thema EDItEUR::L Law::LA Jurisprudence and general issues::LAB Methods, theory and philosophy of law ; thema EDItEUR::Q Philosophy and Religion::QD Philosophy::QDT Topics in philosophy::QDTQ Ethics and moral philosophy ; thema EDItEUR::3 Time period qualifiers::3C BCE period – Protohistory ; thema EDItEUR::1 Place qualifiers::1Q Other geographical groupings: Oceans and seas, historical, political etc::1QB Historical states, empires, territories and regions::1QBA Ancient World::1QBAG Ancient Greece
    Language: English
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  • 8
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    Landscape, Religion, and the Supernatural (2024)
    Oxford University Press
    Details
    Publication Date: 2024-03-19
    Description: Landscape, Religion, and the Supernatural presents a summa of current and classic theorizing on religion and the supernatural in relationship to the land and develops this theorizing further by confronting it with a rich set of folkloristic and historical data. Focusing on the themes of “time and memory,” “repeating patterns,” “identity formation,” “morality,” “labor,” “playfulness and adventure,” “power and subversion,” “sound,” “emotions,” “coping with contingency,” “home and unhomeliness,” and “nature and environment,” the book engages with a broad range of theoretical concepts and approaches from the interdisciplinary field of landscape theory and the study of religions. It brings this theorizing into dialogue with the rich culture of local storytelling and landscape-related traditional beliefs of the Strandir district of the Icelandic Westfjords. In this rural region, landscape-related traditions have been collected since the early nineteenth century and continue to be important to this day. Confronting this rich heritage with the insights of landscape theory both in and beyond the study of religions allows important new contributions to theorizing landscape and religion, especially when it comes to considering the perspectives on landscape held by rural populations rather than the urban upper classes that have stood in the focus of research to date. The example of the Icelandic Westfjords shows the extreme richness of religious and supernatural approaches to the landscape that can be developed in rural communities, and how they are significantly and characteristically different from the urban perspectives of literature and the arts.
    Keywords: landscape, religion, supernatural, space, place, folklore, folk belief, Iceland ; bic Book Industry Communication::J Society & social sciences::JH Sociology & anthropology ; bic Book Industry Communication::H Humanities::HR Religion & beliefs ; bic Book Industry Communication::H Humanities::HB History::HBT History: specific events & topics::HBTP Historical geography ; bic Book Industry Communication::J Society & social sciences::JF Society & culture: general::JFS Social groups::JFSL Ethnic studies::JFSL9 Indigenous peoples
    Language: English
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  • 9
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    Politics and the Urban Frontier (2024)
    Oxford University Press
    Details
    Publication Date: 2024-04-05
    Description: Despite the rise of global technocratic ideals of city-making, cities around the world are not merging into indistinguishable duplicates of one another. In fact, as the world urbanizes, urban formations remain diverse in their socio-economic and spatial characteristics, with varying potential to foster economic development and social justice. This book argues that these differences are primarily rooted in politics, and if we continue to view cities as economic and technological projects to be managed rather than terrains of political bargaining and contestation, the quest for better urban futures is doomed to fail. Dominant critical approaches to urban development tend to explain difference with reference to the variegated impacts of neoliberal regulatory institutions. This, however, neglects the multiple ways in which the wider politics of capital accumulation and distribution drive divergent forms of transformation in different urban places. In order to unpack the politics that shapes differential urban development, this book focuses on East Africa as the global urban frontier: the least urbanized but fastest urbanizing region in the world. Drawing on a decade of research spanning three case-study countries (Ethiopia, Rwanda, and Uganda), Politics and the Urban Frontier provides the first sustained, book-length comparative analysis of urban development trajectories in Eastern Africa and the political dynamics underpinning them. Through a focus on infrastructure investment, urban propertyscapes, street-level trading economies, and urban political protest, it offers a multi-scalar, historically grounded, and interdisciplinary analysis of the urban transformations unfolding in the world’s most dynamic crucible of urban change.
    Keywords: urban development, East Africa, comparative urban politics, late urbanization, infrastructure, planning, protest, Ethiopia, Rwanda, Uganda ; thema EDItEUR::K Economics, Finance, Business and Management::KC Economics::KCM Development economics and emerging economies ; thema EDItEUR::K Economics, Finance, Business and Management::KC Economics::KCV Economics of specific sectors::KCVS Regional / urban economics ; thema EDItEUR::K Economics, Finance, Business and Management::KC Economics::KCP Political economy ; thema EDItEUR::K Economics, Finance, Business and Management::KC Economics::KCG Economic growth ; thema EDItEUR::J Society and Social Sciences::JP Politics and government::JPB Comparative politics ; thema EDItEUR::R Earth Sciences, Geography, Environment, Planning::RG Geography::RGC Human geography::RGCM Economic geography
    Language: English
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  • 10
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    Social Democratic Capitalism (2024)
    Oxford University Press
    Details
    Publication Date: 2024-03-29
    Description: What configuration of institutions and policies is most conducive to human flourishing? The historical and comparative evidence suggests that the answer is social democratic capitalism — a democratic political system, a capitalist economy, good elementary and secondary schooling, a big welfare state, pro-employment public services, and moderate regulation of product and labor markets. Lane Kenworthy shows that this system improves living standards for the least well-off, enhances economic security, and boosts equality of opportunity. And it does so without sacrificing other things we want in a good society, from liberty to economic growth to health and happiness. Its chief practitioners have been the Nordic nations. The Nordics have gone farther than other rich democratic countries in coupling a big welfare state with public services that promote high employment and modest product- and labor-market regulations. Many believe this system isn’t transferable beyond Scandinavia, but Kenworthy shows that social democratic capitalism and its successes can be replicated in other affluent nations, including the United States. Today, the U.S. lags behind other countries in economic security, opportunity, and shared prosperity. If the U.S. expanded existing social programs and added some additional ones, many Americans would have better lives. Kenworthy argues that, despite formidable political obstacles, the U.S. is likely to move toward social democratic capitalism in coming decades. As a country gets richer, he explains, it becomes more willing to spend more in order to safeguard against risk and enhance fairness. He lays out a detailed policy agenda that could alleviate many of America’s problems.
    Keywords: Social democratic capitalism, American politics, comparative politics, Western European politics, democracy, capitalism, welfare state, economic reform, regulation, economic equality ; thema EDItEUR::J Society and Social Sciences::JP Politics and government::JPB Comparative politics ; thema EDItEUR::J Society and Social Sciences::JP Politics and government::JPS International relations::JPSL Geopolitics
    Language: English
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  • 11
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    Languages and Communities in the Late-Roman and Post-Imperial Western Provinces (2024)
    Oxford University Press
    Details
    Publication Date: 2024-04-02
    Description: Languages are central to the creation and expression of identities and cultures, as well as to life itself, yet the linguistic variegation of the later-Roman and post-imperial period in the Roman West is remarkably understudied. A deeper understanding of this important issue is crucial to any reconstruction of the broader story of linguistic continuity and change in Europe and the Mediterranean, as well as to the history of the communities who wrote, read, and spoke Latin and other languages. In spite of intensive study of culture and ethnic identity in late antiquity, language has often been neglected, a neglect encouraged by the disciplinary boundaries between linguists and historians, Romanists, and medievalists. There is no single volume that sets out the main developments, key features, and debates of the later-Roman and post-imperial linguistic environment. The linguistic landscapes of the late-Roman and post-imperial West are difficult to uncover and describe, while attempts to speak across disciplinary divides are challenging. The contributors have tackled this subject by offering detailed coverage of the Iberian Peninsula, North Africa, Gaul, the Germanies, Britain, and Ireland. This volume, the third in the LatinNow series, helps readers to understand better the embeddedness, or not, of Latin, at different social levels and across provinces, to consider (socio)linguistic variegation, bilingualism and multilingualism, and attitudes towards languages, and to confront the complex role of language in the communities, identities, and cultures of the later and post-imperial Roman West.
    Keywords: early middle ages, Gaul, the Germanies, Iberian Peninsula, later Roman world, Latin, local language, sociolinguistics, western provinces ; thema EDItEUR::N History and Archaeology::NH History::NHC Ancient history ; thema EDItEUR::N History and Archaeology::NH History::NHT History: specific events and topics::NHTB Social and cultural history ; thema EDItEUR::C Language and Linguistics::CF Linguistics::CFB Sociolinguistics
    Language: English
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  • 12
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    Gauge theory of elementary particle physics (2024)
    Oxford University Press
    Details
    Publication Date: 2024-04-11
    Description: Students of particle physics often find it difficult to locate resources to learn calculational techniques. Intermediate steps are not usually given in the research literature. To a certain extent, this is also the case even in some of the textbooks. In this book of worked problems we have made an effort to provide enough details so that a student starting in the field will understand the solution in each case. Our hope is that with this step-by-step guidance, students (after first attempting the solution themselves) can develop their skill, and confidence in their ability, to work out particle theory problems.
    Keywords: nuclear physics, mathematical and statistical physics, pure mathematics ; thema EDItEUR::P Mathematics and Science::PH Physics::PHS Statistical physics ; thema EDItEUR::P Mathematics and Science::PH Physics::PHF Materials / States of matter ; thema EDItEUR::P Mathematics and Science::PH Physics::PHF Materials / States of matter::PHFC Condensed matter physics (liquid state and solid state physics) ; thema EDItEUR::P Mathematics and Science::PH Physics::PHQ Quantum physics (quantum mechanics and quantum field theory) ; thema EDItEUR::P Mathematics and Science::PH Physics::PHK Electricity, electromagnetism and magnetism ; thema EDItEUR::P Mathematics and Science::PH Physics::PHU Mathematical physics
    Language: English
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  • 13
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    Babies in Groups (2024)
    Oxford University Press
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    Publication Date: 2024-04-07
    Description: Babies in Groups examines the consequences for science, for childcare policy, and for adult psychotherapy, of findings that young babies capably enjoy participating in groups. The authors’ research on preverbal infants’ capacities for group-communication in all-baby trios and quartets opens up new ways of imagining human development as fundamentally group-based. Babies in Groups highlights the changes a group-based vision of infancy brings to early child education and care by documenting the transformative consequences of introducing group-based practices into a high-quality childcare service in rural Australia. The book also examines the ways in which the belief that one-to-one infant-adult ‘attachments’ grounds human development unnecessarily narrows understanding of human potential, and slants scientific research. This examination culminates by showing how ignoring group contexts in many clinical traditions can distort descriptions of what happens in therapy, producing such unintended consequences as ‘mother-blaming’ for the future problems an infant may experience as she or he grows up.
    Keywords: attachment theory; childcare; childcare policy; cultural criticism; dyadic vision; early education; group psychology; human evolution; intersubjectivity; psychotherapy. ; thema EDItEUR::J Society and Social Sciences::JM Psychology::JMC Child, developmental and lifespan psychology ; thema EDItEUR::J Society and Social Sciences::JN Education::JNL Schools and pre-schools::JNLA Pre-school and kindergarten ; thema EDItEUR::J Society and Social Sciences::JM Psychology::JMH Social, group or collective psychology ; thema EDItEUR::J Society and Social Sciences::JB Society and culture: general::JBC Cultural and media studies::JBCC Cultural studies
    Language: English
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  • 14
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    The Politics of Revenue Bargaining in Africa (2024)
    Oxford University Press
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    Publication Date: 2024-04-03
    Description: This book examines the politics of revenue bargaining in Africa in a time when attention to domestic revenue mobilisation has expanded immensely. Measures to increase taxes and other revenues can -but do not always- lead to a process of bargaining, where revenue providers negotiate for some kind of a return. This book offers in-depth analyses of micro-instances of revenue bargaining across five African countries: Mozambique, Senegal, Tanzania, Togo, and Uganda. All case studies draw on a common theoretical framework combining the fiscal contract theory with the political settlement approach, which enables a systematic exploration into what triggers revenue bargaining; how these processes unfold; and finally, if and when they reach an agreement (whether a fiscal contract or not). From the empirically rich case narratives emerges a story of how power and initial bargaining position influence not only whether bargaining emerges in the first place, but also the processes and their outcomes. Less resourceful taxpayers are in a more difficult position to raise their voice, but in some cases even these groups manage to ally with other civil society groups to protest against tax reforms they perceive as unfair. Indirect taxes such as VAT often trigger protests, and so do sudden changes in tax practices. Revenue providers rarely call for improved services in return for paying tax, which would be expected to nurture the foundation for a fiscal social contract. Instead, revenue providers are more likely to negotiate for tax reductions, implying that governments’ effort to increase revenue is impeded. We do find many instances of state-society reciprocity when ruling elites try to be responsive to revenue providers’ demands. Hence, this book gives insight into the nature and dynamics not only of revenue bargaining but of policy-making in general as well as the implications hereof for state-society reciprocity in Africa.
    Keywords: Revenue bargaining; fiscal contract; political settlement; Africa; taxation; state-society relations; political economy; domestic revenue mobilisation; reciprocity; comparative politics ; thema EDItEUR::K Economics, Finance, Business and Management::KC Economics::KCM Development economics and emerging economies ; thema EDItEUR::K Economics, Finance, Business and Management::KC Economics::KCP Political economy ; thema EDItEUR::J Society and Social Sciences::JP Politics and government::JPB Comparative politics ; thema EDItEUR::J Society and Social Sciences::JP Politics and government::JPQ Central / national / federal government::JPQB Central / national / federal government policies ; thema EDItEUR::1 Place qualifiers::1H Africa
    Language: English
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  • 15
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    The Practical Playbook III (2024)
    Oxford University Press
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    Publication Date: 2024-04-07
    Description: Every day, two or three women die because of pregnancy or childbirth. Nearly 80% of these deaths are preventable. These outcomes disproportionately impact racialized populations, including Black and Indigenous women, who are two to three times more likely to die. The Practical Playbook III: Working Together to Improve Maternal Health is a guide for maternal health stakeholders (like researchers, community activists, providers, and advocates) offering practical tools and strategies to address inequities in maternal health services and outcomes. With contributions from more than 150 authors, each chapter offers a different strategy that stakeholders can apply to improve maternal health in their community. The 50 chapters are divided into six main sections: Section I, Introduction; Section II, Collaborations; Section III, Equity; Section IV, Data; Section V, Innovations; and Section VI, Systems and Scalability. The chapters focus on ways to save mothers by centering equity, collaborating with people with lived experience, building better data systems, piloting and expanding innovations, and leveraging resources to scale and sustain what works. Throughout the book, readers encounter stories from women and birthing people that bring the problems and solutions into better focus. The editors are committed to continuing to share information about initiatives that are moving the needle through our online platforms.
    Keywords: Maternal Mortality, Maternal Morbidity Racial Disparities, maternal health equity, maternal health stakeholders, playbook, Maternal Health Data, Collaboration, Innovation, Sustainability ; thema EDItEUR::M Medicine and Nursing::MB Medicine: general issues::MBN Public health and preventive medicine ; thema EDItEUR::M Medicine and Nursing::MK Medical specialties, branches of medicine::MKC Gynaecology and obstetrics ; thema EDItEUR::M Medicine and Nursing::MB Medicine: general issues::MBN Public health and preventive medicine::MBNS Epidemiology and Medical statistics
    Language: English
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  • 16
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    Comparing the Worth of the While in Fiji and Finland (2024)
    Oxford University Press
    Details
    Publication Date: 2024-03-19
    Description: Comparing the Worth of the While in Fiji and Finland presents comparative case studies of clock time from Fiji and Finland in order to ask what other values is time capable of expressing besides monetary worth – what “else” can time be besides money? Time is a highly particular vehicle for different considerations of what is good or important, but it is also one which is deployed at different settings with surprisingly little consideration for the specificity of this particular a value form. This book looks into the different ways in which time is deployed in value projects in Fiji and Finland, not just to point out the various possible ways of allocating value to time, but to show that European clock-time, just like its Oceanic counterparts, requires a great deal of conceptual work to make it serve as vehicle of valuation. The cases analysed in the book range from considerations of rank and conspicuous leisure in Fiji to Finnish timebanking, taxation, and university auditing.
    Keywords: Fiji, Finland, time, value, anthropology ; bic Book Industry Communication::J Society & social sciences::JH Sociology & anthropology::JHM Anthropology::JHMC Social & cultural anthropology, ethnography ; bic Book Industry Communication::P Mathematics & science::PG Astronomy, space & time::PGZ Time (chronology), time systems & standards ; bic Book Industry Communication::J Society & social sciences::JH Sociology & anthropology::JHM Anthropology
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  • 17
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    The Impact of the Inter-American Human Rights System (2024)
    Oxford University Press
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    Publication Date: 2024-04-07
    Description: The Inter-American Human Rights System (IAHRS) fosters structural transformations throughout the Americas. This collection of analyses builds upon the studies on Ius Constitutionale Commune en América Latina and Latin American transformative constitutionalism to map out both the ground-level human rights impact of the IAHRS and the institutional characteristics that have enabled such fundamental changes in social reality. The volume starts with essays framing the concept and context of IAHRS impact. Then it navigates thematic analyses on specific rights and types of violations that are front and center to the protection of human rights in Latin America. The concluding essays explore whether and how it is possible to optimize the actions of the Inter-American System, indicating possible paths to increase positive human rights impact. The editors contend that the IAHRS victim-centric approach, community of practice, and openness to institutional reinvention have enabled it to create a virtuous cycle that catalyzes human rights in the Americas, furthering democracy and the Rule of Law throughout the continent.
    Keywords: Inter-American System, impact, human rights, Transformative Constitutionalism, Latin America ; thema EDItEUR::L Law::LB International law::LBB Public international law::LBBZ Public international law: criminal law ; thema EDItEUR::1 Place qualifiers::1K The Americas::1KL Latin America – Mexico, Central America, South America ; thema EDItEUR::L Law::LB International law::LBB Public international law::LBBR Public international law: human rights
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  • 18
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    The Nature of Physical Computation (2024)
    Oxford University Press
    Details
    Publication Date: 2024-04-14
    Description: Computing systems are everywhere today. Even the brain is thought to be a sort of computing system. But what does it mean to say that a given organ or system computes? What is it about laptops, smartphones, and nervous systems that they are deemed to compute, and why does it seldom occur to us to describe stomachs, hurricanes, rocks, or chairs that way? The book provides an extended argument for the semantic view of computation, which states that semantic properties are involved in the nature of computing systems. Laptops, smartphones, and nervous systems compute because they are accompanied by representations. Stomachs, hurricanes, and rocks, for instance, which do not have semantic properties, do not compute. The first part of the book argues that the linkage between the mathematical theory of computability and the notion of physical computation is weak. Theoretical notions such as algorithms, effective procedure, program, and automaton play only a minor role in identifying physical computation. The second part of the book reviews three influential accounts of physical computation and argues that while none of these accounts is satisfactory, each of them highlights certain key features of physical computation. The final part of the book develops and argues for a semantic account of physical computation and offers a characterization of computational explanations.
    Keywords: Metaphysics; Philosophy of Mathematics & Logic; Philosophy of Computational Science; Philosophy of Mathematics & Logic ; thema EDItEUR::U Computing and Information Technology::UY Computer science ; thema EDItEUR::U Computing and Information Technology::UY Computer science
    Language: English
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  • 19
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    Social Factors in the Latinization of the Roman West (2024)
    Oxford University Press
    Details
    Publication Date: 2024-05-11
    Description: Latinization is a strangely overlooked topic. Historians have noted it has been ‘taken for granted’ and viewed as an unremarkable by-product of ‘Romanization’, despite its central importance for understanding the Roman provincial world, its life and languages. This volume aims to fill the gap in our scholarship, along with its sister volumes, Latinization, Local Languages and Literacies in the Roman West and Languages and Communities in the Late-Roman and Post-Imperial Western Provinces, all outputs of the European Research Council-funded LatinNow project. Experts have been selected to create a multidisciplinary volume with a thematic approach to the vast subject, tackling administration, army, economy, law, mobility, religion (local and imperial religions and Christianity), social status, and urbanism. They situate the phenomena of Latinization, literacy, bi-, and multilingualism within local and broader social developments and draw together materials and arguments that have not before been coordinated in a single volume. The result is a comprehensive guide to the theme, which also offers original and more experimental work. The sociolinguistic, historical, and archaeological contributions reinforce, expand, and sometimes challenge our vision of Latinization and lay the foundations for future explorations.
