ALBERT

Description: Interpreting the vulnerability of pelagic calcifiers to ocean acidification (OA) is enhanced by an understanding of their critical thresholds and how these thresholds are modified by other climate change stressors (e.g., warming). To address this need, we undertook a three-part data synthesis for pteropods, one of the calcifying zooplankton group. We conducted the first meta-analysis and threshold analysis of literature characterizing pteropod responses to OA and warming by synthetizing dataset comprising of 2,097 datapoints. Meta-analysis revealed the extent to which responses among studies conducted on differing life stages and disparate geographies could be integrated into a common analysis. The results demonstrated reduced calcification, growth, development, and survival to OA with increased magnitude of sensitivity in the early life stages, under prolonged duration, and with the concurrent exposure of OA and warming, but not species-specific sensitivity. Second, breakpoint analyses identified OA thresholds for several endpoints: dissolution (mild and severe), calcification, egg development, shell growth, and survival. Finally, consensus by a panel of pteropod experts was used to verify thresholds and assign confidence scores for five endpoints with a sufficient signal: noise ratio to develop life-stage specific, duration-dependent thresholds. The range of aragonite saturation state from 1.5–0.9 provides a risk range from early warning to lethal impacts, thus providing a rigorous basis for vulnerability assessments to guide climate change management responses, including an evaluation of the efficacy of local pollution management. In addition, meta-analyses with OA, and warming shows increased vulnerability in two pteropod processes, i.e., shell dissolution and survival, and thus pointing toward increased threshold sensitivity under combined stressor effect.

Description: The Sea surface KInematics Multiscale monitoring (SKIM) satellite mission is designed to explore ocean surface current and waves. This includes tropical currents, notably the unknown patterns of divergence and their impact on the ocean heat budget near the Equator, monitoring of the emerging Arctic up to 82.5$(\circ)$N. SKIM will also make unprecedented direct measurements of strong currents, from boundary currents to the Antarctic circumpolar current, and their interaction with ocean waves with expected impacts on air-sea fluxes and extreme waves. For the first time, SKIM will directly measure the ocean surface current vector from space. The main instrument on SKIM is a Ka-band conically scanning, multi-beam Doppler radar altimeter/wave scatterometer that includes a state-of-the-art nadir beam comparable to the Poseidon-4 instrument on Sentinel 6. The well proven Doppler pulse-pair technique will give a surface drift velocity representative of the top two meters of the ocean, after subtracting a large wave-induced contribution. Horizontal velocity components will be obtained with an accuracy better than 7 cm/s for horizontal wavelengths larger than 80~km and time resolutions larger than 15 days, with a mean revisit time of 4 days for of 99\% of the global oceans. This will provide unique and innovative measurements that will further our understanding of the transports in the upper ocean layer, permanently distributing heat, carbon, plankton, and plastics. SKIM will also benefit from co-located measurements of water vapor, rain rate, sea ice concentration, and wind vectors provided by the European operational satellite MetOp-SG(B), allowing many joint analyses. SKIM is one of the two candidate satellite missions under development for ESA Earth Explorer 9. The other candidate is the Far infrared Radiation Understanding and Monitoring (FORUM). The final selection will be announced by September 2019, for a launch in the coming decade.

Description: In this paper we review on the technologies available to make globally quantitative observations of particles, in general, and plankton, in particular, in the world oceans, and for sizes varying from sub-micron to centimeters. Some of these technologies have been available for years while others have only recently emerged. Use of these technologies is critical to improve understanding of the processes that control abundances, distributions and composition of plankton, provide data necessary to constrain and improve ecosystem and biogeochemical models, and forecast changes in marine ecosystems in light of climate change. In this paper we begin by providing the motivation for plankton observations, quantification and diversity qualification on a global scale. We then expand on the state-of-the-art, detailing a variety of relevant and (mostly) mature technologies and measurements, including bulk measurements of plankton, pigment composition, uses of genomic, optical, acoustical methods and analysis using particles counters, flow cytometers and quantitative imaging devices. We follow by highlighting the requirements necessary for a plankton observing system, the approach to achieve it and associated challenges. We conclude with ranked action-item recommendations for the next ten years to move towards our vision of a holistic ocean-wide plankton observing system. Particularly, we suggest to begin with a demonstration project on a GO-SHIP line and/or a long-term observation site and expand from there ensuring that issues associated with methods, observation tools, data analysis, quality assessment and curation are addressed early in the implementation. Global coordination is key for the success of this vision and will bring new insights on processes associated with nutrient regeneration, ocean production, fisheries, and carbon sequestration.

Description: Careful definition and illustrative case studies are fundamental work in developing a Blue Economy. As blue research expands with the world increasingly understanding its importance, policy makers and research institutions worldwide concerned with ocean and coastal regions are demanding further and improved analysis of the Blue Economy. Particularly, in terms of the management connotation, data access, monitoring, and product development, countries are making decisions according to their own needs. As a consequence of this lack of consensus, further dialogue including this cases analysis of the blue economy is even more necessary. This paper consists of four chapters: (I) Understanding the concept of Blue Economy, (II) Defining Blue economy theoretical cases, (III) Introducing Blue economy application cases and (IV) Providing an outlook for the future. Chapters (II) and (III) summarizes all the case studies into nine aspects, each aiming to represent different aspects of the blue economy. This paper is a result of knowledge and experience collected from across the global ocean observing community, and is only made possible with encouragement, support and help of all members. Despite the blue economy being a relatively new concept, we have demonstrated our promising exploration in a number of areas. We put forward proposals for the development of the blue economy, including shouldering global responsibilities to protect marine ecological environment, strengthening international communication and sharing development achievements, and promoting the establishment of global blue partnerships. However, there is clearly much room for further development in terms of the scope and depth of our collective understanding and analysis.

Description: The Atlantic Meridional Overturning Circulation (AMOC) extends from the Southern Ocean to the northern North Atlantic, transporting heat northwards throughout the South and North Atlantic, and sinking carbon and nutrients into the deep ocean. Climate models indicate that changes to the AMOC both herald and drive climate shifts. Intensive trans-basin AMOC observational systems have been put in place to continuously monitor meridional volume transport variability, and in some cases, heat, freshwater and carbon transport. These observational programs have been used to diagnose the magnitude and origins of transport variability, and to investigate impacts of variability on essential climate variables such as sea surface temperature, ocean heat content and coastal sea level. AMOC observing approaches vary between the different systems, ranging from trans-basin arrays (OSNAP, RAPID 26 degrees N, 11 degrees S, SAMBA 34.5 degrees S) to arrays concentrating on western boundaries (e.g., RAPID WAVE, MOVE 16 degrees N). In this paper, we outline the different approaches (aims, strengths and limitations) and summarize the key results to date. We also discuss alternate approaches for capturing AMOC variability including direct estimates (e.g., using sea level, bottom pressure, and hydrography from autonomous profiling floats), indirect estimates applying budgetary approaches, state estimates or ocean reanalyses, and proxies. Based on the existing observations and their results, and the potential of new observational and formal synthesis approaches, we make suggestions as to how to evaluate a comprehensive, future-proof observational network of the AMOC to deepen our understanding of the AMOC and its role in global climate.

Description: The oceans play a key role in global issues such as climate change, food security, and human health. Given their vast dimensions and internal complexity, efficient monitoring and predicting of the planet’s ocean must be a collaborative effort of both regional and global scale. A first and foremost requirement for such collaborative ocean observing is the need to follow well-defined and reproducible methods across activities: from strategies for structuring observing systems, sensor deployment and usage, and the generation of data and information products, to ethical and governance aspects when executing ocean observing. To meet the urgent, planet-wide challenges we face, methods across all aspects of ocean observing should be broadly adopted by the ocean community and, where appropriate, should evolve into “Ocean Best Practices.” While many groups have created best practices, they are scattered across the Web or buried in local repositories and many have yet to be digitized. To reduce this fragmentation, we introduce a new open access, permanent, digital repository of best practices documentation (oceanbestpractices.org) that is part of the Ocean Best Practices System (OBPS). The new OBPS provides an opportunity space for the centralized and coordinated improvement of ocean observing methods. The OBPS repository employs user-friendly software to significantly improve discovery and access to methods. The software includes advanced semantic technologies for search capabilities to enhance repository operations. In addition to the repository, the OBPS also includes a peer reviewed journal research topic, a forum for community discussion and a training activity for use of best practices. Together, these components serve to realize a core objective of the OBPS, which is to enable the ocean community to create superior methods for every activity in ocean observing from research to operations to applications that are agreed upon and broadly adopted across communities. Using selected ocean observing examples, we show how the OBPS supports this objective. This paper lays out a future vision of ocean best practices and how OBPS will contribute to improving ocean observing in the decade to come.

Description: Sustained ocean time series are critical for characterizing marine ecosystem shifts in a time of accelerating, and at times unpredictable, changes. They represent the only means to distinguish between natural and anthropogenic forcings, and are the best tools to explore causal links and implications for human communities that depend on ocean resources. Since the inception of sustained ocean observations, ocean time series have withstood many challenges, most prominently availability of uninterrupted funding and retention of trained personnel. This OceanObs’19 review article provides an overarching vision for sustained ocean time series observations for the next decade, focusing on the growing challenges of maintaining sustained ocean time series, including ship-based and autonomous coastal and open-ocean platforms, as well as remote sensing. In addition to increased diversification of funding sources to include the private sector, NGOs, and other groups, more effective engagement of stakeholders and other end-users will be critical to ensure the sustainability of ocean time series programs. Building a cohesive international time series network will require dedicated capacity to coordinate across observing programs and leverage existing infrastructure and platforms of opportunity. This review article outlines near-term observing priorities and technology needs; explores potential mechanisms to broaden ocean time series data applications and end-user communities; and describes current tools and future requirements for managing increasingly complex multi-platform data streams and developing synthesis products that support science and society. The actionable recommendations outlined herein ultimately form the basis for a robust, sustainable, fit-for-purpose time series network that will foster a predictive understanding of changing ocean systems for the benefit of society.

Description: Almost all the inorganic carbon on Earth is converted into biomass via the Calvin–Benson–Bassham (CBB) cycle. Here, the central carboxylation reaction is catalyzed by ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO), which can be found in numerous primary producers including plants, algae, cyanobacteria, and many autotrophic bacteria. Although RubisCO possesses a crucial role in global biomass production, it is not a perfect catalyst. Therefore, research interest persists on accessing the full potential of yet unexplored RubisCOs. We recently developed an activity-based screen suited to seek active recombinant RubisCOs from the environment—independent of the native host’s culturability. Here, we applied this screen to twenty pre-selected genomic fosmid clones from six cultured proteobacteria to demonstrate that a broad range of phylogenetically distinct RubisCOs can be targeted. We then screened 12,500 metagenomic fosmid clones from six distinct hydrothermal vents and identified forty active RubisCOs. Additional sequence-based screening uncovered eight further RubisCOs, which could then also be detected by a modified version of the screen. Seven were active form III RubisCOs from yet uncultured Archaea. This indicates the potential of the activity-based screen to detect RubisCO enzymes even from organisms that would not be expected to be targeted.

Description: The diversity of life in the sea is critical to the health of ocean ecosystems that support living resources and therefore essential to the economic, nutritional, recreational, and health needs of billions of people. Yet there is evidence that the biodiversity of many marine habitats is being altered in response to a changing climate and human activity. Understanding this change, and forecasting where changes are likely to occur, requires monitoring of organism diversity, distribution, abundance, and health. It requires a minimum of measurements including productivity and ecosystem function, species composition, allelic diversity, and genetic expression. These observations need to be complemented with metrics of environmental change and socio-economic drivers. However, existing global ocean observing infrastructure and programs often do not explicitly consider observations of marine biodiversity and associated processes. Much effort has focused on physical, chemical and some biogeochemical measurements. Broad partnerships, shared approaches, and best practices are now being organized to implement an integrated observing system that serves information to resource managers and decision-makers, scientists and educators, from local to global scales. This integrated observing system of ocean life is now possible due to recent developments among satellite, airborne, and in situ sensors in conjunction with increases in information system capability and capacity, along with an improved understanding of marine processes represented in new physical, biogeochemical, and biological models.

Description: Ocean surface winds, currents, and waves play a crucial role in exchanges of momentum, energy, heat, freshwater, gases, and other tracers between the ocean, atmosphere, and ice. Despite surface waves being strongly coupled to the upper ocean circulation and the overlying atmosphere, efforts to improve ocean, atmospheric, and wave observations and models have evolved somewhat independently. From an observational point of view, community efforts to bridge this gap have led to proposals for satellite Doppler oceanography mission concepts, which could provide unprecedented measurements of absolute surface velocity and directional wave spectrum at global scales. This paper reviews the present state of observations of surface winds, currents, and waves, and it outlines observational gaps that limit our current understanding of coupled processes that happen at the air-sea-ice interface. A significant challenge for the coming decade of wind, current, and wave observations will come in combining and interpreting measurements from (a) wave-buoys and high-frequency radars in coastal regions, (b) surface drifters and wave-enabled drifters in the open-ocean, marginal ice zones, and wave-current interaction “hot-spots,” and (c) simultaneous measurements of absolute surface currents, ocean surface wind vector, and directional wave spectrum from Doppler satellite sensors.

Description: Fluctuations in abundance of dominant species can cause competitive release of resources with consequences on community structure and functioning. In the present study, changes in the intertidal macroinfauna community of an exposed sandy beach were evaluated during two contrasting periods characterized by low and high densities of the yellow clam Amarilladesma mactroides. The increase in clam abundance and biomass was associated with a significant decrease in abundance of the rest of the community. In particular, a decline was observed for the pea crab Austinixa patagoniensis, a commensal species that lives in the burrows of the shrimp Sergio mirim. Our study demonstrates that fluctuations in clam abundance lead to long-term changes in community structure, suggesting the presence of competitive interactions. The environmental stability over the two periods strengthens the hypothesis that the competition between species is crucial for shaping the ecological community. Stable isotope analysis allows discarding trophic competition as mechanism of exclusion. Image maps reveal complementary distribution of species, showing the relevance of the spatial competition, which is mediated by changes in abundance of a third species. Indeed, high densities of A. mactroides reduce the available area for the establishment of the S. mirim burrows, limiting the foraging behavior of its commensal, the pea crab. Such an interaction drives density-dependent exclusion of the pea crab from the intertidal zone following the establishment of the yellow clam population. This study illustrates that spatial competition triggered by the increase of a bed-forming species can have community-wide consequences in exposed sandy beaches

Description: The European Research Infrastructure Consortium “Integrated Carbon Observation System” (ICOS) aims at delivering high quality greenhouse gas (GHG) observations and derived data products (e.g., regional GHG-flux maps) for constraining the GHG balance on a European level, on a sustained long-term basis. The marine domain (ICOS-Oceans) currently consists of 11 Ship of Opportunity lines (SOOP – Ship of Opportunity Program) and 10 Fixed Ocean Stations (FOSs) spread across European waters, including the North Atlantic and Arctic Oceans and the Barents, North, Baltic, and Mediterranean Seas. The stations operate in a harmonized and standardized way based on community-proven protocols and methods for ocean GHG observations, improving operational conformity as well as quality control and assurance of the data. This enables the network to focus on long term research into the marine carbon cycle and the anthropogenic carbon sink, while preparing the network to include other GHG fluxes. ICOS data are processed on a near real-time basis and will be published on the ICOS Carbon Portal (CP), allowing monthly estimates of CO2 air-sea exchange to be quantified for European waters. ICOS establishes transparent operational data management routines following the FAIR (Findable, Accessible, Interoperable, and Reusable) guiding principles allowing amongst others reproducibility, interoperability, and traceability. The ICOS-Oceans network is actively integrating with the atmospheric (e.g., improved atmospheric measurements onboard SOOP lines) and ecosystem (e.g., oceanic direct gas flux measurements) domains of ICOS, and utilizes techniques developed by the ICOS Central Facilities and the CP. There is a strong interaction with the international ocean carbon cycle community to enhance interoperability and harmonize data flow. The future vision of ICOS-Oceans includes ship-based ocean survey sections to obtain a three-dimensional understanding of marine carbon cycle processes and optimize the existing network design.

