Return of naturally sourced Pb to Atlantic surface waters

Anthropogenic emissions completely overwhelmed natural marine lead (Pb) sources during the past century, predominantly due to leaded petrol usage. Here, based on Pb isotope measurements, we reassess the importance of natural and anthropogenic Pb sources to the tropical North Atlantic following the nearly complete global cessation of leaded petrol use. Significant proportions of up to 30-50% of natural Pb, derived from mineral dust, are observed in Atlantic surface waters, reflecting the success of the global effort to reduce anthropogenic Pb emissions. The observation of mineral dust derived Pb in surface waters is governed by the elevated atmospheric mineral dust concentration of the North African dust plume and the dominance of dry deposition for the atmospheric aerosol flux to surface waters. Given these specific regional conditions, emissions from anthropogenic activities will remain the dominant global marine Pb source, even in the absence of leaded petrol combustion

Review of the projected impacts of climate change on coastal fishes in southern Africa

The coastal zone represents one of the most economically and ecologically important ecosystems on the planet, none more so than in southern Africa. This manuscript examines the potential impacts of climate change on the coastal fishes in southern Africa and provides some of the first information for the Southern Hemisphere, outside of Australasia. It begins by describing the coastal zone in terms of its physical characteristics, climate, fish biodiversity and fisheries. The region is divided into seven biogeographical zones based on previous descriptions and interpretations by the authors. A global review of the impacts of climate change on coastal zones is then applied to make qualitative predictions on the likely impacts of climate change on migratory, resident, estuarine-dependent and catadromous fishes in each of these biogeographical zones. In many respects the southern African region represents a microcosm of climate change variability and of coastal habitats. Based on the broad range of climate change impacts and life history styles of coastal fishes, the predicted impacts on fishes will be diverse. If anything, this review reveals our lack of fundamental knowledge in this field, in particular in southern Africa. Several research priorities, including the need for process-based fundamental research programs are highlighted

Biodiversité du milieu marin : Le phytoplankton.

L'évocation de l'environnement en Guyane renvoie intuitivement à la forêt amazonienne, poumon de la Terre, avec ses faunes et flores exubérantes. Il existe pourtant une autre Guyane, moins emblématique, celle des espaces côtiers et littoraux, paradoxalement moins accessible et de ce fait mieux préservée. Entre milieu marin, pointes rocheuses, plages de sable, étendues de vase, mangroves, marais, forêts et savanes, la Guyane côtière recèle en effet des écosystèmes très divers, dont on commence seulement à découvrir la richesse, l'organisation et le fonctionnement. Rédigé par un collectif de chercheurs impliqués dans l'observation, la description et l'analyse de ces environnements et de leurs biodiversités, Guyane océane présente ainsi pour la première fois ces milieux méconnus à un large public