Microplastic (MP) pollution in the marine environment is an environmental issue of concern, but current knowledge on the potential impact on marine organisms remains limited. MPs in the environment can be regarded as complex mixtures of weathered particles from various size ranges and shapes. The potential effects of realistic MPs mixtures and concentrations are still poorly understood. Previous studies have demonstrated that marine organisms can be vulnerable to MPs in several pathways including but not limited to (1) the toxicity of associated chemicals released i.e. leached from the polymer matrix; and (2) altered energy budgeting among growth, maintenance and reproduction due to ingestion of MPs. In realistic scenarios, organisms exposed to MPs in the marine environment are simultaneously subjected to global change driven stressors such as ocean warming (OW), however, the combined effects and potential interaction effects between MPs and OW are rarely understood. Bio-based polymers are seen as  potential alternatives for petroleum-based polymers, however, it remains unexplored whether MPs of bio-based polymers have lower impacts than MPs of petroleum-based polymers under OW conditions.

With this doctoral research project, I will assess the combined impact of MPs, from bio-based polymers and reference petroleum-based polymers, and OW on the population dynamics of the planktonic community . To do so, I will work in work packages and follow a combination of ecotoxicological assays and modelling approaches. The exposure of MPs and OW will be environmentally relevant and based on the worst-case scenarios. To this end, we anticipate that our results will contribute to assessing the impacts of MPs in a multiple-stressors marine environment.