Description: The Global Ocean Observing System (GOOS) and its partners have worked together over the past decade to break down barriers between open-ocean and coastal observing, between scientific disciplines, and between operational and research institutions. Here we discuss some GOOS successes and challenges from the past decade, and present ideas for moving forward, including highlights of the GOOS 2030 Strategy, published in 2019. The OceanObs' 09 meeting in Venice in 2009 resulted in a remarkable consensus on the need for a common set of guidelines for the global ocean observing community. Work following the meeting led to development of the Framework for Ocean Observing (FOO) published in 2012 and adopted by GOOS as a foundational document that same year. The FOO provides guidelines for the setting of requirements, assessing technology readiness, and assessing the usefulness of data and products for users. Here we evaluate successes and challenges in FOO implementation and consider ways to ensure broader use of the FOO principles. The proliferation of ocean observing activities around the world is extremely diverse and not managed, or even overseen by, any one entity. The lack of coherent governance has resulted in duplication and varying degrees of clarity, responsibility, coordination and data sharing. GOOS has had considerable success over the past decade in encouraging voluntary collaboration across much of this broad community, including increased use of the FOO guidelines and partly effective governance, but much remains to be done. Here we outline and discuss several approaches for GOOS to deliver more effective governance to achieve our collective vision of fully meeting society's needs. What would a more effective and well-structured governance arrangement look like? Can the existing system be modified? Do we need to rebuild it from scratch? We consider the case for evolution versus revolution. Community-wide consideration of these governance issues will be timely and important before, during and following the OceanObs' 19 meeting in September 2019.

Description: The air–sea interface is a key gateway in the Earth system. It is where the atmosphere sets the ocean in motion, climate/weather-relevant air–sea processes occur, and pollutants (i.e., plastic, anthropogenic carbon dioxide, radioactive/chemical waste) enter the sea. Hence, accurate estimates and forecasts of physical and biogeochemical processes at this interface are critical for sustainable blue economy planning, growth, and disaster mitigation. Such estimates and forecasts rely on accurate and integrated in situ and satellite surface observations. High-impact uses of ocean surface observations of essential ocean/climate variables (EOVs/ECVs) include (1) assimilation into/validation of weather, ocean, and climate forecast models to improve their skill, impact, and value; (2) ocean physics studies (i.e., heat, momentum, freshwater, and biogeochemical air–sea fluxes) to further our understanding and parameterization of air–sea processes; and (3) calibration and validation of satellite ocean products (i.e., currents, temperature, salinity, sea level, ocean color, wind, and waves). We review strengths and limitations, impacts, and sustainability of in situ ocean surface observations of several ECVs and EOVs. We draw a 10-year vision of the global ocean surface observing network for improved synergy and integration with other observing systems (e.g., satellites), for modeling/forecast efforts, and for a better ocean observing governance. The context is both the applications listed above and the guidelines of frameworks such as the Global Ocean Observing System (GOOS) and Global Climate Observing System (GCOS) (both co-sponsored by the Intergovernmental Oceanographic Commission of UNESCO, IOC–UNESCO; the World Meteorological Organization, WMO; the United Nations Environment Programme, UNEP; and the International Science Council, ISC). Networks of multiparametric platforms, such as the global drifter array, offer opportunities for new and improved in situ observations. Advances in sensor technology (e.g., low-cost wave sensors), high-throughput communications, evolving cyberinfrastructures, and data information systems with potential to improve the scope, efficiency, integration, and sustainability of the ocean surface observing system are explored.

Description: West Mata is a submarine volcano located in the SW Pacific Ocean between Fiji and Samoa in the NE Lau Basin. West Mata was discovered to be actively erupting at its summit in September 2008 and May 2009. Water-column chemistry and hydrophone data suggest it was probably continuously active until early 2011. Subsequent repeated bathymetric surveys of West Mata have shown that it changed to a style of frequent but intermittent eruptions away from the summit since then. We present new data from ship-based bathymetric surveys, high-resolution bathymetry from an autonomous underwater vehicle, and observations from remotely operated vehicle dives that document four additional eruptions between 2012 and 2018. Three of those eruptions occurred between September 2012 and March 2016; one near the summit on the upper ENE rift, a second on the NE flank away from any rift zone, and a third at the NE base of the volcano. The latter intruded a sill into a basin with thick sediments, uplifted them, and then extruded lava onto the seafloor around them. The most recent of the four eruptions occurred between March 2016 and November 2017 along the middle ENE rift zone and produced pillow lava flows with a shingled morphology and tephra as well as clastic debris that mantled the SE slope. ROV dive observations show that the shallower recent eruptions at West Mata include a substantial pyroclastic component, based on thick (〉1 m) tephra deposits near eruptive vents. The deepest eruption sites lack these near-vent tephra deposits, suggesting that pyroclastic activity is minimal below ∼2500 mbsl. The multibeam sonar re-surveys constrain the timing, thickness, area, morphology, and volume of the new eruptions. The cumulative erupted volume since 1996 suggests that eruptions at West Mata are volume-predictable with an average eruption rate of 7.8 × 106 m3/yr. This relatively low magma supply rate and the high frequency of eruptions (every 1–2 years) suggests that the magma reservoir at West Mata is relatively small. With its frequent activity, West Mata continues to be an ideal natural laboratory for the study of submarine volcanic eruptions.

Description: The Global Ocean Ship-Based Hydrographic Investigations Program (GO-SHIP) provides a globally coordinated network and oversight of 55 sustained decadal repeat hydrographic reference lines. GO-SHIP is part of the global ocean/climate observing systems (GOOS/GCOS) for study of physical oceanography, the ocean carbon, oxygen and nutrient cycles, and marine biogeochemistry. GO-SHIP enables assessment of the ocean sequestration of heat and carbon, changing ocean circulation and ventilation patterns, and their effects on ocean health and Earth's climate. Rapid quality control and open data release along with incorporation of the GO-SHIP effort in the Joint Technical Commission for Oceanography and Marine Meteorology (JCOMM) in situ Observing Programs Support Center (JCOMMOPS) have increased the profile of, and participation in, the program and led to increased data use for a range of efforts. In addition to scientific discovery, GO-SHIP provides climate quality observations for ongoing calibration of measurements from existing and new autonomous platforms. This includes biogeochemical observations for the nascent array of biogeochemical (BGC)-Argo floats; temperature and salinity for Deep Argo; and salinity for the core Argo array. GO-SHIP provides the relevant suite of global, full depth, high quality observations and co-located deployment opportunities that, for the foreseeable future, remain crucial to maintenance and evolution of Argo's unique contribution to climate science. The evolution of GO-SHIP from a program primarily focused on physical climate to increased emphasis on ocean health and sustainability has put an emphasis on the addition of essential ocean variables for biology and ecosystems in the program measurement suite. In conjunction with novel automated measurement systems, ocean color, particulate matter, and phytoplankton enumeration are being explored as GO-SHIP variables. The addition of biological and ecosystem measurements will enable GO-SHIP to determine trends and variability in these key indicators of ocean health. The active and adaptive community has sustained the network, quality and relevance of the global repeat hydrography effort through societally important scientific results, increased exposure, and interoperability with new efforts and opportunities within the community. Here we provide key recommendations for the continuation and growth of GO-SHIP in the next decade.

Description: The ocean plays a vital role in the global climate system and biosphere, providing crucial resources for humanity including water, food, energy and raw materials. There is a compelling need to develop an integrated basin-scale ocean observing system to support of ocean management. We articulate a vision for basin-scale ocean observing - A comprehensive All-Atlantic Ocean Observing Systems that benefits all of us living, working and relying on the ocean. Until now, basin-scale ocean observation has been conducted through loosely-aligned arrangements of national and international efforts. The All-Atlantic Ocean Observing System (AtlantOS) is an ntegrated concept for a forward-looking framework and basin-scale partnership to establish a comprehensive ocean observing system for the Atlantic Ocean as a whole. The system will be sustainable, multi-disciplinary, multi-thematic, efficient, and fit-for-purpose. Platforms, networks, and systems do already exist that operate at various maturity levels. AtlantOS will go beyond the status quo by bringing together the observing communities and countries of the Atlantic basin, providing the opportunity to join and support the system. AtlantOS will build upon the coordinated work of the Global Ocean Observing System (GOOS) and the Group on Earth Observations (GEO), two international bodies that support and coordinate global ocean observing. AtlantOS will complement those efforts and offers a new approach to organizing ocean observing at the basin-scale. The new SystemAtlantOS will focus not only on the physics but also the biology, ecology and biogeochemistry of the ocean and seafloor and will enhance new partnerships among between governments, science, civil society and the private sector.

Description: The NW-SE striking volcanic front in Nicaragua is dissected into a western and an eastern segment separated by 20 km of N-S offset. The Chiltepe volcanic complex lies at the eastern end of the western segment and at the northern tip of the Nejapa-Miraflores tectonic and volcanic lineament that traces the arc offset. The Chiltepe peninsula attained its present shape and composition during highly explosive and effusive volcanic activity through the Late Pleistocene and Holocene, which formed the Chiltepe Formation (CF) and culminated in the 1.9 ka plinian eruption of the Chiltepe tephra. The previous evolution of this volcanic system is recorded in the volcaniclastic Mateare Formation (MF) exposed west (downwind) of the peninsula and separated from the CF by a large regional erosional unconformity. We divide the MF into the lower MF-1 member (22 volcaniclastic units) and the upper MF-2 member (17 volcaniclastic units), which are separated by a major erosional unconformity. The MF-1 was formed by variably evolved (basalt to dacite) magmas from a mantle source that was moderately metasomatized by fluids derived from subducted sediments. These high-Al moderately hydrous magmas fractionated in a tholeiitic fashion, with early plagioclase but delayed magnetite fractionation (initial Fe-Ti enrichments). Apart from the variable degree of differentiation, magmatic conditions during MF-1 remained fairly constant. While MF-1 contains several erosional unconformities suggesting tectonic activity, MF-2 is conformably stratified and the tholeiitic magmas persisted during this time. However, during MF-2, Al-poor tholeiitic compositions gradually replaced the Al-rich of MF-1 without significant changes in metasomatism or degree of melting at their mantle sources. At the same time, a different mantle source was tapped that was richer in the sediment components, and which produced more hydrous magmas that differentiated in a calc-alkaline fashion with early fractionation of both plagioclase and magnetite. Hence, two mantle source compositions were active during MF-2. The erosional interval between MF and CF, associated with strike-slip motion at the Mateare Fault, correlates with initiation of Nejapa-Miraflores volcanism. We postulate that extension along the Najapa-Miraflores fault system facilitated rapid ascent of mafic magmas from a mantle source laterally away from the arc axis that was less metasomatized than sources directly below the arc. On the Chiltepe peninsula, the Nejapa-Miraflores and Chiltepe magma systems interacted to form tholeiitic, less hydrous types of magmas (andesite to dacite) that erupted intermittently with the dominant calc-alkaline hydrous dacites. While associations of tholeiitic and calc-alkaline magmas at other subduction zones have often been attributed to variable intracrustal processes, we here argue for changes in the mantle source, particularly hydration by slab-derived fluids, as the main control on subsequent differentiation behavior. We further attribute the long-term changes in mantle source conditions through MF and CF, possibly over about 1 My, to result from temporal heterogeneity caused by mantle wedge solid flow and possibly variable fluid flow from the slab.

Description: The Argo Program has been implemented and sustained for almost two decades, as a global array of about 4000 profiling floats. Argo provides continuous observations of ocean temperature and salinity versus pressure, from the sea surface to 2000 dbar. The successful installation of the Argo array and its innovative data management system arose opportunistically from the combination of great scientific need and technological innovation. Through the data system, Argo provides fundamental physical observations with broad societally-valuable applications, built on the cost-efficient and robust technologies of autonomous profiling floats. Following recent advances in platform and sensor technologies, even greater opportunity exists now than 20 years ago to (i) improve Argo's global coverage and value beyond the original design, (ii) extend Argo to span the full ocean depth, (iii) add biogeochemical sensors for improved understanding of oceanic cycles of carbon, nutrients, and ecosystems, and (iv) consider experimental sensors that might be included in the future, for example to document the spatial and temporal patterns of ocean mixing. For Core Argo and each of these enhancements, the past, present, and future progression along a path from experimental deployments to regional pilot arrays to global implementation is described. The objective is to create a fully global, top-to-bottom, dynamically complete, and multidisciplinary Argo Program that will integrate seamlessly with satellite and with other in situ elements of the Global Ocean Observing System (Legler et al., 2015). The integrated system will deliver operational reanalysis and forecasting capability, and assessment of the state and variability of the climate system with respect to physical, biogeochemical, and ecosystems parameters. It will enable basic research of unprecedented breadth and magnitude, and a wealth of ocean-education and outreach opportunities.

Description: The Mediterranean community represented in this paper is the result of more than 30 years of EU and nationally funded coordination, which has led to key contributions in science concepts and operational initiatives. Together with the establishment of operational services, the community has coordinated with universities, research centers, research infrastructures and private companies to implement advanced multi-platform and integrated observing and forecasting systems that facilitate the advancement of operational services, scientific achievements and mission-oriented innovation. Thus, the community can respond to societal challenges and stakeholders needs, developing a variety of fit-for-purpose services such as the Copernicus Marine Service. The combination of state-of-the-art observations and forecasting provides new opportunities for downstream services in response to the needs of the heavily populated Mediterranean coastal areas and to climate change. The challenge over the next decade is to sustain ocean observations within the research community, to monitor the variability at small scales, e.g., the mesoscale/submesoscale, to resolve the sub-basin/seasonal and inter-annual variability in the circulation, and thus establish the decadal variability, understand and correct the model-associated biases and to enhance model-data integration and ensemble forecasting for uncertainty estimation. Better knowledge and understanding of the level of Mediterranean variability will enable a subsequent evaluation of the impacts and mitigation of the effect of human activities and climate change on the biodiversity and the ecosystem, which will support environmental assessments and decisions. Further challenges include extending the science-based added-value products into societal relevant downstream services and engaging with communities to build initiatives that will contribute to the 2030 Agenda and more specifically to SDG14 and the UN's Decade of Ocean Science for sustainable development, by this contributing to bridge the science-policy gap. The Mediterranean observing and forecasting capacity was built on the basis of community best practices in monitoring and modeling, and can serve as a basis for the development of an integrated global ocean observing system.