    Keywords: army, economy, education, law, Latinization, mobility, religion, Roman western provinces, sociolinguistics, status, urbanism ; thema EDItEUR::N History and Archaeology::NH History::NHC Ancient history ; thema EDItEUR::N History and Archaeology::NH History::NHT History: specific events and topics::NHTB Social and cultural history ; thema EDItEUR::C Language and Linguistics::CF Linguistics::CFB Sociolinguistics
    Language: English
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  • 20
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    Responsibility and Healthcare (2024)
    Oxford University Press
    Details
    Publication Date: 2024-05-13
    Description: Questions of responsibility arise at all levels of health care. Most prominent has been the issue of patient responsibility. Some health conditions that risk death or serious harm are partly the result of lifestyle behaviours such as smoking, lack of exercise, or extreme sports. Are patients with such conditions responsible for them? If so, might healthcare providers, be they state-run systems or private entities, be justified in treating such patients differently? And if they are, which forms of differential treatment are justified? Responsibility isn’t just relevant for patients. Even when individuals affect their health through voluntary behaviour, other influences are also at work before, during, and after the patient’s interaction with the health care system. What are the responsibilities of individual clinicians and other medical professionals, when thinking about individual and public health? What about institutions such as governments or national health care services, or society as a whole? This collection brings together work by world-renowned experts in population ethics, distributive justice, philosophy of action, cognitive science, and medical ethics in order to push the debate forward by elucidating our understanding of these questions, their possible answers, and how they are related.
    Keywords: responsibility, health, health care, ethics, medical ethics ; thema EDItEUR::Q Philosophy and Religion::QD Philosophy::QDT Topics in philosophy::QDTQ Ethics and moral philosophy ; thema EDItEUR::P Mathematics and Science::PS Biology, life sciences::PSA Life sciences: general issues::PSAD Bioethics ; thema EDItEUR::L Law::LN Laws of specific jurisdictions and specific areas of law::LNT Social law and Medical law::LNTJ Public health and safety law ; thema EDItEUR::J Society and Social Sciences::JP Politics and government::JPA Political science and theory
    Language: English
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  • 21
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    Access to Power (2024)
    Oxford University Press
    Details
    Publication Date: 2024-03-29
    Description: Pakistan would desperately like to produce enough electricity, but it usually doesn’t. This is the rare issue on which government and private sector can unite, and it is the cause of suffering for rich and poor alike across the entirety of the country. Despite prioritization by successive governments, targeted reforms shaped by international development actors, and featuring prominently in Chinese Belt and Road Investments, the Pakistani power sector still stifles economic and social life across the country. This book explores state capacity in Pakistan by following the material infrastructure of electricity across the provinces and down into cities and homes. It argues that the national challenges of budgetary constraints and power shortages directly result from conscious strategic decisions that are integral to Pakistan’s infrastructural state. Electricity shortages are one of the many poor governance outcomes characteristic of low- and middle-income countries. Standard development thinking points to an absence of institutions in comparison with an idealized and distant other country, with governance reform programs formulated accordingly. However, an orientation toward what Pakistan is not takes us away from how it actually functions and to whose benefit. Electricity governance in Pakistan reinforces relations of power between provinces and the federal center, contributes to the marginalization of subordinate groups in the city, and orients citizens toward a patronage-based relationship with the state through encounters with street-level bureaucrats. Looking through the lens of the electrical power sector reveals how Pakistan works, and for whom.
    Keywords: state capacity, infrastructure, electricity, Pakistan, urban, ethnography, institutions, political economy, development, China–Pakistan Economic Corridor ; thema EDItEUR::J Society and Social Sciences::JP Politics and government::JPB Comparative politics ; thema EDItEUR::G Reference, Information and Interdisciplinary subjects::GT Interdisciplinary studies::GTP Development studies ; thema EDItEUR::J Society and Social Sciences::JP Politics and government::JPQ Central / national / federal government::JPQB Central / national / federal government policies
    Language: English
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  • 22
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    Would Democratic Socialism Be Better? (2024)
    Oxford University Press
    Details
    Publication Date: 2024-04-03
    Description: The case for a modern democratic humane socialism typically has two parts. The first is that capitalism is bad, at or least not very good. In reaching this conclusion, most have either analyzed a theoretical ideal-type of capitalism or used a single country, often the United States, as a stand-in for capitalism. To fully and fairly assess democratic socialism’s desirability, we need to compare it to the best version of capitalism that humans have devised: social democratic capitalism, or what is often called the Nordic model. Each chapter in this book examines one of the things that we should want in a good society, that contemporary democratic socialists typically say they want, and that socialism might, conceivably, improve our ability to achieve: an end to poverty in rich countries, an end to poverty everywhere, more jobs, decent jobs, faster economic growth, inclusive growth, more public goods and services, affordable healthcare for all, helpful finance, truly democratic politics, economic democracy, less economic inequality, gender and racial equality, more community, and a livable planet. The book offers a close look at the evidence about how capitalist economies have performed on these outcomes, with particular attention to the performance of social democratic capitalism. The second part of the case for democratic socialism is the notion that it would be an improvement. For each of these outcomes, the book considers what, if anything, we can conclude about whether democratic socialism would do better than social democratic capitalism.
    Keywords: capitalism, socialism, Nordic model, poverty, employment, democracy, equality, inclusion, community ; thema EDItEUR::J Society and Social Sciences::JP Politics and government::JPB Comparative politics ; thema EDItEUR::J Society and Social Sciences::JP Politics and government::JPS International relations::JPSL Geopolitics
    Language: English
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  • 23
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    Mental Imagery (2024)
    Oxford University Press
    Details
    Publication Date: 2024-04-08
    Description: This book is about mental imagery and the important work it does in our mental life. It plays a crucial role in the vast majority of our perceptual episodes. It also helps us understand many of the most puzzling features of perception (like the way it is influenced in a top-down manner and the way different sense modalities interact). But mental imagery also plays a very important role in emotions, action execution, and even in our desires. In sum, there are very few mental phenomena that mental imagery doesn’t show up in—in some way or other. The hope is that if we understand what mental imagery is, how it works and how it is related to other mental phenomena, we can make real progress on a number of important questions about the mind. This book aims at an interdisciplinary audience. As it aims to combine philosophy, psychology, and neuroscience to understand mental imagery, I have not presupposed any prior knowledge in any of these disciplines. As a result, readers with no background in any of these disciplines can also follow the arguments.
    Keywords: mental imagery, imagination, perception, philosophy, psychology, neuroscience ; bic Book Industry Communication::H Humanities::HP Philosophy::HPM Philosophy of mind ; bic Book Industry Communication::H Humanities::HP Philosophy::HPN Philosophy: aesthetics ; bic Book Industry Communication::J Society & social sciences::JM Psychology::JMR Cognition & cognitive psychology::JMRP Perception ; bic Book Industry Communication::H Humanities::HP Philosophy ; bic Book Industry Communication::J Society & social sciences::JM Psychology::JMR Cognition & cognitive psychology ; bic Book Industry Communication::P Mathematics & science::PS Biology, life sciences::PSA Life sciences: general issues::PSAN Neurosciences ; thema EDItEUR::Q Philosophy and Religion::QD Philosophy::QDT Topics in philosophy::QDTM Philosophy of mind ; thema EDItEUR::Q Philosophy and Religion::QD Philosophy::QDT Topics in philosophy::QDTN Philosophy: aesthetics ; thema EDItEUR::J Society and Social Sciences::JM Psychology::JMR Cognition and cognitive psychology ; thema EDItEUR::Q Philosophy and Religion::QD Philosophy ; thema EDItEUR::P Mathematics and Science::PS Biology, life sciences::PSA Life sciences: general issues::PSAN Neurosciences
    Language: English
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  • 24
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    Is tree planting an effective strategy for climate change mitigation? (2024)
    Elsevier
    Details
    Publication Date: 2023-11-21
    Description: The world's forests store large amounts of carbon (C), and growing forests can reduce atmospheric CO2 by storing C in their biomass. This has provided the impetus for world-wide tree planting initiatives to offset fossil-fuel emissions. However, forests interact with their environment in complex and multifaceted ways that must be considered for a balanced assessment of the value of planting trees. First, one needs to consider the potential reversibility of C sequestration in trees through either harvesting or tree death from natural factors. If carbon storage is only temporary, future temperatures will actually be higher than without tree plantings, but cumulative warming will be reduced, contributing both positively and negatively to future climate-change impacts. Alternatively, forests could be used for bioenergy or wood products to replace fossil-fuel use which would obviate the need to consider the possible reversibility of any benefits. Forests also affect the Earth's energy balance through either absorbing or reflecting incoming solar radiation. As forests generally absorb more incoming radiation than bare ground or grasslands, this constitutes an important warming effect that substantially reduces the benefit of C storage, especially in snow-covered regions. Forests also affect other local ecosystem services, such as conserving biodiversity, modifying water and nutrient cycles, and preventing erosion that could be either beneficial or harmful depending on specific circumstances. Considering all these factors, tree plantings may be beneficial or detrimental for mitigating climate-change impacts, but the range of possibilities makes generalisations difficult. Their net benefit depends on many factors that differ between specific circumstances. One can, therefore, neither uncritically endorse tree planting everywhere, nor condemn it as counter-productive. Our aim is to provide key information to enable appropriate assessments to be made under specific circumstances. We conclude our discussion by providing a step-by-step guide for assessing the merit of tree plantings under specific circumstances.
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  • 25
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    Seaweed farming environments do not always function as CO2 sink under synergistic influence of macroalgae and microorganisms (2024)
    Elsevier
    Details
    Publication Date: 2023-11-29
    Description: Seaweed farming contributes substantial amounts of organic carbon to the ocean, part of which can be locked for a long term in the ocean and perform the function of ocean carbon sequestration, and the other part can be converted into inorganic carbon through microbial mineralization and aerobic respiration, affecting the pCO2, pHT and dissolved oxygen of seawater. It is generally believed that seaweed farming will cause the seawater to become a sink of CO2 due to carbon fixation by macroalgal photosynthesis. However, little attention has been paid to the fact that seaweed farming environment may sometimes become a source rather than a sink of CO2. Here, through in-situ mesocosm cultivation experiments and eight field investigations covering different kelp growth stages in an intensive farming area in China, we found that compared with the surrounding seawater without kelps, the seawater at the fast-growth stage of kelp was a sink of CO2 (pCO2 decreased by 17−73 μatm), but became a source of CO2 at the aging stage of kelp (pCO2 increased by 20−37 μatm). Concurrently, seawater pHT experienced a transition from increase (by 0.02−0.08) to decline (by 0.03−0.04). In-situ mesocosm cultivation experiments showed that the positive environmental effects (i.e., pCO2 decrease and pHT increase) induced by kelps at the early growth stage could be offset within only 3 days at the late-growth and aging stages. The release of dissolved organic carbon by kelps at the late growth stage increased significantly, supporting the enhancement in microbial abundance and respiration, which was manifested by the remarkable decrease in seawater dissolved oxygen, ultimately leading to CO2 release exceeding photosynthetic CO2 absorption. This study suggests that mature farmed kelps should be harvested in time to best utilize their carbon sink function and environmental benefits, which has guiding significance for the rational management of seaweed farming.
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    Epiphytic and endophytic microbiome of the seagrass Zostera marina: Do they contribute to pathogen reduction in seawater? (2024)
    Elsevier
    Details
    Publication Date: 2023-12-06
    Description: Highlights: • Inhibitory potential of eelgrass microbiome against aquatic and fecal pathogens • Isolation of epiphytes and endophytes associated with eelgrass leaves and roots • Particularly leaf epibiotic bacteria exhibit significant antimicrobial activity. • Rich secondary metabolite composition by untargeted metabolomics • Potential involvement of eelgrass microbiome in seagrass ecosystem services Seagrass meadows provide crucial ecosystem services for coastal environments and were shown to reduce the abundance of waterborne pathogens linked to infections in humans and marine organisms in their vicinity. Among potential drivers, seagrass phenolics released into seawater have been linked to pathogen suppression, but the potential involvement of the seagrass microbiome has not been investigated. We hypothesized that the microbiome of the eelgrass Zostera marina, especially the leaf epiphytes that are at direct interface between the seagrass host and the surrounding seawater, inhibit waterborne pathogens thereby contributing to their removal. Using a culture-dependent approach, we isolated 88 bacteria and fungi associated with the surfaces and inner tissues of the eelgrass leaves (healthy and decaying) and the roots. We assessed the antibiotic activity of microbial extracts against a large panel of common aquatic, human (fecal) and plant pathogens, and mined the metabolome of the most active extracts. The healthy leaf epibiotic bacteria, particularly Streptomyces sp. strain 131, displayed broad-spectrum antibiotic activity superior to some control drugs. Gram-negative bacteria abundant on healthy leaf surfaces, and few endosphere-associated bacteria and fungi also displayed remarkable activities. UPLC-MS/MS-based untargeted metabolomics analyses showed rich specialized metabolite repertoires with low annotation rates, indicating the presence of many undescribed antimicrobials in the extracts. This study contributes to our understanding on microbial and chemical ecology of seagrasses, implying potential involvement of the seagrass microbiome in suppression of pathogens in seawater. Such effect is beneficial for the health of ocean and human, especially in the context of climate change that is expected to exacerbate all infectious diseases. It may also assist future seagrass conservation and management strategies.
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  • 27
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    Variability of total alkalinity in coastal surface waters determined using an in-situ analyzer in conjunction with the application of a neural network-based prediction model (2024)
    Elsevier
    Details
    Publication Date: 2023-12-18
    Description: Total alkalinity (TA) is an important variable of the ocean carbonate system. In coastal oceans, carbonate system dynamics are controlled by a range of processes including photosynthesis and respiration, calcification, mixing of water masses, continental inputs, temperature changes, and seasonal upwelling. Assessments of diel, seasonal and interannual variations in TA are required to understand the carbon cycle in coastal oceans. However, our understanding of these variations remains underdeveloped due to limitations in observational techniques. Autonomous TA measurements are therefore required. In this study, an in situ TA analyzer (ISA-TA) based on a single-point titration with spectrophotometric pH detection was deployed in Tong'an Bay, Xiamen, China, over a five-month period in 2021 to determine diel and seasonal TA variations. The TA observations were combined with an artificial neural network (ANN) model to construct TA prediction models for this area. This provided a simple method to investigate TA variations in this region and was applied to predict surface water TA between March and April 2021. The in situ TA observations showed that TA values in Tong'an Bay varied within a range from 1931 to 2294 μmol kg−1 over the study period, with low TA in late winter, early summer and late summer, and high TA in early winter. The TA variations in late summer and early winter were mainly controlled by mixing of water bodies. The diel variations of TA were greatly determined by tides, with a diel amplitude of 9 to 247 μmol kg−1. The ANN model used temperature, salinity, chlorophyll, and dissolved oxygen to estimate TA, with a root-mean-square error (RMSE) of ∼14 μmol kg−1, with salinity as the input variable with the greatest weight. The approach of combining ISA-TA observations with an ANN model can be extended to study the carbonate system in other coastal regions.
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    Simultaneous preconcentration of 9 Be and cosmogenic 10 Be for determination of the 10 Be / 9 Be ratio in (coastal) seawater (2024)
    Wiley | ASLO
    Details
    Publication Date: 2024-01-11
    Description: Beryllium isotopes have emerged as a quantitative tracer of continental weathering, but accurate and precise determination of the cosmogenic 10 Be and stable 9 Be in seawater is challenging, because seawater contains high concentrations of matrix elements but extremely low concentrations of 9 Be and 10 Be. In this study, we develop a new, time‐efficient procedure for the simultaneous preconcentration of 9 Be and 10 Be from (coastal) seawater based on the iron co‐precipitation method. The concentrations of 9 Be, 10 Be, and the resulting 10 Be/ 9 Be ratio for Changjiang Estuary water derived from the new procedure agree well with those obtained from the conventional procedure requiring separate preconcentration for 9 Be and 10 Be determinations. By avoiding the separate preconcentration, our newly developed procedure contributes toward more time‐efficient handling of samples, less sample cross‐contamination, and a more reliable 10 Be/ 9 Be ratio. Prior to this, we validated the iron co‐precipitation method using artificial seawater and natural water samples from the Amazon Estuary regarding: (1) the “matrix effect” for Be analysis, (2) its extraction efficiency for pg g −1 levels Be in the presence and absence of organic matter, and (3) the data comparability with another preconcentration method. We calculated that for the determination of 9 Be and 10 Be in most open ocean seawater with typical 10 Be concentrations of 〉 500 atoms g −1 , good precisions (〈 5%) can be achieved using less than 3 liters of seawater compared to more than 20 liters routinely used previously. Even for coastal seawater with extremely low 10 Be concentration (e.g., 100 atoms g −1 ), we estimate a maximum amount of 10 liters to be adequate.
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    Does non‐native diversity mirror Earth's biodiversity? (2024)
    Wiley
    Details
    Publication Date: 2024-01-14
    Description: Aim: Human activities have introduced numerous non-native species (NNS) worldwide. Understanding and predicting large-scale NNS establishment patterns remain fundamental scientific challenges. Here, we evaluate if NNS composition represents a proportional subset of the total species pool available to invade (i.e. total global biodiversity), or, conversely, certain taxa are disproportionately pre-disposed to establish in non-native areas. Location: Global. Time period: Present day. Major taxa studied: Global diversity. Methods: We compiled one of the most comprehensive global databases of NNS (36,822 established species) to determine if NNS diversity is a representative proportional subset of global biodiversity. Results: Our study revealed that, while NNS diversity mirrors global biodiversity to a certain extent, due to significant deviance from the null model it is not always a representative proportional subset of global biodiversity. The strength of global biodiversity as a predictor depended on the taxonomic scale, with successive lower taxonomic levels less predictive than the one above it. Consequently, on average, 58%, 42% and 28% of variability in NNS numbers were explained by global biodiversity for phylum, class and family respectively. Moreover, global biodiversity was a similarly strong explanatory variable for NNS diversity among regions, but not habitats (i.e. terrestrial, freshwater and marine), where it better predicted NNS diversity for terrestrial than for freshwater and marine habitats. Freshwater and marine habitats were also greatly understudied relative to invasions in the terrestrial habitats. Over-represented NNS relative to global biodiversity tended to be those intentionally introduced and/or ‘hitchhikers’ associated with deliberate introductions. Finally, randomness is likely an important factor in the establishment success of NNS. Main conclusions: Besides global biodiversity, other important explanatory variables for large-scale patterns of NNS diversity likely include propagule and colonization pressures, environmental similarity between native and non-native regions, biased selection of intentionally introduced species and disparate research efforts of habitats and taxa.
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    A 1500‐year record of North Atlantic storm flooding from lacustrine sediments, Shetland Islands (UK) (2024)
    Wiley
    Details
    Publication Date: 2024-01-14
    Description: Severe storm flooding poses a major hazard to the coasts of north‐western Europe. However, the long‐term recurrence patterns of extreme coastal flooding and their governing factors are poorly understood. Therefore, high‐resolution sedimentary records of past North Atlantic storm flooding are required. This multi‐proxy study reconstructs storm‐induced overwash processes from coastal lake sediments on the Shetland Islands using grain‐size and geochemical data, and the re‐analysis of historical data. The chronostratigraphy is based on Bayesian age–depth modelling using accelerator mass spectrometry 14 C and 137 Cs data. A high XRF‐based Si/Ti ratio and the unimodal grain‐size distribution link the sand layers to the beach and thus storm‐induced overwash events. Periods with more frequent storm flooding occurred 980–1050, 1150–1300, 1450–1550, 1820–1900 and 1950–2000 ce, which is largely consistent with a positive North Atlantic Oscillation mode. The Little Ice Age (1400–1850 ce ) shows a gap of major sand layers suggesting a southward shift of storm tracks and a seasonal variance with more storm floods in spring and autumn. Warmer phases shifted winter storm tracks towards the north‐east Atlantic, indicating a possible trend for future storm‐track changes and increased storm flooding in the northern North Sea region.
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  • 31
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    Identification and differentiation of vertical movement through morphological changes and stratigraphic imprint: Two distinct uplifting mechanisms in the upper Calabrian accretionary wedge, western Ionian Sea (2024)
    Wiley
    Details
    Publication Date: 2024-01-14
    Description: The seafloor morphology reflects both past and on‐going sedimentary, oceanographic and tectonic processes. Vertical movement is one of the drivers responsible for reshaping the seafloor through forming steep flanks that decrease slope stability, favour landslides, change current paths, form minibasins and control the sediment deposition, distribution and geometry. Here, we make use of these interactions to derive vertical movements and constrain the active tectonic processes at the western termination of the upper Calabrian accretionary wedge from the integrated analysis of bathymetric, backscatter, surface attributes and high‐resolution reflection seismic data. Within this area, we identify two types of deformational features and mechanisms that affect the depositional, erosional and tectonic processes at different scales. These include the deviation of channels, landslide scars, mass transport deposits (MTDs), separated drifts, sediment waves, lineaments and offset seafloor structures. The first type (long‐wavelength uplift) is an uplifted 22‐km‐wide region, in which seismic onlap relationships and the dip of deep reflectors suggest long‐lasting but slow tectonic uplift affecting sedimentation, and the second type (short‐wavelength uplift) includes three narrow elongated structures and one circular dome encircling the first region of uplift. We interpret that the first type of uplift feature was caused by tectonic deformation, while the second type is interpreted as formed by the fast uplift, tilting and faulting of modern sediments caused by diapirism due to rapid sedimentation in response to the first tectonically driven uplift. The study provides insight into the complex interaction of tectonic and sedimentary processes in the upper Calabrian accretionary wedge.
