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Running waters contribute substantially to global carbon fluxes through decomposition of terrestrial plant litter by aquatic microorganisms and detritivores. Diversity of this litter may influence instream decomposition globally in ways that are not yet understood. We investigated latitudinal differences in decomposition of litter mixtures of low and high functional diversity in 40 streams on 6 continents and spanning 113 degrees of latitude. Despite important variability in our dataset, we found latitudinal differences in the effect of litter functional diversity on decomposition, which we explained as evolutionary adaptations of litter-consuming detritivores to resource availability. Specifically, a balanced diet effect appears to operate at lower latitudes versus a resource concentration effect at higher latitudes. The latitudinal pattern indicates that loss of plant functional diversity will have different consequences on carbon fluxes across the globe, with greater repercussions likely at low latitudes. This study was part of the DecoDiv project conducted by the GLoBE network (www.globenetwork.es), which is coordinated by L.B. Most research was based on crowdfunding (details on specific funding sources at each region are given in the Supplementary Materials). Project coordination was funded by Basque Government funds (ref. IT951-16) to the Stream Ecology Group (UPV/EHU, Spain). Litter trait analyses were funded by the 2014-2020 Operational Programme FEDER Andalusia, Spain (ref. UAL18-RNM-B006-B to J.J.C.) and the Portuguese Science Foundation, Portugal (ref. UIDB/04292/2020 to MARE).

The Meridional Overturning Circulation (MOC) is a primary mechanism driving oceanic heat redistribution on Earth, thereby affecting Earth’s climate and weather. However, the full-depth structure and variability of the MOC are still poorly understood, particularly in the South Atlantic. This study presents unique multiyear records of the oceanic volume transport of both the upper (<~3100 meters) and abyssal (>~3100 meters) overturning cells based on daily moored measurements in the South Atlantic at 34.5°S. The vertical structure of the time-mean flows is consistent with the limited historical observations. Both the upper and abyssal cells exhibit a high degree of variability relative to the temporal means at time scales, ranging from a few days to a few weeks. Observed variations in the abyssal flow appear to be largely independent of the flow in the overlying upper cell. No meaningful trends are detected in either cell. International audience

This project has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under the Marie Skłodowska-Curie grant agreement no. 766417. Research made possible with the support, permissions, and funding granted by the following organizations, institutions, and grant agreements: Marine Conservation Program of DPIPWE Tasmania; American Bird Conservancy; Bureau of Ocean Energy Management; communities of Isla Mocha and Islas Juan Fernández; Corporación Nacional Forestal and Servicio Agrícola y Ganadería (Chile); Environment Canada; the National Fish and Wildlife Foundation; the National Geographic Society; ProDelphinus; and the Wallis Foundation; NSF grants DEB 9304579, DEB 9629539, DEB9806606, DEB0235818, and DEB 0842199 to D.J.A.; the National Geographic Society; the U.S. Fish and Wildlife Service; U.S. Geological Survey Ecosystems Mission Area, Wake Forest University; Max-Planck Society and State of Baden-Wuerttemberg Innovation funding; Colorado State University International Programs; Swiss Friends of Galapagos; the International Center for Tropical Ecology at University of Missouri-St. Louis; the Instituto Antartico Chileno (INACH) and the Australian Antarctic Division (AAD); LIFE “Marine IBAs IN Spain” (LIFE04NAT/ES/000049, 2004-2009) and LIFE+ INDEMARES (2009-2014); Sea World Research and Rescue Foundation Inc.; Holsworth Wildlife Research Endowment; and Winifred Violet Scott Trust; FCT-Portugal through projects (UIDB/04292/2020 and UIDP/04292/2020 and UIDP/50017/2020 and UIDB/50017/2020, granted to MARE and CESAM, respectively); the Falklands Islands Government; Natural Environmental Research Council (NERC) core funding to British Antarctic Survey Ecosystems Programme and Official Development Assistance Atlantic Islands project (NE/ R000 107/1); the New Zealand Department of Conservation; Ministry for Primary Industries; Ngāti Rehua Ngāti Wai ki Aotea; Falklands Island Conservation; University of Barcelona (APIF/2015, to M.C.-F.); the French Polar Institute (program IPEV n°109 to H.W.); Réserve Naturelle Nationale des Terres Australes Françaises; and the Zones Atelier Antarctique (LTSER France, CNRS-INEE); European funds through the European Commission Training and Mobility of Researchers Programme (ERBFMBICT983030); Spanish funds through the Ministerio de Ciencia y Tecnología (REN2002-01164/GLO), Ministerio de Educación y Ciencia (CGL2006-01315/BOS), Ministerio de Ciencia e Innovación (CGL2009-11278/BOS), and Ministerio de Economía y Competitividad (CGL2013-42585-P); Catalan funds through the Generalitat de Catalunya (2001SGR00091); and additional funding from SEO/BirdLife (programa Migra & proyecto LIFE+ Indemares), Fundación Banco Bilbao Vizcaya Argentaria (BIOCON04/099) and Fundación Biodiversidad (18PCA4328, 2012-2013); NSERC Discovery Grant and Government of Canada’s Program for International Polar Year to W.A.M.; and an ACAP AC Grant in 2013-14, predoctoral contract BES-2017-079874 of the Spanish Ministerio de Industria, Economía y Competitividad (to L.N.-H.); Spanish Foundation for Biodiversity and Spanish Ministry of Science grant ref. CGL2013-42203-R; the Pew Environment Group via the Pew Fellowship Award in Marine Conservation (to M.L.C.); National Research Foundation; South Africa and Oceans and Coasts; Department of Environment, Agriculture and Fisheries; Malta Seabird Project (LIFE10NAT/MT/090) co-funded by the LIFE program of the European Commission and the Maltese Ministry for the Environment, Sustainable Development and Climate Change, in partnership with the Royal Society for the Protection of Bird and the Portuguese Society for the Study of Birds; predoctoral contract BES-2014-068025 of the Spanish Ministerio de Industria, Economía y Competitividad (to V.M.-P.); Scientific Expert PIM initiative (Petites Iles de Méditerranée); the PIM initiative (Petites Iles de Méditerranée); the Tunisian Coastal Protection and Planning Agency (APAL); Ministry of the Environment, Japan; Funding by Fundación Ecocentro, Argentina; Wildlife Conservation Society, USA; and Ministerio de Ciencia, Tecnología e Innovación, Argentina; Centro Nacional Patagónico (CONICET), postdoctoral contracts by Beatriu de Pinós (2010-BP_A-00173), Juan de la Cierva (JCI-2009-05426), PLEAMAR (2017/2349), and Ramón y Cajal (RYC-2017-22055) programme (to R.R.); Seventh Framework Programme (Research Executive Agency of the European Commission, 618841, FP7-PEOPLE-2013-CIG); Fondation Total pour la Biodiversité (project: Trophic ecology and impacts of bycatch on the avifauna communities of Zembra archipelago); Agence de Protection et d’Aménagement du Littoral (APAL-Tunisia); Killam Postdoctoral fellowship from Dalhousie University; South African National Antarctic Programme; ACAP; Papahānaumokuākea Marine National Monument; NOAA; Japan Society for the Promotion of Science Kakenhi grant 19651100 and 15H02857; National Parks and Conservation Service (Mauritius) (to M.L.C.); IPEV Prog 109; and NASA. The use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. government. The scientific results and conclusions, as well as any views or opinions expressed herein, are those of the authors and do not necessarily reflect those of the NOAA or the Department of Commerce. This communication reflects only the authors’ view, and the Research Executive Agency of the European Union is not responsible for any use that may be made of the information it contains. Z.Z. acknowledges funding from a predoctoral grant (APIF/2012) from the University of Barcelona. J.Ad. acknowledges funding from the U.S. Geological Survey Ecosystems Mission Area, U.S. Bureau of Ocean Energy Management, Pacific OCS Region. Migratory marine species cross political borders and enter the high seas, where the lack of an effective global management framework for biodiversity leaves them vulnerable to threats. Here, we combine 10,108 tracks from 5775 individual birds at 87 sites with data on breeding population sizes to estimate the relative year-round importance of national jurisdictions and high seas areas for 39 species of albatrosses and large petrels. Populations from every country made extensive use of the high seas, indicating the stake each country has in the management of biodiversity in international waters. We quantified the links among national populations of these threatened seabirds and the regional fisheries management organizations (RFMOs) which regulate fishing in the high seas. This work makes explicit the relative responsibilities that each country and RFMO has for the management of shared biodiversity, providing invaluable information for the conservation and management of migratory species in the marine realm.

