ALBERT

Description: Tropical South America is one of the three main centres of the global, zonal overturning circulation of the equatorial atmosphere (generally termed the 'Walker' circulation1). Although this area plays a key role in global climate cycles, little is known about South American climate history. Here we describe sediment cores and down-hole logging results of deep drilling in the Salar de Uyuni, on the Bolivian Altiplano, located in the tropical Andes. We demonstrate that during the past 50,000 years the Altiplano underwent important changes in effective moisture at both orbital (20,000-year) and millennial timescales. Long-duration wet periods, such as the Last Glacial Maximum—marked in the drill core by continuous deposition of lacustrine sediments—appear to have occurred in phase with summer insolation maxima produced by the Earth's precessional cycle. Short-duration, millennial events correlate well with North Atlantic cold events, including Heinrich events 1 and 2, as well as the Younger Dryas episode. At both millennial and orbital timescales, cold sea surface temperatures in the high-latitude North Atlantic were coeval with wet conditions in tropical South America, suggesting a common forcing.

Description: Iron (Fe) is an essential micronutrient for marine microbial organisms, and low supply controls productivity in large parts of the world’s ocean. The high latitude North Atlantic is seasonally Fe limited, but Fe distributions and source strengths are poorly constrained. Surface ocean dissolved Fe (DFe) concentrations were low in the study region (〈0.1 nM) in summer 2010, with significant perturbations during spring 2010 in the Iceland Basin as a result of an eruption of the Eyjafjallajökull volcano (up to 2.5 nM DFe near Iceland) with biogeochemical consequences. Deep water concentrations in the vicinity of the Reykjanes Ridge system were influenced by pronounced sediment resuspension, with indications for additional inputs by hydrothermal vents, with subsequent lateral transport of Fe and manganese plumes of up to 250–300 km. Particulate Fe formed the dominant pool, as evidenced by 4–17 fold higher total dissolvable Fe compared with DFe concentrations, and a dynamic exchange between the fractions appeared to buffer deep water DFe. Here we show that Fe supply associated with deep winter mixing (up to 103 nmol m−2 d−1) was at least ca. 4–10 times higher than atmospheric deposition, diffusive fluxes at the base of the summer mixed layer, and horizontal surface ocean fluxes.

Description: To the Editor: Mass spectrometry–based proteomics has become an important component of biological research. Numerous proteomics methods have been developed to identify and quantify the proteins in biological and clinical samples1, identify pathways affected by endogenous and exogenous perturbations2 and characterize protein complexes3. Despite successes, the interpretation of vast proteomics data…

Description: Anthropogenic emissions completely overwhelmed natural marine lead (Pb) sources during the past century, predominantly due to leaded petrol usage. Here, based on Pb isotope measurements, we reassess the importance of natural and anthropogenic Pb sources to the tropical North Atlantic following the nearly complete global cessation of leaded petrol use. Significant proportions of up to 30–50% of natural Pb, derived from mineral dust, are observed in Atlantic surface waters, reflecting the success of the global effort to reduce anthropogenic Pb emissions. The observation of mineral dust derived Pb in surface waters is governed by the elevated atmospheric mineral dust concentration of the North African dust plume and the dominance of dry deposition for the atmospheric aerosol flux to surface waters. Given these specific regional conditions, emissions from anthropogenic activities will remain the dominant global marine Pb source, even in the absence of leaded petrol combustion.

Description: The marine iodine cycle has significant impacts on air quality and atmospheric chemistry. Specifically, the reaction of iodide with ozone in the top few micrometres of the surface ocean is an important sink for tropospheric ozone (a pollutant gas) and the dominant source of reactive iodine to the atmosphere. Sea surface iodide parameterisations are now being implemented in air quality models, but these are currently a major source of uncertainty. Relatively little observational data is available to estimate the global surface iodide concentrations, and this data has not hitherto been openly available in a collated, digital form. Here we present all available sea surface (〈20 m depth) iodide observations. The dataset includes values digitised from published manuscripts, published and unpublished data supplied directly by the originators, and data obtained from repositories. It contains 1342 data points, and spans latitudes from 70°S to 68°N, representing all major basins. The data may be used to model sea surface iodide concentrations or as a reference for future observations.