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    Modulation of Equatorial Currents and Tropical Instability Waves During the 2021 Atlantic Niño (2024)
    AGU (American Geophysical Union) | Wiley
    Details
    Publication Date: 2024-01-17
    Description: In the boreal summer of 2021, the equatorial Atlantic experienced the strongest warm event, that is, Atlantic Niño, since the beginning of satellite observations in the 1970s. Such events have far‐reaching impacts on large‐scale wind patterns and rainfall over the surrounding continents. Yet, developing a paradigm of how Atlantic Niño interacts with the upper‐ocean currents and intraseasonal waves remains elusive. Here we show that the equatorial Kelvin wave associated with the onset of the 2021 Atlantic Niño modulated both the background flow and the eddy flux of the equatorial upper‐ocean circulation, causing an extremely weak and delayed tropical instability wave (TIW) season. TIW‐induced variations of sea surface temperature (SST), sea surface salinity, sea surface height, and eddy temperature advection were exceptionally weak during May to July, the climatological peak of TIW activity, but rebounded in August when higher than normal variability was observed. Moored velocity data at 23°W show that during the peak of the 2021 Atlantic Niño from June to August, the Equatorial Undercurrent was deeper and stronger than usual. An anomalously weak eddy momentum flux strongly suppressed barotropic energy conversion north of the equator from May to July, likely contributing to low TIW activity. Reduced baroclinic energy conversion also might have played a role, as the meridional gradient of SST was sharply reduced during the Atlantic Niño. Despite extremely weak TIW velocities, modest intraseasonal variability of chlorophyll‐a (Chl‐ a ) was observed during the Atlantic Niño, due to pronounced meridional Chl‐ a gradients that partly compensated for the weak TIWs. Plain Language Summary Every few years the eastern equatorial Atlantic Ocean is significantly warmer than usual during boreal summer. Such warm events are referred to as Atlantic Niño events, and share similarities with El Niño events in the Pacific. In 2021, the strongest Atlantic Niño in at least four decades was observed in the equatorial Atlantic. This study is the first that investigates the complex interaction between Atlantic Niño, tropical Atlantic upper‐ocean currents, and equatorial waves based on various observational data sets. We show that the developing 2021 Atlantic Niño weakened both the background flow and the variability of near‐surface currents in May, which in turn largely reduced the strength of intraseasonal (20–50 days) waves that are usually generated by instability of the upper‐ocean zonal currents. As a consequence, the cooling effect that these waves usually have north of the equator and the warming effect along the equator vanished from May to July 2021. Interestingly, variability of chlorophyll concentration was enhanced, suggesting that enhanced meridional chlorophyll gradients compensated for reduced wave activity. Key Points The developing 2021 Atlantic Niño led to weaker equatorial surface currents and reduced vertical shear of upper‐ocean horizontal velocity Strong reduction of the surface flow, eddy flux, and meridional temperature gradient in May caused extremely weak and delayed tropical instability wave (TIW) season Reduced meridional TIW advection contributed to sharpen the north equatorial Chl‐ a front resulting in modest intraseasonal Chl‐ a variability
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    Assessing Phytoplankton Primary Productivity Variability in the Changjiang Estuary, East China Sea From Coupled Fast Repetition Rate (FRR) Fluorometry and Chlorophyll‐ a Measurements (2024)
    AGU (American Geophysical Union) | Wiley
    Details
    Publication Date: 2024-01-17
    Description: Phytoplankton primary productivity (PP) varies significantly over environmental gradients, particularly in physically‐dynamic systems such as estuaries and coastal seas. During summer, runoff peaks in the Changjiang River driving large environmental gradients in both the Changjiang estuary and adjacent East China Sea (ECS), likely driving significant variability in PP. As satellite models of PP often underperform in coastal waters, we aimed to develop a novel approach for assessing net PP variability in such a dynamic environment. Parallel in situ measurements of Fast Repetition Rate (FRR) fluorometry and carbon (C) uptake rates were conducted for the first time in this region during two summer cruises in 2019 and 2021. A series of 13 C‐incubations ( n = 31) were performed, with measured PP ranging from ∼6 to 1,700 mgC m −3 d −1 . Net PP values were significantly correlated with salinity ( r = 0.45), phytoplankton chlorophyll a (Chl‐ a , r = 0.88), Photosystem II (PSII) functional absorption cross‐section ( σ PSII , r = −0.76) and maximum PSII quantum yield ( F v / F m , r = 0.59). Stepwise regression analysis showed that Chl‐ a and σ PSII were the strongest predictors of net PP. A generalized additive model (GAM) was also used to estimate net PP considering nonlinear effects of Chl‐ a and σ PSII . We demonstrate that GAM outperforms linear modeling approaches in estimating net PP in this study, as evidenced by a lower root mean square error (∼140 vs. 250 mgC m −3 d −1 ). Our novel approach provides a valuable tool to examine carbon cycling dynamics in this important region. Plain Language Summary The East China Sea has a complex current system that creates a highly dynamic physical environment for phytoplankton, particularly during the summer months. Net primary productivity (PP) is highly variable in this region, yet characterizing these spatial patterns in PP is difficult due to the lack of a high‐resolution data collecting method. Therefore, a strong need exists for a quick and easily implemented method for monitoring PP in this dynamic system. Based on parallel measurements of phytoplankton biomass and photophysiology, we present a novel approach that allows us to rapidly and easily assess regional PP at a high resolution. The high data volume potentially afforded by our net PP estimation method could not only contribute to a better understanding of PP variations in such a dynamic environment, but also help fill the large gaps in field data needed for validating satellite‐based PP models. Key Points Parallel in situ measurements of net primary productivity (PP) and Fast Repetition Rate fluorometry were conducted in the Changjiang estuary Productivity was highest at stations with high Chl and low σ PSII , typically located along the Chiangjiang river plume front A generalized additive model was developed to estimate net PP, providing an approach for assessing regional C‐cycling dynamics
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    The transition between coastal and offshore areas in the North Sea unraveled by suspended particle composition (2024)
    Elsevier
    Details
    Publication Date: 2024-01-17
    Description: Highlights • SPM concentration and organic fractions are analyzed in coastal-offshore gradients • Diagnostic model of SPM allows separating fresh, labile from less reactive PON • Analysis of PON fractions reveals a characteristic area, the transition zone • There, particle settling is enhanced, fostering their transport back to the coast, which controls the fate of organic matter • The transition zone is generally confined to water depths below 20 m Abstract Identifying the mechanisms that contribute to the variability of suspended particulate matter concentrations in coastal areas is important but difficult, especially due to the complexity of physical and biogeochemical interactions involved. Our study addresses this complexity and investigates changes in the horizontal spread and composition of particles, focusing on cross-coastal gradients in the southern North Sea and the English Channel. A semi-empirical model is applied on in situ data of SPM and its organic fraction to resolve the relationship between organic and inorganic suspended particles. The derived equations are applied onto remote sensing products of SPM concentration, which provide monthly synoptic maps of particulate organic matter concentrations (here, particulate organic nitrogen) at the surface together with their labile and less reactive fractions. Comparing these fractions of particulate organic matter reveals their characteristic features along the coastal-offshore gradient, with an area of increased settling rate for particles generally observed between 5 and 30 km from the coast. We identify this area as the transition zone between coastal and offshore waters with respect to particle dynamics. Presumably, in that area, the turbulence range and particle composition favor particle settling, while hydrodynamic processes tend to transport particles of the seabed back towards the coast. Bathymetry plays an important role in controlling the range of turbulent dissipation energy values in the water column, and we observe that the transition zone in the southern North Sea is generally confined to water depths below 20 m. Seasonal variations in suspended particle dynamics are linked to biological processes enhancing particle flocculation, which do not affect the location of the transition zone. We identify the criteria that allow a transition zone and discuss the cases where it is not observed in the domain. The impact of these particle dynamics on coastal carbon storage and export is discussed.
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    Misconceptions of the marine biological carbon pump in a changing climate: Thinking outside the “export” box (2024)
    Wiley
    Details
    Publication Date: 2024-01-19
    Description: The marine biological carbon pump (BCP) stores carbon in the ocean interior, isolating it from exchange with the atmosphere and thereby coregulating atmospheric carbon dioxide (CO 2 ). As the BCP commonly is equated with the flux of organic material to the ocean interior, termed “export flux,” a change in export flux is perceived to directly impact atmospheric CO 2 , and thus climate. Here, we recap how this perception contrasts with current understanding of the BCP, emphasizing the lack of a direct relationship between global export flux and atmospheric CO 2 . We argue for the use of the storage of carbon of biological origin in the ocean interior as a diagnostic that directly relates to atmospheric CO 2 , as a way forward to quantify the changes in the BCP in a changing climate. The diagnostic is conveniently applicable to both climate model data and increasingly available observational data. It can explain a seemingly paradoxical response under anthropogenic climate change: Despite a decrease in export flux, the BCP intensifies due to a longer reemergence time of biogenically stored carbon back to the ocean surface and thereby provides a negative feedback to increasing atmospheric CO 2 . This feedback is notably small compared with anthropogenic CO 2 emissions and other carbon‐climate feedbacks. In this Opinion paper, we advocate for a comprehensive view of the BCP's impact on atmospheric CO 2 , providing a prerequisite for assessing the effectiveness of marine CO 2 removal approaches that target marine biology.
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    Spatial structure and biodiversity of macrofauna around marine munition dumpsites – A case study from the Baltic Sea (2024)
    Elsevier
    Details
    Publication Date: 2024-01-30
    Description: Coastal German waters contain about 1.6 million tons of dumped munition, mostly left after World Wars. This study investigated the benthic macrofauna around the 'Kolberger Heide' munition dumpsite (Baltic Sea). A total of 93 macrofauna grab samples were obtained in the proximity of the munition dumpsite and in reference areas. Environmental variables analysed included the latitude/longitude, depth, terrain ruggedness, sediment grainsize distribution, TNT concentration in the bottom water and distance to the centre of munition dumpsite. The overall abundance, biomass and diversity varied among these groups, though demonstrated no clear differences regarding the proximity to munition and modelled near-bottom dissolved TNT. Among individual taxa, however, a total of 16 species demonstrated significant correlation with TNT concentration. Moreover, TNT may serve as a predictor for the distribution of three species: molluscs Retusa truncatula, Varicorbula gibba and polychaete Spio goniocephala. Possible reasons for the species distribution including their biological traits are discussed.
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    Widespread slab melting in modern subduction zones (2024)
    Elsevier
    Details
    Publication Date: 2024-01-30
    Description: Highlights • Global primitive arc lavas (Mg# ≥60) display notable δ49/47Ti heterogeneity. • Residual rutile imposes high δ49/47Ti of 0.24 ± 0.06 ‰ on hydrous, silicic slab melts. • Primitive Aleutian rhyodacites have the same δ49/47Ti as predicted for slab melts. • A variably diluted signature of slab melts is found in all eight subduction zones. • A slab melt component is required to generate silicic primitive arc lavas. Abstract It is still a matter of intense debate to what extent partial melting of the subducting slab contributes to arc magmatism in modern subduction zones. In particular, it is difficult to differentiate between silicate melts formed by partial melting of the slab, and aqueous fluids released during subsolidus dehydration as the main medium for slab-to-mantle wedge mass transfer. Here we use δ49/47Ti (the deviation in 49Ti/47Ti of a sample to the OL-Ti reference material) as a robust geochemical tracer of slab melting. Hydrous partial melting of subducted oceanic crust and the superjacent sedimentary layer produces silicic melts in equilibrium with residual rutile. Modelling shows that such silicic slab melts have notably higher δ49/47Ti (+0.24 ± 0.06 ‰) than their protolith due to the strong preference of rutile for the lighter isotopes of Ti. In contrast, even highly saline fluids cannot carry Ti from the slab and hence hydrous peridotite partial melts have δ49/47Ti similar to mid-ocean ridge basalts (MORB; ca. 0 ‰). Primitive (Mg# ≥60) arc lavas from eight subduction zones that are unaffected by fractional crystallisation of Fe-Ti oxides show a more than tenfold larger variation in δ49/47Ti than found in MORB. In particular, primitive arc lavas display a striking correlation between SiO2 content and δ49/47Ti that ranges from island arc basalts overlapping with MORB, to primitive rhyodacites with δ49/47Ti up to 0.26 ‰ erupted in the western Aleutian arc. The elevated δ49/47Ti of these primitive arc lavas provides conclusive evidence for partial melts of the slab as a key medium for mass transfer in subduction zones. The Aleutian rhyodacites represent a rare example of slab melts that have traversed the mantle wedge with minimal modification. More commonly, slab melts interact with the mantle wedge to form an array of primary arc magmas that are a blend of slab- and peridotite-derived melt. We identify primitive arc lavas with a clearly resolvable slab melt signature in all eight subduction zone localities, confirming that slab melting is prevalent in modern subduction zones.
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    Lithostratigraphy of the ignimbrite-dominated Miocene Bükk Foreland Volcanic Area (Central Europe) (2024)
    Elsevier
    Details
    Publication Date: 2024-01-30
    Description: Highlights • An event-scale, complete lithostratigraphic column for the Miocene BFVA was created through extensive field volcanology. • Field volcanology was supplemented by volcanic glass geochemistry to separate the eruptions. • An example is presented how to undertake lithostratigraphy-based classification in poorly preserved, deeply eroded volcanic terrains. • In the ancient BFVA landscape, sea cover during eruptions and terrestrial deposition is evident. Abstract This study documents the volcanic evolution of the Miocene silicic Bükk Foreland Volcanic Area (BFVA), Northern Hungary (Central Europe) at an event-scale. The BFVA is a deeply eroded and dissected volcanic field dominated by multiple, several 10-m thick, valley-filling silicic ignimbrite units, which are chemically and texturally very similar to each other. Hence, establishing lateral correlation is a real challenge due to the sporadic and small-scale outcrops and lack of stratotypes. Detailed field observations allowed us to identify eleven lithological members including fourteen eruption events and establish a nearly complete lithostratigraphic correlation between fifteen outcrops across the BFVA. Primary pyroclastic material of each member was sampled, and volcanic glass was geochemically analyzed for major and trace element composition. The geochemical results confirm the field-based classification of the members and enable the correlation of distinct outcrops. The major and trace element composition of the glassy pyroclasts of each member of the BFVA served as basis to create a field-wide chemical reference database for regional correlational studies. Here, a new lithostratigraphic classification scheme (consisting of one lithostratigraphic formation and eleven members) is presented, which reflects the challenges unraveling the stratigraphy of ancient volcanic terrains. The field-based event-scale lithostratigraphy of the BFVA suggests a wet, partly sea-covered depositional environment in the close vicinity of the eruption centers providing favorable conditions to ‘fuel’ silicic explosive phreatomagmatism. On the contrary, paleosol horizons formed after almost each major eruption event or sequence suggests an overall near-coast terrestrial environment for the BFVA, where the emplacement of the pyroclastic material occurred.
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    Fluid Flow, Mineralization and Deformation in an Oceanic Detachment Fault: Microtextural, Geochemical and Isotopic Evidence From Pyrite at 13°30′N on the Mid‐Atlantic Ridge (2024)
    AGU (American Geophysical Union) | Wiley
    Details
    Publication Date: 2024-01-30
    Description: Hydrothermal fluids in ultramafic‐hosted hydrothermal systems associated with oceanic detachment faults can be more oxidizing compared to mafic‐hosted vent sites. These fluids form a mineral assemblage of pyrite, magnetite and hematite. At 13°30′N on the Mid‐Atlantic Ridge, chlorite‐quartz breccias recovered from an exposed fault scarp contain pyrite, with abundant magnetite and hematite, indicating that the redox of the fluids was variable. In primary micron‐scale zonations in pyrite, Ni, Co, and Se have a decoupled relationship, recording fluctuations in the chemical composition and temperature of hydrothermal fluid as the grains grew. Secondary zonations that erase and overprint primary zonations are limited to the grain margin and permeable regions within the grain core. Secondary zonations formed via two processes: (a) grain dissolution followed by overgrowth, and (b) remobilization of metals during oxidizing fluid flow events. In both instances, Ni and Co have been mobilized and concentrated, and are not lost to the hydrothermal fluid. Superimposed on these features is evidence of grain scale deformation related to periods of fault movement along the detachment surface. Sulfur isotope ratios (δ 34 S) in pyrite systematically decrease from the grain margin to the grain core, indicating that increased amounts of sulfur were derived from thermochemical sulfate reduction of seawater. Thus, pyrite records the evolution of fluid flow and deformation events during exhumation along the detachment surface from ∼1 to 2 km below the seafloor at the base of the lava pile, with temporal fluctuations in fluid redox identified as an important process in controlling Ni and Co enrichment in pyrite. Plain Language Summary Detachment faults are long lived faults that can expose ultramafic rocks at the seafloor. We aim to investigate the links between hydrothermal activity and detachment fault formation. To do this we use pyrite as a tape recorder for past fluid flow events. Across individual mineral grains, distinct zonations in metal content and sulfur isotope ratios show that the incursion of seawater occurred periodically during pyrite growth, increasing during fault movement events that lead to changes in the temperature and pH of the fluids in the fault zone. These changes concentrated metals toward the center of individual mineral grains. Zonations were then overprinted by later deformation‐related events, providing evidence that the samples formed at deeper crustal levels below the seafloor and were progressively exhumed at the seafloor over time. Key Points Microtextural, geochemical, and isotopic variations in subseafloor pyrite record the history of sample exhumation along a detachment fault Nickel and Co are remobilized and concentrated in pyrite across individual mineral grains in response to fluctuating fluid redox conditions Evidence of pyrite deformation and alteration mineralogy of samples indicates sample exhumation from a depth of 1–2 km
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    Governance pathway for coastal eutrophication based on regime shifts in diatom–dinoflagellate composition of the Bohai and Baltic Seas (2024)
    Elsevier
    Details
    Publication Date: 2024-02-01
    Description: Regime shifts in the diatom–dinoflagellate composition have occurred in the Baltic Sea (BS) and Bohai Sea (BHS) under eutrophication and have affected the entire coastal ecosystem, damaging the regulatory, provisioning, cultural, and supporting service functions of marine ecosystems. Therefore, finding a solution to restore the balance of phytoplankton community composition and mitigate eutrophication is of utmost importance. In this study, the Driver (per capita gross domestic product)-Pressure (terrestrial inputs)-State (seawater environmental parameters)-Impact (proportions of diatoms and dinoflagellates)-Response (eutrophication governance projects) framework served as a guide for our analysis of the causal relationship among various environmental components in the coastal system. The relevant data in BS and BHS spanning from the 1950s to the 2010s were collected and used to construct a diatom–dinoflagellate composition single index, which allowed us to identify the shifts in regimes (mutation points and phases) of the diatom–dinoflagellate composition and environmental factors using sequential t-test analysis. We also identified key environmental factors that moderated the diatom–dinoflagellate composition using redundancy analysis and analyzed the partial effects of the main environmental factors on the diatom–dinoflagellate composition using a generalized additive model. Finally, the regulation of the eutrophication governance investment on diatom–dinoflagellate composition was investigated. We found that (1) BS is a “time machine,” with coastal eutrophication governance and regime shift of diatom–dinoflagellate composition and environmental factors two decades earlier than that in BHS; (2) in BS, the key moderation factor of diatom proportion is SiO3-Si and those of dinoflagellates are sea surface salinity and N:P ratio; in BHS, the key moderation factors of diatom proportion are PO4-P and Si:N ratio and those of dinoflagellate are dissolved inorganic nitrogen and N:P and Si:P ratios; (3) it is projected that BHS will enter its recovery phase from eutrophication after mid-2020s. In summary, the N/P/Si stoichiometric relationships should be given greater consideration, with the exception of the “dose-response” relationship in both sea areas. Our results indicate an urgent need for an improved mechanistic understanding of how phytoplankton biodiversity changes in response to changes in nutrient load and how we should ultimately deal with the challenges that arise.
