Influence of microplastic particles on the physiological performance of the marine deposit feeder Uca rapax

Microplastic particles (<5 mm) are ubiquitous in the marine environments and can be ingested by marine organisms. Additionally, microplastics accumulate pollutants from the surrounding seawater and have been suggested to act as vector for the transport of pollutants from the environment into organisms. Therefore, microplastic particles have the potential to harm organisms both physically and chemically. The marine deposit feeding crustacean Uca rapax was exposed to different densities of microplastic particles in the sediment for 56 days. The polymer type was polyvinyl chloride (PVC) and the particles were in a size range of 65 - 250 μm. The plastic material was previously loaded with the pollutant fluoranthene by incubating it in a solution of 2 μg fluoranthene per liter seawater for 21 days. Fluoranthene belongs to the group of polycyclic aromatic hydrocarbons (PAHs) that are found in oil residues and that are known to be carcinogenic. Throughout the exposure experiment, growth, respiration, motility and mortality of the crabs were assessed. Exposure experiments were followed by an hypoxia stress test to assess the survival of the individuals under this stressor. Crabs that were previously exposed to different microplastic densities differed significantly in their motility and showed significantly different survival rates during the experiment. However, no consistent negative effect of the ingestion of microplastic particles incubated with fluoranthene on the physiological performance of U. rapax could be found in this study. The species had the ability to survive and tolerate the presence of environmentally relevant concentrations of microplastic and fluoranthene under experimental conditions.