Potential impacts of microplastic ingestion in Acropora cervicornis and Pseudodiploria clivosa

The prevalence of microplastics (<5 mm) in the marine environment has been of increasing concern over the past decade. Microplastics have been shown to be ingested by aquatic organisms, however the impacts of microplastic ingestion on the health of marine organisms, including coral, are not well understood. The goal of this study was to build upon previous laboratory studies to characterize the physiological responses of ingested microbeads in two cultured Caribbean coral species, Acropora cervicornis and Pseudodiploria clivosa. Ingestion patterns and retention times for five size classes of uncured microbeads (212-250 µm, 425-500 µm, 850-1000 µm, 1.7-2.0 mm, and 2.4-2.8 mm) in individual fragments of both coral species during laboratory exposures were observed. The 212-250 µm size class did not elicit a feeding response in either species, therefore, was not ingested. Preliminary results show that A. cervicornis ingested the 425-500 and 850-1000 µm size classes but not the 1.7-2.0 or 2.4-2.8 sizes. Only a portion of 425-500 µm microbeads remained in A. cervicornis at 48 hours after ingestion, all other sizes were egested. P. clivosa ingested all size classes. The 2.4-2.8 mm size class was fully egested, a portion of microbeads from all other size classes remained in the fragments at 48 hours. Additionally, calcification rates measured over three months in corals exposed to three size classes of cured microbeads (212-250 µm, 425-500 µm, and 850-1000 µm) will be presented. The results of this study will further elucidate species-specific responses of corals to microplastics and provide insight on the expected impacts of microplastics on the growth and survival of corals exposed to microplastics in coral reef ecosystems.