Description: As ocean acidification (OA) sensor technology develops and improves, in situ deployment of such sensors is becoming more widespread. However, the scientific value of these data depends on the development and application of best practices for calibration, validation, and quality assurance as well as on further development and optimization of the measurement technologies themselves. Here, we summarize the results of a 2-day workshop on OA sensor best practices held in February 2018, in Victoria, British Columbia, Canada, drawing on the collective experience and perspectives of the participants. The workshop on in situ Sensors for OA Research was organized around three basic questions: 1) What are the factors limiting the precision, accuracy and reliability of sensor data? 2) What can we do to facilitate the quality assurance/quality control (QA/QC) process and optimize the utility of these data? and 3) What sort of data or metadata are needed for these data to be most useful to future users? A synthesis of the discussion of these questions among workshop participants and conclusions drawn is presented in this paper.

Description: The OceanGliders program started in 2016 to support active coordination and enhancement of global glider activity. OceanGliders contributes to the international efforts of the Global Ocean Observation System (GOOS) for Climate, Ocean Health, and Operational Services. It brings together marine scientists and engineers operating gliders around the world: (1) to observe the long-term physical, biogeochemical, and biological ocean processes and phenomena that are relevant for societal applications; and, (2) to contribute to the GOOS through real-time and delayed mode data dissemination. The OceanGliders program is distributed across national and regional observing systems and significantly contributes to integrated, multi-scale and multi-platform sampling strategies. OceanGliders shares best practices, requirements, and scientific knowledge needed for glider operations, data collection and analysis. It also monitors global glider activity and supports the dissemination of glider data through regional and global databases, in real-time and delayed modes, facilitating data access to the wider community. OceanGliders currently supports national, regional and global initiatives to maintain and expand the capabilities and application of gliders to meet key global challenges such as improved measurement of ocean boundary currents, water transformation and storm forecast.

Description: The Baltic Sea is prone to oxygen deficiency due to the restricted water exchange with the North Sea in coincidence with a high biological oxygen demand. The partitioning of organic carbon between respiration, accumulation and export is co-determined by phytoplankton primary production and its subsequent bacterial remineralization. Here, we investigated net phytoplankton primary production, heterotrophic bacterial biomass production and dark CO2 fixation by on-board incubations with radiolabeled tracers in the Baltic Proper and in the Gulf of Riga after the main spring bloom. Results show that low phytoplankton standing stocks of ≤1.6 μg chlorophyll a L–1 sustained net primary production of 161–724 mg C m–2 d–1 under nitrogen limitation. Estimates of bacterial carbon remineralization suggest that freshly produced organic carbon was supplied to the aphotic zone at all stations. In the southern Baltic Proper, net primary production exceeded the bacterial carbon demand in the surface mixed layer, suggesting that organic matter derived from nutrient-limited primary production was available for export to bacterial communities below the oxycline. On average, 46% of heterotrophic bacterial production was mediated in oxygen minimum zones, revealing the high importance of organic matter recycling under hypoxic and anoxic conditions for the carbon budget. Dark CO2 fixation of up to 4.33 μg C L–1 d–1 in sulfide-free waters equaled 9–54% of the co-inciding heterotrophic bacterial carbon demand and may have provided another organic carbon source for heterotrophic activity. Substantially higher dark CO2 fixation up to 25.46 μg C L–1 d–1 was determined in sulfidic waters. Since our study was conducted 5 months after the major Baltic inflow event in winter 2014/2015, potential effects of deep water ventilation could be investigated. In the Gotland Basin, heterotrophic bacterial production in renewed oxygen-rich bottom water was similar to that in the uplifted oxygen-deficient former bottom water, while it was significantly reduced in sulfidic waters. Hence, our results suggest that the removal of hydrogen sulfide by inflow events has a high potential to increase bacterial carbon remineralization.

Description: Future mining of polymetallic nodules in the Clarion Clipperton Zone (Northeastern Pacific) is expected to affect all benthic ecosystems. The diversity, distribution, and environmental functions of microorganisms inhabiting abyssal sediments are barely understood. To understand consequences of deep-sea mining, experimental in vitro systems needs to be established to test hypotheses on the environmental impact of mining. For this, 40 bacterial strains, belonging to proteobacteria, actinobacteria and firmicutes were isolated from deep-sea sediments and nodules sampled at depths of ≥ 4000 m. Phenotypic characterization revealed a strong inter-species and moderate intra-species variability. Determination of metal minimum inhibitory concentrations indicated the presence of acute manganese-resistant bacteria such as Rhodococcus erythropolis (228.9 mM), Loktanella cinnabarina (57.2 mM), and Dietzia maris (14.3 mM) that might be suitable systems for testing the effects of release of microbes from nodules and their interactions with sediment particles in plumes generated during mining. Comparative genomic analysis indicated the presence of manganese efflux systems relevant for future transcriptomics or proteomics approaches with environmental samples and might serve in paving the way to develop model systems including representative organisms which are currently not cultivable. Monitoring deep-sea mining activity at abyssal depth is a challenge that has to be tackled. We proposed the use of API strips as a fast on-board methodology for bacterial monitoring as an indicator for sediment plume dispersions within the water column.

Description: Significance During the Holocene (11,600 y ago to present), northern peatlands accumulated significant C stocks over millennia. However, virtually nothing is known about peatlands that are no longer in the landscape, including ones formed prior to the Holocene: Where were they, when did they form, and why did they disappear? We used records of peatlands buried by mineral sediments for a reconstruction of peat-forming wetlands for the past 130,000 y. Northern peatlands expanded across high latitudes during warm periods and were buried during periods of glacial advance in northern latitudes. Thus, peat accumulation and burial represent a key long-term C storage mechanism in the Earth system. Abstract Glacial−interglacial variations in CO2 and methane in polar ice cores have been attributed, in part, to changes in global wetland extent, but the wetland distribution before the Last Glacial Maximum (LGM, 21 ka to 18 ka) remains virtually unknown. We present a study of global peatland extent and carbon (C) stocks through the last glacial cycle (130 ka to present) using a newly compiled database of 1,063 detailed stratigraphic records of peat deposits buried by mineral sediments, as well as a global peatland model. Quantitative agreement between modeling and observations shows extensive peat accumulation before the LGM in northern latitudes (〉40°N), particularly during warmer periods including the last interglacial (130 ka to 116 ka, MIS 5e) and the interstadial (57 ka to 29 ka, MIS 3). During cooling periods of glacial advance and permafrost formation, the burial of northern peatlands by glaciers and mineral sediments decreased active peatland extent, thickness, and modeled C stocks by 70 to 90% from warmer times. Tropical peatland extent and C stocks show little temporal variation throughout the study period. While the increased burial of northern peats was correlated with cooling periods, the burial of tropical peat was predominately driven by changes in sea level and regional hydrology. Peat burial by mineral sediments represents a mechanism for long-term terrestrial C storage in the Earth system. These results show that northern peatlands accumulate significant C stocks during warmer times, indicating their potential for C sequestration during the warming Anthropocene.

Description: Stable isotope ratio analysis offers a unique opportunity to obtain information on ecosystem processes. The increase in atmospheric CO2 as a consequence of fossil fuel combustion and land-use change is altering the stable carbon isotope composition (δ13C) of the atmosphere and ocean. This work investigates the application of using δ13C measurements of seawater samples to explore the biogeochemical responses of marine ecosystems to anthropogenic CO2 perturbations. The combination of isotopic and non-isotopic measurements from a subtropical North-Atlantic mesocosm experiment provided a holistic view of the biogeochemical mechanisms that affect carbon dynamics under a gradient of pCO2 ranging from ~350 up to ~1,000 μatm during a phytoplankton succession. A clear CO2 response was detected in the isotopic datasets with 13C shifts of up to ~5%0, but increased CO2 levels only had a subtle effect on the concentrations of the dissolved and particulate organic carbon pools. Distinctive δ13C signatures of the particulate organic carbon pools in the water column and sediment traps were detectable for the different CO2 treatments after a nutrient stimulated phytoplankton bloom. These signatures were strongly correlated (p 〈 0.05) with the δ13C signatures of the inorganic carbon but not with the δ13C of the dissolved organic carbon pools (p 〉 0.05). Fractionation of carbon isotopes in phytoplankton was positively affected (9.6 〈 ε 〈 16.5%0) by high CO2 levels either because of the higher CO2 availability or because of a shift in phytoplankton community composition. Nevertheless, phytoplankton bloom intensity and development was independent of CO2 concentrations, and higher CO2 levels had no significant effect on inorganic nutrient uptake. Results from this mesocosm experiment showed that variations in the carbon isotopic signature of the carbon pools depend on both physical (air-sea exchange) and biological (community composition) drivers opening the door to new approaches for investigations of carbon cycling in marine ecosystems.

Description: Marine image analysis faces a multitude of challenges: data set size easily reaches Terabyte-scale; the underwater visual signal is often impaired to the point where information content becomes negligible; human interpreters are scarce and can only focus on subsets of the available data due to the annotation effort involved etc. Solutions to speed-up the analysis process have been presented in the literature in the form of semi-automation with artificial intelligence methods like machine learning. But the algorithms employed to automate the analysis commonly rely on large-scale compute infrastructure. So far, such an infrastructure has only been available on-shore. Here, a mobile compute cluster is presented to bring big image data analysis capabilities out to sea. The Sea-going High-Performance Compute Cluster (SHiPCC) units are mobile, robustly designed to operate with electrically impure ship-based power supplies and based on off-the-shelf computer hardware. Each unit comprises of up to eight compute nodes with graphics processing units for efficient image analysis and an internal storage to manage the big image data sets. The first SHiPCC unit has been successfully deployed at sea. It allowed us to extract semantic and quantitative information from a Terabyte-sized image data set within 1.5 h (a relative speedup of 97 compared to a single four-core CPU computer). Enabling such compute capability out at sea allows to include image-derived information into the cruise research plan, for example by determining promising sampling locations. The SHiPCC units are envisioned to generally improve the relevance and importance of optical imagery for marine science.

Description: The increasing use of rare earth elements (REEs) in diverse technological applications has augmented the demand and exploitation of these worldwide, leading to a higher input of REEs + Yttrium (Y) in the marine environment. The present study investigated the ecotoxicity of Lanthanum (La) and Y to Mytilus galloprovincialis developing embryos and juveniles. This was achieved by quantifying the embryogenesis success after 48 h, and survival of juveniles after 96 h of exposure to different concentrations of La and Y. Results show that both La and Y are more toxic to developing embryos and larvae than to juveniles of M. galloprovincialis. Predicted no-effect concentration (PNEC) values were also derived for the embryo development as a preliminary approach to assess the environmental risk for these compounds to marine organisms. Results revealed that La is more toxic than Y. The high sensitivity of the early developmental stages to these compounds highlight the relevance of including these stages when evaluating the toxicity of chemicals where little information is available. Although older life stages may be more tolerant to toxicants, the population survival will be compromised if new recruits are not viable, with implications to the whole ecosystem health and functioning of the impacted area. Information on the ecotoxicity of chemicals with expanded technological use and that may be released during deep-sea mining activities is urgent in order to help estimate environmental impacts.

Description: Abyssal plains of the Clarion Clipperton Fracture Zone (CCZ) in the NE Pacific Ocean probably harbour one of the world’s most diverse ecosystems. Gaining a basic understanding of the mechanisms underlying the evolution and persistence of CCZ biodiversity in terms of biogeography and connectivity has both scientific merit and informs the development of policy related to potential future deep-sea mining of mineral resources at an early stage in the process. Existing archives of polychaetes and isopods were sorted using a combined molecular and morphological approach, which uses nucleotide sequences (cytochrome c oxidase subunit I (COI)) and morphological information to identify appropriate sample sets for further investigations. Basic patterns of genetic diversity, divergence and demographic history of five polychaete and five isopod species were investigated. Polychaete populations were found to be genetically diverse. Pronounced long- and short-distance dispersal produces large populations that are continuously distributed over large geographic scales. Although analyses of isopod species suggest the same, spatial genetic structuring of populations do imply weak barriers to gene flow. Mining-related, large-scale habitat destruction has the potential to impact the continuity of both isopod and polychaete populations as well as their long-term dispersal patterns, as ecosystem recovery after major impacts is predicted to occur slowly at evolutionary time scales.

Description: Nowadays, most biodiversity assessments involving meiofauna are mainly carried out using very time-consuming, specimen-wise morphological identifications, which demands comprehensive taxonomic knowledge. Animals have to be examined for minor differences of setae compositions, mouthpart morphology or number of segments for various extremities. DNA-based methods such as metabarcoding as well as recently emerged rapid analyses using MALDI-TOF mass spectrometry to identify specimens based on a proteome fingerprint could vastly accelerate the process of specimen identification in biodiversity assessments. However, these techniques depend on reference libraries to connect collected data to morphologically described species. In this study the success rate of both approaches have been tested based on reference libraries constructed using part of the samples from a new study area to identify unknown samples. Using MALDI-TOF MS we found, that species which do not exist in an incomplete mass spectra reference library only have minor impact on the results, when employing a post hoc test for Random Forest classifications. This test reveals specimens that demand morphological re-examination for the final species assignment. Metabarcoding however strongly demands a rich reference library to provide correct MOTU assessments in congruence with morphological determination. Nevertheless, with a complete library and a suitable data transformation [herein log(x + 1)], the number of reads per MOTU reflects relative species abundances in metabarcoding inference. The results of this study facilitate specimen identification by using MALDI-TOF MS, which is incomparably cheap for specimen-by-specimen identification, but when it comes to sample-wise analyses, metabarcoding outperforms other techniques by far.

Description: The Earth will exhibit continued global surface warming in response to a sustained increase of atmospheric carbon dioxide (CO2) levels. Massive meltwater input from the Antarctic ice sheet into the Southern Ocean could be one consequence of this warming. Here we investigate the impacts which this meltwater input may have on Earth’s surface climate and ocean circulation in a warming world. To this end a set of ensemble experiments has been conducted with a global climate model forced by increasing atmospheric CO2-concentration and an idealized Antarctic meltwater input to the Southern Ocean with varying amplitude and spatial pattern. As long as the atmospheric CO2-concentration stays moderate, i.e. below approximately twice the preindustrial concentration, and if a strong meltwater forcing of either 0.05 or 0.1 Sv is applied, enhanced Antarctic sea–ice cover and surface air temperature cooling over most parts of the Southern Ocean is observed. When the atmospheric CO2-concentration becomes larger than twice the preindustrial concentration, the meltwater only plays a minor role. The Antarctic meltwater drives significant slowing of the Southern Ocean meridional overturning circulation (MOC). Again, the meltwater influence only is detectable as long as the CO2-forcing is moderate. Much larger MOC changes develop in response to highly elevated atmospheric CO2-levels independent of whether or not a meltwater forcing is applied. The response of the Antarctic circumpolar current (ACC) is nonlinear. Substantial and persistent ACC slowing is simulated when solely the meltwater forcing of 0.1 Sv is applied, which is due to the halt of Weddell Sea deep convection and subsequent collapse of the Southern Ocean MOC. When the increasing atmospheric CO2-concentration additionally drives the model the ACC partly recovers in the long run. The partial recovery is due to strengthening westerly wind stress over the Southern Ocean, which intensifies the Ekman Cell. This study suggests that Southern Hemisphere climate projections for the twenty-first century could benefit from incorporating interactive Antarctic ice sheet.