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    Reproductive biology of the electric lanternfish Electrona risso (Myctophidae) and the bigscale fishes Melamphaes polylepis and Scopelogadus mizolepis (Melamphaidae) (2024)
    Wiley
    Details
    Publication Date: 2024-02-01
    Description: This study was the first to investigate the key reproductive traits of the electric lantern fish Electrona risso (Myctophidae, n = 918) and the bigscale fishes (Melamphaidae) Melamphaes polylepis (n = 260) and Scopelogadus mizolepis (n = 649). Specimens of these mesopelagic species were collected in March and April 2015 in the eastern Central Atlantic (0–24° N, 20–26° W). Sex ratio was not significantly different from 1:1 in E. risso and M. polylepis but significantly skewed toward female dominance in S. mizolepis. Reproductive phases were determined macroscopically and by histological analyses on selected individuals. Female length at 50% maturity (L50) was 55.1 mm standard length (LS) in E. risso, with an observed female maximum length (Lmax) of 81.2 mm LS. M. polylepis females had an L50 of 40.2 mm LS and an Lmax of 86.7 mm LS. S. mizolepis had an L50 of 46 mm LS and an Lmax of 97.9 mm LS. The three species show histological features of iteroparity, but the E. risso population appears to occur in two year-classes and experience only one spawning season per lifetime in the study region. All three species are batch-spawners. A batch fecundity of 2668 eggs was estimated from one E. risso individual, with a relative batch fecundity of 369 eggs g−1 gonad-free body mass. M. polylepis had a batch fecundity of 1027 eggs and a relative batch fecundity of 149 eggs g−1 (n = 3). S. polylepis had a batch fecundity of 1545 eggs and a relative batch fecundity of 215 eggs g−1 (n = 21). The median gonado-somatic index during the actively spawning phase of E. risso was 4.5, significantly lower than that of M. polylepis (7.5) and S. mizolepis (7.1). No regressing or regenerating phases were observed in this study. Batch-spawning in all three species is suggested to be advantageous to cope with intra-annual variability in food supply and other risks for offspring survival. With what appears to be in effect a (facultative) semelparous strategy in combination with a short life span in E. risso, interannual differences would have a great effect on population dynamics of this species. Knowledge is still lacking on temporal aspects of reproduction such as the duration of the spawning season and the frequency of spawning, as well as age and growth.
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    The appendicularian Oikopleura dioica can enhance carbon export in a high CO2 ocean (2024)
    Wiley
    Details
    Publication Date: 2024-02-02
    Description: Gelatinous zooplankton are increasingly recognized to play a key role in the ocean's biological carbon pump. Appendicularians, a class of pelagic tunicates, are among the most abundant gelatinous plankton in the ocean, but it is an open question how their contribution to carbon export might change in the future. Here, we conducted an experiment with large volume in situ mesocosms (~55–60 m3 and 21 m depth) to investigate how ocean acidification (OA) extreme events affect food web structure and carbon export in a natural plankton community, particularly focusing on the keystone species Oikopleura dioica, a globally abundant appendicularian. We found a profound influence of O. dioica on vertical carbon fluxes, particularly during a short but intense bloom period in the high CO2 treatment, during which carbon export was 42%–64% higher than under ambient conditions. This elevated flux was mostly driven by an almost twofold increase in O. dioica biomass under high CO2. This rapid population increase was linked to enhanced fecundity (+20%) that likely resulted from physiological benefits of low pH conditions. The resulting competitive advantage of O. dioica resulted in enhanced grazing on phytoplankton and transfer of this consumed biomass into sinking particles. Using a simple carbon flux model for O. dioica, we estimate that high CO2 doubled the carbon flux of discarded mucous houses and fecal pellets, accounting for up to 39% of total carbon export from the ecosystem during the bloom. Considering the wide geographic distribution of O. dioica, our findings suggest that appendicularians may become an increasingly important vector of carbon export with ongoing OA.
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    Ascending phase of solar cycle 25 tilts the current El Niño–Southern oscillation transition (2024)
    Elsevier
    Details
    Publication Date: 2024-02-05
    Description: A La Niña condition in the equatorial Pacific began in the early summer of 2020 and has lasted more than two and a half years (referred to as the 2020 La Niña hereafter). Predicting its temporal evolution had attracted a lot of attention. Considering the possible phase-locked impact of the 11-year solar cycle on the tropical Pacific variability, in this study the authors present the possible modulations by the solar cycle 25 (SC25) started from December 2019, on the future temporal evolution of the 2020 La Niña. Based on statistical features of historical solar cycles, the authors propose three possible scenarios of the timing of the SC25 maximum year and discuss its possible impacts on the temporal evolution of the 2020 La Niña in the next two years. The ongoing ascending phase of SC25 dampens the development of a super El Niño condition to some extent in 2023.
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    Spatial distribution and habitat relationship of sea urchin assemblages (Echinodermata: Echinoidea) in Hong Kong waters (2024)
    Elsevier
    Details
    Publication Date: 2024-02-12
    Description: Highlights: • Change in sea urchin species composition from RBC and NRBC habitats. • Sand coverage is an important factor that influences the sea urchin species composition. • The relationship between sea urchins and their habitat is species-specific. Sea urchins are important components of marine ecosystems and can act as bioindicators, reflecting the health of reefs. The spatial patterns of sea urchins are largely shaped by the type of habitat. In Hong Kong, coral communities are divided into two distinct types: reef -building coral habitats and non -reef -building coral habitats. In summer 2020, a qualitative survey was conducted using SCUBA at 56 sites across eastern and western waters, recording a total of 11 species from 6 families of sea urchins. Out of these 56 sites, 14 were selected for a quantitative survey to investigate the relationship between sea urchin assemblages and the two types of coral habitat. We found that the species composition of sea urchins differed significantly between the two habitats, and the presence of sand was a critical factor influencing the species composition of sea urchins. Sand coverage had a positive effect on Salmasic sphaeroides abundance but a negative effect on the abundance of Diadema setosum and Heliocidaris crassispina. The distribution of sea urchins across different degrees of sand coverage may be associated with food availability or species -specific adaptive behaviour, likely due to niche preferences.
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  • 45
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    Effects of global warming and Tibetan Plateau uplift on East Asian climate during the mid-Cretaceous (2024)
    Elsevier
    Details
    Publication Date: 2024-02-12
    Description: Highlights • East Asian climate evolution was dependent on the latitude of the proto-Tibetan Plateau in the deep past; • Global warming induced wetting at mid-latitude East Asian in the mid-Cretaceous; • The proto-Tibetan Plateau uplift led to drying in the subtropical East Asian in the mid-Cretaceous. Abstract Sedimentary records indicate that subtropical and mid-latitude East Asia exhibited considerable drying and wetting, respectively, during the mid-Cretaceous, which is considered to be relevant to much higher atmospheric carbon dioxide (pCO2) concentrations and/or proto-Tibetan Plateau (proto-TP) uplift. In order to explore and compare their roles on the East Asian climate evolution, we conducted simulations of the mid-Cretaceous climate system with different atmospheric pCO2 levels and varying topographies. The results show that both factors had significant influences on the East Asian climate. As the increase in atmospheric pCO2 levels from ∼560–1120 ppmv to ∼1120–2240 ppmv, the precipitation increases considerably over mid-latitude East Asia, but only small changes in the subtropical portion of East Asia occur. Simultaneously, the effects of the proto-TP uplift are opposite to those of global warming trend during that period. Generally, it leads to a precipitation decrease over subtropical East Asia, but rather minor changes over mid-latitude East Asia. These changes are qualitatively consistent with the deduction based on the geological records, but the magnitudes of the modeled precipitation changes are relatively smaller. Therefore, we can conclude that the subtropical East Asian drying during the mid-Cretaceous can be partly explained by the proto-TP uplift, while the mid-latitude East Asian wetting was partly due to global warming. However, additional factor(s) also played a significant role in the East Asian climate evolution during the mid-Cretaceous.
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    An earth system governance research agenda for carbon removal (2024)
    Elsevier
    Details
    Publication Date: 2024-02-12
    Description: Carbon dioxide removal (CDR) – the creation, enhancement, and upscaling of carbon sinks – has become a pillar of national and corporate commitments towards Net Zero emissions, as well as pathways towards realizing the Paris Agreement's ambitious temperature targets. In this perspective, we explore CDR as an emerging issue of Earth System Governance (ESG). We draw on the results of a workshop at the 2022 Earth System Governance conference that mapped a range of actors, activities, and issues relevant to carbon removal, and refined them into research questions spanning four intersecting areas: modeling and systems assessment, societal appraisal, policy, and innovation and industry. We filter these questions through the five lenses of the ESG framework and highlight several key ‘cross-cutting’ issues that could form the basis of an integrated ESG research agenda on CDR.
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    Distribution of copper-binding ligands in Fram Strait and influences from the Greenland Shelf (GEOTRACES GN05) (2024)
    Elsevier
    Details
    Publication Date: 2024-02-12
    Description: Highlights • Cu complexation was measured for the first time in the Fram Strait region. • Cu-binding ligand concentrations and binding strength varied longitudinally in the Fram Strait. • More than 99 % of dCu was organically complexed by strong ligands. • On the Greenland shelf the Transpolar Drift and the coastal processes were the main sources of Cu ligands. Abstract The Fram Strait represents the major gateway of Arctic Ocean waters towards the Nordic Seas and North Atlantic Ocean and is a key region to study the impact of climate change on biogeochemical cycles. In the region, information about trace metal speciation, such as copper, is scarce. This manuscript presents the concentrations and conditional stability constants of copper-binding ligands (LCu and log KcondCu2+L) in the water column of Fram Strait and the Greenland shelf (GEOTRACES cruise GN05). Cu-binding ligands were analysed by Competitive Ligand Exchange-Adsorptive Cathodic Stripping Voltammetry (CLE-ACSV) using salicylaldoxime (SA) as competitive ligand. Based on water masses and the hydrodynamic influences, three provinces were considered (coast, shelf, and Fram Strait) and differences were observed between regions and water masses. The strongest variability was observed in surface waters, with increasing LCu concentrations (mean values: Fram Strait = 2.6 ± 1.0 nM; shelf = 5.2 ± 1.3 nM; coast = 6.4 ± 0.8 nM) and decreasing log KcondCu2+L values (mean values: Fram Strait = 15.7 ± 0.3; shelf = 15.2 ± 0.3; coast = 14.8 ± 0.3) towards the west. The surface LCu concentrations obtained above the Greenland shelf indicate a supply from the coastal environment to the Polar Surface Water (PSW) which is an addition to the ligand exported from the central Arctic to Fram Strait. The significant differences (in terms of LCu and log KcondCu2+L) between shelf and coastal samples were explained considering the processes which modify ligand concentrations and binding strengths, such as biological activity in sea-ice, phytoplankton bloom in surface waters, bacterial degradation, and meltwater discharge from 79NG glacier terminus. Overall, the ligand concentration exceeded those of dissolved Cu (dCu) and kept the free copper (Cu2+) concentrations at femtomolar levels (0.13–21.13 fM). This indicates that Cu2+ toxicity limits were not reached and dCu levels were stabilized in surface waters by organic complexes, which favoured its transport to the Nordic Seas and North Atlantic Ocean and the development of microorganism.
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    Innovative aquaculture cage “Flow2Vortex” ensures a sustainable biomass delivery for low trophic level aquaculture (2024)
    Elsevier
    Details
    Publication Date: 2024-02-14
    Description: The increasing global demand for seafood, coupled with the limitations of current fish stocks and aquaculture practices, requires the development of sustainable aquaculture solutions. In this context, this study explores the potential of a novel cage technology - Flow2Vortex - for the cultivation of jellyfish, a low-trophic-level organism with increasing market demand. The unique cage design creates a laminar and circular water flow, providing optimal conditions for cultivating fragile planktonic species. Indoor experiments demonstrated the successful growth of jellyfish in the cage, with growth rates of up to 11.6% per day. In addition, field tests in open waters confirmed the cage's ability to maintain a diffuse and controlled flow inside, even under strong external currents. The cage also maintained significantly higher zooplankton concentrations than the surrounding environment, offering a consistent food source for the cultivated jellyfish. These findings highlight the potential of the Flow2Vortex cage for scalable indoor and outdoor cultivation of low-trophic-level organisms, such as jellyfish, contributing to the diversification and sustainability of aquaculture practices.
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    Genetic diversity and population structure of farmed and wild Nile tilapia (Oreochromis niloticus) in Uganda: The potential for aquaculture selection and breeding programs (2024)
    Elsevier
    Details
    Publication Date: 2024-02-21
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    Corrigendum to “Oceanic seismotectonics from regional earthquake recordings: The 4–5°N Mid-Atlantic Ridge” [de Melo, G. W., Mitchell, N. C., Zahradnik, J., Dias, F., & do Nascimento, A. F. (2021). Tectonophysics, 819, 229063]. (2024)
    Elsevier
    Details
    Publication Date: 2024-02-22
    Type: Article , NonPeerReviewed
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    Economic impact disharmony in global biological invasions (2024)
    Elsevier
    Details
    Publication Date: 2024-02-22
    Description: Highlights • More diverse non-native taxa generally include more economically costly species. • Chordates, nematodes and pathogens are among significantly over-represented taxa. • Monetary cost magnitude links positively to numbers of costly invasive species. • Costs are biased towards a few ‘hyper-costly’ invasive species groups. • Future invasion rates will continue to harbour new economically costly species. Abstract A dominant syndrome of the Anthropocene is the rapid worldwide spread of invasive species with devastating environmental and socio-economic impacts. However, the dynamics underlying the impacts of biological invasions remain contested. A hypothesis posits that the richness of impactful invasive species increases proportionally with the richness of non-native species more generally. A competing hypothesis suggests that certain species features disproportionately enhance the chances of non-native species becoming impactful, causing invasive species to arise disproportionately relative to the numbers of non-native species. We test whether invasive species with reported monetary costs reflect global numbers of established non-native species among phyla, classes, and families. Our results reveal that numbers of invasive species with economic costs largely reflect non-native species richness among taxa (i.e., in 96 % of families). However, a few costly taxa were over- and under-represented, and their composition differed among environments and regions. Chordates, nematodes, and pathogenic groups tended to be the most over-represented phyla with reported monetary costs, with mammals, insects, fungi, roundworms, and medically-important microorganisms being over-represented classes. Numbers of costly invasive species increased significantly with non-native richness per taxon, while monetary cost magnitudes at the family level were also significantly related to costly invasive species richness. Costs were biased towards a few ‘hyper-costly’ taxa (such as termites, mosquitoes, cats, weevils, rodents, ants, and asters). Ordination analysis revealed significant dissimilarity between non-native and costly invasive taxon assemblages. These results highlight taxonomic groups which harbour disproportionately high numbers of costly invasive species and monetary cost magnitudes. Collectively, our findings support prevention of arrival and containment of spread of non-native species as a whole through effective strategies for mitigation of the rapidly amplifying impacts of invasive species. Yet, the hyper- costly taxa identified here should receive greater focus from managers to reduce impacts of current invasive species.
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    A Synthesis of Global Coastal Ocean Greenhouse Gas Fluxes (2024)
    AGU (American Geophysical Union) | Wiley
    Details
    Publication Date: 2024-02-22
    Description: The coastal ocean contributes to regulating atmospheric greenhouse gas concentrations by taking up carbon dioxide (CO2) and releasing nitrous oxide (N2O) and methane (CH4). In this second phase of the Regional Carbon Cycle Assessment and Processes (RECCAP2), we quantify global coastal ocean fluxes of CO2, N2O and CH4 using an ensemble of global gap-filled observation-based products and ocean biogeochemical models. The global coastal ocean is a net sink of CO2 in both observational products and models, but the magnitude of the median net global coastal uptake is similar to 60% larger in models (-0.72 vs. -0.44 PgC year-1, 1998-2018, coastal ocean extending to 300 km offshore or 1,000 m isobath with area of 77 million km2). We attribute most of this model-product difference to the seasonality in sea surface CO2 partial pressure at mid- and high-latitudes, where models simulate stronger winter CO2 uptake. The coastal ocean CO2 sink has increased in the past decades but the available time-resolving observation-based products and models show large discrepancies in the magnitude of this increase. The global coastal ocean is a major source of N2O (+0.70 PgCO2-e year-1 in observational product and +0.54 PgCO2-e year-1 in model median) and CH4 (+0.21 PgCO2-e year-1 in observational product), which offsets a substantial proportion of the coastal CO2 uptake in the net radiative balance (30%-60% in CO2-equivalents), highlighting the importance of considering the three greenhouse gases when examining the influence of the coastal ocean on climate. The coastal ocean regulates greenhouse gases. It acts as a sink of carbon dioxide (CO2) but also releases nitrous oxide (N2O) and methane (CH4) into the atmosphere. This synthesis contributes to the second phase of the Regional Carbon Cycle Assessment and Processes (RECCAP2) and provides a comprehensive view of the coastal air-sea fluxes of these three greenhouse gases at the global scale. We use a multi-faceted approach combining gap-filled observation-based products and ocean biogeochemical models. We show that the global coastal ocean is a net sink of CO2 in both observational products and models, but the coastal uptake of CO2 is similar to 60% larger in models than in observation-based products due to model-product differences in seasonality. The coastal CO2 sink is strengthening but the magnitude of this strengthening is poorly constrained. We also find that the coastal emissions of N2O and CH4 counteract a substantial part of the effect of coastal CO2 uptake in the atmospheric radiative balance (by 30%-60% in CO2-equivalents), highlighting the need to consider these three gases together to understand the influence of the coastal ocean on climate. We synthesize air-sea fluxes of CO2, nitrous oxide and methane in the global coastal ocean using observation-based products and ocean models The coastal ocean CO2 sink is 60% larger in ocean models than in observation-based products due to systematic differences in seasonality Coastal nitrous oxide and methane emissions offset 30%-60% of the CO2 coastal uptake in the net radiative balance
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    The Pauzhetka tephra (South Kamchatka): A key middle Pleistocene isochron for the Northwest Pacific and Okhotsk Sea sediments (2024)
    Elsevier
    Details
    Publication Date: 2024-02-23
    Description: Highlights: • Ca. 418 ka Pauzhetka tephra from South Kamchatka was found in 11 marine sediment cores. • New major and trace element analyses allow identification of tephra glasses. • K/Ti and K/Fe maxima mark the Pauzhetka tephra presence in marine sediments. • The tephra occurs at Marine Isotope Stages 12 to 11c and below the Bermuda excursion. • The revised ash dispersal covers vast areas in the NW Pacific and Okhotsk Sea. Abstract: The distal Pauzhetka tephra, formed by a large caldera-forming volcanic eruption in South Kamchatka, has been identified in eleven recently recovered marine sediment cores based on major and trace element compositions of tephra glass. Ten SO264 cores form a transect along the Emperor Seamount Chain (ESC) in the Northwest (NW) Pacific between ∼50.3° and ∼45°N, 800–1200 km southeast of the Pauzhetka caldera. One additional core LV28-41-4 was retrieved in the Okhotsk Sea, ∼600 km west of the caldera. The Pauzhetka tephra glass shards have a characteristic medium-K rhyolite composition and trace element content compatible with the rear-arc position of the source volcano that ensures their identification. In the NW Pacific SO264 cores, the tephra is preserved as layers in cores 33, 47, 49, 53, 55, 56 and 62, as a lens in core 45, and as cryptotephra in cores 57 and 66. It forms a cryptotephra in the Okhotsk Sea core LV28-41-4. Distinctively high XRF-retrieved K/Ti and K/Fe ratios compared to those for the host sediments help identify the Pauzhetka tephra. According to our refined stable oxygen isotope (δ18O)- and magneto-stratigraphy of two studied and two reference cores, the Pauzhetka tephra occurs within a local δ18O maximum during a transition from marine isotope stage 12 to 11c (Termination V) and below a paleointensity minimum referred to as the Bermuda excursion, at ca. 418 ka. Using the tephra age as an isochron, we show that average linear sedimentation rates decrease southward along a transect of the SO264 cores, except in core 55. It partially reflects an intensification of mid-depth currents causing winnowing, erosion or non-deposition along the ESC over the past 418 kyr. An increased linear sedimentation rate in core 55, recovered from the southern leeward side of the Minnetonka Seamount, appears to record the pelagic accumulation protected from the mid-depth current influence. Our findings expand the former ash dispersal area farther southeast in the NW Pacific and southwest in the Okhotsk Sea. The new data on the tephra thickness supports the axis direction of the fallout zone southeast of the Pauzhetka caldera. Our results suggest the Pauzhetka tephra as a key middle Pleistocene isochron for the stratigraphy and correlation of the NW Pacific and Okhotsk Sea sediments.
