Microplastics in the food web of cetaceans – a review
P.atricia Burkhardt-Holm and Anouk NGuyen
International Whaling Commission
Current knowledge on microplastic ingestion by cetacean species is still very limited. So far, only three studies report direct evidence of microplastic ingestion cetaceans. Furthermore, microplastic uptake has been suggested by studies analysing phthalate concentrations in blubber and water samples. In this study, we use the common minke whale Balaenoptera acutorostrata to infer the poten-tial for microplastic ingestion by cetaceans via their prey species. In a first step, we review available information about prey species of the common minke whale. In a second step, we review available evidence of microplastic ingestion by these prey species. We include both peer-reviewed papers as well as documents from the IWC scientific meetings (2011-2017). We found that common minke whale is an opportunistic feeder that preys on spatially and temporally available species. This suggests that minke whales feeding in different geographic areas are exposed to different risks of ingesting microplastics. Generally, prey species in coastal areas show higher levels of microplastic contamination than those in coastal areas, putting common minke whale feeding in these areas at higher risk of microplastic ingestion than those feeding in offshore areas. Specifically, we found highest levels of microplastic con-tamination reported for Scombridae and Gadidae. These species are among the most fre-quently observed prey species of common minke whale in the Northwest Pacific Ocean, indi-cating a risk for microplastic ingestion in this area. However, Scombridae as well as Gadidae in these regions have not yet been analysed for microplastic ingestion. Studies investigating microplastic ingestion of cephalopods, Ammodytidae, Engraulidae and Osmeridae are lacking for all areas. We suggest that research on MP ingestion of prey species belonging to these families are urgently needed and we recommend collaborating with scientists having access to fisheries research vessels, especially in the Northern Pacific.