Description: The microbial community composition and its functionality was assessed for hydrothermal fluids and volcanic ash sediments from Haungaroa and hydrothermal fluids from the Brothers volcano in the Kermadec island arc (New Zealand). The Haungaroa volcanic ash sediments were dominated by epsilonproteobacterial Sulfurovum sp. Ratios of electron donor consumption to CO2 fixation from respective sediment incubations indicated that sulfide oxidation appeared to fuel autotrophic CO2 fixation, coinciding with thermodynamic estimates predicting sulfide oxidation as the major energy source in the environment. Transcript analyses with the sulfide-supplemented sediment slurries demonstrated that Sulfurovum prevailed in the experiments as well. Hence, our sediment incubations appeared to simulate environmental conditions well suggesting that sulfide oxidation catalyzed by Sulfurovum members drive biomass synthesis in the volcanic ash sediments. For the Haungaroa fluids no inorganic electron donor and responsible microorganisms could be identified that clearly stimulated autotrophic CO2 fixation. In the Brothers hydrothermal fluids Sulfurimonas (49%) and Hydrogenovibrio/Thiomicrospira (15%) species prevailed. Respective fluid incubations exhibited highest autotrophic CO2 fixation if supplemented with iron(II) or hydrogen. Likewise catabolic energy calculations predicted primarily iron(II) but also hydrogen oxidation as major energy sources in the natural fluids. According to transcript analyses with material from the incubation experiments Thiomicrospira/Hydrogenovibrio species dominated, outcompeting Sulfurimonas. Given that experimental conditions likely only simulated environmental conditions that cause Thiomicrospira/Hydrogenovibrio but not Sulfurimonas to thrive, it remains unclear which environmental parameters determine Sulfurimonas’ dominance in the Brothers natural hydrothermal fluids.

Description: The Arctic Svalbard Archipelago hosts the world’s northernmost cold-water ‘carbonate factories’ thriving here despite of presumably unfavourable environmental conditions and extreme seasonality. Two contrasting sites of intense biogenic carbonate production, the rhodolith beds in Mosselbukta in the north of the archipelago and the barnacle-mollusc dominated carbonate sediments accumulating in the strong hydrodynamic regime of the Bjørnøy-Banken south of Spitsbergen, were the targets of the RV Maria S. Merian cruise 55 in June 2016. By integrating data from physical oceanography, marine biology, and marine geology, the present contribution characterises the environmental setting and biosedimentary dynamics of these two polar carbonate factories. Repetitive CTD profiling in concert with autonomous temperature/salinity loggers on a long-term settlement platform identified spatiotemporal patterns in the involved Atlantic and Polar water masses, whereas short-term deployments of a lander revealed fluctuations of environmental variables in the rhodolith beds in Mosselbukta and at same depth (46 m) at Bjørnøy-Banken. At both sites, dissolved inorganic nutrients in the water column were found depleted (except for elevated ammonium concentrations) and show an overall increase in concentration and N:P ratios toward deeper waters. This indicates that a recycling system was fuelling primary production after the phytoplankton spring bloom at the time of sampling in June 2016. Accordingly, oxygen levels were found elevated and carbon dioxide concentrations (pCO2) markedly reduced, on average only half the expected equilibrium values. Backed up by seawater stable carbon and oxygen isotope signatures, this is interpreted as an effect of limited air-sea gas exchange during seasonal ice cover in combination with a boost in community photosynthesis during the spring phytoplankton bloom. The observed trends are enhanced by the onset of rhodophyte photosynthesis in the rhodolith beds during the polar day upon retreat of sea-ice. Potential adverse effects of ocean acidification on the local calcifier community are thus predicted to be seasonally buffered by the marked drop in pCO2 during the phase of sea-ice cover and spring phyto-plankton bloom, but this effect will diminish should the seasonal sea-ice formation continue to decline. Among the 25 macrobenthos taxa identified from images captured by the lander’s camera system, all but three species were calcifiers contributing to the carbonate production. Biodiversity was found to be much higher in Mosselbukta (21 taxa) compared to Bjørnøy-Banken (8 taxa), which is considered as a result of enhanced habitat diversity provided in the rhodolith beds by the bioengineering crustose alga Lithothamnion glaciale. Filter-feeding activity of selected key species did reveal group-specific but no common activity patterns. Biotic disturbance of the filtering activity was common, in contrast to abiotic factors, with hermit crabs representing the primary trigger. Motion tracking of rhodoliths revealed a high frequency of dislocation, triggered not by abiotic factors but by the activity of benthic invertebrates, in particular echinoids ploughing below or moving over the rhodoliths. The echinoid Strongylocentrotus sp. is the most abundant component of the associated fauna, thereby considerably contributing both to carbonate production and to grazing bioerosion. Together, these results portray a high degree of seasonal as well as short-term dynamics in environmental conditions that despite many similarities support distinctly different communities and biodiversity patterns in the calcifying macrobenthos at the two studied polar carbonate factories.

Description: An interactive (multi-access) global identification key (OncIdent) has been developed for the pelagic marine microcopepod family Oncaeidae and made accessible online. Details of the general approach and development of the key are given in Bottger-Schnack and Schnack (J Nat Hist 49:2727-2741, 2015). After beta-testing, new additions include illustrations for all species and feature attributes considered, plus a textual summary of each species' feature states in the key. Additional taxonomic notes are given where required, highlighting morphological or molecular genetic peculiarities or problems, with links to large data bases leading directly to more comprehensive information about each species. The present paper briefly reviews the taxonomic background for key construction, summarizes the opportunities and limitations of the current online version OncIdent2.0, and provides guidance for its practical use.

Description: Colonial non-zooxanthellate corals from deep-water coral reefs, Lophelia pertusa and Madrepora oculata, produce large amounts of extracellular mucus (EMS). This mucus has various functions, e.g., an antifouling capability protecting the coral skeleton from attacks of endolithic and boring organisms. Both corals show thick epithecal and exothecal skeletal parts with a clear lamellar growth pattern. The formation of the epitheca is unclear. It is supposed that the EMS play a central role during the calcification process of the epithecal skeletal parts. Staining with the fluorochrome tetracycline has shown an enrichment of Ca2+ ions in the mucus. In order to investigate this hypothesis, the protein content of the mucus and the intracrystalline organic matter from newly formed epithecal aragonite of Madrepora oculata was determined via sodium dodecyl sulfate (SDS) gel electrophoresis. Identical band patterns within both substances could be detected, one around 45 kDa molecular weight and a cluster around 30-35 kDa molecular weight. The occurrence of identical protein patterns within the mucus and in the newly formed aragonite confirms the idea that the mucus plays an important role during the organomineralization of the coral epitheca.

Description: The incorporation of hydrogen in enstatite in a hydrous system containing various amounts of NaCl was investigated at 25 kbar. The hydrogen content in enstatite shows a clear negative correlation to the NaCl-concentration in the system. The most favourable explanation is the reduction of water fugacity due to dilution. Other reasons for the limited hydrogen incorporation at high NaCl levels, such as a significant influence of Na+ on the defect chemistry or an exchange between OH- and Cl-in enstatite, appear much less important. A partition coefficient D Na En/Fluid = 0.0013 could be determined, demonstrating that Na is less incompatible in enstatite than H. The new results support the idea that dissolved components have to be considered when the total hydrogen storage capacity in nominally anhydrous minerals is estimated, especially in geological settings with high levels of halogens, such as subduction zones.

Description: The coprecipitation of U (VI) with iron corrosion products from aqueous solutions by zero valent iron was investigated. The evidence of coprecipitation was demonstrated by conducting experiments with well characterized scrap iron,pyrite and a mixture of both materials with experimental durations of up to four months. Results indicate that under anoxic conditions only less than one tenth of the immobilized U(VI) was associated with the surface of scrap iron, whereas theremaining amount is entrapped in aging corrosion products.

Description: Five volcanic tuffs ranging from dacitic tuffs of Hungary to rhyolite, phonolite and basaltic tuffs of Germany were consolidated under laboratory conditions. Prior to consolidation an anti-hygro, a hydrous consolidant, which reduces the swelling ability of clay minerals, was applied. The three consolidants, a silicic acid ester (SAE), an elastic silicic acid ester (eSAE) and an acrylate resin (PMMA) were applied on test specimens under vacuum. Petrographic characterisation (polarizing microscopy, XRD, SEM) provided data for fabric analyses and the mineral composition of the tuffs. Changes in fabric, effective porosity, density, tensile strength, ultrasonic wave velocity were evaluated after the treatment. Weathering simulation tests such as hygric dilatation and thermal dilatation aimed to prove the effectiveness of consolidation and the durability of consolidated tuff samples. More than 500 samples were analysed. The tests showed that SAE caused the highest increase in indirect tensile strength. The water absorption and the pore size distribution of the tuffs were modified by consolidation. The PMMA reduced the water absorption the most, whereas SAE modified it the least. All the tested consolidants increased the thermal dilatation of the tuffs. The changes in hygric dilatation were not uniform: for most tuffs SAE increased and PMMA decreased the hygric dilatation, although the clay-rich Habichtswald tuff showed the opposite trend. The changes in hygric and thermal behaviour of consolidated tuff require special care when specific consolidants are chosen. These products modify the physical properties of consolidated tuffs and change the behaviour of weathering.

Description: A 782 d solubilization study using not shaken batch experiments and involving one uranium-bearing rock and three natural carbonate minerals was conducted to characterize uranium (U) leaching under oxic conditions. Results showed that aqueous U concentration increased continuously with a solubilization rate of 0.16 mgm-2h-1 for the first 564 d (1.5 y). After 1.5 y, U concentration reached a maximum value (saturation) and decreased afterwards. The saturation concentration of 54 mgL-1 (mean value) was influenced to various extent by the presence of carbonate minerals. Dissolution/precipitation, adsorption or ion exchange processes appear to control U solubilization.

Description: The veneer cladding of the Oeconomicum (OEC, Göttingen), the State Theatre of Darmstadt (STD, Darmstadt) and of the State and University Library (SUB, Göttingen) is characterised by pronounced bowing after a short time of exposure. Direct comparison of bowing data related to measurements from 2000 to 2003 at the SUB clearly show that the amplitude in bowing had significantly increased. The bowing is different in intensity and orientation (concave, convex). The cladding material (Peccia marble, Rosa Estremoz marble and Carrara marble) are different in lattice preferred orientation, grain size distribution and grain interlocking. Depending on the bowing, panels may show cracks mostly initiated at the dowels. The percentage of visible cracks and breakouts increases with the amplitude of bowing except for the STD. Repetitive heatingcooling under dry conditions leads to considerable inelastic residual strain only after the first or second thermal cycle. The residual strain continuously increases again if water is present, whereby the moisture content after a thermal cycle has a certain impact on the decay rate. The water-enhanced thermal dilatation strongly correlates with the deterioration rate obtained from the laboratory bow test. Detailed petrophysical investigations provide evidence that with increasing bowing a decrease of mechanical properties (flexural strength or breaking load at dowel hole) occur. Marble degradation is also connected with the increase in porosity and a general shift of the maximum pore radii to larger pore sizes...

Description: Afforestation of the Sahara has been proposed as a climate engineering method to sequester a substantial amount of carbon dioxide, potentially effective to mitigate climate change. Earlier studies predicted changes in the atmospheric circulation system. These atmospheric feedbacks raise questions about the self-sustainability of such an intervention, but have not been investigated in detail. Here, we investigate changes in precipitation and circulation in response to Saharan large-scale afforestation and irrigation with NCAR’s CESM-WACCM Earth system model. Our model results show a Saharan temperature reduction by 6 K and weak precipitation enhancement by 267 mm/year over the Sahara. Only 26% of the evapotranspirated water re-precipitates over the Saharan Desert, considerably large amounts are advected southward to the Sahel zone and enhance the West African monsoon (WAM). Different processes cause circulation and precipitation changes over North Africa. The increase in atmospheric moisture leads to radiative cooling above the Sahara and increased high-level cloud coverage as well as atmospheric warming above the Sahel zone. Both lead to a circulation anomaly with descending air over the Sahara and ascending air over the Sahel zone. Together with changes in the meridional temperature gradient, this results in a southward shift of the inner-tropical front. The strengthening of the Tropical easterly jet and the northward displacement of the African easterly jet is associated with a northward displacement and strengthening of the WAM precipitation. Our results suggest complex atmospheric circulation feedbacks, which reduce the precipitation potential over an afforested Sahara and enhance WAM precipitation.

Description: Numerical models of magmatic hydrothermal systems have become powerful tools for linking surface and seafloor observations to chemical and fluid-dynamic processes at depth. This task requires resolving multi-phase flow over large distances of several kilometers, a wide range of pressure (p) and temperature (T) conditions, and over timescales of several thousands of years. The key numerical challenge is that realistic simulations have to consider the high nonlinearity and strong coupling of the governing conservation equations for mass and energy, while also being numerically efficient so that the required spatial and temporal scales can be resolved. Here we outline possible solutions to this problem by evaluating different implementation strategies and presenting a numerical scheme for fully coupled accurate and efficient flow solutions. The general scheme, based on the Newton–Raphson (NR) method, is presented for the simplified case of 2-D pure water convection and uses a control volume discretization on unstructured meshes. We find that the presented techniques significantly reduce the computational effort with respect to sequential/decoupled schemes. Key to this is a theta-time-differencing method for better accuracy, stability and convergence behavior of the NR-iterations, as well as improvements regarding upwinding. These features make the presented methods useful for coupled simulations of magmatic hydrothermal systems and a potential basis for future 3-D multi-phase codes.

Description: A novel actinobacterium, strain DB165T, was isolated from cold waters of Llullaillaco Volcano Lake (6170 m asl) in Chile. Phylogenetic analysis based on 16S rRNA gene sequences identified strain DB165T as belonging to the genus Subtercola in the family Microbacteriaceae, sharing 97.4% of sequence similarity with Subtercola frigoramans DSM 13057T, 96.7% with Subtercola lobariae DSM 103962T, and 96.1% with Subtercola boreus DSM 13056T. The cells were observed to be Gram-positive, form rods with irregular morphology, and to grow best at 10–15 °C, pH 7 and in the absence of NaCl. The cross-linkage between the amino acids in its peptidoglycan is type B2γ; 2,4-diaminobutyric acid is the diagnostic diamino acid; the major respiratory quinones are MK-9 and MK-10; and the polar lipids consist of phosphatidylglycerol, diphosphatidylglycerol, 5 glycolipids, 2 phospholipids and 5 additional polar lipids. The fatty acid profile of DB165T (5% 〉) contains iso-C14:0, iso-C16:0, anteiso-C15:0, anteiso-C17:0, and the dimethylacetal iso-C16:0 DMA. The genomic DNA G+C content of strain DB165T was determined to be 65 mol%. Based on the phylogenetic, phenotypic, and chemotaxonomic analyses presented in this study, strain DB165T (= DSM 105013T = JCM 32044T) represents a new species in the genus Subtercola, for which the name Subtercola vilae sp. nov. is proposed.

