Ocean sciences

  • Article
    | Open Access

    How acute deoxygenation events affect tropical marine ecosystems remains poorly understood. This study integrates analyses of coral reef benthic communities with microbial community sequencing to show how a deoxygenation event rapidly altered a shallow tropical coral reef ecosystem in the Caribbean.

    • Maggie D. Johnson
    • , Jarrod J. Scott
    •  & Andrew H. Altieri
  • Article
    | Open Access

    The deep North Pacific is the end of the road for global ocean circulation, but the circulation patterns and ventilation are poorly understood. Here the authors show that diffusive transports both along and across density layers play a leading role in returning 1,400 year old water to the surface.

    • Mark Holzer
    • , Tim DeVries
    •  & Casimir de Lavergne
  • Article
    | Open Access

    Nitrogen fixation by diazotrophs is critical for marine primary production. Using Tara Oceans datasets, this study combines a quantitative image analysis pipeline with metagenomic mining to provide an improved global overview of diazotroph abundance, diversity and distribution.

    • Juan José Pierella Karlusich
    • , Eric Pelletier
    •  & Rachel A. Foster
  • Article
    | Open Access

    Estimating velocities in gas liquid flows is of importance in many engineering applications. Hohermuth et al. show that previous bubble velocities obtained from intrusive probes have been underestimated and provide a correction scheme for more accurate velocity measurements.

    • B. Hohermuth
    • , M. Kramer
    •  & D. Valero
  • Article
    | Open Access

    N2 fixation by heterotrophic bacteria has recently been found to take place on sinking marine particles, but an understanding of its regulation and importance is lacking. Here the authors develop a trait-based model for this N2 fixation, finding that this once overlooked process could have global importance.

    • Subhendu Chakraborty
    • , Ken H. Andersen
    •  & Lasse Riemann
  • Article
    | Open Access

    How sea-level in the western Mediterranean reacts to climate changes is not well known. Here, the authors present a regional reconstruction and show that temperatures influenced sea-level change rates during the Holocene, while recent sea-level rise is happening faster than during any other period of the last 4000 years.

    • Matteo Vacchi
    • , Kristen M. Joyse
    •  & Alessio Rovere
  • Article
    | Open Access

    Reprocessed data from satellite altimetry show that the mean significant wave height decreases globally by 22% on average from 30 km to 3 km from the coast. By combining these data with wave period from reanalysis, we estimate a mean reduction of 38% concerning the mean wave energy flux.

    • Marcello Passaro
    • , Mark A. Hemer
    •  & Florian Seitz
  • Article
    | Open Access

    As sea levels rise, coasts are being increasingly  threatened by overtopping caused by the combination of sea level rise, storm surge and wave runup. Here the authors find that global coastal overtopping has increased by over 50% in the last two decades, and under a RCP 8.5 scenario this could increase up to 50 times by 2100 compared to today.

    • Rafael Almar
    • , Roshanka Ranasinghe
    •  & Elodie Kestenare
  • Article
    | Open Access

    North Atlantic deep water (NADW) formation influences the climate and carbon cycle, but the contribution of Arctic waters is difficult to constrain. Here the authors use Pa/Th proxy measurements to determine the amount of Arctic Ocean water that flows through the Fram Strait and contributes to NADW.

    • Lauren E. Kipp
    • , Jerry F. McManus
    •  & Markus Kienast
  • Article
    | Open Access

    Primary productivity in the oligotrophic ocean sustains Earth’s ecosystems, but nutrient concentrations are vanishingly low. Here the authors measure nanomolar macronutrient concentrations in the North Pacific and find that net community production is sustained through high rates of phosphorus recycling.

    • Fuminori Hashihama
    • , Ichiro Yasuda
    •  & Masao Ishii
  • Article
    | Open Access

    The middle of the Gulf of Mexico is stratified and highly oligotrophic, yet there are anomalously high fluxes of sinking particulate matter from the euphotic zone. Here the authors show that lateral advection of organic matter supports nitrogen export in the Gulf of Mexico’s open ocean.

    • Thomas B. Kelly
    • , Angela N. Knapp
    •  & Michael R. Stukel
  • Article
    | Open Access

    Up to 40% of the ocean’s fixed nitrogen is lost in oxygen minimum zones (OMZs) by anammox, but despite the importance of this process, nitrogen loss patterns in OMZs are difficult to predict. Here the authors show that ammonium release from small particles is a major control of anammox in the Peruvian OMZ.