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    Understanding volcanic margin evolution through the lens of Norway's youngest granite (2024)
    Wiley
    Details
    Publication Date: 2024-02-23
    Description: Three boreholes drilled during the International Ocean Discovery Program (IODP) Expedition 396 have yielded unexpected findings of altered granitic rocks covered by basalt flows, interbedded sediments and glacial mud near the continent‐ocean transition of the mid‐Norwegian margin. U‐Pb and K‐Ar geochronological analyses were conducted on both protolithic and authigenically formed K‐bearing minerals to determine the age of granite crystallisation and subsequent alteration episodes. The granite's crystallisation age based on 104 zircons is 56.3 ± 0.2 Ma, and subsequent exhumation along with alteration/weathering events took place between 54.7 ± 1 and 37.1 ± 1 Ma. This intrusion represents the youngest granite discovered in Norway and intruded at an extremely shallow crustal level before a rapid rift‐to‐drift transition. The shallow emplacement of granitic rock and its fast exhumation before and during the onset of volcanism holds significant implications for the syn‐ and post‐breakup tectonic evolution of volcanic margins.
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    Preliminary Characterization of Submarine Basalt Magnetic Mineralogy Using Amplitude‐Dependence of Magnetic Susceptibility (2024)
    AGU (American Geophysical Union) | Wiley
    Details
    Publication Date: 2024-02-23
    Description: The past ∼200 million years of Earth's geomagnetic field behavior have been recorded within oceanic basalts, many of which are only accessible via scientific ocean drilling. Obtaining the best possible paleomagnetic measurements from such valuable samples requires an a priori understanding of their magnetic mineralogies when choosing the most appropriate protocol for stepwise demagnetization experiments (either alternating field or thermal). Here, we present a quick, and non‐destructive method that utilizes the amplitude‐dependence of magnetic susceptibility to screen submarine basalts prior to choosing a demagnetization protocol, whenever conducting a pilot study or other detailed rock‐magnetic characterization is not possible. We demonstrate this method using samples acquired during International Ocean Discovery Program Expedition 391. Our approach is rooted in the observation that amplitude‐dependent magnetic susceptibility is observed in basalt samples whose dominant magnetic carrier is multidomain titanomagnetite (∼TM 60–65 , (Ti 0.60–0.65 Fe 0.35–0.40 )Fe 2 O 4 ). Samples with low Ti contents within titanomagnetite or samples that have experienced a high degree of oxidative weathering do not display appreciable amplitude dependence. Due to their low Curie temperatures, basalts that possess amplitude‐dependence should ideally be demagnetized either using alternating fields or via finely‐spaced thermal demagnetization heating steps below 300°C. Our screening method can enhance the success rate of paleomagnetic studies of oceanic basalt samples. Plain Language Summary Oceanic basalts are ideal recorders of the Earth's magnetic field. To decipher magnetic histories recorded in rocks, paleomagnetists need to isolate the magnetization directions and intensities within rocks by one of two possible methods. One method typically involves progressively heating the samples to high temperatures. The other method involves exposing samples to alternating magnetic fields with increasing peak field intensities. Both of these methods are ultimately destructive to the original magnetization preserved within rocks. However, without knowledge of a given rock's magnetic mineralogy, randomly choosing thermal or alternating field demagnetization methods may result in high failure rates. We developed a pre‐screening method to help decide which cleaning method will likely be more successful for a given sample based on low‐field magnetic susceptibility measurements. These measurements do not affect the original magnetic information recorded in a rock, thereby permitting subsequent paleomagnetic studies on the same sample. Our technique can be performed as rapidly as 2 min per sample, is non‐destructive, and does not require complicated sample preparation. Key Points Paleomagnetic studies utilize either alternating field or thermal demagnetization, but it is difficult to choose the best protocol a priori Amplitude‐dependence of magnetic susceptibility measurements permits preliminary magnetic mineralogy characterization in submarine basalts Rapid amplitude‐dependence measurements may aid in deciding upon the best demagnetization protocol for submarine basalt samples
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    Influence of Hydrodynamics on the Composition and Reactivity of Particulate Organic Matter in a Large River Influenced Ocean Margin (2024)
    AGU (American Geophysical Union) | Wiley
    Details
    Publication Date: 2024-02-23
    Description: Marginal seas influenced by large rivers are characterized by complex hydrodynamic and organic matter cycling processes. However, the impacts of hydrodynamics on the composition and reactivity of particulate organic matter (POM) remain unclear. Here we conducted a comprehensive study on the bulk, molecular and biological properties of suspended POM in the Changjiang Estuary and adjacent area subjected to strong currents, eddies as well as typhoons during spring and autumn. D/L‐enantiomers of particulate amino acids (PAA) were analyzed to evaluate the bioreactivity of POM and quantify bacterial‐derived organic carbon. We found that POM bioavailability as indicated by carbon‐normalized yields of PAA (PAA‐C%) reflected the ecosystem productivity. Relatively high PAA‐C% values (20−35%) were observed in productive areas influenced by Changjiang River plume, cyclonic eddies and typhoons, likely related to the enhanced nutrient availability arising from hydrodynamic processes. In contrast, the oligotrophic Taiwan Warm Current‐influenced regions featured relatively low POM bioavailability (PAA‐C% 〈 10%) despite typhoons facilitating water mixing. The PAA‐C% values showed a significant positive correlation with extracellular enzyme activity, indicating that bioavailable POM can rapidly stimulate heterotrophic transformation. Hot spots of elevated bioavailable POM showed high contributions of bacterial organic carbon. A large portion (∼2/3) of bacterial organic carbon was present in the form of bacterial detritus, suggesting that patches of these biological hot spots represent important sites of carbon sequestration. Together, our findings indicate that fresh POM production is largely controlled by nutrient supply driven by hydrodynamic processes, with important implications for carbon sequestration in the dynamic ocean margins. Plain Language Summary Marginal seas are subject to complex hydrodynamic processes and play an important role in carbon sequestration. Disentangling the linkages between hydrodynamics and organic carbon reactivity and composition is crucial to understanding the regional carbon cycle. Here we collected suspended particulate organic matter (POM) in the Changjiang Estuary and adjacent coastal areas. Based on the biomarker D/L‐amino acids, we assessed the bioavailability of POM and quantified the organic carbon originating from bacteria. We found that high bioactivity of POM occurred in productive Changjiang River plume, cyclonic eddy, and typhoon influenced areas. These hydrodynamic processes appear to increase nutrient availability, therefore promoting phytoplankton growth. Bioavailable POM can rapidly stimulate heterotrophic activity and facilitate the transformation of algal‐derived organic carbon to bacterial detritus, thus contributing to carbon sequestration. Our findings suggest that the production of bioavailable POM is largely controlled by hydrodynamically driven nutrient supply. Key Points We use D/L‐amino acids to assess the bioreactivity and bacterial origins of particulate organic matter (POM) in the dynamic Changjiang Estuary and adjacent area High bioavailability of POM occurs in productive regions affected by Changjiang River plume, cyclonic eddies and typhoons Hot spots of bioavailable POM represent important sites for carbon sequestration
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    The Influence of Freshwater Input on the Evolution of the 1995 Benguela Nino (2024)
    Wiley | AGU (American Geological Society)
    Details
    Publication Date: 2024-02-23
    Description: Key Points: - Freshwater input has significantly contributed to the surface warming at the peak of the 1995 Benguela Niño - Anomalously high river discharge and precipitation increased stratification and reduced turbulent heat loss by creating barrier layers - Combination of high freshwater input and strong poleward surface current might play a role in temperature variability off Angola Benguela Nino events are characterized by strong warm sea surface temperature (SST) anomalies off the Angolan and Namibian coasts. In 1995, the strongest event in the satellite era took place, impacting fish availability in both Angolan and Namibian waters. In this study, we use direct observations, satellite data, and reanalysis products to investigate the impact that the up-until-now unnoticed mechanism of freshwater input from Congo River discharge (CRD) and precipitation had on the evolution of the 1995 Benguela Nino. In the onset phase of the event, anomalous rainfall in November/December 1994 at around 6 degrees S, combined with a high CRD, generated a low salinity plume. The plume was advected into the Angola-Namibia region in the following February/March 1995 by an anomalously strong poleward surface current generated by the relaxation of the southerly winds and shifts in the coastal wind stress curl. The presence of this low surface salinity anomaly of about -2 psu increased ocean stability by generating barrier layers, thereby reducing the turbulent heat loss, since turbulent mixing acted on a weak vertical temperature gradient. A mixed layer heat budget analysis demonstrates that southward advection of Angolan waters drove the warming at the onset, while reduced mixing played the main role at the event's peak. We conclude that a freshwater input contributed to the SST increase in this exceptionally strong event and suggest that this input can influence the SST variability in Angola-Namibia waters through a combination of high CRD, precipitation, and the presence of a strong poleward surface current. Benguela Nino events are characterized by excessive warming of the sea surface temperature off the Angolan and Namibian coasts. One of the strongest-ever recorded warm events dates back to 1995, impacting fish availability in both Angolan and Namibian waters. In our research, we investigate if freshwater from rain and from the Congo River could have impacted the evolution of this 1995 Benguela Nino. In the event's early stage, high precipitation and river discharge generated a low salinity pool at the Congo River mouth, which in February/March 1995 was taken to the south by an exceptionally strong surface current, generated by changes in wind strength and direction at the African coast. This low sea surface salinity in a shallow layer in the upper meters of the ocean increased the ocean's stability. As the stabilized waters diminished the usual mixing from the depths below which cools down the surface waters, it contributed to an increase in warming in the surface layer of the ocean. We conclude that the warming of the surface waters in the region was indeed influenced by the combination of high precipitation and high Congo River discharge with a strong surface current toward the south. Freshwater input has significantly contributed to the surface warming at the peak of the 1995 Benguela Nino Anomalously high river discharge and precipitation increased stratification and reduced turbulent heat loss by creating barrier layers Combination of high freshwater input and strong poleward surface current might play a role in temperature variability off Angola
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    Early Diagenetic Controls on Sedimentary Iodine Release and Iodine‐To‐Organic Carbon Ratios in the Paleo‐Record (2024)
    AGU (American Geophysical Union) | Wiley
    Details
    Publication Date: 2024-02-23
    Description: Iodine cycling in the ocean is closely linked to productivity, organic carbon export, and oxygenation. However, iodine sources and sinks at the seafloor are poorly constrained, which limits the applicability of iodine as a biogeochemical tracer. We present pore water and solid phase iodine data for sediment cores from the Peruvian continental margin, which cover a range of bottom water oxygen concentrations, organic carbon rain rates and sedimentation rates. By applying a numerical reaction‐transport model, we evaluate how these parameters determine benthic iodine fluxes and sedimentary iodine‐to‐organic carbon ratios (I:C org ) in the paleo‐record. Iodine is delivered to the sediment with organic material and released into the pore water as iodide (I − ) during early diagenesis. Under anoxic conditions in the bottom water, most of the iodine delivered is recycled, which can explain the presence of excess dissolved iodine in near‐shore anoxic seawater. According to our model, the benthic I − efflux in anoxic areas is mainly determined by the organic carbon rain rate. Under oxic conditions, pore water dissolved I − is oxidized and precipitated at the sediment surface. Much of the precipitated iodine re‐dissolves during early diagenesis and only a fraction is buried. Particulate iodine burial efficiency and I:C org burial ratios do increase with bottom water oxygen. However, multiple combinations of bottom water oxygen, organic carbon rain rate and sedimentation rate can lead to identical I:C org , which limits the utility of I:C org as a quantitative oxygenation proxy. Our findings may help to better constrain the ocean's iodine mass balance, both today and in the geological past. Key Points The impact of early diagenesis on benthic iodine fluxes and iodine burial was quantitatively evaluated using a reaction‐transport model Dissolved iodine anomalies in the water column are indicative of benthic efflux from anoxic sediments with high organic carbon turnover Not only bottom water oxygen but also organic carbon delivery and sedimentation rate determine sedimentary iodine‐to‐organic carbon ratios
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    Assessment of Chalk as an Archive for the Lithium Isotope Composition of Seawater (2024)
    AGU (American Geophysical Union) | Wiley
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    Publication Date: 2024-02-23
    Description: The understanding of silicate weathering and its role as a sink for atmospheric CO 2 is important to get a better insight into how the Earth shifts from warm to cool climates. The lithium isotope composition (δ 7 Li) of marine carbonates can be used as a proxy to track the past chemical weathering of silicates. A high‐resolution δ 7 Li record would be helpful to evaluate the role of silicate weathering during the late Cretaceous climate cooling. Here, we assess chalk as a potential archive for reconstructing Late Cretaceous seawater Li isotope composition by comparing Maastrichtian chalk from Northern Germany (Hemmoor, Kronsmoor) to a Quaternary coccolith ooze from the Manihiki Plateau (Pacific Ocean) as a lithological analog to modern conditions. We observe a negative offset of 3.9 ± 0.6‰ for the coccolith ooze relative to the modern seawater Li isotope composition (+31.1 ± 0.3‰; 2SE; n = 54), a value that falls in the range of published offsets for modern core‐top samples and for brachiopod calcite. Further, the negative offset between the Li isotope compositions of Manihiki coccolith ooze and modern planktonic foraminifera is 2.3 ± 0.6‰. Although chalk represents a diagenetically altered modification of pelagic nannofossil ooze, manifested by changes in the composition of trace elements, we observe a consistent offset of Li isotope data between Maastrichtian chalk and Maastrichtian planktonic foraminiferal data (−1.4 ± 0. 5‰) that lies within the uncertainty of modern values. We therefore suggest that chalk can be used as a reliable archive for δ 7 Li reconstructions. Key Points Chalk is a reliable archive for the Li isotope composition of seawater Coccolith ooze has a negative offset of 3.9 ± 0.6‰ from modern seawater for Li isotope ratios The estimated mean value for the late Maastrichtian seawater Li isotope composition is +27.5 ± 1.0‰
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    An Amphibole Perspective on the Recent Magmatic Evolution of Mount St. Helens (2024)
    Oxford University Press
    Details
    Publication Date: 2024-02-23
    Description: Compositional variations of amphibole stratigraphically recovered from multiple eruptions at a given volcano have a great potential to archive long-term magmatic processes in its crustal plumbing system. Calcic amphibole is a ubiquitous yet chemically and texturally diverse mineral at Mount St. Helens (MSH), where it occurs in dacites and in co-magmatic enclaves throughout the Spirit Lake stage (last ~4000 years of eruptive history). It forms three populations with distinct geochemical trends in key major and trace elements, which are subdivided into a high-Al (11–14.5 wt% Al2O3), a medium-Al (10–12.5 wt% Al2O3), and a low-Al (7.5–10 wt% Al2O3) amphibole population. The oldest investigated tephra record (Smith Creek period, 3900–3300 years BP) yields a bimodal amphibole distribution in which lower-crustal, high-Al amphibole cores (crystallized dominantly from basaltic andesite to andesite melts) and upper-crustal, low-Al amphibole rims (crystallized from rhyolitic melt) document occasional recharge of a shallow silicic mush by a more mafic melt from a lower-crustal reservoir. The sudden appearance of medium-Al amphiboles enriched in incompatible trace elements in eruptive periods younger than 2900 years BP is associated with a change in reservoir conditions toward hotter and drier magmas, which indicates recharge of the shallow silicic reservoir by basaltic melt enriched in incompatible elements. Deep-crystallizing, high-Al amphibole, however, appears mostly unaffected by such incompatible-element-enriched basaltic recharge, suggesting that these basalts bypass the lower crustal reservoir. This could be the result of the eastward offset position of the lower crustal reservoir relative to the upper crustal storage zone underneath the MSH edifice. Amphibole has proven to be a sensitive geochemical archive for uncovering storage conditions of magmas at MSH. In agreement with geophysical observations, storage and differentiation have occurred in two main zones: an upper crustal and lower crustal reservoir (the lower one being chemically less evolved). The upper crustal silicic reservoir, offset to the west of the lower crustal reservoir, has captured compositionally unusual mafic recharge (drier, hotter, and enriched in incompatible trace elements in comparison to the typical parental magmas in the region), resulting in an increased chemical diversity of amphiboles and their carrier intermediate magmas, in the last ~3000 years of MSH’s volcanic record.
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    Impacts of North Atlantic Model Biases on Natural Decadal Climate Variability (2024)
    AGU (American Geophysical Union) | Wiley
    Details
    Publication Date: 2024-02-26
    Description: Key Points: - North Atlantic biases are alleviated by an eddying nested ocean configuration embedded in a global climate model, FOCI-VIKING10 - It is indicated that reduction of the North Atlantic biases could improve the representation of NAO sub-decadal (8 years) variability - For detecting weak external imprints with limited computational resources, an ensemble with a coarse-resolution model is favorable Increasing the horizontal resolution of an ocean model is frequently seen as a way to reduce the model biases in the North Atlantic, but we are often limited by computational resources. Here, a two-way nested ocean model configuration (VIKING10) that consists of a high-resolution (1/10°) component and covers the northern North Atlantic, is embedded in a 1/2° ocean grid as part of the global chemistry-climate model, FOCI (called FOCI-VIKING10). This configuration yields a significantly improved path of the North Atlantic current (NAC), which here reduces the North Atlantic cold bias by ∼50%. Compared with the coarse-resolution, non-eddying model, the improved thermal state of upper ocean layers and surface heat fluxes in a historical simulation based on FOCI-VIKING10 are beneficial for simulating the subdecadal North Atlantic Oscillation (NAO) variability (i.e., a period of 8 years). A northward drift of the NAO-forced ocean thermal anomalies as seen in observations and the eddying FOCI-VIKING10, provide a lagged ocean feedback to the NAO via changes in the net surface heat flux, leading to the NAO periodicity of 8 years. This lagged feedback and the 8 years variability of the NAO cannot be captured by the non-eddying standard FOCI historical simulation. Furthermore, the argumentative responses of the North Atlantic to the 11-year solar cycle are re-examined in this study. The reported solar-induced NAO-like responses are confirmed in the 9-member ensemble mean based on FOCI but with low robustness among individual members. A lagged NAO-like response is only found in the nested eddying simulation but absent from the non-eddying reference simulation, suggesting North Atlantic biases importantly limit climate model capability to realistically solar imprints in North Atlantic climate.
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    Introduction of isotopically light barium from the Rainbow hydrothermal system into the deep Atlantic Ocean (2024)
    Elsevier
    Details
    Publication Date: 2024-02-29
    Description: Highlights • Negligible Ba removal observed in the Rainbow hydrothermal system. • Insignificant modification of Ba isotope composition of the vent fluid endmember. • Rainbow vent introduces isotopically light Ba (−0.17) to the deep Atlantic Ocean. • Hydrothermal inputs contribute 4.6 ± 2.2 Gmol/yr Ba to the ocean. Abstract The marine barium (Ba) cycle is closely connected to the short-timescale carbon cycle, and Ba serves as a valuable paleo proxy for export production, ocean alkalinity, and terrestrial inputs. However, the marine Ba budget is poorly constrained, particularly regarding the fluxes of hydrothermally sourced Ba, which hinders our understanding of the Ba cycle and use of Ba-based proxies. Recent studies have suggested a modern source-sink imbalance of Ba isotopes in the global ocean, with sources being overall isotopically heavier than the sinks, and the hydrothermal Ba inputs were considered isotopically heavy sources. In this study, we present the first investigation of Ba and its isotopes in a non-buoyant hydrothermal plume based on dissolved and particulate samples collected from the Rainbow hydrothermal vent field on the Mid-Atlantic Ridge. Our data reveal strong hydrothermal signals at near-field stations, as evidenced by helium isotopes, accompanied by elevated concentrations of dissolved and particulate Ba. Dissolved Ba isotope compositions (δ138Ba) in hydrothermally influenced deep waters (∼0.3 ) are lighter than at similar depths of far-field stations (∼0.45 ) in the Atlantic Ocean. The concentrations and isotopic compositions of dissolved and labile particulate Ba in the non-buoyant hydrothermal plume can be explained by conservative mixing between a Ba-enriched hydrothermal component and North Atlantic Deep Water. By extrapolating the correlations to the vent fluid endmember, our results suggest that there is negligible removal of Ba, and insignificant modification of Ba isotopic signatures, from the vent fluid endmember to the non-buoyant hydrothermal plume. This indicates that the Rainbow hydrothermal system introduces isotopically light Ba (−0.17 ± 0.05 ) to the deep Atlantic Ocean. We estimate that global hydrothermal inputs of Ba are 4.6 ± 2.2 Gmol/yr. These observations highlight the potential of hydrothermal Ba to be an isotopically light source component of the marine Ba isotope budget.