Description: Pockmarks are variably sized crater-like structures that occur in young continental margin sediments. They are formed by gas eruptions and/or long-term release of fluid or gas. So far no pockmarks were known from the Pacific coast of South America between 51°S and 55°S. This article documents an extensive and previously unknown pockmark field in the Seno Otway (Otway Sound, 52°S) with multibeam bathymetry and parametric echosounding as well as sediment drill cores. Up to 31 pockmarks per square kilometer occur in water depths of 50 to 〉100 m in late glacial and Holocene sediments. They are up to 150 m wide and 10 m deep. Below and near the pockmarks, echosounder profiles image acoustic blanking as well as gas chimneys often crosscutting the 20 to 〉30 m thick glacial sediments above the acoustic basement, in particular along fault zones. Upward-migrating gas is trapped within the sediment strata, forming dome-like features. Two 5 m long piston cores from inside and outside a typical pockmark give no evidence for gas storage within the uppermost sediments. The inside core recovered poorly sorted glacial sediment, indicating reworking and re-deposition after several explosive events. The outside core documents an undisturbed stratigraphic sequence since ~15 ka. Many buried paleo-pockmarks occur directly below a prominent seismic reflector marking the mega-outflow event of the Seno Otway at 14.3 ka, lowering the proglacial lake level by about 80 m. This decompression would have led to frequent eruptions of gas trapped in reservoirs below the glacial sediments. However, the sediment fill of pockmarks formed after this event suggests recurrent events throughout the Holocene until today. Most pockmarks occur above folded hydrocarbon-bearing Upper Cretaceous and Paleogene rocks near the western margin of the Magallanes Basin, constraining them as likely source rocks for thermogenic gas.

Description: Shallow shore zones are generally considered to provide juvenile habitats for many invertebrate and fish species and additionally serve as spawning grounds for important components of oceanic food webs and fishery resources such as herring (Clupea spp.). Herring attach their demersal eggs to benthic substrates, rendering reproduction success vulnerable to environmental changes and local habitat alterations. However, little information is available on the effects of different substrates on the survival of demersal eggs. Hypothesizing that the structural complexity of spawning substrates generally affects herring egg survival and that the effect magnitude depends on the suitability of ambient environment, field experiments were conducted on a major spawning ground of C. harengus in the Southwestern Baltic Sea. Herring eggs were artificially spawned on substrates of different structural complexities and incubated in situ under differing temperature regimes, at the beginning and the end of the natural herring spawning season, to include the full suite of stressors occurring on littoral spawning beds. Results of this study indicate a positive relation between high structural complexity of spawning substrates and herring egg survival. Mean egg mortality was three times higher on substrates of lowest complexity than on highly complex substrates. These differences became even more prominent under unfavorable conditions that appeared with rising water temperatures later in the spawning season. Although the mechanisms are still unclear, we conclude that structural complexity, particularly formed by submerged aquatic vegetation, provides a crucial prerequisite for the successful reproduction of substrate spawning marine fishes such as herring in the Baltic Sea.

Description: Insight into a species’ native and introduced range is essential in understanding the invasion process. Genetic diversity, propagule pressure and environmental conditions all have been recognised as playing a determinant role in invasion success. Here, we aimed to investigate the genetic diversity and population genetic structure (using the COI mtDNA gene region and 22 nDNA microsatellite markers) of the Asian green mussel Perna viridis within its potential native range in Asia and at introduced locations in the USA and the Caribbean. We also analyse genetic data from vessel intercepts and an incursion. By doing so, we aimed to identify genetic signatures that could allow to track vessel samples to their source and provide further insight into potential high-risk invasive populations or areas. Three top hierarchical clusters were identified using the individual-based Bayesian clustering method in STRUCTURE, corresponding to populations in three world regions: (1) USA and Caribbean, (2) India and (3) Southeast Asia. Within Southeast Asia, additional analysis indicate a shallow genetic differentiation of three subgroups consisting of (3a) Thailand, (3b) Taiwan and Hong-Kong, and (3c) a cluster of Singapore–Indonesia samples. Overall, the population structure found in this study suggests that the markers used could be useful in identifying source populations, particularly between the three mains world regions. Most surprisingly however, this study shows that the genetic diversity of samples collected from vessel intercepts and incursions did not differ significantly from established populations in Southeast Asia. In this region, in addition to the high vessel connectivity and number of P. viridis transported, all sampled populations are likely to pose a comparable risk in terms of genetic diversity. The present work represents the most comprehensive population genetic study of P. viridis, and the first to address the potential genetic introduction risk posed by populations of this species. The information and genetic markers in this study constitute a valuable addition to the tools already used to infer on potential high-risk source populations of P. viridis. They should therefore prove useful for biosecurity surveillance and management actions directed at this species.

Description: The Azores archipelago is geochemically distinct amongst the oceanic intraplate volcanoes in that it has trace element and radiogenic Sr–Nd–Pb–Hf isotope signatures that cover much of the global variation observed in Ocean Island Basalts. Thus, it is the prime example of an intraplate melting anomaly preserving the compositional heterogeneity of the Earth’s mantle. Here, we review the trace element and radiogenic isotope geochemistry of the Azores islands and few submarine samples analysed and published over the past decades and summarise these findings and conclusions. The volcanoes of all islands erupted lavas of the alkaline series and their compositions broadly range from basalts to trachytes (see also Chapter “ Petrology of the Azores Islands” by Larrea et al.). Temperatures and pressures of melting imply that melting in the Azores occurs as a result of both slightly increased temperatures in the mantle (~35 °C) and addition of volatile elements into the mantle source. Basalts from the island of São Miguel show a stronger enrichment in highly incompatible elements like K and the Light Rare Earth Elements than the other islands further to the west. The older and easternmost island Santa Maria has lavas that are more silica-undersaturated than the rocks occurring on the younger islands. Each of the eastern islands shows a different and distinct radiogenic isotope composition and much of this variability can be explained by variably enriched recycled components of different age in their source regions. Amongst the global array, the lavas from eastern São Miguel are uniquely enriched in that they display radiogenic 206Pb/204Pb, 208Pb/204Pb and 87Sr/86Sr isotope ratios best explained by a distinct source in the mantle. The implication of the preservation of such unique, enriched sources in the mantle may indicate that stirring processes in the Azores mantle are not efficiently homogenising heterogeneities over the timescales of recycling of 0.1–1 Ga and possibly even up to 2.5 Ga. One possible explanation is the low buoyancy flux of the Azores mantle when compared to other intraplate settings. The preservation of these source signatures in the lavas on the easternmost Azores islands are the result of smaller degrees of partial melting due to a thicker lithosphere. This likely prevents a homogenisation during magma ascent compared to the western islands, preferentially sampling deep, low degree partial melts from the more fertile mantle sources. The geochemical signatures of the two islands west of the Mid-Atlantic Ridge (Corvo and Flores) imply a source enrichment and degrees of partial melting similar to those east of the ridge. Melting underneath the western islands is the result of a source that must be related to the Azores melting anomaly but has been modified by shallow level processes such as assimilation of oceanic crustal material.

Description: The potential harvest of polymetallic nodules will heavily impact the abyssal, soft sediment ecosystem by removing sediment, hard substrate, and associated fauna inside mined areas. It is therefore important to know whether the ecosystem can recover from this disturbance and if so at which rate. The first objective of this study was to measure recovery of phytodetritus processing by the benthic food web from a sediment disturbance experiment in 1989. The second objective was to determine the role of holothurians in the uptake of fresh phytodetritus by the benthic food web. To meet both objectives, large benthic incubation chambers (CUBEs; 50 × 50 × 50 cm) were deployed inside plow tracks (with and without holothurian presence) and at a reference site (holothurian presence, only) at 4100 m water depth. Shortly after deployment, 13C- and 15N-labeled phytodetritus was injected in the incubation chambers and during the subsequent 3-day incubation period, water samples were taken five times to measure the production of 13C-dissolved inorganic carbon over time. At the end of the incubation, holothurians and sediment samples were taken to determine biomass, densities and incorporation of 13C and 15N into bacteria, nematodes, macrofauna, and holothurians. For the first objective, the results showed that biomass of bacteria, nematodes and macrofauna did not differ between reference sites and plow track sites when holothurians were present. Additionally, meiofauna and macrofauna taxonomic composition was not significantly different between the sites. In contrast, total 13C uptake by bacteria, nematodes and holothurians was significantly lower at plow track sites compared to reference sites, though the number of replicates was low. This result suggests that important ecosystem functions such as organic matter processing have not fully recovered from the disturbance that occurred 26 years prior to our study. For the second objective, the analysis indicated that holothurians incorporated 2.16 × 10−3 mmol labile phytodetritus C m−2 d−1 into their biomass, which is one order of magnitude less as compared to bacteria, but 1.3 times higher than macrofauna and one order of magnitude higher than nematodes. Additionally, holothurians incorporated more phytodetritus carbon per unit biomass than macrofauna and meiofauna, suggesting a size-dependence in phytodetritus carbon uptake.

Description: Recently, measurements of oxygen concentration in the ocean-one of the most classical parameters in chemical oceanography-are experiencing a revival. This is not surprising, given the key role of oxygen for assessing the status of the marine carbon cycle and feeling the pulse of the biological pump. The revival, however, has to a large extent been driven by the availability of robust optical oxygen sensors and their painstakingly thorough characterization. For autonomous observations, oxygen optodes are the sensors of choice: They are used abundantly on Biogeochemical-Argo floats, gliders and other autonomous oceanographic observation platforms. Still, data quality and accuracy are often suboptimal, in some part because sensor and data treatment are not always straightforward and/or sensor characteristics are not adequately taken into account. Here, we want to summarize the current knowledge about oxygen optodes, their working principle as well as their behavior with respect to oxygen, temperature, hydrostatic pressure, and response time. The focus will lie on the most widely used and accepted optodes made by Aanderaa and Sea-Bird. We revisit the essentials and caveats of in-situ in air calibration as well as of time response correction for profiling applications, and provide requirements for a successful field deployment. In addition, all required steps to post-correct oxygen optode data will be discussed. We hope this summary will serve as a comprehensive, yet concise reference to help people get started with oxygen observations, ensure successful sensor deployments and acquisition of highest quality data, and facilitate post-treatment of oxygen data. In the end, we hope that this will lead to more and higher-quality oxygen observations and help to advance our understanding of ocean biogeochemistry in a changing ocean.

Description: Recruitment patterns of sessile species often do not reflect the composition of the local propagule pool. This is, among other processes, attributed to the stimulation or inhibition of settlement by resident species. In an experimental study, we evaluated the effects of different densities of the ascidian Diplosoma listerianum on the settlement of the hydrozoan Obelia sp. For this, we monitored the cover of the dominant fouler Obelia sp. on vertically orientated PVC tiles, which were either bare or pre-seeded with two different densities (sparse or dense) of Diplosoma colonies, over the course of 8 weeks. The settlement tiles were deployed at two study sites in La Herradura Bay, Chile. The presence of D. listerianum enhanced the settlement or the growth or both of the colonial hydrozoan, but this effect disappeared within 4–8 weeks. Furthermore, we tested whether the initial enhancement of Obelia sp. by Diplosoma colonies goes back to the fact that larvae, which reject the ascidian tunic as a settlement substratum after a first contact, colonize nearby surfaces because of their limited mobility. However, we found no support for this assumption. We rather suggest that D. listerianum facilitated colonization indirectly by the accumulation of organic material in its vicinity and/or by its pumping activity. Initial resident-mediated enhancement of the hydrozoan was overridden by processes such as competition between later colonizers within the course of weeks and we could not detect any lasting effects of D. listerianum on the structure of the developing communities.

Description: We present the development and validation of a numerical modeling suite for bubble and droplet dynamics of multiphase plumes in the environment. This modeling suite includes real-fluid equations of state, Lagrangian particle tracking, and two different integral plume models: an Eulerian model for a double-plume integral model in quiescent stratification and a Lagrangian integral model for multiphase plumes in stratified crossflows. Here, we report a particle tracking algorithm for dispersed-phase particles within the Lagrangian integral plume model and a comprehensive validation of the Lagrangian plume model for single- and multiphase buoyant jets. The model utilizes literature values for all entrainment and spreading coefficients and has one remaining calibration parameter (Formula presented.), which reduces the buoyant force of dispersed phase particles as they approach the edge of a Lagrangian plume element, eventually separating from the plume as it bends over in a crossflow. We report the calibrated form (Formula presented.), where b is the plume half-width, and r is the distance of a particle from the plume centerline. We apply the validated modeling suite to simulate two test cases of a subsea oil well blowout in a stratification-dominated crossflow. These tests confirm that errors from overlapping plume elements in the Lagrangian integral model during intrusion formation for a weak crossflow are negligible for predicting intrusion depth and the fate of oil droplets in the plume. The Lagrangian integral model has the added advantages of being able to account for entrainment from an arbitrary crossflow, predict the intrusion of small gas bubbles and oil droplets when appropriate, and track the pathways of individual bubbles and droplets after they separate from the main plume or intrusion layer.

Description: Increasing interest in deep-sea mineral resources, such as polymetallic nodules, calls for environmental research about possible impacts of mineral exploitation on the deep-sea ecosystem. So far, little geochemical comparisons of deep-sea sediments before and after mining induced disturbances have been made, and thus long-term environmental effects of deep-sea mining are unknown. Here we present geochemical data from sediment cores from an experimental disturbance area at 4,100 m water depth in the Peru Basin. The site was revisited in 2015, 26 years after a disturbance experiment mimicking nodule mining was carried out and compared to sites outside the experimental zone which served as a pre-disturbance reference. We investigated if signs of the disturbance are still visible in the solid phase and the pore water after 26 years or if pre-disturbance conditions have been re-established. Additionally, a new disturbance was created during the cruise and sampled 5 weeks later to compare short- and longer-term impacts. The particulate fraction and pore water were analyzed for major and trace elements to study element distribution and processes in the surface sediment. Pore water and bottom water samples were also analyzed for oxygen, nitrate, dissolved organic carbon, and dissolved amino acids, to examine organic matter degradation processes. The study area of about 11 km2 was found to be naturally more heterogeneous than expected, requiring an analysis of spatial variability before the disturbed and undisturbed sites can be compared. The disturbed sites exhibit various disturbance features: some surface sediments were mixed through, others had the top layer removed and some had additional material deposited on top. Pore water constituents have largely regained pre-disturbance gradients after 26 years. The solid phase, however, shows clear differences between disturbed and undisturbed sites in the top 20 cm so that the impact is still visible in the plowed tracks after 26 years. Especially the upper layer, usually rich in manganese-oxide and associated metals, such as Mo, Ni, Co, and Cu, shows substantial differences in metal distribution. Hence, it can be expected that disturbances from polymetallic nodule mining will have manifold and long-lasting impacts on the geochemistry of the underlying sediment.

