Microplastics: the invisible threat

Abstract

Plastic pollution is affecting marine ecosystems on a global scale. Microplastic particles are of particular concern as, due to their size, they can enter marine food webs. The damage that microplastics can cause, not only physical, due to ingestion, but also the effects of the associated chemical pollutants in marine life, is still unknown. Within the MICROTROPHIC project we evaluated the levels of microplastics and associated chemical pollutants on beaches, sea surface and fish in the Canary Islands. In the north and northeast oriented beaches, maximum abundances of up to 244 gr/m2 were found in the tidal line. On the sea surface, the maximum values were found at Las Canteras Beach, a semi-enclosed bay, with concentrations of more than one million particles/Km2. On the other hand, in 78% of the fish studied, microplastics were found in the gastrointestinal content, mainly fibres. Finally, chemical contaminants associated with microplastics were analyzed on 4 beaches with different levels of anthropogenic pressure. High levels of persistent organic pollutants (POPs) were found, among them DDT, Polycyclic Aromatic Hydrocarbons (PAH), and emerging contaminants such as those derived from UV filters. The sum of DDT and its metabolites was significantly higher in Gran Canaria, the most inhabited and industrialized island, with maximum values of 13.488 ng/g. On the other hand, UV filter levels were higher in Las Canteras and Famara, the beaches with higher touristic pressure, with maximum values of 3.740 ng/g. The values, both the concentration of microplastics and POPs, are similar to those found in the most polluted sites on the planet. The next step in our research is to determine, in controlled laboratory experiments, the possible effects of these contaminant levels on the physiology of fish, jellyfish and crustaceans.