Ecological and molecular approach to the assessment of oil pollution: a comparative study between two coastal marine (Mediterranean and Patagonian) ecoregions

Microorganisms are considered as sentinels of environmental changes, but microbial response to the presence of contaminants, such as hydrocarbons, is still not fully understood. This study aimed at assessing the response of the microbial community to the presence of oil pollution, by comparison of two ecosystems, Milazzo Gulf (Sicily, Italy) and Caleta Cordova (Argentina), as representative of two different temperate Mediterranean and cold-temperate Patagonian ecoregions, respectively. Water and sediments were sampled at coastal stations characterized by different levels of hydrocarbon contamination and analyzed for their microbial enzymatic activity rates; the presence of hydrocarbon-degrading bacteria was also determined. The study approach allowed to determine that microbial metabolism was significantly reduced at the polluted stations, suggesting the detrimental effects of contaminants on organic matter degradation process. The isolation of strains of hydrocarbon-degrading bacteria confirmed that the oil contamination favoured the growth of strains specifically adapted to metabolize hydrocarbons and actively involved in the remediation processes.