Description: Certification of trace metals in seawater certified reference materials (CRMs) NASS-7 and CASS-6 is described. At the National Research Council Canada (NRC), column separation was performed to remove the seawater matrix prior to the determination of Cd, Cr, Cu, Fe, Pb, Mn, Mo, Ni, U, V, and Zn, whereas As was directly measured in 10-fold diluted seawater samples, and B was directly measured in 200-fold diluted seawater samples. High-resolution inductively coupled plasma mass spectrometry (HR-ICPMS) was used for elemental analyses, with double isotope dilution for the accurate determination of B, Cd, Cr, Cu, Fe, Pb, Mo, Ni, U, and Zn in seawater NASS-7 and CASS-6, and standard addition calibration for As, Co, Mn, and V. In addition, all analytes were measured using standard addition calibration with triple quadrupole (QQQ)-ICPMS to provide a second set of data at NRC. Expert laboratories worldwide were invited to contribute data to the certification of trace metals in NASS-7 and CASS-6. Various analytical methods were employed by participants including column separation, co-precipitation, and simple dilution coupled to ICPMS detection or flow injection analysis coupled to chemiluminescence detection, with use of double isotope dilution calibration, matrix matching external calibration, and standard addition calibration. Results presented in this study show that majority of laboratories have demonstrated their measurement capabilities for the accurate determination of trace metals in seawater. As a result of this comparison, certified/reference values and associated uncertainties were assigned for 14 elements in seawater CRMs NASS-7 and CASS-6, suitable for the validation of methods used for seawater analysis.

Description: Marine macroalgae in temperate regions are constantly exposed to colonization by fouling organisms, but the intensity of fouling fluctuates in time. We, therefore, hypothesized that a macroalgal species from these latitudes should be able to adjust its antifouling defense to the prevailing colonization pressure. To test this assumption, fouling pressure in the Western Baltic Sea as well as the activity of surface extracts gained from the non-native Gracilaria vermiculophylla against the diatom Stauroneis constricta and the filamentous alga Ceramium tenuicorne were assessed over one vegetation period on a monthly basis. We used two solvents with different polarities to extract chemical compounds from the alga. Both, hexane and dichloromethane (DCM) surface extracts, inhibited settlement of C. tenuicorne, while only hexane surface extracts deterred S. constricta. Furthermore, the activities of both extracts fluctuated on the scale of months and the fluctuations in the activity against C. tenuicorne, which were observed in DCM extracts, correlated with the intensity of fouling pressure that C. tenuicorne inflicted on G. vermiculophylla in the field. Thus, G. vermiculophylla appears to be able to adjust its antifouling defenses—at least partly—to fouling pressure.

Description: Marine macrophytes are the foundation of algal forests and seagrass meadows-some of the most productive and diverse coastal marine ecosystems on the planet. These ecosystems provide nursery grounds and food for fish and invertebrates, coastline protection from erosion, carbon sequestration, and nutrient fixation. For marine macrophytes, temperature is generally the most important range limiting factor, and ocean warming is considered the most severe threat among global climate change factors. Ocean warming induced losses of dominant macrophytes along their equatorial range edges, as well as range extensions into polar regions, are predicted and already documented. While adaptive evolution based on genetic change is considered too slow to keep pace with the increasing rate of anthropogenic environmental changes, rapid adaptation may come about through a set of non-genetic mechanisms involving the functional composition of the associated microbiome, as well as epigenetic modification of the genome and its regulatory effect on gene expression and the activity of transposable elements. While research in terrestrial plants demonstrates that the integration of non-genetic mechanisms provide a more holistic picture of a species' evolutionary potential, research in marine systems is lagging behind. Here, we aim to review the potential of marine macrophytes to acclimatize and adapt to major climate change effects via intraspecific variation at the genetic, epigenetic, and microbiome levels. All three levels create phenotypic variation that may either enhance fitness within individuals (plasticity) or be subject to selection and ultimately, adaptation. We review three of the most important phenotypic variations in a climate change context, including physiological variation, variation in propagation success, and in herbivore resistance. Integrating different levels of plasticity, and adaptability into ecological models will allow to obtain a more holistic understanding of trait variation and a realistic assessment of the future performance and distribution of marine macrophytes. Such multi-disciplinary approach that integrates various levels of intraspecific variation, and their effect on phenotypic and physiological variation, is of crucial importance for the effective management and conservation of seagrasses and macroalgae under climate change.

Description: Estuaries are among the most valuable aquatic systems in terms of their services to human welfare. They offer an ideal framework to assess multiscale processes linking climate and food web dynamics through the hydrological cycle. Resolving food web responses to climate change is fundamental to resilience management of these threatened ecosystems under global change scenarios. Here, we examined the temporal variability of the plankton food web in the Mondego Estuary, central Iberian Peninsula, over the period 2003 to 2012. The results pointed out a cascading effect from climate to plankton communities that follow a non-stationary behavior shaped by the climate variance envelope. Concurrent changes in hydrographic processes at the regional, that is, upwelling intensity, and local, that is, estuarine hydrology, scales were driven by climatic forcing promoted by the North Atlantic Oscillation; the influence of which permeated the physical environment in the estuary affecting both autotrophic and heterotrophic communities. The most conspicuous change arose around 2008 and consisted of an obvious decrease in freshwater taxa along with a noticeable increase in marine organisms, mainly driven by gelatinous zooplankton. The observed increase in small-sized cosmopolitan copepods, that is, Clausocalanus arcuicornis, Oithona plumifera, thermophilic species, that is, Penilia avirostris, and gelatinous zooplankton suggests a structural change in the Mondego plankton community. These results provide empirical support to the expectation that expanding climate variance changes plankton structure and functioning, likely fostering trophic interactions in pelagic food webs.

Description: Marine biofouling is a paramount phenomenon in the marine environment and causes serious problems to maritime industries worldwide. Marine algae are known to produce a wide variety of chemical compounds with antibacterial, antifungal, antialgal, and anti-macrofouling properties, inhibiting the settlement and growth of other marine fouling organisms. Significant investigations and progress have been made in this field in the last two decades and several antifouling extracts and compounds have been isolated from micro- and macroalgae. In this minireview, we have summarized and evaluated antifouling compounds isolated and identified from macroalgae and microalgae between January 2010 and June 2016. Future directions for their commercialization through metabolic engineering and industrial scale up have been discussed. Upon comparing biogeographical regions, investigations from Southeast Asian waters were found to be rather scarce. Thus, we have also discussed the need to conduct more chemical ecology based research in relatively less explored areas with high algal biodiversity like Southeast Asia.

Description: The height, volume, and alongshore extent of the foredune are primary controls on the response of barrier islands to the elevated storm surge that accompanies hurricanes and extra-tropical storms. In this respect, the ability of the foredune to recover following a storm determines whether a barrier island can maintain elevation as sea level rises and the island migrates landward through the redistribution of sediment to the back of the island through washover and breaching. This chapter provides a review of a body of recent fieldwork on the role of the foredune in controlling island transgression. It is argued that the role of the foredune to control washover and island transgression is analogous to that of a variable resistor in an electrical circuit, with the strength of the resistor dependent on the ability of the dune to recover in height and extent following each storm. Recovery of the foredune requires that sediment removed to the nearshore during a storm be returned to the beachface through the landward migration and welding of the innermost bars where it is eventually transported to the backshore and trapped by vegetation. Field observations from Padre Island in Texas, Santa Rosa Island in Florida, and Assateague Island in Virginia suggest that the recovery of dune height can be modeled using a sigmoidal growth curve, and that recovery can take up to a decade. The slow rate of dune recovery suggests that the resiliency of barrier islands to sea level rise is dependent on whether there is a change in the frequency and magnitude of storm events or an interruption to the exchange of sediment among the nearshore, beach, and dune. Ultimately, the height and volume of the foredune can be controlled by the framework geology (to varying degrees), which determines beach and nearshore state through the availability and texture of sediment and structural controls. In this respect, the response of barrier islands to sea level rise can be expected to vary regionally and alongshore as a reflection of diverse framework geology. The local response to sea level rise depends on the ability of the dune to recover following storms. Assuming no new sediment from alongshore or offshore sources, an increase in the frequency of washover will limit the ability of the dune to recover, and recent field evidence suggests that a change in dune height and volume is self-reinforcing, which suggests a lack of island resiliency. Further testing is required to determine how the field observations and modeling described in this chapter from a select group of barrier islands around the United States are applicable to other islands and consistent throughout the evolution of a barrier island.

Description: Two different photosystems for performing bacteriochlorophyll-mediated photosynthetic energy conversion are employed in different bacterial phyla. Those bacteria employing a photosystem II type of photosynthetic apparatus include the phototrophic purple bacteria (Proteobacteria), Gemmatimonas and Chloroflexus with their photosynthetic relatives. The proteins of the photosynthetic reaction center PufL and PufM are essential components and are common to all bacteria with a type-II photosynthetic apparatus, including the anaerobic as well as the aerobic phototrophic Proteobacteria. Therefore, PufL and PufM proteins and their genes are perfect tools to evaluate the phylogeny of the photosynthetic apparatus and to study the diversity of the bacteria employing this photosystem in nature. Almost complete pufLM gene sequences and the derived protein sequences from 152 type strains and 45 additional strains of phototrophic Proteobacteria employing photosystem II were compared. The results give interesting and comprehensive insights into the phylogeny of the photosynthetic apparatus and clearly define Chromatiales, Rhodobacterales, Sphingomonadales as major groups distinct from other Alphaproteobacteria, from Betaproteobacteria and from Caulobacterales (Brevundimonas subvibrioides). A special relationship exists between the PufLM sequences of those bacteria employing bacteriochlorophyll b instead of bacteriochlorophyll a. A clear phylogenetic association of aerobic phototrophic purple bacteria to anaerobic purple bacteria according to their PufLM sequences is demonstrated indicating multiple evolutionary lines from anaerobic to aerobic phototrophic purple bacteria. The impact of pufLM gene sequences for studies on the environmental diversity of phototrophic bacteria is discussed and the possibility of their identification on the species level in environmental samples is pointed out. © 2018 Imhoff, Rahn, Künzel and Neulinger.

Description: The maintenance and resilience of host-associated microbiota during development is a fundamental process influencing the fitness of many organisms. Several host properties were identified as influencing factors on bacterial colonization, including the innate immune system, mucus composition and diet. In contrast, the importance of bacteria-bacteria interactions on host colonization is less understood. Here, we use bacterial abundance data of the marine model organism Nematostella vectensis to reconstruct potential bacteria-bacteria interactions through co-occurrence networks. The analysis indicates that bacteria-bacteria interactions are dynamic during host colonization and change according to the host’s developmental stage. To assess the predictive power of inferred interactions, we tested bacterial isolates with predicted cooperative or competitive behavior for their ability to influence bacterial recolonization dynamics. Within three days of recolonization all tested bacterial isolates affected bacterial community structure, while only competitive bacteria increased bacterial diversity. Already one week after recolonization almost no differences in bacterial community structure could be observed between control and treatments. These results show that predicted competitive bacteria can influence community structure for a short period of time, verifying the in silico predictions. However, within one week, the effects of the bacterial isolates are neutralized, indicating a high degree of resilience of the bacterial community. Hanna Domin1, Yazmín H. Zurita-Gutiérrez2, Marco Scotti3, Jann Buttlar1, Ute Hentschel Humeida2 and Sebastian Fraune1*

Description: Silicon (Si) is the second most abundant element in the Earth’s crust and is an important nutrient in the ocean. The global Si cycle plays a critical role in regulating primary productivity and carbon cycling on the continents and in the oceans. Development of the analytical tools used to study the sources, sinks, and fluxes of the global Si cycle (e.g., elemental and stable isotope ratio data for Ge, Si, Zn, etc.) have recently led to major advances in our understanding of the mechanisms and processes that constrain the cycling of Si in the modern environment and in the past. Here, we provide background on the geochemical tools that are available for studying the Si cycle and highlight our current understanding of the marine, freshwater and terrestrial systems. We place emphasis on the geochemistry (e.g., Al/Si, Ge/Si, Zn/Si, δ13 C, δ15 N, δ18 O, δ30 Si) of dissolved and biogenic Si, present case studies, such as the Silicic Acid Leakage Hypothesis, and discuss challenges associated with the development of these environmental proxies for the global Si cycle. We also discuss how each system within the global Si cycle might change over time (i.e., sources, sinks, and processes) and the potential technical and conceptual limitations that need to be considered for future studies.

Description: A thorough literature review in combination with an analysis of fossil material from collections enables a detailed reconstruction of the ecosystem of the lower Gatun Formation (Serravallian to Tortonian; late middle to early late Miocene) of Central Panama. The fossil record is highly diverse and includes foraminifers, sponges, corals, mollusks, polychaetes, crustaceans, bryozoans, echinoderms, and vertebrates. The fauna indicates fully marine conditions in a shallow basin with a soft, stable substrate and mostly low water energy. The benthic life is dominated by suspension-feeding bivalves and carnivores including mainly gastropods and crustaceans. Herbivores are strikingly rare. Predator-prey relationships can be directly inferred from abundant drill holes in mollusk shells caused by naticid and muricid gastropods showing strong prey selectivity. Additionally, deep and narrow incisions at the outer lip of the apertures of gastropod shells are reported for the first time and proposed to be caused by crustaceans. Investigating the life habits of the benthic organisms revealed a moderate tiering of the fauna and the importance of empty shells as habitats for a variety of taxa. The nektonic life is highly diverse including nautilids, fishes, rays, sharks, sea turtles, crocodiles, and toothed whales. An analysis of the food preferences of the fossil fauna enables the reconstruction of a trophic web for the ecosystem of the lower Gatun Formation.

Description: It is unclear whether transport by human vectors can increase the robustness of translocated populations and thereby enhance their invasiveness. To test this concept, we investigated the effect of heat stress on the tolerance of mussel populations towards a second stress event of the same kind. The heat challenges we mimicked can be faced by marine invertebrates that are transported through regions with high sea surface temperatures on ship hulls or in ballast water tanks. The study included 5 mussel species that were collected at sites in Brazil, Chile, Finland, Germany (Baltic Sea) and Portugal. In parallel laboratory experiments, monospecific groups of individuals were exposed to heat challenges that caused 60–83% mortality in the experimental groups within 15–28 days. The surviving individuals were exposed to a second stress event of the same kind, while their survival was then compared to the robustness of conspecifics that had not been exposed to elevated temperatures before. We observed that thermal tolerance was significantly enhanced by previous heat stress experience in case of Semimytilus algosus from Chile and in case of Mytilus edulis from Germany. Our results suggest that heat challenges, which marine invertebrates experience during transport, can enhance stress tolerance in founder populations of these species in their non-native range by potentially increasing the frequency of genetically adapted genotypes. This points at the necessity to learn more about selection acting on organisms during human-mediated transport—in the aquatic but also in the terrestrial environment.

Description: The geological, hydrological and microbiological features of the Salar de Atacama, the most extensive evaporitic sedimentary basin in the Atacama Desert of northern Chile, have been extensively studied. In contrast, relatively little attention has been paid to the composition and roles of microbial communities in hypersaline lakes which are a unique feature in the Salar. In the present study biochemical, chemical and molecular biological tools were used to determine the composition and roles of microbial communities in water, microbial mats and sediments along a marked salinity gradient in Laguna Puilar which is located in the “Los Flamencos” National Reserve. The bacterial communities at the sampling sites were dominated by members of the phyla Bacteroidetes, Chloroflexi, Cyanobacteria and Proteobacteria. Stable isotope and fatty acid analyses revealed marked variability in the composition of microbial mats at different sampling sites both horizontally (at different sites) and vertically (in the different layers). The Laguna Puilar was shown to be a microbially dominated ecosystem in which more than 60% of the fatty acids at particular sites are of bacterial origin. Our pioneering studies also suggest that the energy budgets of avian consumers (three flamingo species) and dominant invertebrates (amphipods and gastropods) use minerals as a source of energy and nutrients. Overall, the results of this study support the view that the Salar de Atacama is a heterogeneous and fragile ecosystem where small changes in environmental conditions may alter the balance of microbial communities with possible consequences at different trophic levels.

