Effects of macroplastic on the performance of aggregates of Mytilus spp. and their associated biota

• Main Author: Berning, Alisa
• Format: Thesis
• Language: English
• Published: 2021
• Subjects: Course of study: MSc Biological Oceanography; Ocean acidification
• Online Access: https://oceanrep.geomar.de/id/eprint/54887/; https://oceanrep.geomar.de/id/eprint/54887/1/MSc_Berning_A_2021.pdf

The presence of macroplastic in the ocean poses a threat to many marine organisms. The majority of recent studies, however, is focused on the impact of microplastic. Existing studies on the influence of macroplastic mainly assessed effects on the organism level. Thus, studies on populations and assemblages in particular of invertebrates are needed. In this experiment, I investigated the impact of the presence of a low and a high amount of plastic bottles and plastic bags on Mytilus spp. aggregates. A 49-day exposure to macroplastic in the Kiel Fjord resulted in significant effects on the associated biota of the aggregates. A varying "Amount" altered the abundance and composition of the epibionts, while a varying "Rigidness" of the plastic impacted the abundance and composition of the mobile fauna. Hence, plastic debris has the potential to alter the quality of the habitat provided by mussel beds. Furthermore, a high amount of macroplastic reduced mussel filtration rates, which are important to intercept eutrophication in the Baltic Sea. The presence of macroplastic had no effect on the net oxygen production, body condition index, stability of the aggregates, the amount of total particulate matter that accumulated in the aggregates and the increase in the mussel surface area within each aggregate. Also, species richness and evenness of the epibionts and of the mobile fauna associated with the aggregates were not affected by the plastic. Nevertheless, it is possible that interactive effects could occur in the future, or small effects could be amplified when the effect of plastic is combined with several stressors such as higher temperatures, increased ocean acidification, decreased salinity, hypoxia or a high amount of pollutants.