Hydrocarbon Degradation in Coastal Muddy Areas and Anoxic Ecosystems (DHYVA Project): Role of Bacterial Mechanisms and Bioturbation Effects on the Biodisponibility of Organic Pollutants

Abstract

Muddy areas and more or less coastal anoxic zones play a key role in maintaining the integrity of estuarine and coastal ecosystems. By their localization, these areas are frequently exposed to pollutant damage, such as oil spills or accidental events, and accumulate various pollutants released by continental hydrosystems. Due to their composition (fine silt sediments), actual remediation techniques are not adapted. These artificial compounds accumulate in different sites, constituting ``pollutant reservoirs{''} that are threats for the ecosystem as well as for human health. Microorganisms play a key role in hydrocarbon degradation. However, most of our knowledge has been obtained by studies on isolated bacterial strains. In addition, bacterial cooperation within different microbial groups has been demonstrated for the degradation of complex hydrocarbon mixtures. Silt sediments are located at the oxic/anoxic interface where various bacterial metabolisms coexist and follow one another through the function of the tides. Moreover, burrowing organisms can influence the bacterial metabolisms by making the oxygen penetration easier. It thus seems judicious to tackle the problem of hydrocarbon degradation in a global way, trying to understand how bacterial metabolisms interact in the degradation of the pollutants and to estimate the bioturbation effects of these activities. This is the main objective of the project DHYVA (Degradation des HYdrocarbures dans les VAsieres), with a special focus on anaerobic degradation mechanisms, about which we have limited knowledge. ({*}) CEntre de Documentation, de Recherche et d'Experimentation sur les pollutions accidentelles des eaux