Ocean sciences

  • Article
    | Open Access

    Eddy heat fluxes crucially affect large-scale oceanic currents but are challenging to monitor on a global scale. Here the authors develop a Deep Learning model to predict the eddy heat fluxes from sea surface height data only, bypassing the need for simultaneous observations of the deep ocean.

    • Tom M. George
    • , Georgy E. Manucharyan
    •  & Andrew F. Thompson
  • Article
    | Open Access

    The Southern Ocean takes up the most heat and carbon, yet because of its remote and harsh location, it remains relatively sparsely measured. Here the authors use a 25 year temperature series which shows a clear, long term trend in subsurface warming that emerges from interannual variability.

    • Matthis Auger
    • , Rosemary Morrow
    •  & Rebecca Cowley
  • Article
    | Open Access

    The expansion of oceanic anoxia during the Paleocene Eocene Thermal Maximum has important implications for faunal turnover patterns and global biogeochemical cycles. Here the authors use uranium isotopes and a biogeochemical model to suggest that the areal expansion of anoxia must have been limited to 10-fold.

    • Matthew O. Clarkson
    • , Timothy M. Lenton
    •  & Derek Vance
  • Article
    | Open Access

    The relative roles of the ocean and atmosphere for the Atlantic Niño is poorly understood. Here, we show that its seasonality is governed by atmospheric diabatic heating that is associated with the seasonal migration of the inter-tropical convergence zone.

    • Hyacinth C. Nnamchi
    • , Mojib Latif
    •  & Ingo Richter
  • Article
    | Open Access

    Microplastics have spread across the globe and reached even the most remote locations, but an understanding of their origins remains largely elusive. Here the authors quantify and characterise microplastics across the North Pole, finding that synthetic fibers like polyester are dominant and likely sourced from the Atlantic Ocean.

    • Peter S. Ross
    • , Stephen Chastain
    •  & Bill Williams
  • Article
    | Open Access

    The Arctic Ocean is influenced by carbon and nutrients from rivers and erosion, but how this affects phytoplankton productivity is not understood. Here, the authors use a spatio-temporally resolved biogeochemical model to estimate that the input of carbon and nutrients fuels 28–51% of annual Arctic Ocean productivity.

    • Jens Terhaar
    • , Ronny Lauerwald
    •  & Laurent Bopp
  • Article
    | Open Access

    Groundwater discharge is a mechanism that transports chemicals from inland systems to the ocean, but it has been considered of secondary influence compared to rivers. Here the authors assess the global significance of groundwater discharge, finding that it has a unique and important contribution to ocean chemistry and Earth-system models.

    • Kimberley K. Mayfield
    • , Anton Eisenhauer
    •  & Adina Paytan
  • Article
    | Open Access

    Climate change and local anthropogenic stressors threaten the persistence of coral reefs. Here the authors track coral bleaching over the course of a heatwave and find that some colonies recovered from bleaching while high temperatures persisted, but only at sites lacking in other strong anthropogenic stressors.

    • Danielle C. Claar
    • , Samuel Starko
    •  & Julia K. Baum
  • Article
    | Open Access

    Multiple co-occurring stressors may affect food webs in ways that are not predictable by studying individual stressors. Here the authors apply a network interaction model to a marine food web in the Arctic, finding that nonlinear interactions between stressors can more than double the risk of population collapse compared to simpler simulations.

    • K. R. Arrigo
    • , Gert L. van Dijken
    •  & R. M. Bailey
  • Article
    | Open Access

    It has been hypothesized that domestication can occur through the ‘commensal pathway’ in which the domesticate takes advantage of a niche created as a byproduct by the domesticator. Here, Brooker et al. provide evidence for a commensal domestication process between longfin damselfish and mysid shrimps.

    • Rohan M. Brooker
    • , Jordan M. Casey
    •  & William E. Feeney
  • Article
    | Open Access

    How and why the ‘Snowball Earth’ occurred during the Cryogenian period is debated. Here, the authors show that the cryogenian ocean hosted diminished tidal amplitudes and associated energy dissipation rates, reaching 10-50% of today’s rates thus perhaps contributing to prolonged glaciations.

    • J. A. Mattias Green
    • , Hannah S. Davies
    •  & Christopher Scotese
  • Article
    | Open Access

    Zooplankton biomass in the dark ocean is thought to be low and weakly coupled to epipelagic primary production, but recent evidence suggests otherwise. Here the authors analyse data from the Malaspina Circumnavigation Expedition and published data to estimate bathypelagic zooplankton biomass and assess its relationship to primary production, currently not well accounted for in oceanic C budget.