    • Clarissa Karthäuser
    • , Soeren Ahmerkamp
    •  & Marcel M. M. Kuypers
  • Article
    | Open Access

    The macroalgae Sargassum has grown for centuries in the oligotrophic North Atlantic supported by natural nutrient sources and cycling. Here the authors show that changes in tissue nutrient contents since the 1980s reflect global anthropogenic nitrogen enrichment, causing blooms in the wider Atlantic basin.

    • B. E. Lapointe
    • , R. A. Brewton
    •  & P. L. Morton
  • Article
    | Open Access

    A large fraction of ice sheet discharge enters the ocean subsurface from underneath large floating ice-tongues. Here the authors show that associated nutrient export may be governed by shelf circulation and, especially for Fe, particle-dissolved phase exchanges, which is largely independent from freshwater Fe content.

    • Stephan Krisch
    • , Mark James Hopwood
    •  & Eric Pieter Achterberg
  • Article
    | Open Access

    New data from five hot-water drilled boreholes show how atmospheric anomalies affect the circulation beneath Filchner-Ronne Ice Shelf on multi-year time scales. The apparent link of the dense water formation to remote teleconnections is an important step for better predicting contributions to future sea level rise from this sector of Antarctica.

    • Tore Hattermann
    • , Keith W. Nicholls
    •  & Torsten Kanzow
  • Article
    | Open Access

    The Arctic Ocean cooling machine, currently the Barents Sea, plays a crucial role in both regulating the climate and determining the deep ocean circulation. Here the authors show that the efficiency of the cooling machine is poleward enhanced in a warming climate, which pushes Arctic Atlantification poleward.

    • Qi Shu
    • , Qiang Wang
    •  & Fangli Qiao
  • Article
    | Open Access

    Marine snow is a major route through which photosynthetically fixed carbon is transported to the deep ocean, but the factors affecting flux are largely unknown. Here the authors use high frequency imaging of marine snow particles collected during phytoplankton blooms to categorize and quantify transport.

    • Emilia Trudnowska
    • , Léo Lacour
    •  & Lars Stemmann
  • Article
    | Open Access

    The COVID-19 response has led to unparalleled changes in the functioning of human society, from travel restrictions to changes in consumption. Here the authors use high resolution satellite data to track the global reduction in marine traffic during the pandemic, and more recent hints of recovery to pre-lockdown levels.

    • David March
    • , Kristian Metcalfe
    •  & Brendan J. Godley
  • Article
    | Open Access

    Warming ocean water plays a significant role in accelerating Arctic sea ice melt. Here the authors present detailed observations of warm water of Pacific origin entering and diving beneath the Arctic ocean surface, and explore the dynamical processes governing its evolution.

    • Jennifer A. MacKinnon
    • , Harper L. Simmons
    •  & Kevin R. Wood
  • Article
    | Open Access

    Microplastic pollution is a major threat to marine food webs, but the wider ranging impacts on global ocean biogeochemistry are poorly understood. Here the authors use an Earth system model to determine that zooplankton grazing on microplastics could exacerbate trends in ocean oxygen loss.

    • K. Kvale
    • , A. E. F. Prowe
    •  & A. Oschlies
  • Article
    | Open Access

    Ocean warming and changing circulation as a result of climate change are driving down oxygen levels and threatening ecosystems. Here the author shows that though immediate cessation of anthropogenic CO2 emissions would halt upper ocean oxygen loss, it would continue in the deep ocean for 100 s of years.

    • Andreas Oschlies
  • Article
    | Open Access

    Extracting functional information from 16S rRNA data surveys would provide a valuable tool for large-scale functional ecology. Here, the authors use PICRUSt2 to infer metabolic functions from bacterial marker gene data across the South Pacific Ocean, and compare them with rate data, biomass estimators and predictions based on shotgun metagenomes.

    • Eric J. Raes
    • , Kristen Karsh
    •  & Anya M. Waite
  • Article
    | Open Access

    New simulations find that one of Antarctica’s largest ice shelves, the Filchner–Ronne, may be less vulnerable to climate change than previously thought. Melting of the ice shelf initially decreases for many decades, and only increases when global warming exceeds approximately 7 °C.

