Development and application of a marine biotic index for the evaluation of the influence of aquaculture activities on the benthic ecosystem in Mediterranean coastal areas.

The project was oriented to the development of an innovative tool for a more complete evaluation of the effect of marine aquaculture on the benthic ecosystem. Due to their high sensitivity, the attention was focused on the macroinvertebrates communities and on their use as descriptor of the marine soft bottom “health status”. Therefore, the AMBI, an existing marine biotic index already applied to detect impacts along European Coasts but never for the evaluation of the effects of aquaculture in the Mediterranean Sea, was developed and tested in four cases study: two off-shore fish farms, one in Sardinia and another one in Cyprus and two land-based fish farms in Tuscany. Assigning the macrobenthic species to one of the five Ecological Groups defined by this index, related to species sensitivity to disturbance, the AMBI gives back a classification of the site based on the benthic community “health status”. Thus, for each fish farm, samples of sediment were collected and chemical (total nitrogen, total carbon, organic matter, water content), physical (granulometry) and biological analysis (quantitative and qualitative indices calculation) were carried out. Concerning the biological analysis, all the organisms collected were counted and identified to the lowest possible taxon. The obtained data were used to calculate biological indices, including AMBI. For each case study, new species were added to the AMBI database, and this allowed the correct calculation of the index. The obtained results underlined the potentiality of AMBI in detecting effects of aquaculture on the benthic ecosystem and the development of this index database extended the possibility to use it also for the Mediterranean Sea.