Plastic pollution and ocean giants: Investigating the extent and impacts of plastic ingestion by marine megafauna

Plastic production has exponentially increased since the 1950s when it became a popular material for household items. Misuse, mishandling and a lack of effective waste management has seen plastic pollution become extensive and persistent. Over the past 20 years, evidence of the negative effects plastic pollution is having on marine organisms has grown. It is estimated that over 900 species are impacted by marine debris, the majority of which is plastic. Marine megafauna are of particular concern given their importance in the functioning and maintenance of marine ecosystems. These large marine vertebrates, namely marine mammals (e.g. cetaceans and pinnipeds), elasmobranchs (sharks and rays), and marine turtles can act as sentinels for the marine environment indicating ecosystem health. In addition to plastic pollution, many of these species are already of conservation concern due to a range of anthropogenic pressures both historic and emerging. Plastic ingestion can lead to lethal and sub-lethal impacts, including intestinal blockage and internal injury, dietary dilution, malnutrition, exposure to chemical contaminants and increased susceptibility to disease and infection. There is a paucity of information on the fate and impacts of very small plastic particles, such as microplastics and nanoplastics, within large marine vertebrate gastrointestinal tracts. This PhD study aims to address this knowledge gap. The first step is to develop a robust and repeatable sampling methodology to examine the gastrointestinal tracts of large, stranded individuals for the presence of microplastics. Plastic debris will be quantified and characterised to infer potential sources. Further ambitions for this research include exploring techniques to examine digestive contents for the presence and fate of nanoplastics and investigating the link between ingested plastic and associated chemicals (eg. phthalates). Also see: https://micro2024.sciencesconf.org/574288/document