Description: The Atlantic Ocean receives warm, saline water from the Indo-Pacific Ocean through Agulhas leakage around the southern tip of Africa. Recent findings suggest that Agulhas leakage is a crucial component of the climate system and that ongoing increases in leakage under anthropogenic warming could strengthen the Atlantic overturning circulation at a time when warming and accelerated meltwater input in the North Atlantic is predicted to weaken it. Yet in comparison with processes in the North Atlantic, the overall Agulhas system is largely overlooked as a potential climate trigger or feedback mechanism. Detailed modelling experiments—backed by palaeoceanographic and sustained modern observations—are required to establish firmly the role of the Agulhas system in a warming climate.

Description: Subduction of oceanic crust and the formation of volcanic arcs above the subduction zone are important components in Earth’s geological and geochemical cycles. Subduction consumes and recycles material from the oceanic plates, releasing fluids and gases that enhance magmatic activity, feed hydrothermal systems, generate ore deposits and nurture chemosynthetic biological communities. Among the first lavas to erupt at the surface from a nascent subduction zone are a type classified as boninites. These lavas contain information about the early stages of subduction, yet because most subduction systems on Earth are old and well-established, boninite lavas have previously only been observed in the ancient geological record. Here we observe and sample an active boninite eruption occurring at 1,200 m depth at the West Mata submarine volcano in the northeast Lau Basin, southwest Pacific Ocean. We find that large volumes of H2O, CO2 and sulphur are emitted, which we suggest are derived from the subducting slab. These volatiles drive explosive eruptions that fragment rocks and generate abundant incandescent magma-skinned bubbles and pillow lavas. The eruption has been ongoing for at least 2.5 years and we conclude that this boninite eruption is a multi-year, low-mass-transfer-rate eruption. Thus the Lau Basin may provide an important site for the long-term study of submarine volcanic eruptions related to the early stages of subduction.

Description: The direct effects of temperature increases and differences among life-history might affect the impacts of native and invasive predators on recipient communities. Comparisons of functional responses can improve our understanding of underlying processes involved in altering species interaction strengths and may predict the effect of species invading new communities. Therefore, we investigated the functional responses of the mourning gecko Lepidodactylus lugubris (Duméril & Bibron, 1836) to explore how temperature, body-size and prey density alter gecko predatory impacts in ecosystems. We quantified the functional responses of juvenile and adult geckos in single-predator experiments at 20, 23 and 26 °C. Both displayed saturating Type-II functional responses, but juvenile functional responses and the novel Functional Response Ratio were positively affected by temperature as juvenile attack rates (a) increased as a function of increased temperature. Handling times (h) tended to shorten at higher temperature for both predator stages. We demonstrate that the effects of temperature on functional responses of geckos differ across ontogeny, perhaps reflecting life-history stages prioritising growth and maturation or body maintenance. This indicates that temperature-dependent gecko predatory impacts will be mediated by population demographics. We advocate further comparisons of functional responses to understand the invasiveness and future predatory impacts of geckos, and other invasive species globally, as temperatures change.

