17 results match your criteria African Journal Of Marine Science[Journal]

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Hemispheric asymmetry in ocean change and the productivity of ecosystem sentinels.

Science 2021 05;372(6545):980-983

U.S. Fish and Wildlife Service, Anchorage, AK, USA.

Climate change and other human activities are causing profound effects on marine ecosystem productivity. We show that the breeding success of seabirds is tracking hemispheric differences in ocean warming and human impacts, with the strongest effects on fish-eating, surface-foraging species in the north. Hemispheric asymmetry suggests the need for ocean management at hemispheric scales. Read More

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Ecological insights from three decades of animal movement tracking across a changing Arctic.

Science 2020 11;370(6517):712-715

National Park Service, Denali National Park and Preserve, Denali Park, AK, USA.

The Arctic is entering a new ecological state, with alarming consequences for humanity. Animal-borne sensors offer a window into these changes. Although substantial animal tracking data from the Arctic and subarctic exist, most are difficult to discover and access. Read More

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November 2020

Last Interglacial Iberian Neandertals as fisher-hunter-gatherers.

Science 2020 03;367(6485)

Sociedade Torrejana de Espeleologia e Arqueologia, Quinta da Lezíria, 2350-510, Torres Novas, Portugal.

Marine food-reliant subsistence systems such as those in the African Middle Stone Age (MSA) were not thought to exist in Europe until the much later Mesolithic. Whether this apparent lag reflects taphonomic biases or behavioral distinctions between archaic and modern humans remains much debated. Figueira Brava cave, in the Arrábida range (Portugal), provides an exceptionally well preserved record of Neandertal coastal resource exploitation on a comparable scale to the MSA and dated to ~86 to 106 thousand years ago. Read More

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Abrupt cloud clearing of marine stratocumulus in the subtropical southeast Atlantic.

Science 2018 08 19;361(6403):697-701. Epub 2018 Jul 19.

Department of Geography and Atmospheric Science, University of Kansas, Lawrence, KS, USA.

We document rapid and abrupt clearings of large portions of the subtropical marine low cloud deck that have implications for the global radiation balance and climate sensitivity. Over the southeast Atlantic, large areas of stratocumulus are quickly eroded, yielding partial or complete clearing along sharp transitions hundreds to thousands of kilometers in length that move westward at 8 to 12 meters per second and travel as far as 1000+ kilometers from the African coast. The westward-moving cloudiness reductions have an annual peak in occurrence in the period from April through June. Read More

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Positive biodiversity-productivity relationship predominant in global forests.

Science 2016 10;354(6309)

Wageningen University and Research (Alterra), Team Vegetation, Forest and Landscape Ecology-6700 AA, Netherlands.

The biodiversity-productivity relationship (BPR) is foundational to our understanding of the global extinction crisis and its impacts on ecosystem functioning. Understanding BPR is critical for the accurate valuation and effective conservation of biodiversity. Using ground-sourced data from 777,126 permanent plots, spanning 44 countries and most terrestrial biomes, we reveal a globally consistent positive concave-down BPR, showing that continued biodiversity loss would result in an accelerating decline in forest productivity worldwide. Read More

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October 2016

ECOLOGY. Aquatic animal telemetry: A panoramic window into the underwater world.

Science 2015 Jun 11;348(6240):1255642. Epub 2015 Jun 11.

Ocean Tracking Network, Department of Biology, Dalhousie University, 1355 Oxford Road, Halifax, Nova Scotia B3H 4R2, Canada.

The distribution and interactions of aquatic organisms across space and time structure our marine, freshwater, and estuarine ecosystems. Over the past decade, technological advances in telemetry have transformed our ability to observe aquatic animal behavior and movement. These advances are now providing unprecedented ecological insights by connecting animal movements with measures of their physiology and environment. Read More

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155,000 years of West African monsoon and ocean thermal evolution.

Science 2007 Jun;316(5829):1303-7

Department of Earth Science and Marine Science Institute, University of California, Santa Barbara, CA 93106-9630, USA.

A detailed reconstruction of West African monsoon hydrology over the past 155,000 years suggests a close linkage to northern high-latitude climate oscillations. Ba/Ca ratio and oxygen isotope composition of planktonic foraminifera in a marine sediment core from the Gulf of Guinea, in the eastern equatorial Atlantic (EEA), reveal centennial-scale variations of riverine freshwater input that are synchronous with northern high-latitude stadials and interstadials of the penultimate interglacial and the last deglaciation. EEA Mg/Ca-based sea surface temperatures (SSTs) were decoupled from northern high-latitude millennial-scale fluctuation and primarily responded to changes in atmospheric greenhouse gases and low-latitude solar insolation. Read More

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Coupled thermal and hydrological evolution of tropical Africa over the last deglaciation.

Science 2007 Mar;315(5819):1701-4

Royal Netherlands Institute for Sea Research, Department of Marine Biogeochemistry and Toxicology, Post Office Box 59, 1790 AB Den Burg-Texel, Netherlands.

