A baseline study of the soft-bottom macrofauna from the North Adriatic gas field, gas platform Ana

The present study aimed to; 1) assess the potential impact of drilling on the soft-bottom benthic community in the North Adriatic gas field (44°41.7’N - 13°16.1’E; 44 m depth) and 2) to provide a baseline for assessment of environmental impact related to the future gas exploitation. The structural and functional characteristics of the macrobenthos were studied at eight sampling sites arranged in a star shaped formation around a drill hole at 100 m distance in N, S, E, W directions, and at 300 m distance in SW, NW, NE, SE directions. Samples were taken with the Van Veen grab (sampling area of 0.1 m2). At each site, we obtained four replicate samples for qualitative and quantitative analysis of macrofauna, and samples for sediment analyses. Macrobenthic community structure was analysed using univariate, multivariate and distributional techniques; functional diversity following classification by Grall and Glémarec (1997) and ecological status was assessed using AMBI and M-AMBI biotic indices. Results indicated no differences in macrobenthic structure among sampling sites, both related to distance from the drill hole (100 and 300 m) and sampling time (before and after installation of gas platform). All study sites can be ranked into the class of high ecological status. This study should provide objective benchmarks for potential environmental impact on the poorly sorted sand community in the Northern Adriatic offshore waters, as well as for ecological status assessment.