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    Origin, evolution and significance of giant buried sediment mounds near the Sahara Slide Complex, North‐west African margin (2024)
    IAS (International Association of Sedimentologists) | Wiley
    Details
    Publication Date: 2024-03-01
    Description: Mixed turbidite–contourite depositional systems result from interactions between down‐slope turbidity currents and along‐slope bottom currents, comprising excellent records of past oceanographic currents. Modern and ancient systems have been widely documented along the continental margins of the Atlantic Ocean. Yet, few examples have so far been identified on the North‐west African continental margin, limiting understanding of the sedimentary and palaeoceanographic evolution in this area. This work uses two‐dimensional seismic reflection profiles to report, for the first time, the presence of three giant sediment mounds beneath the headwall region of the Sahara Slide Complex. The sediment mounds are elongated and separated by two broad canyons, showing a north‐west/south‐east orientation that is roughly perpendicular to the continental margin. These mounds are 24 to 37 km long and 12 to 17 km wide, reaching a maximum height of ca 1000 m. Numerous slide scarps are observed within and along the flanks of the mounds, hinting at the occurrence of submarine landslides during their development. Based on their geometries, external shapes, internal seismic architecture and stratigraphic stacking patterns, it is proposed that these sediment mounds comprise down‐slope elongated mounded drifts formed in a mixed turbidite–contourite system during four evolutionary stages: onset, growth, maintenance and burial. The significance of this work is that it demonstrates the gradual transition from a turbidite system to a full mixed turbidite–contourite system to be associated, in the study area, with the establishment of strong ocean currents along north‐west Africa.
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    The effects of primary and secondary bacterial exposure on the seahorse (Hippocampus erectus) immune response (2024)
    Elsevier
    Details
    Publication Date: 2024-03-01
    Description: Highlights: • Transcriptomic immune response assessments in seahorse (Hippocampus erectus). • Seahorses exposed in two phases to heat-killed Vibrio and Tenacibaculum strains. • Adaptive immune memory evidence (double-exposed) and increased naivety to Tenacibaculum. • Upregulated gene expression pertaining to potential innate ‘trained immunity’. • Trained immunity potential compensator for deduced MHC II loss of function. Evolutionary adaptations in the Syngnathidae teleost family (seahorses, pipefish and seadragons) culminated in an array of spectacular morphologies, key immune gene losses, and the enigmatic male pregnancy. In seahorses, genome modifications associated with immunoglobulins, complement, and major histocompatibility complex (MHC II) pathway components raise questions concerning their immunological efficiency and the evolution of compensatory measures that may act in their place. In this investigation heat-killed bacteria (Vibrio aestuarianus and Tenacibaculum maritimum) were used in a two-phased experiment to assess the immune response dynamics of Hippocampus erectus. Gill transcriptomes from double and single-exposed individuals were analysed in order to determine the differentially expressed genes contributing to immune system responses towards immune priming. Double-exposed individuals exhibited a greater adaptive immune response when compared with single-exposed individuals, while single-exposed individuals, particularly with V. aestuarianus replicates, associated more with the innate branch of the immune system. T. maritimum double-exposed replicates exhibited the strongest immune reaction, likely due to their immunological naivety towards the bacterium, while there are also potential signs of innate trained immunity. MHC II upregulated expression was identified in selected V. aestuarianus-exposed seahorses, in the absence of other pathway constituents suggesting a possible alternative or non-classical MHC II immune function in seahorses. Gene Ontology (GO) enrichment analysis highlighted prominent angiogenesis activity following secondary exposure, which could be linked to an adaptive immune process in seahorses. This investigation highlights the prominent role of T-cell mediated adaptive immune responses in seahorses when exposed to sequential foreign bacteria exposures. If classical MHC II pathway function has been lost, innate trained immunity in syngnathids could be a potential compensatory mechanism.
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    How Hydrothermal Cooling and Magmatic Sill Intrusions Control Flip‐Flop Faulting at Ultraslow‐Spreading Mid‐Ocean Ridges (2024)
    AGU (American Geophysical Union) | Wiley
    Details
    Publication Date: 2024-03-01
    Description: “Flip‐flop” detachment mode represents an endmember type of lithosphere‐scale faulting observed at almost amagmatic sections of ultraslow‐spreading mid‐ocean ridges. Recent numerical experiments using an imposed steady temperature structure show that an axial temperature maximum is essential to trigger flip‐flop faults by focusing flexural strain in the footwall of the active fault. However, ridge segments without significant melt budget are more likely to be in a transient thermal state controlled, at least partly, by the faulting dynamics themselves. Therefore, we investigate which processes control the thermal structure of the lithosphere and how feedbacks with the deformation mechanisms can explain observed faulting patterns. We present results of 2‐D thermo‐mechanical numerical modeling including serpentinization reactions and dynamic grain size evolution. The model features a novel form of parametrized hydrothermal cooling along fault zones as well as the thermal and rheological effects of periodic sill intrusions. We find that the interplay of hydrothermal fault zone cooling and periodic sill intrusions in the footwall facilitates the flip‐flop detachment mode. Hydrothermal cooling of the fault zone pushes the temperature maximum into the footwall, while intrusions near the temperature maximum further weaken the rock and promote the formation of new faults with opposite polarity. Our model allows us to put constraints on the magnitude of two processes, and we obtain most reasonable melt budgets and hydrothermal heat fluxes if both are considered. Furthermore, we frequently observe two other faulting modes in our experiments complementing flip‐flop faulting to yield a potentially more robust alternative interpretation for existing observations. Plain Language Summary At mid‐ocean ridges, two plates diverge and new seafloor is created. The nature and appearance of this new seafloor strongly depend on spreading velocity and the availability of magmatic melts. At one of the melt‐poorest and slowest‐spreading ridges, a special form of large‐scale tectonic faults, so‐called flip‐flop detachments, can be observed. Tectonic faults can act as pathways for fluids circulating through the seafloor, which provides a significant cooling effect for the young plate. The interplay of magmatic activity, faulting and fluid circulation is evident at many different ridges with different magmatic activity and spreading rates. Flip‐flop faulting is restricted to only a few ridge sections worldwide, and we here investigate the prerequisites for this special spreading mode. To do so, we set up a computer model of an ultraslow‐spreading mid‐ocean ridge including the effects of sparse magmatism as well as the cooling effect associated with fluid circulation. We find that feedbacks between faulting dynamics, hydrothermal cooling and magmatic activity control the magnitude and spatial location of each individual process. Seafloor and subsurface observations are best explained by calculations with moderate melt input and hydrothermal circulation acting together. Key Points We implemented hydrothermal cooling and magmatic intrusion in a thermo‐mechanical model to explain detachment faulting at ultraslow ridges Stable flip‐flop detachment faulting is observed for setups considering both melt input and hydrothermal heat fluxes at realistic magnitudes Two other faulting modes frequently observed in our model offer potential alternative interpretations for existing seafloor observations
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    The rise, fall and rebirth of ocean carbon sequestration as a climate 'solution' (2024)
    Elsevier
    Details
    Publication Date: 2024-03-05
    Description: Highlights • Solutions to the climate crisis are not ahistorical. • Both social and technical processes explain their rise (or fall) on the agenda. • Thinking about ocean CDR closely co-evolved with scientific understandings of global climate change. • Ocean CDR methods have followed cycles of hype, controversy and disappointment. • Key sociotechnical configurations and narrative changes explain the new hype around ocean CDR. Abstract While the ocean has long been portrayed as a victim of climate change, threatened by ocean warming and acidification, it is now increasingly framed as a key solution to the climate crisis. In particular, the promising carbon sequestration potential of the ocean is being emphasised. In this paper, we seek to historicise the practices, discourses and actors that have constructed the ocean as a climate change solution space. We conceptualise the debate about the mitigation potential of the ocean as a contested site of governance, where varying actors form alliances and different sociotechnical narratives about climate action play out. Using an innovative quali-quantitative methodology which combines scientometrics with document analysis, observational fieldwork, and interviews, we outline three historical phases in the history of ocean carbon sequestration that follow recurring cycles of hype, controversy and disappointment. We argue that the most recent hype around ocean carbon sequestration was not triggered by a technological breakthrough or a reduction in scientific uncertainty, but by new socio-technical configurations and coalitions. We conclude by showing that how climate change solutions are put on the agenda and become legitimised is both a scientific and political process, linked to how science frames the climate crisis, and ultimately, its governance.
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    Co-occurrence of native and invasive macroalgae might be facilitated under global warming (2024)
    Elsevier
    Details
    Publication Date: 2024-03-04
    Description: Climate change is driving compositional shifts in ecological communities directly by affecting species and indirectly through changes in species interactions. For example, competitive hierarchies can be inversed when competitive dominants are more susceptible to climate change. The brown seaweed Fucus vesiculosus is a foundation species in the Baltic Sea, experiencing novel interactions with the invasive red seaweed Gracilaria vermiculophylla, which is known for its high tolerance to environmental stress. We investigated the direct and interactive effects of warming and co-occurrence of the two algal species on their performance, by applying four climate change-relevant temperature scenarios: 1) cooling ) 2 °C below ambient – representing past conditions), 2) ambient summer temperature (18 °C), 3) IPCC RCP2.6 warming scenario (1 °C above ambient), and 4) RCP8.5 warming (3 °C above ambient) for 30 days and two compositional levels (mono and co-cultured algae) in a fully-crossed design. The RCP8.5 warming scenario increased photosynthesis, respiration, and nutrients' uptake rates of mono- and co-cultured G. vermiculophylla while growth was reduced. An increase in photosynthesis and essential nutrients' uptake and, at the same time, a growth reduction might result from increasing stress and energy demand of G. vermiculophylla under warming. In contrast, the growth of mono-cultured F. vesiculosus significantly increased in the highest warming treatment (+3 °C). The cooling treatment (−2 °C) exerted a slight negative effect only on co-cultured F. vesiculosus photosynthesis, compared to the ambient treatment. Interestingly, at ambient and warming (RCP2.6 and RCP8.5 scenarios) treatments, both F. vesiculosus and G. vermiculophylla appear to benefit from the presence of each other. Our results suggest that short exposure of F. vesiculosus to moderate or severe global warming scenarios may not directly affect or even slightly enhance its performance, while G. vermiculophylla net performance (growth) could be directly hampered by warming.
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    Evaluating the physics of outcrop-to-outcrop flow with hydrothermal flow models (2024)
    Wiley | AGU (American Geophysical Union)
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    Publication Date: 2024-03-07
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    Characterization and future projection of marine heatwaves under climate change in the South China Sea (2024)
    Elsevier
    Details
    Publication Date: 2024-03-08
    Description: Marine heatwaves (MHWs) are widely recognized as prolonged periods of significantly elevated sea surface temperatures, leading to substantial adverse impacts on marine ecosystems. However, a comprehensive understanding of their characteristics and potential changes under climate change in the South China Sea (SCS, 0 ∼ 25°N, 105 ∼ 125°E) remains insufficient. Here, utilizing the OISST V2.0 reanalysis dataset, our study first examines MHW characteristics and their trends in the SCS during the historical period (1982 ∼ 2014). Then, in accordance with the criteria established in this study, GFDL-ESM4, EC-Earth3-Veg, NESM3, EC-Earth3, and GFDL-CM4 are identified from the CMIP6 ensemble of 19 models for their enhanced simulations of historical MHW characteristics. Moreover, considering that the fixed and sliding threshold methods offer distinct perspectives on the future evolution of MHWs, we employ both approaches to evaluate MHW characteristics under projected scenarios for the future period (2015 ∼ 2100) and subsequently compare the disparities between the two methodologies. The outcomes obtained using these methods consistently indicate that MHWs in the SCS are anticipated to intensify and persist for longer durations in the future. Besides, addressing seasonal variability, the peak intensity of MHWs falls in May during both the historical period and the four projected future scenarios. This study provides valuable insights into the behavior of MHWs in the SCS within the context of climate change, underscoring the urgency of adopting effective mitigation strategies. Especially, the use of two definition methods provides a more comprehensive set of information for understanding the future changes of MHWs in the SCS.
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    Volcanic flank collapse, secondary sediment failure and flow-transition: multi-stage landslide emplacement offshore Montserrat, Lesser Antilles (2024)
    AGU (American Geophysical Union) | Wiley
    Details
    Publication Date: 2024-03-14
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    Stimulation of small phytoplankton drives enhanced sinking particle formation in a subtropical ocean eddy (2024)
    Wiley | ASLO (Association for the Sciences of Limnology and Oceanography)
    Details
    Publication Date: 2024-03-15
    Description: Nutrient transfer into the sunlit surface ocean by cyclonic eddies is potentially crucial for sustaining primary productivity in the stratified subtropical gyres. However, the nature of productivity enhancements, including the flow of matter to higher trophic levels and its impact on carbon fluxes, remain poorly resolved. Here, we report a detailed assessment of the biogeochemical response to a cyclonic eddy in the subtropical Northwest Pacific via a combination of ship‐based and autonomous platforms. Primary production was enhanced twofold within the eddy core relative to reference sites outside, whereas phytoplankton biomass even decreased. Pico‐phytoplankton (〈 2 μ m) dominated (〉 80%) both phytoplankton biomass and primary production inside and outside the eddy. The stimulated primary production in the eddy core was accompanied by an approximately twofold increase in mesozooplankton abundance, an approximately threefold increase in particle formation in the deep chlorophyll maximum layer, as well as significantly enhanced surface oceanic CO 2 uptake and net community production. We suggest these observations carry important implications for understanding carbon export in the subtropical ocean and highlight the need to include such subtropical eddy features in ocean carbon budget analyses.
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    Niche width and overlap of benthic invertebrates in surf zones increase with distance from the estuarine source of organic matter (2024)
    Elsevier
    Details
    Publication Date: 2024-03-15
    Description: Highlights: • Microphytobenthos contributed to the particulate organic matter in both beaches. • Allochthonous materials provide relevant contributions to the POM in surf zones. • Estuarine subsidies' availability determines changes in consumers' isotopic niches. • Higher estuarine trophic subsidies resulted in narrower niches of dominant species. Abstract: Benthic invertebrates in the surf zone of exposed sandy beaches represent important links for energy circulation between benthic and pelagic food webs. This work assesses the trophic ecology of co-occurring epi- and hyper-benthic invertebrates inhabiting the surf zone of sandy beaches located close to an estuarine mouth. It illustrates that different sources of organic matter induce changes in resource utilization. The trophic positions, and the niche width and overlap of species were described using δ13C and δ15N stable isotope analysis. The contribution of different sources to the particulate organic matter was quantified through stable isotopes analysis and fatty acids profiles. Shifts in the trophic niches of dominant species reflected a decrease in the contribution of estuarine carbon to the diets along the coast. This change in contribution of estuarine carbon also influenced trophic niche properties: more diverse resources availability resulted in narrower niches without overlap while less diverse resources resulted in broad isotopic niches and a highest overlap. Results show that spatial variations in the availability of resources can modify carbon pathways and trophic interactions in coastal food webs. Whenever resources are abundant, species display a more specialized diet while food scarcity leads to broader diets, a pattern consistent with the optimal foraging theory. This resource maximization behavior commonly observed in nature is also occurring in surf zone ecosystems.
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    Switches between nitrogen limitation and nitrogen–phosphorus co‐limitation in the subtropical North Atlantic Ocean (2024)
    Wiley | ASLO
    Details
    Publication Date: 2024-03-15
    Description: Concentrations of bioavailable inorganic nitrogen (N) and phosphorus (P) are simultaneously depleted in the (sub)tropical North Atlantic Ocean, but it remains unclear if phytoplankton growth rates are N limited or N–P co‐limited. Here we present findings from three bottle‐scale experiments using a four‐by‐four matrix of low‐level N and P additions, conducted at one site in the subtropical North Atlantic Ocean. Phytoplankton responses were assessed both in terms of bulk chlorophyll a (Chl a ) concentrations and intracellular Chl a of dominant Prochlorococcus and Synechococcus groups. Two matrix experiments suggested that N was independently limiting in situ growth, with no co‐limiting role for P, while the third showed co‐limitation by both N and P in this region. This switch from N limitation to N–P co‐limitation was attributed to an episodic wet deposition event that supplied N, thereby stimulating phytoplankton growth and consuming available P. Such rapid transitions in nutrient limitation in response to environmental forcing might be common in oceanic systems with multiple depleted nutrients.
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    Accurate measurement of K/Ca in low‐[K] carbonate samples using laser‐ablation sector‐field inductively coupled plasma mass spectrometry (2024)
    Wiley
    Details
    Publication Date: 2024-03-15
    Description: Rationale Potassium (K) is a major component of several silicate minerals and seawater, and, therefore, constraining past changes in the potassium cycle is a promising way of tracing large‐scale geological processes on Earth. However, [K] measurement using inductively coupled plasma mass spectrometry (ICP‐MS) is challenging due to an ArH + interference, which may be of a similar magnitude to the K + ion beam in samples with 〈0.1% m/m [K]. Methods In this work, we investigated the effect of the ArH + interference on K/Ca data quality by comparing results from laser‐ablation (LA)‐ICP‐MS measured in medium and high mass resolution modes and validating our LA results via solution ICP‐optical emission spectroscopy (OES) and solution ICP‐MS measurements. To do so, we used a wide range of geological reference materials, with a particular focus on marine carbonates, which are potential archives of past changes in the K cycle but are typically characterised by [K] 〈 200 μg/g. In addition, we examine the degree to which trace‐element data quality is driven by downhole fractionation during LA‐ICP‐MS measurements. Results Our results show that medium mass resolution (MR) mode is sufficiently capable of minimising the effect of the ArH + interference on K + . However, the rate of downhole fractionation for Na and K varies between different samples as a result of their differing bulk composition, resulting in matrix‐specific inaccuracy. We show how this can be accounted for via downhole fractionation corrections, resulting in an accuracy of better than 1% and a long‐term reproducibility (intermediate precision) of 〈6% (relative standard deviation) in JCp‐1NP using LA‐ICP‐MS in MR mode. Conclusion Our [K] measurement protocol is demonstrably precise and accurate and applicable to a wide range of materials. The measurement of K/Ca in relatively low‐[K] marine carbonates is presented here as a key example of a new application opened up by these advances.
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    Spatial and temporal variations in the micronutrient Fe across the Peruvian shelf from 1984-2017 (2024)
    Elsevier
    Details
    Publication Date: 2024-03-22
    Description: High dissolved iron (dFe) concentrations of the order of 10-100 nmol L-1 are a feature of waters influenced by sedimentary inputs in oxygen minimum zones (OMZ). However, the temporal development of dFe concentrations is poorly defined due to a general reliance on snapshot cross-shelf sections to study marine trace metal dynamics. Multiple cruise campaigns since the 1980s have investigated Fe dynamics over the Peruvian shelf, particularly between 9-17°S where the shelf is broad, extremely productive and known to feature benthic dFe effluxes which are amongst the highest measured globally. This extensive long-term dataset uniquely allows us to study the interannual variability in dFe concentrations and their response to El Niño–Southern Oscillation (ENSO) events. By combining data from 11 cruises during the period 1984-2017 we are able to evaluate dFe dynamics on interannual timescales in a major OMZ. The region where average dFe concentrations are sensitive to variations in ENSO is confined to a subsurface layer at depths between 50-150 m, particularly in the narrow coastal region within 50 km of the coastline. Subsurface dFe concentrations were generally low during El Niño events (0.7-15.4 nmol L-1) and relatively high with a wider range of variability during the cold ENSO phase (1.1-52.1 nmol L-1). Inverse relationships between wind speed and surface/subsurface dFe were evident. In the subsurface layer, this may be attributable to enhanced dFe offshore transport along isopycnals when upwelling-favorable winds relax in accordance with previously outlined theories. Surface layer (〈40 m) dFe variability was likely associated with a dilution and/or oxidation effect depending on the strength of wind driven water column mixing. Upwelling brings macronutrient-rich water into the euphotic zone, but its intensity had a limited impact on upper layer dFe concentrations possibly due to the influence of an onshore geostrophic flow. Interannual variability in surface chlorophyll-a (Chl-a) was found to correlate with dFe concentration in the offshore zone of northern Peru. This is consistent with bioassay experiments and climatological residual nitrate concentrations which both indicate proximal Fe limitation of phytoplankton growth over and beyond the northern Peruvian shelf. Overall, our work highlights the importance of physical factors driving short-term variations in Fe availability in one of the world’s most economically important fishery regions and suggests that, despite pronounced spatial and temporal variability in dFe concentrations, the ENSO phase has an impact on dFe availability.
