| dc.description.abstract | The benthic marine habitat is a sink for microplastics, however, our understanding of their impacts on marine organisms is still limited. This thesis investigates the ingestion and subsequent impacts of microplastics in the marine benthic dwelling polychaete worms, Hediste diversicolor and Ophryotrocha labronica. Firstly, microplastic ingestion by H. diversicolor in three estuaries across South Devon, UK, each of which were exposed to either high, medium or low levels of infrastructure and human population was assessed. The data showed 58.58% of H. diversicolor individuals ingested plastic-like particles, with fibres accounting for 86.8 % of all plastics observed. However, no significant differences in the amount of plastic-like particles ingested between sites were found. Microplastic fibres are the most commonly reported plastic shape in environmental samples, such as sediments, and during gut contents analysis of numerous phyla worldwide. However, the majority of research assessing the impacts of ingested plastics focus on microplastic spherical in shape. Therefore, the difference in toxicity between microplastic beads and fibres in H. diversicolor was investigated. The project found ingested fibres induced a greater oxidative stress response compared to that of microbeads and consequently caused cellular damage in the form of lipid peroxidation. Cellular repair and maintaining homeostasis is energetically expensive and in turn, may impact an individual’s fitness. Therefore, the impacts of microplastic exposure on the feeding and fitness of O. labronica were assessed. O. labronica exposed to plastics produced less offspring and significantly smaller eggs than unexposed mating pairs, which ultimately could lead to deleterious impacts at the population level. However, the protein content of those eggs had a similar energetic content and consequently, there was no difference in the offspring survival rate. | en_GB |