The prevailing hypothesis for lower atmospheric carbon dioxide (CO2) concentrations during glacial periods is an increased efficiency of the ocean’s biological pump. However, tests of this and other hypotheses have been hampered by the difficulty to accurately quantify ocean carbon components. Here, we use an observationally constrained earth system model to precisely quantify these components and the role that different processes play in simulated glacial-interglacial CO2 variations. We find that air-sea disequilibrium greatly amplifies the effects of cooler temperatures and iron fertilization on glacial ocean carbon storage even as the efficiency of the soft-tissue biological pump decreases. These two processes, which have previously been regarded as minor, explain most of our simulated glacial CO2 drawdown, while ocean circulation and sea ice extent, hitherto considered dominant, emerge as relatively small contributors. Temperature and iron fertilization are more important in driving glacial-interglacial CO2 cycles than previously thought.

The exact timing, route, and process of the initial peopling of the Americas remains uncertain despite much research. Archaeological evidence indicates the presence of humans as far as southern Chile by 14.6 thousand years ago (ka), shortly after the Pleistocene ice sheets blocking access from eastern Beringia began to retreat. Genetic estimates of the timing and route of entry have been constrained by the lack of suitable calibration points and low genetic diversity of Native Americans. We sequenced 92 whole mitochondrial genomes from pre-Columbian South American skeletons dating from 8.6 to 0.5 ka, allowing a detailed, temporally calibrated reconstruction of the peopling of the Americas in a Bayesian coalescent analysis. The data suggest that a small population entered the Americas via a coastal route around 16.0 ka, following previous isolation in eastern Beringia for ~2.4 to 9 thousand years after separation from eastern Siberian populations. Following a rapid movement throughout the Americas, limited gene flow in South America resulted in a marked phylogeographic structure of populations, which persisted through time. All of the ancient mitochondrial lineages detected in this study were absent from modern data sets, suggesting a high extinction rate. To investigate this further, we applied a novel principal components multiple logistic regression test to Bayesian serial coalescent simulations. The analysis supported a scenario in which European colonization caused a substantial loss of pre-Columbian lineages. Native American population history is reexamined using a large data set of pre-Columbian mitochondrial genomes.