    • S. Hernández-León
    • , R. Koppelmann
    •  & C. M. Duarte
  • Article
    | Open Access

    Iceberg melting releases large volumes of freshwater in fjords, yet the impact on oceanic heat delivery to tidewater glaciers is unknown. Here the authors show that iceberg melting invigorates fjord circulation in a large, iceberg-congested fjord, thereby increasing oceanic heat delivery to its tidewater glaciers.

    • B. J. Davison
    • , T. R. Cowton
    •  & A. J. Sole
  • Perspective
    | Open Access

    Marine aquaculture is widely proposed as compatible with ocean sustainability, biodiversity conservation, and human nutrition goals. In this Perspective, Belton and colleagues dispute the empirical validity of such claims and contend that the potential of marine aquaculture has been much exaggerated.

    • Ben Belton
    • , David C. Little
    •  & Shakuntala H. Thilsted
  • Article
    | Open Access

    Fish production is predicted to decrease with anthropogenic global warming. Here the authors analyse fish fossil assemblages from 62–46 My old deep-sea sediments and instead find a positive correlation between fish production and ocean temperature over geological timescales, which a data-constrained model explains in terms of trophic transfer efficiency and primary production.

    • Gregory L. Britten
    •  & Elizabeth C. Sibert
  • Article
    | Open Access

    Overflow water is an important part of the Atlantic Meridional Overturning Circulation, yet how it reaches the Greenland-Scotland Ridge is not fully known. Here, the authors show that the interior of the Greenland Sea gyre is the primary wintertime source of the densest portion of both Denmark Strait and Faroe Bank Channel overflows.

    • Jie Huang
    • , Robert S. Pickart
    •  & Fanghua Xu
  • Article
    | Open Access

    Dense water from the Nordic Seas sustains the Atlantic Meridional Overturning Circulation, yet the upstream pathways are not fully known. Here, the authors provide evidence of a deep current between Iceland and the Faroe Islands, which supplies 50% of the transport through the Faroe Bank Channel overflow.

    • Stefanie Semper
    • , Robert S. Pickart
    •  & Bogi Hansen
  • Article
    | Open Access

    How the El Niño Southern Oscillation depends on the background conditions is not well known. Here, the authors present individual foraminifera distributions which show that central Pacific variability is related to the warmth and depth of the thermocline across varying climate background conditions over the past ~285,000 years.

    • Gerald T. Rustic
    • , Pratigya J. Polissar
    •  & Sarah M. White
  • Article
    | Open Access

    Phytoplankton are biogeochemically important but the drivers of their seasonal cycles in the Southern Ocean are poorly resolved. Here the authors use seven years of ARGO float data to measure bloom initiation, decline and termination throughout the Southern Ocean, finding that bloom dynamics are especially sensitive to the coupling between cell division rates and loss processes.

    • Lionel A. Arteaga
    • , Emmanuel Boss
    •  & Jorge L. Sarmiento
  • Article
    | Open Access

    The Si cycle is important to ocean productivity and nutrient cycling, however there are uncertainties in global budgets. Here the authors use a multi-isotope approach on seafloor sediments and pore fluids, finding that an unappreciated source of Si to the ocean is the degradation of seafloor serpentinites.

    • Sonja Geilert
    • , Patricia Grasse
    •  & Catriona D. Menzies
  • Article
    | Open Access

    This study investigates the effect of changing sea level on deep sea gas emissions in the Arctic. The results show that small decreases in sea-level favors gas release. This implies that sea-level rise may partially counterbalance the effect of warming oceans on gas emissions overall.

    • Nabil Sultan
    • , Andreia Plaza-Faverola
    •  & Jochen Knies
  • Article
    | Open Access

    Exposure to extreme events is a major concern in coastal regions where human populations and stressed ecosystems are at risk to such phenomena. Here the authors show a marine heatwave on the continental shelf resulted from a novel set of compounding effects due to a tropical storm followed by an atmospheric heatwave.

    • B. Dzwonkowski
    • , J. Coogan
    •  & T. Lee
  • Article
    | Open Access

    A significant part of the subpolar North Atlantic has warmed less over the past century than the rest of the global ocean, a feature called the North Atlantic warming hole. Here, the authors show that this anomaly can be explained by remote atmospheric forcing from the rapidly warming Indian Ocean.

