Evaluation of the ecological impact of gas platforms in the Adriatic Sea

Starting from 1998 multidisciplinary studies were performed by ISMAR-CNR, Marine Fishery Section of Ancona (Italy), in co-operation with ENI S.p.A. - AGIP Division, to evaluate the ecological impact generated by the installation of gas platforms in the Adriatic sea. These studies included investigations on the hydrological characteristics of water column (currents, temperature, nutrients, etc.), analysis of chemical and physical features of sediments, quali-quantitative assessment of benthic communities, analysis of heavy metal concentrations in mussels (Mytilus galloprovincialis) settled on the platforms' jacket as well as the temporal evolution of fish assemblages. Several gas platforms placed at different depths, water circulation conditions and bottom types were investigated in this way. The surveys generally started a few months after the end of the set up operations and lasted three years, so allowing the evaluation of the ecological impact level due to the construction of the structures and its temporal evolution. This multi-disciplinary approach lead to identify two main scenarios including most of the Adriatic platforms: the former concerns the structures placed in shallow water (up to 25-30 m depth), on muddy bottoms, and subjected to a strong influence of the Adriatic general cyclonic circulation, wave motion and rivers inflow; the latter includes the platforms sited in deeper water up to about 80 m, on relitic sands, which are less affected by the above mentioned environmental factors. Two examples of the two scenarios have been reported in this contest: platform "Regina", representing a typical Adriatic inshore gas platform, and "Barbara NW", which is a good example of the Adriatic offshore gas platforms.