Reef-building corals have been found to incorporate microplastics (MP, i.e., plastic < 1 mm) in their tissue and skeleton after ingestion, adhesion, or overgrowth. This makes coral reefs important environmental sinks for marine MP. However, the mechanisms that affect incorporation rates remain poorly understood. Also, previous experimental studies on MP incorporation in corals have mostly focused on single MP types. To investigate the factors that influence MP incorporation in reef-building corals, we exposed the two species Stylophora pistillata and Pocillopora verrucosa to different pollution scenarios in two independent experiments: 1) distinct mixtures of MP, chosen to represent major anthropogenic pollutants (i.e., fragmented marine plastic waste, residues from the automobile sector, and artificial fibers), and 2) a standardized mixture of MP, chosen to represent the MP types mainly found in nature (PE, PVC, PS, PA, PP, and PET), applied at different concentrations (0, 0.1, 1, 10, and 100 mg/l). To quantify the incorporation of the MP, we separately dissolved coral tissue and skeleton, extracted MP, and standardized the numbers of MP found to the coral’s surface area and accreted skeleton. Our results show similar incorporation rates across different MP mixtures, suggesting the absence of selective processes for the incorporation of MP into the tissue and afterwards skeleton of reef-building corals. Overall, our results shed light on the processes underlying the incorporation of MP in reef-building corals under environmentally realistic scenarios.

Primary Presenter: Vanessa Tirpitz, Justus Liebig University (vanessa.tirpitz@bio.uni-giessen.de)

Authors:

Vanessa Tirpitz, Justus Liebig University Giessen, Department of Animal Ecology and Systematics  (Vanessa.Tirpitz@bio.uni-giessen.de)

Maren Ziegler, Justus Liebig University Giessen, Department of Animal Ecology and Systematics  (Maren-Ziegler@bio.uni-giessen.de)

Thomas Wilke, Justus Liebig University Giessen, Department of Animal Ecology and Systematics  (Thomas.Wilke@allzool.bio.uni-giessen.de)

Jessica Reichert, University of Hawai'i, Hawai'i Institute of Marine Biology  (jreichert.sci@gmail.com)