Bacterial Communities in Hydrocarbon-Contaminated Marine Coastal Environments

Abstract

There are very different types of coastal areas: sandy or rocky beaches, mud flats or mangroves, sediments or saltmarshes. All of these contain hydrocarbons (HC) which derive from natural or anthropogenic sources. On sites with natural seeps or with long chronic pollutions, microorganisms have adapted to the hydrocarbons and form stable communities. However, in cases of acute contaminations, such as tanker accidents or other spills, microbial communities have to cope with a high impact of hydrocarbons. The hydrocarbons exhibit a selective pressure which may cause considerable changes in the community’s composition and activity. Microbial communities are the key players in biodegradation of hydrocarbons. Among the HC-degrading organisms, the obligate hydrocarbonoclastic bacteria (OHCB) form an important group, due to their global distribution and their frequently described domination of HC-degrading communities. The composition and activity of HC-degrading communities are influenced by abiotic factors, such as temperature, wave activity, concentration of inorganic nutrients, and presence of hydrocarbons. They also are influenced by biological factors such as interspecies cooperations which seem to be of high importance especially for the use of polycyclic aromatic hydrocarbons (PAHs) or complex hydrocarbon mixtures. Due to the intricate interplay of pollutant composition and development of communities, our knowledge about the relationship between community structure and nutritional condition is limited. Therefore, a comprehensive understanding of the physico-chemical and biological interactions should be the object of future research. This would not only enhance our basic knowledge, but also make it possible to improve bioremediation measures in cases of hydrocarbon pollutions.