Trophic-level investigations of microplastics in marine pelagic fish and squid

• Main Author: Bothma, Francois
• Other Authors: Bouwman, H., 10063773 - Bouwman, Hindrik (Supervisor)
• Format: Thesis
• Language: English
• Published: North-West University (South Africa) 2023
• Subjects: Anchovy; Squid; Microplastic; Indian Ocean; South Atlantic Ocean; Trophic transfer; Indian
• Online Access: http://hdl.handle.net/10394/42124

MSc (Environmental Sciences), North-West University, Potchefstroom Campus Microplastics (MPs) are ubiquitous in marine environments, with a large number of species constantly being exposed to contamination. Fish ingest MPs, and much research has gone into the reporting on MP ingestion by different species from different environments. There are, however, very few studies on MPs that have discoursed on MPs translocated into the tissues of marine organisms. Each environment provides a new perspective on how MPs contaminate biota. There is, however, a lack of information on conspecifics in two adjacent oceans, each ocean having different MP concentrations and MP characteristics. South Africa is bordered by two oceans, the South Atlantic Ocean associated with the cold Benguela Current, and the Indian Ocean associated with the warm Agulhas Current. The two oceans are uniquely different, making them ideal for comparative studies on shared species. Available water data show that the Indian Ocean has two-to-three-times higher concentrations of MPs than the South Atlantic Ocean. In this study, two species occurring in both oceans were sampled from both oceans: anchovy (Engraulis encrasicolus) and chokka squid (Loligo reynaudii). These two commercially important species make up a large proportion of South Africa’s fisheries industry. Samples were analysed for MPs that have translocated into their tissues. I compared the MP concentration differences in the two organisms between the two oceans. This was done vide two manuscripts, one for each species. Microplastics from 2.39 μm to 5000 μm were found in the muscle tissue of anchovy, and mantle tissue, gills, and digestive glands of the chokka squid, regardless of ocean. Anchovy from the Indian Ocean showed lower concentrations of MPs in their muscle tissue compared with South Atlantic Ocean anchovy. The South Atlantic Ocean anchovy were younger and filter feed instead of particulate feeding, compared with the larger anchovy from the Indian Ocean, possibly explaining the ...