Description: Experts release a roadmap for harnessing the potential of assisted evolution to help save corals. The IPCC predicts that if warming reaches 2°C, 99% of all coral reefs will be lost in less than 30 years. It is clear that to ensure the future of corals, the highest priority must be reducing global greenhouse gas emissions. However, even with swift and substantial reductions in emissions, corals will continue to face increasing temperatures for the foreseeable future, which can result in extensive coral mortality and local extinction of some coral species. While recent studies have shown that corals may exhibit some degree of adaptation to ocean warming, it is unclear whether corals are able to survive the rate of temperature change during heat waves that will become more frequent under several climate change scenarios. If corals lack what it takes to naturally rapidly adapt to new environmental regimes, they may fail to survive a warming ocean. This is where assisted evolution could be a game-changer. Growing our understanding of the power of adaptation In January 2023, we held a workshop on assisted evolution co-organized with the Australian Institute of Marine Sciences (AIMS) as part of CORDAP’s Scoping Studies (a series of planning sessions and technology roadmap studies to shape our funding priorities). Our aim was to develop a visionary roadmap, offering recommendations on how to prioritise assisted evolution in R&D investment in the future. Assisted evolution is the use of human interventions to speed up the natural evolutionary process. It may allow coral species to adapt faster than they would if left unaided, allowing reefs and corals to keep better pace with the ocean’s environmental changes. The first step in creating this strategy was to pinpoint where we are now in our understanding regarding the potential and impacts of assisted evolution on enhancing coral tolerance to stress conditions like ocean warming. Our experts unanimously agreed that assisted evolution methods cannot be understood and evaluated without a solid foundational understanding of natural adaptation, and identified some knowledge gaps that can be closed with relatively minimal effort and others that will require substantial investment of time and resources. Key Findings: - Standardising methods, experimental designs, species selection guidelines, and terminologies will help to understand natural adaptation and assisted evolution more rapidly. - Long-term funding is critical to facilitate multigenerational studies, which are needed to deliver essential but largely missing information about coral evolution. Building the best pathway for research and investment This roadmap sets out tangible recommendations for future investment and research, to help fill critical knowledge gaps that could assist natural adaptation and evolution of coral reefs in a warming world. Overall, the roadmap recommends investment in a mixed portfolio of R&D, ranging from technologies with lower perceived risks to those with higher percieved risks and longer R&D horizons. This strategy is advised because of the uncertainty around future heating trajectories and thus requirements for enhancement of tolerance. The roadmap outlined four main areas of work that need to be undertaken: 1. Leading global coordination and synthesis. Recommendation: Building global infrastructure to support research would dramatically accelerate the generation of knowledge around the natural and assisted evolution of corals. This could include compiling and committing to a set of standards and methods that will allow more studies to be used in predictive models, as well as establishing a global resource-sharing network and database to facilitate meta-analysis and synthesis. 2. Optimising generation and use of knowledge. Recommendation: Make sure new studies are well designed and timely. Optimize published and future studies by characterizing relationships between heat stress metrics and other facets of coral fitness. Having funding set aside to be able to quickly respond to bleaching events will ensure vital knowledge is captured rather than lost if and when those events occur. 3. Filling critical knowledge gaps in multigenerational coral data in the laboratory and field. Recommendation: Given the slow-growing nature of coral, longer-term funding would allow researchers to gain critical knowledge needed to estimate the multi-generational benefits and risks of implementing assisted evolution methods in the wild. Standardised approaches repeated in different parts of the world would add confidence to generalise those results. 4. Supporting the advance of existing and new technologies. Recommendation: Methods that may yield a larger effect (e.g., gene editing, hybridisation between species, and assisted migration) are also potentially of greater risk and would need considerable R&D. Expanding support for some of the riskier long-term projects currently being overlooked, could potentially offer a greater return on investment, but should be balanced with continued investment in less risky technologies. CORDAP will be using these recommendations to prepare new accelerator program and we believe that they will assist academia in understanding gaps and needs for future research as well as helping to guide funding agencies on where their money will be most effective. The roadmap identifies the funding structures and research priorities that are most likely to yield the knowledge needed to ensure that assisted evolution methods can be implemented effectively. Ultimately, conserving and restoring coral reefs in warming climates will require an inclusive infrastructure involving many partners at a local, national, and international level.

Description: Landslide-dams, which are often transient, can strongly affect the geomorphology, and sediment and geochemical fluxes, within subaerial fluvial systems. The potential occurrence and impact of analogous landslide-dams in submarine canyons has, however, been difficult to determine due to a scarcity of sufficiently time-resolved observations. Here we present repeat bathymetric surveys of a major submarine canyon, the Congo Canyon, offshore West Africa, from 2005 and 2019. We show how an ~0.09 km3 canyon-flank landslide dammed the canyon, causing temporary storage of a further ~0.4 km3 of sediment, containing ~5 Mt of primarily terrestrial organic carbon. The trapped sediment was up to 150 m thick and extended 〉26 km up-canyon of the landslide-dam. This sediment has been transported by turbidity currents whose sediment load is trapped by the landslide-dam. Our results suggest canyon-flank collapses can be important controls on canyon morphology as they can generate or contribute to the formation of meander cut-offs, knickpoints and terraces. Flank collapses have the potential to modulate sediment and geochemical fluxes to the deep sea and may impact efficiency of major submarine canyons as transport conduits and locations of organic carbon sequestration. This has potential consequences for deep-sea ecosystems that rely on organic carbon transported through submarine canyons.