Description: The surface microlayer (SML) is the uppermost thin layer of the ocean and influencing interactions between the air and sea, such as gas exchange, atmospheric deposition and aerosol emission. Organic matter (OM) plays a key role in air-sea exchange processes, but studying how the accumulation of organic compounds in the SML relates to biological processes is impeded in the field by a changing physical environment, in particular wind speed and wave breaking. Here, we studied OM dynamics in the SML under controlled physical conditions in a large annular wind wave channel, filled with natural seawater, over a period of 26 days. Biology in both SML and bulk water was dominated by bacterioneuston and -plankton, respectively, while autotrophic biomass in the two compartments was very low. In general, SML thickness was related to the concentration of dissolved organic carbon (DOC) but not to enrichment of DOC or of specific OM components in the SML. Pronounced changes in OM enrichment and molecular composition were observed in the course of the study and correlated significantly to bacterial abundance. Thereby, hydrolysable amino acids, in particular arginine, were more enriched in the SML than combined carbohydrates. Amino acid composition indicated that less degraded OM accumulated preferentially in the SML. A strong correlation was established between the amount of surfactants coverage and γ-aminobutric acid, suggesting that microbial cycling of amino acids can control physiochemical traits of the SML. Our study shows that accumulation and cycling of OM in the SML can occur independently of recent autotrophic production, indicating a widespread biogenic control of process across the air-sea exchange.

Description: We investigate the quality of simulating tropical Atlantic (TA) sector climatology and interannual variability in integrations of the Kiel climate model (KCM) with varying atmosphere model resolution. The ocean model resolution is kept fixed. A reasonable simulation of TA sector annual-mean climate, seasonal cycle and interannual variability can only be achieved at sufficiently high horizontal and vertical atmospheric resolution. Two major reasons for the improvements are identified. First, the western equatorial Atlantic westerly surface wind bias in spring can be largely eliminated, which is explained by a better representation of meridional and especially vertical zonal momentum transport. The enhanced atmospheric circulation along the equator in turn greatly improves the thermal structure of the upper equatorial Atlantic with much reduced warm sea surface temperature (SST) biases. Second, the coastline in the southeastern TA and steep orography are better resolved at high resolution, which improves wind structure and in turn reduces warm SST biases in the Benguela upwelling region. The strongly diminished wind and SST biases at high atmosphere model resolution allow for a more realistic latitudinal position of the intertropical convergence zone. Resulting stronger cross-equatorial winds, in conjunction with a shallower thermocline, enable a rapid cold tongue development in the eastern TA in boreal spring. This enables simulation of realistic interannual SST variability and its seasonal phase locking in the KCM, which primarily is the result of a stronger thermocline feedback. Our findings suggest that enhanced atmospheric resolution, both vertical and horizontal, could be a key to achieving more realistic simulation of TA climatology and interannual variability in climate models.

Description: Gas hydrate dissociation is often considered as a precursor or triggering factor for submarine slope failures occurring in relatively deep waters where the bulk of the gas hydrate is found in fine-grained sediments. However, there are actually relatively few studies that focus on the effect of gas hydrate dissociation on the behavior of clays, and very few on what physically happens to clay during and after the dissociation process and how gas hydrate dissociation affects the geotechnical properties of clays. In this paper, we illustrate the effects of hydrate dissociation in clays from laboratory strength tests (direct simple shear) combined with visualization including very-high-resolution 3D imaging (computed tomography), using R11 as the hydrate forming fluid in both laponite and Onsøy clay. The test results reveal that the hydrate dissociation creates bubbles in the surrounding clay matrix and around pipe/well models. In addition, we use CO2-saturated water as the pore fluid in soft clay, and test results show that cracks may develop, allowing gas migration to take place after reducing back pressure in an oedometer cell. Direct simple shear tests show that the undrained shear strength decreases by up to ∼15% due to this process. The test results were then implemented in a 2D finite element model to assess the influence of hydrate dissociation on submarine slope stability. We chose a slope segment west of Svalvard—an area where methane gas bubbles escape from the seabed. The gas bubbling in this area is likely due to climate-controlled hydrate-dissociation (warming of bottom water masses). In the finite-element model, we include the change of methane hydrate stability zone (MHSZ) with time as well as the hydrate-dissociation-induced failure zone, which may be a potential leakage pathway. The numerical study indicates that the hydrate dissociation caused by bottom water warming is unlikely to be the main cause generating a leakage pathway or failure plane. However, the hydrate dissociation causing the reduction in shear strength facilitates a potentially unstable condition. The results imply that the hydrate dissociation may contribute to slope failure as a secondary driver, but are unlikely the main driving force. The aim of this study was to improve our understanding of the physical processes of gas expansion, migration and effect of hydrate dissociation through visualization and a finite element model. In addition, this study discussed methods to detect gas hydrate through a case study, and it was found possible to predict average gas hydrate saturation at sites where the sulfate-methane transition depth is known.

Description: The Atlantic Niño is the dominant mode of interannual sea surface temperature (SST) variability in the eastern equatorial Atlantic. Current coupled global climate models struggle to reproduce its variability. This is thought to be partly related to an equatorial SST bias that inhibits summer cold tongue growth. Here, we address the question whether the equatorial SST bias affects the ability of a coupled global climate model to produce realistic dynamical SST variability. We assess this by decomposing SST variability into dynamical and stochastic components. To compare our model results with observations, we employ empirical linear models of dynamical SST that, based on the Bjerknes feedback, use the two predictors sea surface height and zonal surface wind. We find that observed dynamical SST variance shows a pronounced seasonal cycle. It peaks during the active phase of the Atlantic Niño and is then roughly 4–7 times larger than stochastic SST variance. This indicates that the Atlantic Niño is a dynamical phenomenon that is related to the Bjerknes feedback. In the coupled model, the SST bias suppresses the summer peak in dynamical SST variance. Bias reduction, however, improves the representation of the seasonal cold tongue and enhances dynamical SST variability by supplying a background state that allows key feedbacks of the tropical ocean–atmosphere system to operate in the model. Due to the small zonal extent of the equatorial Atlantic, the observed Bjerknes feedback acts quasi-instantaneously during the dynamically active periods of boreal summer and early boreal winter. Then, all elements of the observed Bjerknes feedback operate simultaneously. The model cannot reproduce this, although it hints at a better performance when using bias reduction.

Description: Gas hydrate dissociation is often considered as a precursor or triggering factor for submarine slope failures occurring in relatively deep waters where the bulk of the gas hydrate is found in fine-grained sediments. However, there are actually relatively few studies that focus on the effect of gas hydrate dissociation on the behavior of clays, and very few on what physically happens to clay during and after the dissociation process and how gas hydrate dissociation affects the geotechnical properties of clays. In this paper, we illustrate the effects of hydrate dissociation in clays from laboratory strength tests (direct simple shear) combined with visualization including very-high-resolution 3D imaging (computed tomography), using R11 as the hydrate forming fluid in both laponite and Onsøy clay. The test results reveal that the hydrate dissociation creates bubbles in the surrounding clay matrix and around pipe/well models. In addition, we use CO2- saturated water as the pore fluid in soft clay, and test results show that cracks may develop, allowing gas migration to take place after reducing back pressure in an oedometer cell. Direct simple shear tests show that the undrained shear strength decreases by up to ∼15% due to this process. The test results were then implemented in a 2D finite element model to assess the influence of hydrate dissociation on submarine slope stability. We chose a slope segment west of Svalvard—an area where methane gas bubbles escape from the seabed. The gas bubbling in this area is likely due to climate-controlled hydrate-dissociation (warming of bottom water masses). In the finite-element model, we include the change of methane hydrate stability zone (MHSZ) with time as well as the hydrate-dissociation-induced failure zone, which may be a potential leakage pathway. The numerical study indicates that the hydrate dissociation caused by bottom water warming is unlikely to be the main cause generating a leakage pathway or failure plane. However, the hydrate dissociation causing the reduction in shear strength facilitates a potentially unstable condition. The results imply that the hydrate dissociation may contribute to slope failure as a secondary driver, but are unlikely the main driving force. The aim of this study was to improve our understanding of the physical processes of gas expansion, migration and effect of hydrate dissociation through visualization and a finite element model. In addition, this study discussed methods to detect gas hydrate through a case study, and it was found possible to predict average gas hydrate saturation at sites where the sulfate-methane transition depth is known.

Description: Marine copepods provide the major food-web link between primary producers and higher trophic levels, and their feeding ecology is of acute interest in light of global change impacts on food-web functioning. Recently, quantitative polymerase chain reaction (qPCR) protocols have been developed, which can complement classic diet quantification methods, such as stable isotope or fatty acid analyses tools. Here, we present first results of feeding experiments assessing sex- and stage-specific food intake by the ubiquitous calanoid copepod Acartia tonsa by 18S targeted qPCR and microscopic grazing assessment. In triplicated mixed-diet feeding treatments, three suitable A. tonsa diets, the cryptophyte Rhodomonas balthica, the haptophyte Isochrysis galbana, and the diatom Thalassiosira weissflogii, were offered in equal biomass proportions under constant conditions. Prey uptake substantially varied between different algal species, as did the extent of sex- and stage-specificity of prey uptake. Male adult copepods had higher R. balthica gut contents than females, and nauplii contained more of this prey source than copepodites or adult copepods in mixed treatments. A trend towards higher amounts of ingested T. weissflogii in adult females than in males and in nauplii than in other stages was detected. Genetic gut content quantifications indicated low feeding on I. galbana, and no consistent sex- or stage-specific differences of I. galbana content in A. tonsa. Our results highlight diet-specific feeding differences between Acartia life stages and sexes, which can have implications on food-web dynamics and specific nutrient transfer to higher trophic levels in copepod populations of varying age composition under changing environmental parameters, such as rising temperatures and increasing ocean acidification.

Description: Sharks are a diverse group of mobile predators that forage across varied spatial scales and have the potential to influence food web dynamics. The ecological consequences of recent declines in shark biomass may extend across broader geographic ranges if shark taxa display common behavioural traits. By tracking the original site of photosynthetic fixation of carbon atoms that were ultimately assimilated into muscle tissues of 5,394 sharks from 114 species, we identify globally consistent biogeographic traits in trophic interactions between sharks found in different habitats. We show that populations of shelf-dwelling sharks derive a substantial proportion of their carbon from regional pelagic sources, but contain individuals that forage within additional isotopically diverse local food webs, such as those supported by terrestrial plant sources, benthic production and macrophytes. In contrast, oceanic sharks seem to use carbon derived from between 30° and 50° of latitude. Global-scale compilations of stable isotope data combined with biogeochemical modelling generate hypotheses regarding animal behaviours that can be tested with other methodological approaches.

Description: The Rare Earth Elements (REEs) have been widely used to investigate marine biogeochemical processes as well as the sources and mixing of water masses. However, there are still important uncertainties about the global aqueous REE cycle with respect to the contributions of highly reactive basaltic minerals originating from volcanic islands and the role of Submarine Groundwater Discharge (SGD). Here we present dissolved REE concentrations obtained from waters at the island-ocean interface (including SGD, river, lagoon and coastal waters) from the island of Tahiti and from three detailed open ocean profiles on the Manihiki Plateau (including neodymium (Nd) isotope compositions), which are located in ocean currents downstream of Tahiti. Tahitian fresh waters have highly variable REE concentrations that likely result from variable water–rock interaction and removal by secondary minerals. In contrast to studies on other islands, the SGD samples do not exhibit elevated REE concentrations but have distinctive REE distributions and Y/Ho ratios. The basaltic Tahitian rocks impart a REE pattern to the waters characterized by a middle REE enrichment, with a peak at europium similar to groundwaters and coastal waters of other volcanic islands in the Pacific. However, the basaltic island REE characteristics (with the exception of elevated Y/Ho ratios) are lost during transport to the Manihiki Plateau within surface waters that also exhibit highly radiogenic Nd isotope signatures. Our new data demonstrate that REE concentrations are enriched in Tahitian coastal water, but without multidimensional sampling, basaltic island Nd flux estimates range over orders of magnitude from relatively small to globally significant. Antarctic Intermediate Water (AAIW) loses its characteristic Nd isotopic signature (-6 to-9) around the Manihiki Plateau as a consequence of mixing with South Equatorial Pacific Intermediate Water (SEqPIW), which shows more positive values (-1 to -2). However, an additional Nd input/exchange along the pathway of AAIW, eventually originating from the volcanic Society, Tuamotu and Tubuai Islands (including Tahiti), is indicated by an offset from the mixing array of AAIW and SEqPIW to more radiogenic Nd isotope compositions.

Description: Study of the microstructure and isotopic composition of authigenic tubule-shaped carbonate concretions from sediment core PS51/154-11 on the western Laptev Sea continental slope (present water depth 270 m) has allowed for reconstruction of the conditions prevailing during their formation and identification of the mechanisms controlling their genesis. Concretions were collected from the basal sediment unit with an extrapolated age estimate of 16.3–17.6 cal.ka. Crystallization of carbonate tubules occurred at the beginning of the last deglaciation when the site was located in the proximity to the former coastline and the mouths of the Olenek and Anabar-Khatanga rivers in water depths of about 150–170 m. Microprobe analysis showed that the studied carbonate tubules consist of the minerals belonging to the siderite–rhodochrosite isomorphic series. The measured isotopic composition of δ13С and δ18O in the carbonates varies between − 21.0 and − 17.0‰ and between − 9.86 and 1.72‰ VPDB, respectively. The δ18O values in the authigenic carbonates give evidence for the gradual transition from a freshwater affected to modern-like marine sedimentation environment during carbonate crystallization. Water freshening is confirmed by the co-occurrence of authigenic Fe–Mn carbonates and Fe-phosphate vivianite that is a typical mineral of freshwater environments. The dominant source of dissolved inorganic carbon in the pore water was the isotopically light carbon derived from the diagenetic decomposition of organic matter. Two possible scenarios of authigenic carbonates formation are proposed: penetration of freshened ground waters and/or enhanced freshwater influence during short seasonal floods in combination with geochemical processes in a narrow marginal filter zone that was located extremely close to the Laptev Sea continental slope and the studied core site.

Description: Rhodopila globiformis: is the most acidophilic anaerobic anoxygenic phototrophic purple bacterium and was isolated from a warm acidic sulfur spring in Yellowstone Park. Its genome is larger than genomes of other phototrophic purple bacteria, containing 7248 Mb with a G + C content of 67.1% and 6749 protein coding and 53 RNA genes. The genome revealed some previously unknown properties such as the presence of two sets of structural genes pufLMC for the photosynthetic reaction center genes and two types of nitrogenases (Mo-Fe and V-Fe nitrogenase), capabilities of autotrophic carbon dioxide fixation and denitrification using nitrite. Rhodopila globiformis assimilates sulfate and utilizes the C1 carbon substrates CO and methanol and a number of organic compounds, in particular, sugars and aromatic compounds. It is among the few purple bacteria containing a large number of pyrroloquinoline quinone-dependent dehydrogenases. It has extended capacities to resist stress by heavy metals, demonstrates different resistance mechanisms to antibiotics, and employs several toxin/antitoxin systems.