We analyzed the distribution of branched tetraether membrane lipids derived from soil bacteria in a marine sediment record that was recovered close to the Congo River outflow, and the results enabled us to reconstruct large-scale continental temperature changes in tropical Africa that span the past 25,000 years. Tropical African temperatures gradually increased from approximately 21 degrees to 25 degrees C over the last deglaciation, which is a larger warming than estimated for the tropical Atlantic Ocean. A direct comparison with sea-surface temperature estimates from the same core revealed that the land-sea temperature difference was, through the thermal pressure gradient, an important control on central African precipitation patterns. Read More

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Middle Paleolithic shell beads in Israel and Algeria.

Science 2006 Jun;312(5781):1785-8

Centre for the Evolution of Cultural Diversity, University College London, 31-34 Gordon Square, London WC1H OPY, UK. Ethnologie Préhistorique, CNRS UMR 7041, 21 Allée de l'Université, F-92023 Nanterre, France.

Perforated marine gastropod shells at the western Asian site of Skhul and the North African site of Oued Djebbana indicate the early use of beads by modern humans in these regions. The remoteness of these sites from the seashore and a comparison of the shells to natural shell assemblages indicate deliberate selection and transport by humans for symbolic use. Elemental and chemical analyses of sediment matrix adhered to one Nassarius gibbosulus from Skhul indicate that the shell bead comes from a layer containing 10 human fossils and dating to 100,000 to 135,000 years ago, about 25,000 years earlier than previous evidence for personal decoration by modern humans in South Africa. Read More

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African droughts and dust transport to the Caribbean: climate change implications.

Science 2003 Nov;302(5647):1024-7

Cooperative Institute for Marine and Atmospheric Studies, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149-1098, USA.

Great quantities of African dust are carried over large areas of the Atlantic and to the Caribbean during much of the year. Measurements made from 1965 to 1998 in Barbados trade winds show large interannual changes that are highly anticorrelated with rainfall in the Soudano-Sahel, a region that has suffered varying degrees of drought since 1970. Regression estimates based on long-term rainfall data suggest that dust concentrations were sharply lower during much of the 20th century before 1970, when rainfall was more normal. Read More

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November 2003

The giant crocodyliform Sarcosuchus from the Cretaceous of Africa.

Science 2001 Nov 25;294(5546):1516-9. Epub 2001 Oct 25.

Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637, USA.

New fossils of the giant African crocodyliform Sarcosuchus imperator clarify its skeletal anatomy, growth patterns, size, longevity, and phylogenetic position. The skull has an expansive narial bulla and elongate jaws studded with stout, smooth crowns that do not interlock. The jaw form suggests a generalized diet of large vertebrates, including fish and dinosaurs. Read More

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November 2001

Plio-Pleistocene African climate.

P B deMenocal

Science 1995 Oct;270(5233):53-9

Lamont-Doherty Earth Observatory, Palisades, NY 10964, USA.

Marine records of African climate variability document a shift toward more arid conditions after 2.8 million years ago (Ma), evidently resulting from remote forcing by cold North Atlantic sea-surface temperatures associated with the onset of Northern Hemisphere glacial cycles. African climate before 2. Read More

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October 1995

Himalayan tectonics, weathering processes, and the strontium isotope record in marine limestones.

J M Edmond

Science 1992 Dec;258(5088):1594-7

The time evolution of the isotopic composition of seawater strontium (the ratio of strontium-87 to strontium-86) over the last 500 million years has the form of an asymmetric trough. The values are highest in the Cambrian and Recent (0.7091) and lowest in the Jurassic (0. Read More

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December 1992

Moroccan crustal response to continental drift.

Science 1973 Jun;180(4089):950-2

The formation and development of a zone of spreading beneath the continental crust resulted in the breakup of Pangea and formation of the Atlantic Ocean. The crust of Morocco bears an extremely complete record of the crustal response to this episode of mantle dynamics. Structural and related depositional patterns indicate that the African margin had stabilized by the Middle Jurassic as a marine carbonate environment; that it was dominated by tensile stresses in the early Mesozoic, resulting in two fault systems paralleling the Atlantic and Mediterranean margins and a basin and range structural-depositional style; and that it was affected by late Paleozoic metamorphism and intrusion. Read More

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Central North Atlantic Plate Motions over the Last 40 Million Years.

Science 1970 Nov;170(3959):727-9

The relative motion vector for the North American and African plates has been determined from detailed charting of the trend of the Atlantis fracture zone for over 1000 kilometers in the central North Atlantic near 30 degrees N and from identification of marine magnetic anomalies and deep-sea drilling results. The vector (pole) is located at 52.5 degrees N, 34 degrees W and has a magnitude (opening rate) of 5. Read More

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November 1970

Pesticdies: transatlantic movements in the northeast trades.

Science 1968 Mar;159(3820):1233-6

Concentrations of chlorinated hydrocarbons in airborne dust carried by the trade winds from the European-African land areas to Barbados range from less than 1 to 164 parts per billion. The lower limit of the average content of 1 cubic meter of air is 7.8 x 10-(14) gram. Read More

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