Abstract :
[en] In 2014, 311 million tonnes of plastics were produced worldwide while it is estimated that 10% ended up in the oceans. Plastics adsorb many pollutants, cause entanglements in many vertebrates and provoke blockage of the digestive tract of marine mammals, birds and turtles. Plastics also fragment in smaller parts, forming microplastics (<5 mm). These microplastics have the same size than planktonic organisms and can thus be ingested by filter-feeders and planktivorous organisms including fish. Although planktivorous Clupeiforme species are the most fished species in the world (17 million tonnes in 2013), the possible impact of microplastic ingestion on this group has received little attention.
The aim of this study was to quantify and to characterize the ingested anthropogenic particles (AP) in herrings (Clupea harengus), sardines (Sardina pilchardus) and anchovies (Engraulis encrasicolus). Twenty individuals of each species were sampled. Herrings and sardines were caught in the Channel and in the North Sea in January 2013 and in January 2014. Anchovies were sampled in July 2013. The stomach contents were digested by sodium hypochlorite to isolate AP and then they were analysed by Raman spectroscopy and measured. AP were constituted of microplastics (MP) and cellulose fibres, sometimes associated with dyes. We found several plastic families: polyethylene (PE), polypropylene (PP), polystyrene, polyacrylonitrile, polyethylene terephthalate, polyamide and poly(butyl methacrylate). MP occurred in 35%, 50% and 40% of stomach contents of anchovies, sardines and herrings, respectively. Anchovies ingested bigger AP (2 mm) than the two other species. MP was in majority PE followed by PP. Our study shows that highly commercial species are exposed to MP. Further research is needed as MP are transport medium for organic pollutants and their fate once in the organism is unknown.