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    Advanced underwater image restoration in complex illumination conditions (2024)
    Elsevier
    Details
    Publication Date: 2024-03-22
    Description: Underwater image restoration has been a challenging problem for decades since the advent of underwater photography. Most solutions focus on shallow water scenarios, where the scene is uniformly illuminated by the sunlight. However, the vast majority of uncharted underwater terrain is located beyond 200 meters depth where natural light is scarce and artificial illumination is needed. In such cases, light sources co-moving with the camera, dynamically change the scene appearance, which make shallow water restoration methods inadequate. In particular for multi-light source systems (composed of dozens of LEDs nowadays), calibrating each light is time-consuming, error-prone and tedious, and we observe that only the integrated illumination within the viewing volume of the camera is critical, rather than the individual light sources. The key idea of this paper is therefore to exploit the appearance changes of objects or the seafloor, when traversing the viewing frustum of the camera. Through new constraints assuming Lambertian surfaces, corresponding image pixels constrain the light field in front of the camera, and for each voxel a signal factor and a backscatter value are stored in a volumetric grid that can be used for very efficient image restoration of camera-light platforms, which facilitates consistently texturing large 3D models and maps that would otherwise be dominated by lighting and medium artifacts. To validate the effectiveness of our approach, we conducted extensive experiments on simulated and real-world datasets. The results of these experiments demonstrate the robustness of our approach in restoring the true albedo of objects, while mitigating the influence of lighting and medium effects. Furthermore, we demonstrate our approach can be readily extended to other scenarios, including in-air imaging with artificial illumination or other similar cases.
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    Degradation and accumulation of organic matter in euxinic surface sediments (2024)
    Elsevier
    Details
    Publication Date: 2024-03-25
    Description: The impact of oxygen on the preservation of organic matter in marine surface sediments is still controversial. We revisited this long-standing debate by determining the burial efficiency of sedimentary organic matter in the Black Sea, the largest anoxic and euxinic basin in the modern ocean. Surface sediments were sampled in the Danube paleodelta on the northwestern margin of the Black Sea at 420–1550 m water depth. Steady-state modeling of solid species (particulate organic carbon and nitrogen) and solutes (ammonium, sulfate, and total alkalinity) in sediments was performed to quantify rates of mass accumulation, particulate organic matter (POM) degradation, and POM burial. We develop a novel analytical model to quantify these rates applying an inverse modelling approach to down core data accounting for molecular diffusion, sediment burial and compaction. Our model results indicate that 56.7 ± 6.6 % of the particulate organic matter deposited in the study area is not degraded in surface sediments but accumulates below 10 cm sediment depth. This burial efficiency is substantially higher than those previously derived for seafloor areas underlying oxygenated bottom waters. Hence, our study confirms previous studies showing that euxinic bottom water conditions promote the preservation of particulate organic matter in marine sediments.
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    Variations in isoprenoid tetraether lipids through the water column of the Western Pacific Ocean: Implications for sedimentary TEX86 records (2024)
    Elsevier
    Details
    Publication Date: 2024-03-25
    Description: The TetraEther indeX of 86 carbon atoms (TEX86) is widely used as a proxy to reconstruct past sea surface temperatures. Most current applications of TEX86 are primarily based on analyzing the composition of isoprenoid glycerol dialkyl glycerol tetraethers (isoGDGTs) that comprise TEX86 in sediments, with the assumption that the sedimentary isoGDGTs are mainly derived from the surface mixed layer. Here we report on the variations in the isoGDGT distribution, archaeal abundance and community through the water column of the Western Pacific Ocean, directly testing the export depth of isoGDGTs and constraining the temperature records of TEX86. Our data show that maximum isoGDGT concentrations occurred in subsurface waters (150–200 m) with maximum archaeal abundances. The ratio between isoGDGTs bearing 2 vs. 3 cyclopentane moieties, i.e. [2/3] ratio, increased with depth, which is likely related to the shift of the archaeal community from Ca. Nitrosopelagicus-dominance to norank_f__Nitrosopumilaceae-dominance. Models based on the [2/3] ratios in the water column predicted an average export depth of isoGDGTs to sediments of around 150–200 m, consistent with the robust relationship between the compiled sedimentary TEX86 and the annual mean subsurface temperature. Taken together, our findings support that TEX86 records subsurface rather than surface temperatures in the open ocean.
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    New Technologies for Monitoring and Upscaling Marine Ecosystem Restoration in Deep-Sea Environments (2024)
    Elsevier
    Details
    Publication Date: 2024-03-25
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  • 80
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    Surface ocean biogeochemistry and deep ocean circulation control relationships between nutrient-type trace metals (Cd, Ni, Cu, and Zn) and nutrients in the South Atlantic Ocean near the subtropical front (2024)
    Elsevier
    Details
    Publication Date: 2024-03-25
    Description: The ocean region along the latitude of 40oS in the South Atlantic, characterized by enhanced primary productivity, forms a transition zone between the nutrient replete but iron depleted Southern Ocean, and the nitrate and iron depleted Subtropical Gyre. Here, we present distributions of nutrient-type dissolved and particulate trace metals (dTMs and pTMs) including cadmium (Cd), nickel (Ni), copper (Cu), and zinc (Zn) in the South Atlantic from the GEOTRACES GA10 cruises. Phytoplankton uptake, riverine and atmospheric inputs shaped dTM and pTM concentrations in surface waters (dCd 27.8±36.0 pmol kg-1, n=222; dCu 0.732±0.429 nmol kg-1, n=222; dNi 3.38±0.52 nmol kg-1, n=219; dZn 0.332±0.398 nmol kg-1, n=214). Subsurface nutrients and dTMs (dCd 563±184 pmol kg-1, n=335; dCu 1.819±0.773 nmol kg-1, n=334; dNi 6.19±1.06 nmol kg-1, n=330; dZn 3.71±2.10 nmol kg-1, n=333) were controlled by the mixing of Antarctic origin waters and North Atlantic Deep Waters (NADW) with negligible contributions from local remineralization. Dissolved and particulate TMs in the Argentine Basin showed elevated concentrations towards the seafloor because of benthic inputs. Direct hydrothermal inputs of dTMs and pTMs to deep waters were not observed along the transect. The Cd-Cu-Zn-phosphate stoichiometries of Antarctic origin waters were set by a combination of dynamic physical circulation and preferential uptake of Cd, Cu, and Zn relative to phosphate in surface waters because of a dominance by diatoms in the Southern Ocean. Water mass mixing subsequently produced convoluted dCu-P and dZn-P relationships and apparent linear dCd-P and dNi-P relationships in the South Atlantic. More importantly, endmember characteristics of Antarctic waters and NADW are largely fixed in their formation regions in high latitude oceans. Therefore, the highly dynamic high latitude oceans are key regions that supply nutrients and TMs at specific ratios to low latitude oceans via the thermohaline circulation. Changes to processes in the high latitude oceans may have consequences for marine primary productivity downstream, and hence the global carbon cycle.
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  • 81
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    Comprehensive molecular‐isotopic characterization of archaeal lipids in the Black Sea water column and underlying sediments (2024)
    Wiley
    Details
    Publication Date: 2024-03-25
    Description: The Black Sea is a permanently anoxic, marine basin serving as model system for the deposition of organic-rich sediments in a highly stratified ocean. In such systems, archaeal lipids are widely used as paleoceanographic and biogeochemical proxies; however, the diverse planktonic and benthic sources as well as their potentially distinct diagenetic fate may complicate their application. To track the flux of archaeal lipids and to constrain their sources and turnover, we quantitatively examined the distributions and stable carbon isotopic compositions (delta 13C) of intact polar lipids (IPLs) and core lipids (CLs) from the upper oxic water column into the underlying sediments, reaching deposits from the last glacial. The distribution of IPLs responded more sensitively to the geochemical zonation than the CLs, with the latter being governed by the deposition from the chemocline. The isotopic composition of archaeal lipids indicates CLs and IPLs in the deep anoxic water column have negligible influence on the sedimentary pool. Archaeol substitutes tetraether lipids as the most abundant IPL in the deep anoxic water column and the lacustrine methanic zone. Its elevated IPL/CL ratios and negative delta 13C values indicate active methane metabolism. Sedimentary CL- and IPL-crenarchaeol were exclusively derived from the water column, as indicated by non-variable delta 13C values that are identical to those in the chemocline and by the low BIT (branched isoprenoid tetraether index). By contrast, in situ production accounts on average for 22% of the sedimentary IPL-GDGT-0 (glycerol dibiphytanyl glycerol tetraether) based on isotopic mass balance using the fermentation product lactate as an endmember for the dissolved substrate pool. Despite the structural similarity, glycosidic crenarchaeol appears to be more recalcitrant in comparison to its non-cycloalkylated counterpart GDGT-0, as indicated by its consistently higher IPL/CL ratio in sediments. The higher TEX86, CCaT, and GDGT-2/-3 values in glacial sediments could plausibly result from selective turnover of archaeal lipids and/or an archaeal ecology shift during the transition from the glacial lacustrine to the Holocene marine setting. Our in-depth molecular-isotopic examination of archaeal core and intact polar lipids provided new constraints on the sources and fate of archaeal lipids and their applicability in paleoceanographic and biogeochemical studies.
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  • 82
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    Implications of ocean acidification on micronutrient elements-iron, copper and zinc, and their primary biological impacts: A review (2024)
    Elsevier
    Details
    Publication Date: 2024-03-26
    Description: This review has been undertaken to understand the effectiveness of ocean acidification on oceanic micronutrient metal cycles (iron, copper and zinc) and its potential impacts on marine biota. Ocean acidification will slow down the oxidation of Fe(II) thereby retarding Fe(III) formation and subsequent hydrolysis/precipitation leading to an increase in iron bioavailability. Further, the increased primary production sustains enzymatic bacteria assisted Fe(III) reduction and subsequently the binding of weaker ligands favours the dissociation of free Fe(II) ions, thus increasing the bioavailability. The increasing pCO2 condition increases the bioavailability of copper ions by decreasing the availability of free CO32− ligand concentration. The strong complexation by dissolved organic matter may decrease the bioavailable iron and zinc ion concentration. Since ocean acidification affects the bioavailability of essential metals, studies on the uptake rates of these elements by phytoplankton should be carried out to reveal the future scenario and its effect on natural environment.
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  • 83
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    Introduction to special issue on seabed prospecting technology (2024)
    Wiley
    Details
    Publication Date: 2024-04-03
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  • 84
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    CS2 Cycling in Seawater: Dark Production and UV Light Driven Consumption (2024)
    AGU (American Geophysical Union) | Wiley
    Details
    Publication Date: 2024-04-03
    Description: Carbon disulfide (CS2) has recently gained attention as an important precursor for the atmospheric trace gas carbonyl sulfide (OCS), which delivers sulfur to the stratospheric sulfur layer and impacts the radiative budget of the Earth. CS2 is naturally produced in the ocean and emitted to the atmosphere. However, the magnitude of its marine emissions is only poorly constrained due to lacking understanding of its production and consumption processes. Here, we present incubation experiments with and without UV light treatment and provide evidence for a previously not considered UV-light-driven degradation process of CS2 in seawater, following first-order kinetics. In addition to its already known photochemical production process, CS2 production is found in the dark, depending on the amount of dissolved organic sulfur present in seawater. We provide novel production and consumption rates of CS2 in seawater that pave the way toward mechanistically quantifying marine emissions of this important trace gas. Key Points: - Carbon disulfide in seawater is degraded by UV light at time scales of days - Carbon disulfide is produced in seawater without UV light at rates comparable to photochemical production - Carbon disulfide dark production is limited by dissolved organic sulfur
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  • 85
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    Optical Characterization of Marine Aerosols Using a Morphologically Realistic Model With Varying Water Content: Implications for Lidar Applications and Passive Polarimetric Remote Sensing (2024)
    AGU (American Geological Society) | Wiley
    Details
    Publication Date: 2024-04-03
    Description: Retrieving the physical properties and water content of marine aerosols requires understanding the links between the particles' optical and microphysical properties. By using a morphologically realistic model with varying salt mass fractions fm, describing the transition from irregularly shaped, dry salt crystals to brine-coated geometries, optical properties relevant to polarimetric remote sensing are computed at wavelengths of 532 and 1,064 nm. The extinction cross section and its color ratio depend on particle size, but are insensitive to changes in fm; thus, measured extinction coefficients at two wavelengths contain information on both particle number and size. The lidar ratio's dependence on both size and wavelength has implications for inverting the lidar equation. The results suggest that active observations of the backscattering cross section's color ratio and the depolarization ratio, as well as, passive observations of the degree of linear polarization offer avenues to obtain the water content of marine aerosols. Key Points: - Modeled extinction coefficient of marine aerosol depends on particle radius and wavelength, but not on water content - The depolarization ratio and the color ratio of the backscattering cross section generally decrease with growing aerosol water content - The linear polarization peak near backscattering angles at NIR wavelength could be used in passive polarimetry to retrieve water content
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  • 86
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    Noble gases in groundwater reflect wet-season temperature in an arid, monsoonal, and mountainous environment (2024)
    Elsevier
    Details
    Publication Date: 2024-04-03
    Description: Highlights • Present day infiltration conditions in an monsoonal environment are studied. • Noble gas concentrations in groundwater are fixed near the soil surface. • Noble gas temperatures represent seasonal infiltration conditions in the monsoon. • Holocene and modern infiltration conditions are quite similar in southern Oman. Abstract Comparing directly measured soil temperatures with noble gas recharge temperatures (NGTs) inferred from noble gas concentrations indicates that the infiltrating soil water equilibrates with soil air near the soil surface during the rainy season. Therefore, NGTs of groundwater recently recharged by the Indian Summer Monsoon (ISM) in the Dhofar Mountains in southern Oman reflect the soil temperatures of the 3-month period and do not represent an annual mean. This finding highlights the need to account for seasonality when interpreting NGT data in regions with pronounced dry and wet seasons. We extend the observations from the southern flank of the Dhofar Mountains to three wells situated on the northern flank of the Dhofar Mountains. Two of these wells yield water of Holocene age that was recharged by the monsoon, their NGT signals are therefore classified as seasonal. The NGT calculated from a third well for recharge conditions during the Last Glacial Maximum (LGM), when the ISM was absent, is approximately 3 °C lower than that of the two Holocene wells. The lower LGM noble gas temperature corresponds well with the lower annual Sea Surface Temperature (SST) in the nearby Arabian Sea. NGTs from published studies from northern Oman are 1–3 °C higher when compared with our data of the same period in the southern Oman. We explain this regional difference of reconstructed temperatures for the LGM and Holocene groundwater with a more continental climatic influence on the infiltration conditions further to the north. The published NGTs from northern Oman show a large temperature difference between the late Holocene and the LGM. In view of our finding of seasonal NGT signals under monsoonal climate, part of this difference may reflect a change in the precipitation regime rather than in air temperature.
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    Numerical analysis of the dynamic gas hydrate system and multiple BSRs in the Danube paleo-delta, Black Sea (2024)
    Elsevier
    Details
    Publication Date: 2024-04-03
    Description: Highlights • This study simulates the sedimentation-driven development of multiple stacked BSRs in the Danube paleo-delta, Black Sea. • Formation of multiple BSRs in the Black Sea is controlled by the sequence of sedimentation events of the levees induced by sea-level changes. • Kinetics of phase transitions plays a key role in the coexistence, location, and timing of the multiple BSRs. • Development of multiple stacked BSRs is possible only under a narrow range of parameters, unique for the Danube delta setting. Abstract The gas hydrate stability zone (GHSZ) is defined by pressure-temperature-salinity (pTS) constraints of natural gas hydrate (GH) system. It refers to a depth interval which usually extends several hundred meters into the sediment column at sufficient water depths. The lower boundary of the GHSZ often coincides in seismic reflection data with a bottom simulating reflector (BSR), which indicates the transition between the underlying free gas and the overlying no-free gas zone at the thermodynamic stability boundary. The GHSZ in geological systems is dynamic and can shift in response to sedimentation processes and/or changes in environmental conditions such as bottom water temperatures, hydrostatic pressure, and water salinity. The appearance of multiple BSRs has been interpreted as remnants of former GHSZ shifts which have persisted over geological timescales. In this study, we numerically simulate the sedimentation-driven development of multiple stacked BSRs in the Danube deep-sea fan in the Black Sea. We show that in this dynamic sediment depositional regime sufficient amounts of residual gas remain trapped in the former GHSZ, given sufficiently high initial gas hydrate saturations, so that paleo-BSRs could persist over long time scales (similar to 300 kyr). In particular, the formation and persistence of multiple BSRs in the Danube Delta is controlled by the sequence of sedimentation events of the levees induced by sea-level change. The kinetics of methane phase transitions between gas hydrate, dissolved methane, and free gas plays a key role in the coexistence, location and timing of the multiple BSRs. Thus, For a given permeability, distinct multiple BSRs appear only for a narrow range of GH formation (10(-14) 〈 k(f) [mol/m(2) Pa s] 〈= 10(-12)) and dissociation rates (10(-16) 〈 k(d) [mol/m(2) Pa s] 〈 10(-14)).
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  • 88
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    The decline of kilkas, sturgeons and seals in the Caspian Sea: The potential of qualitative loop analysis for the cumulative assessment of multiple drivers of stress (2024)
    Elsevier
    Details
    Publication Date: 2024-04-03
    Description: Multiple stressors often act concomitantly on ecosystems but detection of species responses follows the “single species-single driver” strategy, and cumulative impacts are seldom considered. During 1990–2010, multiple perturbations in the Caspian Sea, led to the decline of kilka, sturgeon and Caspian seal populations. Specific causes for their collapse were identified but a cumulative assessment has never been carried out. Using loop analysis, a qualitative modelling technique suitable in poor-data contexts, we show how multiple drivers can be combined to assess their cumulative impact. We confirm that the decline of kilka, sturgeon and Caspian seal populations is compatible with a net effect of the concomitant perturbations. Kilkas collapse was certainly due to the outburst of M. leidyi and overfishing. In addition, the excess nutrient might have conspired to reduce these populations. The interplay between concurrent drivers produces trade-offs between opposite effects and ecosystem management must face this challenge
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  • 89
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    Slow Slip Events in New Zealand: Irregular, yet Predictable? (2024)
    AGU (American Geophysical Union) | Wiley
    Details
    Publication Date: 2024-04-03
    Description: Current earthquake forecasting approaches are mainly based on probabilistic assumptions, as earthquakes seem to occur randomly. Such apparent randomness can however be caused by deterministic chaos, rendering deterministic short‐term forecasts possible. Due to the short historical and instrumental record of earthquakes, chaos detection has proven challenging, but more frequently occurring slow slip events (SSE) are promising candidates to probe for determinism. Here, we characterize the SSE signatures obtained from GNSS position time series in the Hikurangi Subduction Zone (New Zealand) to investigate whether the seemingly random SSE occurrence is governed by chaotic determinism. We find evidence for deterministic chaos for stations recording shallow SSEs, suggesting that short‐term deterministic forecasting of SSEs, similar to weather forecasts, might indeed be possible over timescales of a few weeks. We anticipate that our findings could open the door for next‐generation SSE forecasting, adding new tools to existing probabilistic approaches. Plain Language Summary Since earthquakes appear to occur randomly, the currently available probabilistic predictions are based on past earthquake records. These predictions estimate the likelihood of an earthquake of a given magnitude occurring within a defined time period. In contrast to such probabilistic approaches, deterministic systems are fully predictable, albeit often confined to short time scales due to their potential chaotic behavior. Probing for deterministic predictability in the earthquake cycle is intractable due to the limited historical instrumental record. However, frequently occurring slow slip events ‐ captured by transient GNSS displacements that can last several weeks ‐ provide a unique opportunity to explore deterministic predictability in these types of slow earthquakes. By studying GNSS time series from various stations on New Zealand’s North Island, we have discovered evidence suggesting that these irregularly occurring slow slip events might be governed by chaotic determinism. This implies the potential to forecast both timing and magnitude of slow slip events a few weeks in advance using deterministic methods, much like we predict weather patterns. Consequently, our theoretical findings could therefore pave the way for innovative approaches to short‐term slow slip forecasting. Key Points Nonlinear analysis of GNSS displacement time series unveils evidence for deterministic chaos in slow slip events in New Zealand Our theoretical findings imply that irregularly occurring slow slip events could potentially be forecasted a few weeks in advance
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  • 90
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    Mid-Miocene silicic explosive volcanism of the Tokaj Mts., eastern-central Europe: Eruption chronology, geochemical fingerprints and petrogenesis (2024)
    Elsevier
    Details
    Publication Date: 2024-04-03
    Description: Highlights • Four rhyolitic explosive eruption events were distinguished from 13.1 Ma to 11.6 Ma. • Silicic volcanism occurred at termination of subduction in a thinning lithosphere. • Rhyolites show extreme magma differentiation and reduced-dry character. • Zircon trace element and Hf isotope fingerprint is an effective correlation tool. Abstract The Tokaj Mts. volcanism occurred in a thinning continental lithosphere regime at the final stage of the subduction process. Using high-precision zircon U-Pb dating, four major explosive eruption events were distinguished. Among them the 13.1 Ma Sátoraljaújhely and the 12.0 Ma Szerencs eruptions could have yielded large amount of volcanic material (possibly 〉 100 km3) and they were associated with caldera collapse as shown by the several hundred-metre-thick pyroclastic deposits and the long (〉100 km) runout pyroclastic flow in case of the 13.1 Ma eruption. The 12.3 Ma Hegyköz and the 11.6 Ma Vizsoly eruptions were relatively smaller. The volcanic products can be readily distinguished by zircon and glass trace elements and trace element ratios, which can be used for fingerprinting and to correlate with distal deposits. The Rb, Ba, Sr content and strong negative Eu-anomaly of the glasses reflect extreme crystal fractionation, particularly for the Szerencs rhyolitic magma. The silicic volcanic products of the Tokaj Mts. show compositional similarities with the so-called ‘dry–reduced–hot’ rhyolite type consistent with an origin in an extensional environment, where the primary magmas were formed by near-adiabatic decompression melting in the mantle with subordinate fluid flux. In contrast, some of the older Bükkalja rhyolitic magmas evolved via more hydrous evolutionary paths, where amphibole played a role in the control of the trace element budget. The significant increase of zircon ε Hf values from −8.8 to + 0.2 in the rhyolitic pyroclastic rocks of Tokaj Mts. with time implies that mantle-derived magmas became more dominant. This can be explained by the specific tectonic setting, i.e. the final stage of subduction when the descending subducted slab became almost vertical, which exerted a pull in the upper lithosphere leading to thinning and accelerated subsidence as well as asthenospheric mantle flow just before the slab detachment.
