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Scleractinian coral microplastic ingestion: Potential calcification effects, size limits, and retention
Citation:
Hankins, C., A. Duffy, AND K. Drisco. Scleractinian coral microplastic ingestion: Potential calcification effects, size limits, and retention. MARINE POLLUTION BULLETIN. Elsevier Science Ltd, New York, NY, 135:587-593, (2018). https://doi.org/10.1016/J.marpolbul.2018.07.067
Impact/Purpose:
Coral reefs are sensitive habitats that are impacted by land-based and global stressors. Plastic pollution in the marine environment is a stressor that can cause direct physical harm to organisms as well as act as a vector for pollutants and bacteria. Microplastics (<5mm) can originate from various sources including degradation of macroplastic, industrial processes, synthetic clothing, tire fibers, and personal care products. This study examined the effects of ingested microplastics on coral calcification as well as investigated limits on microplastic sizes ingested by small and large polyp corals. Additionally, retention times were observed for all ingested microplastics. Coral calcification was not effected during the two day exposure, however, it was determined that corals egest a large portion of ingested microplastics. There was no size class of microplastic that was not ingested by either the small or large polyp coral but there was a different in ingestion rates. The results of this study provide a solid foundation of information to which additional research can be performed looking at additional stressors such as disease and pollutants. Protecting coral reef ecosystems from land-based stressors would help improve their resiliency, making them less susceptible to global environmental threats.
Description:
The impact that microplastics (<5 mm) have on scleractinian coral is largely unknown. This study investigated calcification effects, size limits, and retention times of microbeads and microfibers in two Caribbean species, Montastraea cavernosa and Orbicella faveolata, in a series of three experiments. No calcification effects were seen in the two-day exposure to a microbead concentration of 30 mg L−1. M. cavernosa and O. faveolata actively ingested microbeads ranging in size from 425 μm–2.8 mm, however, a 212–250 μm size class did not elicit a feeding response. The majority of microbeads were expelled within 48 h of ingestion. There was no difference in ingestion or retention times of 425–500 μm microbeads versus 3–5 mm long microfibers. M. cavernosa and O. faveolata have the ability to recognize and reject indigestible material, yet, there is still a need to study effects of energetics and microplastic contamination as a result of ingestion and egestion.
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DOI: Scleractinian coral microplastic ingestion: Potential calcification effects, size limits, and retention