Seafloor integrity of the Mar Piccolo Basin (Southern Italy): quantifying anthropogenic impact

The Mar Piccolo Basin is a coastal brackish marine ecosystem located along the northern coast of the Gulf of Taranto (Southern Italy). Despite the ecological relevance of the area (Site of Community Importance IT9130004, Regional Reserve ‘Palude La Vela’ EUAP1189), the entire basin is subjected to intensive human usage. The main activities include extensive mussel farming, important industrial activities, a military harbor and densely populated shores. The goal of our study was to spatially quantify human pressure within the basin and its relationship with biocoenoses. A broad set of data was integrated including acoustic remote data (obtained using a multibeam echosounder and side scan sonar devices), direct observations obtained by SCUBA diving and from a trawled camera, an orthophoto and ESRI® Imagery Basemap. At least eight categories of anthropogenic infrastructure and marks of past and present-day human activities were identified within the Mar Piccolo Basin water column and on the seafloor. These included line farms, pole farms, breeding frame structures, anchoring scars, excavations, buoys, wrecks and undefined traces. Each category was mapped and described using morphometric characterization. The integration of all available data allowed the production of an original map providing the Mar Piccolo seafloor disturbance by anthropogenic impact and an updated distribution of benthic communities, showing their spatial relation. Through the production of a specific thematic map, our work provides the first quantitative assessment of the extent and density of the identified human impact in order to evaluate seafloor integrity.