The PlasticPelagos Project: microplastics, convergence areas and fin whales in the Pelagos Sanctuary (northwestern Mediterranean Sea)

The Mediterranean Sea is one of the areas most affected by litter in the world. The highest percentage (~80%) of marine litter consists of plastic including microplastics (plastic fragments smaller than 5 mm). Research on the impact of microplastics on large filter-feeding species, such as fin whale (Balaenoptera physalus), is still in its infancy. Here we present the results of the PlasticPelagos pilot project focused to investigate the overlap between microplastics and fin whale feeding ground in convergence areas (gyres) of the SPAMI Pelagos Sanctuary (northwestern Mediterranean Sea). A sampling cruise carried out in September 2014 along 967 miles allowed collecting surface microplastics samples (n=21), counting macrolitter, monitoring cetaceans and collecting skin biopsies of fin whales. Two operational models of ocean circulation (LaMMA) and fin whale potential habitat (JRC) were used to localize possible convergence areas of marine litter and probable presence of foraging fin whales respectively. A multi-layer approach was used to investigate the possible overlap between microplastics convergence areas and fin whale feeding ground. The three layers of field data, microplastics abundance (items-micro/m2), macroplastics abundance (items-macro/km2) and cetacean presence were compared with the maps of ocean circulation and fin whale potential feeding habitat. The plastic data set has revealed high occurrence of microplastics (from 0.009 to 0.260 items/m2) in the investigated surface neustonic/planktonic samples and a significant overlap with the areas showing high macroplastic density (0.6127, R. Spearman). Moreover the areas of high densities of microplastics detected on circulation maps largely overlapped with fin whale potential feeding grounds suggesting that whales are particularly exposed to microplastics threat when foraging in the Pelagos Sanctuary during summer. The ecotoxicological analysis of the collected fin whale skin biopsies will be carried out to elaborate further on this hypothesis.