The benthic ecosystems are a natural deposit site for a huge variety of potentially pollutant compounds such as heavy metals and plastic. In marine ecosystems, the vast majority of plastics found are of small dimensions, called microplastics, with diameters inferior to 5mm. Due to their small size, many organisms confound with their prey and end up ingesting them. Consequently, microplastics are passed throughout the food web by interactions of predator-prey. The presence of the microplastics can result in lack of fitness of individuals (i.e. chicks during breeding season) and even death when big quantities are ingested.
In this edition of Science in the clear, we present a study about the presence of microplastics in the Arctic and sub-Arctic regions. A chinese research team conducted a bottom trawl survey in the Sea of Chukchi and Bering (Fig. 1), sampling a total of 11 species, including organisms such as starfish, brittle stars, shrimps, whelks and bivalves (Fig. 2). In the lab, all animals were dissected and the microplastic quantity assessed using specialized equipment for microscopic scale analyses.
The team found out that starfish species – which occupy the higher trophic levels, feeding on bivalves, barnacles and gastropods – presented the bigger quantity of microplastics. This result supports the possibility that microplastics may be transferred from prey to predator through ingestion. The plastics found had sizes between 0.2mm – 2mm, which facilitates the ingestion from lower trophic-level organisms of this benthic communities.
Moreover, the biggest quantity of microplastics was registered in the most northern latitudes (Fig. 1) and, after the composition analysis, it was determined that their possible origin was from textiles, plastic packaging and fishing gear (e.g. nylon nets). The presence of big quantities might be associated with anthropogenic activities (e.g. fishing) or transportation of those microplastics through the sea ice and strong oceanic currents.
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Source: Fang, C., Zheng, R., Zhang, Y., Hong, F., Mu, J., Chen, M., Song, P., Lin, L., Lin, H., Le, F., Bo, J., Microplastic contamination in benthic organisms from the Arctic and sub-Arctic regions, Chemosphere (2018), doi: 10.1016/j.chemosphere.2018.06.101.
Author: Ricardo Matias
