Benthic-pelagic coupling mediates interactions in Mediterranean mixed fisheries: An ecosystem modeling approach

Benthic--pelagic coupling plays a pivotal role in aquatic ecosystems but the effects of fisherydriven interactions on its functioning has been largely overlooked. Disentangling thebenthic--pelagic links including effects of mixed fisheries, however, needs sketching awhole description of ecosystem interactions using quantitative tools. A holistic food webmodel has been here developed in order to understand the interplay between the benthicpelagiccoupling and mixed fisheries in a Mediterranean system such as the Strait of Sicily.The reconstruction of the food web required review and integration of a vast set of local andregional biological information from bacteria to large pelagic species that were aggregatedinto 72 functional groups. Fisheries were described by 18 fleet segments resulting fromcombination of fishing gears and fishing vessel size. The input-output analysis on the foodweb of energy pathways allowed identifying effects of biological and fishery components.Results showed that the structure of the Strait of Sicily food web is complex. Similarly toother Mediterranean areas, the food web of the Strait of Sicily encompasses 4.5 trophic levels(TLs) with the highest TLs reached by bluefin tuna, swordfish and large hake and largelyimpacted by bottom trawling and large longline. Importantly, benthic-pelagic coupling isaffected by direct and indirect impacts among groups of species, fleets and fleets-speciesthrough the whole trophic spectrum of the food web. Moreover, functional groups ableto move on large spatial scales or life history of which is spent between shelf and slopedomains play a key role in linking subsystems together and mediate interactions in the Mediterraneanmixed fisheries.