    • Shineng Hu
    •  & Alexey V. Fedorov
  • Article
    | Open Access

    Due to legislative shortfalls, species of global conservation concern can still be captured in commercial fisheries. Here the authors show that 91 threatened species are reported in catch/landing databases, 13 of which are traded internationally despite their conservation concern.

    • Leslie A. Roberson
    • , Reg A. Watson
    •  & Carissa J. Klein
  • Article
    | Open Access

    The blooming alga Emiliania huxleyi and its viruses are a model for density-dependent virulent dynamics. However, Knowles et al. show that this host–virus system exhibits temperate dynamics at natural host densities, in a manner dependent on host physiology.

    • Ben Knowles
    • , Juan A. Bonachela
    •  & Kay D. Bidle
  • Article
    | Open Access

    Trough mouth fans are created via repeated glacigenic sediment transport from ice sheets. Here the authors use 3D seismic reflection data to present a formation model for the North Sea Fan and find that exceptionally large volumes of meltwater may mean that freshwater supply is underestimated during glacial cycles.

    • Benjamin Bellwald
    • , Sverre Planke
    •  & Reidun Myklebust
  • Article
    | Open Access

    Ecosystem Based Management measures developed to prevent overfishing could be particularly important under climate change. Here the authors combine climate and fish stock modelling to show that EBM cap implementation reduces climate-driven fishery declines under RCP 4.5 and 8.5 before midcentury. However, there are thermal tipping points beyond which potential collapses are predicted.

    • K. K. Holsman
    • , A. C. Haynie
    •  & A. E. Punt
  • Article
    | Open Access

    Ocean uptake of carbon dioxide impacts the climate, but flux estimates from surface measurements have not been corrected for temperature differences between surface and water sampling depth. Making that correction, the authors find previous estimates for ocean uptake have been substantially underestimated.

    • Andrew J. Watson
    • , Ute Schuster
    •  & Lonneke Goddijn-Murphy
  • Article
    | Open Access

    Determination of 3D molecular structures remains challenging for natural products or organic compounds available in minute amounts. Here, the authors determine the structure of complex molecules, including few micrograms of briarane B-3 isolated from Briareum asbestinums, through measurement of 1H residual chemical shift anisotropy.

    • Nilamoni Nath
    • , Juan Carlos Fuentes-Monteverde
    •  & Christian Griesinger
  • Article
    | Open Access

    The asymmetry between El Niño and La Niña episodes in the tropical Pacific is often not well represented in models. Here, the authors show that this asymmetry is related to subsurface nonlinear dynamical heating and that a realistic representation of this process can potentially improve tropical climate projections.

    • Michiya Hayashi
    • , Fei-Fei Jin
    •  & Malte F. Stuecker
  • Article
    | Open Access

    East Antarctic ice shelves typically have cold ice cavities with low basal melt rates. Here the authors direct observational evidence of high basal melt rates beneath Shirase Glacier Tongue in East Antarctica, driven by inflowing warm water guided by a deep continuous trough extending to the continental slope.

    • Daisuke Hirano
    • , Takeshi Tamura
    •  & Shigeru Aoki
  • Article
    | Open Access

    The risks posed by plastic contamination of the ocean cannot be assessed as their amount and location remain largely unknown. Here the authors show that large quantities of microplastics exist below the ocean surface over the entire Atlantic in quantities greater than previously estimated.

    • Katsiaryna Pabortsava
    •  & Richard S. Lampitt
  • Article
    | Open Access

    Some palaeotemperature proxies suffer from inaccuracies related to kinetic fractionations occurring during carbonate mineral growth. Here, the authors show that dual clumped isotope thermometry can identify the origin of these kinetic biases and allows for the reconstruction of accurate environmental temperatures.

    • David Bajnai
    • , Weifu Guo
    •  & Jens Fiebig
  • Article
    | Open Access

    Ocean cold seeps are poorly understood relative to related systems like hydrothermal vents. Here the authors use high pressure bioreactors and microbial communities from a cold seep mud volcano and find a previously missing step of methane conversion to acetate that likely fuels heterotrophic communities.

    • Shanshan Yang
    • , Yongxin Lv
    •  & Yu Zhang
  • Article
    | Open Access

    How the tropical mixed layer of the ocean reacts to near-inertial waves has rarely been observed directly. Here, the authors present new data that shows strongly elevated vertical diffusive heat flux in the presence of near-inertial waves, causing a cooling of the mixed layer that is particularly strong in summer.