    • Kaitlin A. Naughten
    • , Jan De Rydt
    •  & Jeff K. Ridley
  • Article
    | Open Access

    Sea-level rise is an important part of climate change, but most sea-level budgets are global and cannot capture important regional changes. Here the authors estimate sea-level budgets along the U.S. Atlantic coast, finding a faster rate of rise during the 20th century than any time in the past 2000 years.

    • Jennifer S. Walker
    • , Robert E. Kopp
    •  & Benjamin P. Horton
  • Article
    | Open Access

    El Niño-Southern Oscillation (ENSO) is a key mode of climate variability with worldwide climate impacts. Here, the authors show that improved representation of summer equatorial Atlantic variability and its lagged teleconnection mechanism with the Pacific, relates to enhanced predictive capacity of autumn/winter ENSO.

    • Eleftheria Exarchou
    • , Pablo Ortega
    •  & Chloé Prodhomme
  • Article
    | Open Access

    Anoxic marine zones are expanding and intensifying with climate change. Here the authors show that microbial dark carbon fixation influences the carbonate system and the stable isotope composition in waters off Chile, contributing up to 35% of the organic carbon reaching the mesopelagic region.

    • Cristian A. Vargas
    • , Sebastian I. Cantarero
    •  & Joe Salisbury
  • Article
    | Open Access

    The extent to which chemical products of water radiolysis could sustain subseafloor microbial life is unknown. Here the authors show that sediment catalyzes radiolytic production of H2 and oxidants, providing the primary energy source for life in ancient marine sediment.

    • Justine F. Sauvage
    • , Ashton Flinders
    •  & Steven D’Hondt
  • Article
    | Open Access

    Atmospheric rivers are responsible for much of the poleward water vapour transport in the mid-latitudes and can cause extreme precipitation after landfall. Here, the authors show that ocean fronts and eddies can influence atmospheric rivers and increase the associated precipitation along the North American west coast.

    • Xue Liu
    • , Xiaohui Ma
    •  & Christina M. Patricola
  • Article
    | Open Access

    The Beaufort Gyre in the western Arctic Ocean has accumulated a large amount of freshwater. Here, the authors show that a historical release in the 1980s resulted in a strong freshening of the western Labrador Sea, suggesting that a future release of the current freshwater volume could even be more impactful.

    • Jiaxu Zhang
    • , Wilbert Weijer
    •  & Milena Veneziani
  • Article
    | Open Access

    The Getz region of West Antarctica is losing ice at an increasing rate; however, the forcing mechanisms remain unclear. Here we show for the first time that since 1994, widespread speedup has occurred on the majority of glaciers in the Getz drainage basin, with some glaciers speeding up by over 44 %.

    • Heather L. Selley
    • , Anna E. Hogg
    •  & Tae-Wan Kim
  • Article
    | Open Access

    Primary productivity in the Southern Ocean plays an important role in the drawdown of atmospheric CO2, but phytoplankton growth is limited by iron. Here the authors show that iron from hydrothermal vents fuels massive phytoplankton blooms in the Southern Ocean that have recurred in the same location for decades.

    • Casey M. S. Schine
    • , Anne-Carlijn Alderkamp
    •  & Kevin R. Arrigo
  • Article
    | Open Access

    The fate of ocean carbon is determined by the balance between primary productivity and heterotrophic breakdown of that photosynthate. Here the authors show that diatoms produce a polysaccharide that resists bacterial degradation, accumulates, aggregates and stores carbon during spring blooms.

    • Silvia Vidal-Melgosa
    • , Andreas Sichert
    •  & Jan-Hendrik Hehemann
  • Article
    | Open Access

    Evaluating sea-level projections used by the IPCC is challenging due to the short overlap with measurements. Here, the authors show that observed global and regional sea-level trends confirm projections and that the acceleration of sea-level rise is between the one expected from the scenarios RCP4.5 and RCP8.5.

    • Jinping Wang
    • , John A. Church
    •  & Xianyao Chen
  • Article
    | Open Access

    Southern Ocean productivity is a crucial component of the carbon cycle, but phytoplankton there are thought to be limited by iron. Here the authors conduct trace metal incubation experiments across the Drake Passage, finding that manganese can play an unexpected role in restricting phytoplankton growth.

    • Thomas J. Browning
    • , Eric P. Achterberg
    •  & Edward Mawji
  • 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