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    Plankton community changes during the last 124 000 years in the subarctic Bering Sea derived from sedimentary ancient DNA (2024)
    Oxford University Press
    Details
    Publication Date: 2024-04-05
    Description: Current global warming results in rising sea-water temperatures, and the loss of sea ice in arctic and subarctic oceans impacts the community composition of primary producers with cascading effects on the food web and potentially on carbon export rates. This study analyzes metagenomic shotgun and diatom rbcL amplicon-sequencing data from sedimentary ancient DNA (sedaDNA) of the subarctic western Bering Sea that records phyto- and zooplankton community changes over the last glacial–interglacial cycle, including the last interglacial period (Eemian). Our data show that interglacial and glacial plankton communities differ, with distinct Eemian and Holocene plankton communities. The generally warm Holocene period is dominated by pico-sized cyanobacteria and bacteria-feeding heterotrophic protists, while the Eemian period is dominated by eukaryotic pico-sized chlorophytes and Triparmaceae. In contrast, the glacial period is characterized by micro-sized phototrophic protists, including sea-ice associated diatoms in the family Bacillariaceae and co-occurring diatom-feeding crustaceous zooplankton. Our deep-time record of plankton community changes reveals a long-term decrease in phytoplankton cell size coeval with increasing temperatures, and resembling community changes in the currently warming Bering Sea. The phytoplankton community in the warmer-than-present Eemian period is distinct from modern communities and limits the use of the Eemian as an analog for future climate scenarios. However, under enhanced future warming, the expected shift towards the dominance of small-sized phytoplankton and heterotrophic protists might result in an increased productivity, whereas the community’s potential of carbon export will be decreased, thereby weakening the subarctic Bering Sea’s function as an effective carbon sink.
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  • 92
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    Deep Fault‐Controlled Fluid Flow Driving Shallow Stratigraphically Constrained Gas Hydrate Formation: Urutī Basin, Hikurangi Margin, New Zealand (2024)
    AGU (American Geophysical Union) | Wiley
    Details
    Publication Date: 2024-04-05
    Description: The Hikurangi Margin east of New Zealand's North Island hosts an extensive gas hydrate province with numerous gas hydrate accumulations related to the faulted structure of the accretionary wedge. One such hydrate feature occurs in a small perched upper‐slope basin known as Urutī Basin. We investigated this hydrate accumulation by combining a long‐offset seismic line (10‐km‐long receiver array) with a grid of high‐resolution seismic lines acquired with a 600‐m‐long hydrophone streamer. The long‐offset data enable quantitative velocity analysis, while the high‐resolution data constrain the three‐dimensional geometry of the hydrate accumulation. The sediments in Urutī Basin dip landward due to ongoing deformation of the accretionary wedge. These strata are clearly imaged in seismic data where they cross a distinct bottom simulating reflection (BSR) that dips counterintuitively in the opposite direction to the regional dip of the seafloor. BSR‐derived heat flow estimates reveal a distinct heat flow anomaly that coincides spatially with the upper extent of a landward‐verging thrust fault. We present a conceptual model of this gas hydrate system that highlights the roles of fault‐controlled fluid flow at depth merging into strata‐controlled fluid flow into the hydrate stability zone. The result is a layer‐constrained accumulation of concentrated gas hydrate in the dipping strata. Our study provides new insight into the interplay between deep faulting, fluid flow and gas hydrate formation within an active accretionary margin. Plain Language Summary Gas hydrates are ice‐like substances in which natural gas molecules are trapped in a cage of water molecules. They exist where the pressure is high, temperature is cold, and enough methane is present. These conditions exist in the marine environment at water depths greater than 300–500 m near sediment‐rich continental margins and in polar regions. It is important to study gas hydrates because they represent a significant part of the Earth's carbon budget and influence the flow of methane into the oceans and atmosphere. In this study, we use the seismic reflection method to generate images of gas‐hydrate‐bearing marine sediments east of New Zealand. Our data reveal an intriguing relationship between deep‐sourced fluid flow upward along a tectonic fault, and shallower flow through dipping sediments. This complex fluid flow pattern has led to disruption of the gas hydrate system and the formation of concentrated gas hydrate deposits within the dipping sediments. Our study highlights the relationships between relatively deep tectonic processes (faulting and fluid flow) and the shallow process of gas hydrate formation in an active subduction zone. Key Points A distinct gas‐hydrate to free‐gas transition is mapped using high‐ and low‐frequency seismic data Gas and hydrate accumulations in the Urutī Basin are controlled by the structural setting, ongoing deep‐sourced fluid flow, and near surface stratigraphy Regions of high modeled heat flow can be directly related to accumulations of gas and gas hydrates
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  • 93
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    Can Glacial Sea‐Level Drop‐Induced Gas Hydrate Dissociation Cause Submarine Landslides? (2024)
    AGU (American Geophysical Union) | Wiley
    Details
    Publication Date: 2024-04-05
    Description: We conducted two‐dimensional numerical simulations to investigate the mechanisms underlying the strong spatiotemporal correlation observed between submarine landslides and gas hydrate dissociation due to glacial sea‐level drops. Our results suggest that potential plastic deformation or slip could occur at localized and small scales in the shallow‐water portion of the gas hydrate stability zone (GHSZ). This shallow‐water portion of the GHSZ typically lies within the area enclosed by three points: the BGHSZ–seafloor intersection, the seafloor at ∼600 m below sea level (mbsl), and the base of the GHSZ (BGHSZ) at ∼1,050 mbsl in low‐latitude regions. The deep BGHSZ (〉1,050 mbsl) could not slip; therefore, the entire BGHSZ was not a complete slip surface. Glacial hydrate dissociation alone is unlikely to cause large‐scale submarine landslides. Observed deep‐water (much greater than 600 mbsl) turbidites containing geochemical evidence of glacial hydrate dissociation potentially formed from erosion or detachment in the GHSZ pinch‐out zone. Plain Language Summary Many submarine landslides spatiotemporally correlate with gas hydrate dissociation. However, direct mechanical evidence supporting whether the overpressure and deformation due to glacial sea‐level drop‐induced hydrate dissociation are adequate for triggering submarine landslides is lacking. Here, we present two‐dimensional thermal‐hydraulic‐chemical and geomechanical models of a gas‐hydrate system in response to glacial sea‐level drops and conduct sensitivity analyses of the model behavior under a wide range of key conditions from a global perspective. Our simulations suggest that glacial hydrate dissociation might induce plastic deformation or slip at localized and small scales only possibly within the shallow‐water portion of the hydrate stability zone. The deep part (〉1,050 m below sea level) of the bottom boundary of the hydrate stability zone could not slip; therefore, the entire bottom boundary of the hydrate stability zone was not a complete slip surface. We demonstrate that glacial hydrate dissociation alone is unlikely to trigger large‐scale submarine landslides. Our work highlights the vicinity of the upper limit of the hydrate stability zone (where the base of the hydrate stability zone intersects the seafloor) as an important area for investigating overpressure and focused fluid flow, localized plastic deformation or slip, and downslope sediment transport related to glacial hydrate dissociation. Key Points Glacial hydrate dissociation might cause potential plastic deformation or slip at localized and small scales in shallow parts of the GHSZ The large deformation surface at the BGHSZ boundary of the potential plastic deformation zone was not a complete slip surface Glacial sea‐level drop‐induced gas hydrate dissociation alone is unlikely to have caused large‐scale submarine landslides
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    A single Prochlorococcus ecotype dominates the tropical Bay of Bengal with ultradian growth (2024)
    Wiley
    Details
    Publication Date: 2024-04-10
    Description: The Bay of Bengal (BoB) spans 〉2.2 million km(2) in the northeastern Indian Ocean and is bordered by dense populations that depend upon its resources. Over recent decades, a shift from larger phytoplankton to picoplankton has been reported, yet the abundance, activity, and composition of primary producer communities are not well-characterized. We analysed the BoB regions during the summer monsoon. Prochlorococcus ranged up to 3.14 x 10(5) cells mL(-1 )in the surface mixed layer, averaging 1.74 +/- 0.46 x 10(5) in the upper 10 m and consistently higher than Synechococcus and eukaryotic phytoplankton. V1-V2 rRNA gene amplicon analyses showed the High Light II (HLII) ecotype formed 98 +/- 1% of Prochlorococcus amplicons in surface waters, comprising six oligotypes, with the dominant oligotype accounting for 65 +/- 4% of HLII. Diel sampling of a coherent water mass demonstrated evening onset of cell division and rapid Prochlorococcus growth between 1.5 and 3.1 div day-1, based on cell cycle analysis, as confirmed by abundance-based estimates of 2.1 div day(-1). Accumulation of Prochlorococcus produced by ultradian growth was restricted by high loss rates. Alongside prior Arabian Sea and tropical Atlantic rates, our results indicate Prochlorococcus growth rates should be reevaluated with greater attention to latitudinal zones and influences on contributions to global primary production.
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    Vertical acoustic blanking in seismic data from the German North Sea: a spotlight to shallow gas‐bearing incised channels (2024)
    Wiley
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    Publication Date: 2024-04-10
    Description: Seismic data from the North Sea commonly show vertical acoustic blanking (VAB) often interpreted as fluid conduits with implications for Quaternary development. The robustness of this interpretation has long been controversial as the infill of tunnel valleys can also cause vertical blanking. Using 2D and 3D seismic data and sediment echosounder data from the German North Sea, we investigate VAB to determine a geological or imaging origin of these anomalies. We detected multiple VAB occurrences throughout the North Sea. 3D data from the Ducks Beak (‘Entenschnabel’) reveal a correlation of VAB with bright spots in incised channels directly below the seafloor. Large source–receiver distances allow imaging the subsurface below the channel without signal penetrating through it (undershooting). This method removes the blanking. Energy absorption by shallow biogenic gas trapped within the channels explains the observed VAB. Hence, the blanking represents an imaging artifact, highlighting the need for careful seismic processing with sufficient offset before interpreting such anomalies as fluid pathways. The channels belong to a postglacial channel system related to the now submerged lowlands of Doggerland. This work demonstrates the usability of mapping VAB to detect shallow features for paleo‐landscape reconstruction and identification of shallow gas for hazard assessments, for example.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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    The Arctic summer microbiome across Fram Strait: Depth, longitude, and substrate concentrations structure microbial diversity in the euphotic zone (2024)
    Wiley
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    Publication Date: 2024-04-10
    Description: The long-term dynamics of microbial communities across geographic, hydrographic, and biogeochemical gradients in the Arctic Ocean are largely unknown. To address this, we annually sampled polar, mixed, and Atlantic water masses of the Fram Strait (2015–2019; 5–100 m depth) to assess microbiome composition, substrate concentrations, and oceanographic parameters. Longitude and water depth were the major determinants (~30%) of microbial community variability. Bacterial alpha diversity was highest in lower-photic polar waters. Community composition shifted from west to east, with the prevalence of, for example, Dadabacteriales and Thiotrichales in Arctic- and Atlantic-influenced waters, respectively. Concentrations of dissolved organic carbon peaked in the western, compared to carbohydrates in the chlorophyll-maximum of eastern Fram Strait. Interannual differences due to the time of sampling, which varied between early (June 2016/2018) and late (September 2019) phytoplankton bloom stages, illustrated that phytoplankton composition and resulting availability of labile substrates influence bacterial dynamics. We identified 10 species clusters with stable environmental correlations, representing signature populations of distinct ecosystem states. In context with published metagenomic evidence, our microbial-biogeochemical inventory of a key Arctic region establishes a benchmark to assess ecosystem dynamics and the imprint of climate change.
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    Controls on distributions of aluminium, manganese and cobalt in the South Atlantic Ocean along GEOTRACES transect GA10 (2024)
    Elsevier
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    Publication Date: 2024-04-10
    Description: Trace metals (TMs) manganese (Mn), cobalt (Co), and aluminium (Al) have important geochemical and biological roles in the ocean. Here, we present full depth profiles of dissolved (d) and particulate Al, Mn, and Co along the latitude of 40 °S in the South Atlantic Ocean from the GEOTRACES GA10 cruises that operated in austral spring 2010 and summer 2011. The region is characterized by enhanced primary productivity and forms a key transition zone between the Southern Ocean and South Atlantic Subtropical Gyre. The mean concentrations of dAl, dCo, and dMn (±standard deviation) were 3.36 ± 2.65 nmol kg−1, 35.3 ± 17.6 pmol kg−1, and 0.624 ± 1.08 nmol kg−1, respectively. Their distributions in surface waters were determined by external sources and complex internal biogeochemical processes. Specifically, surface ocean dCo was controlled by the interplay between phytoplankton uptake, remineralization and external inputs; dMn was likely determined by the formation and photoreduction of Mn-oxides; and dAl was supplied by atmospheric deposition and removed by scavenging onto particles. Fluvial and sedimentary inputs near the Rio de La Plata estuary and benthic sources from the Agulhas Bank resulted in elevated dTM concentrations in near-shore surface waters. These externally sourced dTMs were effectively delivered to the open ocean by offshore diffusion and/or advection, and potentially facilitated enhanced primary productivity along the transect. The distributions of dTMs at depth were predominantly controlled by the mixing of North Atlantic Deep Water (NADW) and waters of Antarctic origin (e.g., Upper Circumpolar Water (UCDW) and Antarctic Bottom Water (AABW)). The calculated endmember concentrations of dAl and dCo in NADW showed minor decreases in the SASTG following north–south transport, suggesting removal rates of 0.064 nM/year and 0.035–0.075 pM/year, respectively. The endmember concentration of dCo in AABW was maintained at ∼30 pmol kg−1 without evidence for scavenging removal in the Southern Ocean and SASTG (time frame 〉400 years). The concentrations of dMn in NADW and AABW were between 0.1 and 0.16 nmol kg−1, and any elevated dMn concentrations were ascribed to local external inputs (e.g., from sediments in the Argentine Basin and hydrothermal activity near the Mid-Atlantic Ridge). Hence, four controlling factors (sources, internal cycling, water mass mixing and time) need to be considered when assessing TM distributions in the global ocean, even for TMs that are vulnerable to scavenging removal processes. Because the deep waters formed in high latitude oceans are crucial components of the global thermohaline overturning system, any processes (e.g., glacier melting, upwelling and sinking, and biological activity) that impact the preformed dTM concentrations in high latitude oceans will determine the downstream dTM distributions. Therefore, the sources and sinks of TMs and associated biological activity in high latitude oceans could engender basin to global scale impacts on seawater distributions of Al, Co, and Mn and their stoichiometric relationships with macronutrients, and the global biogeochemical cycles of these scavenged-type TMs.
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    Taming the terminological tempest in invasion science (2024)
    Wiley
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    Publication Date: 2024-04-10
    Description: Standardised terminology in science is important for clarity of interpretation and communication. In invasion science - a dynamic and rapidly evolving discipline - the proliferation of technical terminology has lacked a standardised framework for its development. The result is a convoluted and inconsistent usage of terminology, with various discrepancies in descriptions of damage and interventions. A standardised framework is therefore needed for a clear, universally applicable, and consistent terminology to promote more effective communication across researchers, stakeholders, and policymakers. Inconsistencies in terminology stem from the exponential increase in scientific publications on the patterns and processes of biological invasions authored by experts from various disciplines and countries since the 1990s, as well as publications by legislators and policymakers focusing on practical applications, regulations, and management of resources. Aligning and standardising terminology across stakeholders remains a challenge in invasion science. Here, we review and evaluate the multiple terms used in invasion science (e.g. 'non-native', 'alien', 'invasive' or 'invader', 'exotic', 'non-indigenous', 'naturalised', 'pest') to propose a more simplified and standardised terminology. The streamlined framework we propose and translate into 28 other languages is based on the terms (i) 'non-native', denoting species transported beyond their natural biogeographic range, (ii) 'established non-native', i.e. those non-native species that have established self-sustaining populations in their new location(s) in the wild, and (iii) 'invasive non-native' - populations of established non-native species that have recently spread or are spreading rapidly in their invaded range actively or passively with or without human mediation. We also highlight the importance of conceptualising 'spread' for classifying invasiveness and 'impact' for management. Finally, we propose a protocol for classifying populations based on (i) dispersal mechanism, (ii) species origin, (iii) population status, and (iv) impact. Collectively and without introducing new terminology, the framework that we present aims to facilitate effective communication and collaboration in invasion science and management of non-native species.
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    Physicochemical controls on seawater (2024)
    Elsevier
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    Publication Date: 2024-04-09
    Description: The overriding physicochemical controls in seawater discussed here are the chemical composition and the state of master variables including temperature, pressure, salinity, pH and redox status. Dissolved Organic Matter also plays a major role, but since its properties are not sufficiently well quantified it is described as an emergent master variable at this stage. The theoretical basis for the treatment of equilibrium chemistry and kinetics is presented, together with projections of the future development of seawater chemistry resulting from climate change. Key points • Composition of seawater • Master variables (temperature, pressure, pH, oxygen/redox state) • The role of Dissolved Organic Matter • Equilibrium chemistry • Kinetics • The consequences of ongoing global changes
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    Understanding the complex dynamics of zebra mussel invasions over several decades in European rivers: drivers, impacts and predictions (2024)
    Wiley
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    Publication Date: 2024-04-11
    Description: The zebra mussel Dreissena polymorpha is one of the most successful, notorious, and detrimental aquatic invasive non-native species worldwide, having invaded Europe and North America while causing substantial ecological and socio-economic impacts. Here, we investigated the spatiotemporal trends in this species' invasion success using 178 macroinvertebrate abundance time series, containing 1451 records of D. polymorpha collected across nine European countries between 1972–2019. Using these raw (absolute) abundance data, we examined trends and drivers of occurrences and relative abundances of D. polymorpha within invaded communities. Meta-regression models revealed non-significant trends both at the European level and for the majority of the invaded countries, except for France (significant decreasing trend) and Hungary (marginally positive trend). At the European level, the number of D. polymorpha occurrences over time followed a flat-top bell-shaped distribution, with a steep increase between 1973–1989 followed by a plateau phase prior to significantly declining post-1998. Using a series of climatic and hydromorphological site-specific characteristics of invaded and uninvaded sites from two periods (1998–2002; 2011–2015), we found that native richness, non-native abundance, distance to the next barrier, and elevation were associated with the occurrence of D. polymorpha. We also found that higher native richness and lower latitude were related to lower relative abundances. Using Cohen's D as a measure of D. polymorpha impact, we found that biodiversity within the invaded sites was initially higher than in uninvaded ones, but then declined, suggesting differences in biodiversity trends across invaded and uninvaded sites. While our results emphasise the high invasion success of D. polymorpha, increasing stressors within the context of global change – particularly ongoing climate change – are likely to enhance invasion rates and the impact of D. polymorpha in the near future, exacerbated by the lack of timely and effective management actions.
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