Description: Estuaries are highly dynamic systems that serve as nursery areas to fishes and are likely to vary in nursery function, mostly due to habitat quality and food availability. Mangroves are thought to be good nurseries as they enhance food availability and protection, improving growth and survival of juvenile fishes. Food quantity and quality may be reflected in nutritional condition, which may in turn be a useful proxy for growth and survival of larval fishes. This study compared the nutritional condition and growth rate of 793 late stage larvae of estuarine roundherring, Gilchristella aestuaria, by using RNA:DNA indices to indirectly compare the feeding environment among similar warm-temperate mangrove and non-mangrove estuaries in South Africa during January 2015 and 2016. Results indicated that G. aestuaria larvae had differing nutritional conditions within the sampling years and within the estuaries. The standardised RNA:DNA (sRD) as well as the RNA residual index values were higher within mangrove estuaries only in 2016. The instantaneous growth rates (Gi) of larvae in mangrove and non-mangrove estuaries were similar; however, post-flexion larvae were found to have a higher Gi and sRD in mangrove estuaries. Turbidity was the major factor influencing the nutritional condition of G. aestuaria larvae. Mangroves have been found to act as sediment sinks and thus may provide advantages that increase feeding success for post-flexion larvae; however, more is yet to be understood in terms of feeding environment dynamics and how habitat quality influences the survival of larval fishes.

Description: Ocean acidification (OA) is considered an important threat to coral reef ecosystems, because it reduces the availability of carbonate ions that reef-building corals need to produce their skeletons. However, while theory predicts that coral calcification rates decline as carbonate ion concentrations decrease, this prediction is not consistently borne out in laboratory manipulation experiments or in studies of corals inhabiting naturally low-pH reefs today. The skeletal growth of corals consists of two distinct processes: extension (upward growth) and densification (lateral thickening). Here, we show that skeletal density is directly sensitive to changes in seawater carbonate ion concentration and thus, to OA, whereas extension is not. We present a numerical model of Porites skeletal growth that links skeletal density with the external seawater environment via its influence on the chemistry of coral calcifying fluid. We validate the model using existing coral skeletal datasets from six Porites species collected across five reef sites and use this framework to project the impact of 21st century OA on Porites skeletal density across the global tropics. Our model predicts that OA alone will drive up to 20.3 ± 5.4% decline in the skeletal density of reef-building Porites corals.

Description: The benthic environment is a crucial component of marine systems in the provision of ecosystem services, sustaining biodiversity and in climate regulation, and therefore important to human society. With the contemporary increase in computational power, model resolution and technological improvements in quality and quantity of benthic data, it is necessary to ensure that benthic systems are appropriately represented in coupled benthic-pelagic biogeochemical and ecological modelling studies. In this paper we focus on five topical challenges related to various aspects of modelling benthic environments: organic matter reactivity, dynamics of benthic-pelagic boundary layer, microphytobenthos, biological transport and small-scale heterogeneity, and impacts of episodic events. We discuss current gaps in their understanding and indicate plausible ways ahead. Further, we propose a three-pronged approach for the advancement of benthic and benthic-pelagic modelling, essential for improved understanding, management and prediction of the marine environment. This includes: (A) development of a traceable and hierarchical framework for benthic-pelagic models, which will facilitate integration among models, reduce risk of bias, and clarify model limitations; (B) extended cross-disciplinary approach to promote effective collaboration between modelling and empirical scientists of various backgrounds and better involvement of stakeholders and end-users; (C) a common vocabulary for terminology used in benthic modelling, to promote model development and integration, and also to enhance mutual understanding.

Description: In the surface ocean, microorganisms are both a source of extracellular H2O2 and, via the production of H2O2 destroying enzymes, also one of the main H2O2 sinks. Within microbial communities, H2O2 sources and sinks may be unevenly distributed and thus microbial community structure could influence ambient extracellular H2O2 concentrations. Yet the biogeochemical cycling of H2O2 and other reactive oxygen species (ROS) is rarely investigated at the community level. Here, we present a time series of H2O2 concentrations during a 28-day mesocosm experiment where a pCO2 gradient (400–1,450 μatm) was applied to subtropical North Atlantic waters. Pronounced changes in H2O2 concentration were observed over the duration of the experiment. Initially H2O2 concentrations in all mesocosms were strongly correlated with surface H2O2 concentrations in ambient seawaters outside the mesocosms which ranged from 20 to 92 nM over the experiment duration (Spearman Rank Coefficients 0.79–0.93, p-values 〈 0.001–0.015). After approximately 9 days of incubation however, H2O2 concentrations had increased across all mesocosms, later reaching 〉300 nM in some mesocosms (2–6 fold higher than ambient seawaters). The correlation with ambient H2O2 was then no longer significant (p 〉 0.05) in all treatments. Furthermore, changes in H2O2 could not be correlated with inter-day changes in integrated irradiance. Yet H2O2 concentrations in most mesocosms were inversely correlated with bacterial abundance (negative Spearman Rank Coefficients ranging 0.59–0.94, p-values 〈 0.001–0.03). Our results therefore suggest that ambient H2O2 concentration can be influenced by microbial community structure with shifts toward high bacterial abundance correlated with low extracellular H2O2 concentrations. We also infer that the nature of mesocosm experiment design, i.e., the enclosure of water within open containers at the ocean surface, can strongly influence extracellular H2O2 concentrations. This has potential chemical and biological implications during incubation experiments due to the role of H2O2 as both a stressor to microbial functioning and a reactive component involved in the cycling of numerous chemical species including, for example, trace metals and haloalkanes.

Description: We have assessed how varying CO2 (180, 380, and 720 μatm) and growth light intensity (40 and 400 μmol photons m−2 s−1) affected Trichodesmium erythraeum IMS101 growth and photophysiology over free iron (Fe′) concentrations between 20 and 9,600 pM. We found significant iron dependencies of growth rate and the initial slope and maximal relative PSII electron transport rates (rPm). Under iron-limiting concentrations, high-light increased growth rates and rPm; possibly indicating a lower allocation of resources to iron-containing photosynthetic proteins. Higher CO2 increased growth rates across all iron concentrations, enabled growth to occur at lower Fe′ concentrations, increased rPm and lowered the iron half saturation constants for growth (Km). We attribute these CO2 responses to the operation of the CCM and the ATP spent/saved for CO2 uptake and transport at low and high CO2, respectively. It seems reasonable to conclude that T. erythraeum IMS101 can exhibit a high degree of phenotypic plasticity in response to CO2, light intensity and iron-limitation. These results are important given predictions of increased dissolved CO2 and water column stratification (i.e., higher light exposures) over the coming decades.

Description: This observational study compares seasonal variations of surface fluxes (turbulent, radiative, and soil heat) and other ancillary atmospheric/surface/permafrost data based on in-situ measurements made at terrestrial research observatories located near the coast of the Arctic Ocean. Hourly-averaged multiyear data sets collected at Eureka (Nunavut, Canada) and Tiksi (East Siberia, Russia) are analyzed in more detail to elucidate similarities and differences in the seasonal cycles at these two Arctic stations, which are situated at significantly different latitudes (80.0°N and 71.6°N, respectively). While significant gross similarities exist in the annual cycles of various meteorological parameters and fluxes, the differences in latitude, local topography, cloud cover, snowfall, and soil characteristics produce noticeable differences in fluxes and in the structures of the atmospheric boundary layer and upper soil temperature profiles. An important factor is that even though higher latitude sites (in this case Eureka) generally receive less annual incoming solar radiation but more total daily incoming solar radiation throughout the summer months than lower latitude sites (in this case Tiksi). This leads to a counter-intuitive state where the average active layer (or thaw line) is deeper and the topsoil temperature in midsummer are higher in Eureka which is located almost 10° north of Tiksi. The study further highlights the differences in the seasonal and latitudinal variations of the incoming shortwave and net radiation as well as the moderating cloudiness effects that lead to temporal and spatial differences in the structure of the atmospheric boundary layer and the uppermost ground layer. Specifically the warm season (Arctic summer) is shorter and mid-summer amplitude of the surface fluxes near solar noon is generally less in Eureka than in Tiksi. During the dark Polar night and cold seasons (Arctic winter) when the ground is covered with snow and air temperatures are sufficiently below freezing, the near-surface environment is generally stably stratified and the hourly averaged turbulent fluxes are quite small and irregular with on average small downward sensible heat fluxes and upward latent heat and carbon dioxide fluxes. The magnitude of the turbulent fluxes increases rapidly when surface snow disappears and the air temperatures rise above freezing during spring melt and eventually reaches a summer maximum. Throughout the summer months strong upward sensible and latent heat fluxes and downward carbon dioxide (uptake by the surface) are typically observed indicating persistent unstable (convective) stratification. Due to the combined effects of day length and solar zenith angle, the convective boundary layer forms in the High Arctic (e.g., in Eureka) and can reach long-lived quasi-stationary states in summer. During late summer and early autumn all turbulent fluxes rapidly decrease in magnitude when the air temperature decreases and falls below freezing. Unlike Eureka, a pronounced zero-curtain effect consisting of a sustained surface temperature hiatus at the freezing point is observed in Tiksi during fall due to wetter and/or water saturated soils.

Description: According to historical oceanographic data, anomalies in the dynamic topography during the winter period were calculated and two climatic stages of dynamic condition of the Arctic Ocean were defined: 1949–1993 and 2007–2013. The associativity of opposition of anomalies in the dynamic topography of the Eurasian and Amerasian basins with fluctuations in the thermal condition of the Northern Atlantic and Pacific oceans, the indexes of atmospheric circulation, river runoff, and change in the area of ice in August of the Laptev, East Siberian, and Chukchi seas is established.

Description: The AlpArray programme is a multinational, European consortium to advance our understanding of orogenesis and its relationship to mantle dynamics, plate reorganizations, surface processes and seismic hazard in the Alps–Apennines–Carpathians–Dinarides orogenic system. The AlpArray Seismic Network has been deployed with contributions from 36 institutions from 11 countries to map physical properties of the lithosphere and asthenosphere in 3D and thus to obtain new, high-resolution geophysical images of structures from the surface down to the base of the mantle transition zone. With over 600 broadband stations operated for 2 years, this seismic experiment is one of the largest simultaneously operated seismological networks in the academic domain, employing hexagonal coverage with station spacing at less than 52 km. This dense and regularly spaced experiment is made possible by the coordinated coeval deployment of temporary stations from numerous national pools, including ocean-bottom seismometers, which were funded by different national agencies. They combine with permanent networks, which also required the cooperation of many different operators. Together these stations ultimately fill coverage gaps. Following a short overview of previous large-scale seismological experiments in the Alpine region, we here present the goals, construction, deployment, characteristics and data management of the AlpArray Seismic Network, which will provide data that is expected to be unprecedented in quality to image the complex Alpine mountains at depth.

Description: Parasitic and commensal species can impact the structure and function of ecological communities and are typically highly specialized to overcome host defences. Here, we report multiple instances of a normally free-living species, the blue mussel Mytilus edulis Linnaeus, 1758, inhabiting the branchial chamber of the shore crab Carcinus maenas (Linnaeus, 1758) collected from widely separated geographical locations. A total of 127 C. maenas were examined from four locations in the English Channel, one location in the Irish Sea and two locations at the entrance of the Baltic Sea. The branchial chambers of three crabs (one from the English Channel and two from Gullmar Fjord, Sweden) were infested with mussels resembling the genus Mytilus. Sequencing at the Me15/16 locus on the polyphenolic adhesive protein gene confirmed the identity as M. edulis. Bivalve infestation always occurred in larger red male individuals. Up to 16 mussels, ranging from 2 to 11 mm in shell length, were found in each individual, either wedged between gill lamellae or attached to the branchial chamber inner wall. This is one of the first reports of a bivalve inhabiting crustacean gills and is an intriguing case of a normally free-living prey species infesting its predator

Description: The ultimate, possibly geodynamic control and potential impact of changes in circulation activity and salt discharge of Mediterranean outflow waters (MOW) on Atlantic meridional overturning circulation have formed long-standing objectives in paleoceanography. Late Pliocene changes in the distal advection of MOW were reconstructed on orbital timescales for northeast Atlantic DSDP/ODP sites 548 and 982 off Brittany and on Rockall Plateau, supplemented by a proximal record from Site U1389 west off Gibraltar, and compared to Western Mediterranean surface and deep-water records of Alboran Sea Site 978. From ~3.43 to 3.3 Ma, MOW temperatures and salinities form a prominent rise by 2–4 °C and ~3 psu, induced by a preceding and coeval rise in sea surface and deep-water salinity and increased summer aridity in the Mediterranean Sea. We speculate that these changes triggered an increased MOW flow and were ultimately induced by a persistent 2.5 °C cooling of Indonesian Through-Flow waters. The temperature drop resulted from the northward drift of Australia that crossed a threshold value near 3.6–3.3 Ma and led to a large-scale cooling of the eastern subtropical Indian Ocean and in turn, to a reduction of African monsoon rains. Vice versa, we show that the distinct rise in Mediterranean salt export after ~3.4 Ma induced a unique long-term rise in the formation of Upper North Atlantic Deep Water, that followed with a phase lag of ~100 ky. In summary, we present evidence for an interhemispheric teleconnection of processes in the Indonesian Gateways, the Mediterranean and Labrador Seas, jointly affecting Pliocene climate.

Description: Seafloor elongated depressions are indicators of gas seepage or slope instability. Here we report a sequence of slope-parallel elongated depressions that link to headwalls of sediment slides on upper slope. The depressions of about 250 m in width and several kilometers in length are areas of focused gas discharge indicated by bubble-release into the water column and methane enriched pore waters. Sparker seismic profiles running perpendicular and parallel to the coast, show gas migration pathways and trapped gas underneath these depressions with bright spots and seismic blanking. The data indicate that upward gas migration is the initial reason for fracturing sedimentary layers. In the top sediment where two young stages of landslides can be detected, the slope-parallel sediment weakening lengthens and deepens the surficial fractures, creating the elongated depressions in the seafloor supported by sediment erosion due to slope-parallel water currents.

Description: Seafloor morphology plays a key role in submarine mineral exploration as precious minerals are associated with specific geomorphological settings. Mn-nodules occur in abyssal plains, seafloor massive sulphides are strongly connected to volcanic areas and sand, gravel and other marine minable aggregates are deposited in coastal environments. For resource assessments and exploitation, a detailed knowledge of the seafloor morphology is essential to evaluate areas of terrain that cannot be mined due to technical limitations, and to estimate abundance, extent and thickness of the deposits. The most important method used is multibeam mapping, from which bathymetric and backscatter data are derived. These are often linked to side scan sonar surveys and sub-bottom profiling. Optical video and photo data provide additional information about substrate type and ecology, and help improve and adapt exploration and exploitation plans and technology. For the three most important marine mineral types—sand and gravel, Mn-nodules and seafloor massive sulphides—exploration and exploitation methods are described and the environmental impacts associated with mining these resources are discussed.