    • Rebecca Hummels
    • , Marcus Dengler
    •  & Peter Brandt
  • Article
    | Open Access

    Brandl, Johansen et al. compare organismal traits, community structure, and productivity dynamics of cryptobenthic reef fishes across two locations, the Arabian Gulf and the Gulf of Oman, the former of which harbors the world’s hottest coral reefs. They show that environmental extremes in the Arabian Gulf result in dramatically less diverse, abundant, and productive cryptobenthic fish assemblages, which could foreshadow the future of coral reef biodiversity and functioning.

    • Simon J. Brandl
    • , Jacob L. Johansen
    •  & John A. Burt
  • Article
    | Open Access

    Predicted sea-level rise is widely anticipated to lead to increased coastal erosion, however, assessing how rocky coasts will respond to changes in marine conditions is difficult to constrain. Here, the authors find that a North Yorkshire rocky cliff has been eroding at a similar rate over the last 7 kyr, and they do not observe an increase in erosion rates in response to modern sea level rise.

    • Zuzanna M. Swirad
    • , Nick J. Rosser
    •  & John Barlow
  • Article
    | Open Access

    Ocean oxygen minimum zones (OMZs) are known to emit the powerful greenhouse gas N2O, but global emission dynamics are not constrained. Here the authors use air trajectory analyses and find that air masses pick up N2O as they pass over OMZs, and that overall concentrations are elevated during La Niña events.

    • Andrew R. Babbin
    • , Elisabeth L. Boles
    •  & Ray F. Weiss
  • Perspective
    | Open Access

    Oceans provide important natural resources, but the management and governance of the ocean is complex and the ecosystem is suffering as a result. The authors discuss current barriers to sustainable ocean governance and suggest pathways forward.

    • Tanya Brodie Rudolph
    • , Mary Ruckelshaus
    •  & Philile Mbatha
  • Article
    | Open Access

    Anthropogenic stressors affect many aspects of marine organismal health. Here, the authors expose surgeonfish to temperature and pesticide stressors and show that the stressors, separately and in combination, have adverse effects on thyroid signaling, which disrupts several sensory systems and important predation defenses.

    • Marc Besson
    • , William E. Feeney
    •  & David Lecchini
  • Article
    | Open Access

    Microbial ammonia oxidation is important in marine nutrient cycling and greenhouse gas dynamics, but the responses to ocean warming are unclear. Here coast to open ocean incubations show that projected year 2100 temperatures might be too hot for these microbes in oligotrophic regions to handle, but may facilitate oxidation rates in coastal waters.

    • Zhen-Zhen Zheng
    • , Li-Wei Zheng
    •  & Shuh-Ji Kao
  • Article
    | Open Access

    Little is known about gene expression of organisms in the deep sea, partially owing to constraints on sampling these organisms in situ. Here the authors circumvent this problem, fixing tissue of a deep-sea mussel at 1,688 m in depth, and later analyzing transcriptomes to reveal gene expression patterns showing tidal oscillations.

    • Audrey M. Mat
    • , Jozée Sarrazin
    •  & Marjolaine Matabos
  • Article
    | Open Access

    Monomethylmercury is a toxin that humans can be exposed to after consumption of seafood in which it has bioaccumulated. Here the authors show that amphipods in the deepest point of the global ocean contain monomethylmercury with surface origins, suggesting rapid sinking of this toxin on particles.

    • Ruoyu Sun
    • , Jingjing Yuan
    •  & Congqiang Liu
  • Article
    | Open Access

    The authors here report tensile properties of polycrystalline methane hydrate at the micron scale by applying a contactless, thermos-induced stress to a tenuous shell of hydrate grown in a thin glass capillary. The results suggest that the cohesive strength of methane hydrate in marine settings may be an order of magnitude less than currently thought.

    • Dyhia Atig
    • , Daniel Broseta
    •  & Ross Brown
  • Article
    | Open Access

    Satellites can observe marine phytoplankton, but observations are sparse in seasonally dark, cloudy environments like the Southern Ocean. These authors use Argo floats to track the fate of phytoplankton blooms off Antarctica and determine 10% of biomass is exported, while 90% is prey to grazing.

    • Sébastien Moreau
    • , Philip W. Boyd
    •  & Peter G. Strutton