The Marine Strategy Framework Directive (MSFD) aims to reduce the marine debris burden in the marine environment by 2020. This requires an assessment of the actual situation, which includes the occurrence as well as the caused impacts. Information on both is scarce when it comes to top predators like marine mammals and the burden of microplastic. This is hampered by the limited access to free ranging marine mammals for collecting samples, as well as sample handling. The present study investigated gastrointestinal tracts and faecal samples of harbour seals (Phoca vitulina) and grey seals (Halichoerus grypus) regularly occurring in the German North Sea and Baltic Sea with the aim of gaining information on the occurrence of microplastics. In total, 255 particles ≥100 µm (70 fibres, 185 fragments) were found in exemplary ten intestine and nine faecal samples. The findings ranged from zero fibres and six fragments, up to 35 fibres and 55 fragments per sample. Additionally, this study established a protocol for sample handling, microplastic isolation (≥100 µm) and quantification of gastrointestinal tracts and faecal samples of marine mammals with a low share of contamination. This approach helps to quantify the presence of microplastics in free-ranging marine mammals and is therefore applicable to assess the real burden of microplastic presence in the marine environment.

Microplastic ingestion by lower trophic level organisms is well known, whereas information on microplastic ingestion, egestion and accumulation by top predators such as cetaceans is still lacking. This study investigates microplastics in intestinal samples from harbour porpoises (Phocoena phocoena) found along the coastline of Schleswig-Holstein (Germany) between 2014 and 2018. Out of 30 individuals found along the North Sea (NS) and the Baltic Sea (BS) coast, 28 specimens contained microplastic. This study found a relationship between the nutritional status of cetaceans and the amount of found microplastics. Harbour porpoises with a good or moderate nutritional status contained a higher number of microplastics, when compared with specimens in a poor nutritional status. In addition, when individuals died accidently due to suspected bycatch in gillnets, where a feeding event is highly assumed or a pharyngeal entrapment happened, the microplastic burden was higher. In total, 401 microplastics (≥100 μm), including 202 fibres and 199 fragments were found. Intestines of the specimens of the BS contained more microplastics than the ones from the NS. Differences in the share of fibres could be revealed: for BS fibres constituted 51.44% and for NS, fibres constituted 47.97%. The polymers polyester, polyethylene, polypropylene, polyamide, acrylic (with nitrile component) and an acrylic/alkyd paint chip (with styrene and kaolin components) were identified. This is the first study investigating the occurrence of microplastics in harbour porpoises from German waters and will, thus, provide valuable information on the actual burden of microplastics in cetaceans from the North and Baltic Seas.

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Ich würde mich freuen, wenn Voluntaris kritische Wissenschaft veröffentlicht, die diese Fragen analysiert und Ergebnisse dazu vorlegt. Und wenn in der Zeitschrift Initiativen und Projekte Platz finden, die emanzipatorische Konzepte in der Praxis und ganz konkret umsetzen.Freiwilligendienste kreieren Freiräume. Deswegen gibt es in ihnen so viel zu entdecken. Gebt uns Einsicht in diese Freiräume und zeigt uns, was alles möglich ist.

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