An assessment of plastic ingestion in selected Australian pinniped species

Pollution of the marine environment by plastic debris is a global issue, with harmful biological and ecotoxicological impacts recorded for a plethora of marine species. Scats of Australian sea lions (Neophoca cinerea), Australian fur seals (Arctocephalus pusillus doriferus) and long nosed fur seals (Arctocephalus forsteri) of southern Australia were analysed for plastic ingestion. The current study is the first record of plastic ingestion in Australian sea lions. The frequency of occurrence of microplastic ingestion varies between colonies - Kangaroo Island(64.71%, n=17), Lady Julia Percy Island (50%, n=6) and Phillip Island (21.43%, n=14). There isa significant relationship between the amounts of microplastics ingested by pinnipeds and the microplastics polluting waters directly surrounding studied colonies, suggesting that plastic loads of nearby urban centres are reflected in microplastics being ingested. Over one third (38.7%) of ingested microplastics were small (<2mm) blue fibres, suggesting that there exists a major source of microplastic pollution of this type in southern Australia, or perhaps that prey species selectively ingest microplastics. Plastics are likely ingested through trophic transfer, but direct ingestion may occur during benthic foraging, similar to the ingestion of gastroliths. Methods of microplastic extraction from pinniped scats are recommended for standardisation