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Ocean vorticity equations Ocean dynamics is known to give rise to huge persistent vortices that host especially interesting ecosystems. To study their evolution, mathematicians have developed a simplified model that reproduces the fundamental mechanisms required for their formation. When used in numerical simulations, the model (which filters out small-scale phenomena) could for instance help predict the location of such vortices or their stability under the impact of climate change. 45 Duke Mathematical Journal April 2012 Detailed views of diatom skeletons. Acidity makes diatom skeletons brittle Diatoms, single-cell algae that live in every aquatic environment, are unusual in that they have a glass exoskeleton. Now, a study has shown that ocean acidification has a direct, short-term impact on the morphogenesis of the skeleton. By combining microscopic observations with fluorescent labeling, researchers were able to view in real time the growth of this outer skeleton in varying pH conditions, and found that its rate of formation and porosity decreased with acidification of the surrounding environment. PLOS ONE October 2012 online The Southern Ocean with the Antarctic Circumpolar Current and subtropical currents. Small-scale processes influence global ocean circulation Flows of Antarctic Intermediate Water from the South Atlantic and the Indian Ocean join off southern Africa. Based on a regional numerical simulation with high spatial and temporal resolution, researchers have been able to highlight the decisive importance of small-scale dynamic processes such as eddies in the mixing of these intermediate water masses – and hence in global ocean circulation. The scientists now hope to support their numerical analysis with field observations off the coast of South Africa. Journal of Geophysical Research August 2012 online Using genomics to study the ocean iron cycle Iron in the oceans is of vital importance for the microorganisms that live in surface waters. However, the strategies allowing them to use this nutrient remain poorly understood. By analyzing the genome of natural populations of marine microorganisms, scientists have now shown that the distribution of the various iron metabolic pathways at the ocean surface is not uniform. The study reveals that iron(II) is preferred by organisms living near coasts whereas uptake of iron(III) predominates in the middle of the ocean. PLOS ONE February 2012 online 2012 A year at CNRS Antarctic South America Africa Australia Atlantic Ocean Southern Ocean Southern Ocean Indian Ocean Pacific Ocean C. Falklands


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