Plastic Debris: a Carrier of Coral Disease

This is a post by Emily Markert. See her bio at the bottom of this post.

A new study led by researchers from Cornell University, including Drew Harvell of this research network, found that plastic debris in the ocean increases the risk for disease in coral.  Plastic debris has been shown to negatively impact coral in a number of ways; plastic items, specifically those made of polypropylene, provide “ ‘ideal vessels’ ” for bacteria associated with white syndromes, a “ ‘globally devastating group of coral diseases’ ”, as Joleah Lamb explains in the Cornell Chronicle.  Plastic pieces can also scratch the surface of coral, or block light from reaching it, which weakens the coral and makes it even more susceptible to disease.  The research team behind this study assessed the relationship between plastic debris and disease in coral by surveying 159 coral reefs throughout the Asia-Pacific region, and have published their findings in Science Magazine.

Plastic debris caught on a coral reef

Image Credit:  Kathryn Berry/James Cook University  (found in the Cornell Chronicle)

Of the coral reefs examined, coral in contact with plastic debris was found to be 20 times more likely to be affected by disease.  This statistic is especially concerning, since diseases such as white syndromes cause permanent coral tissue loss and can spread throughout a reef.  Additionally, the already high volume of plastic trash entering the ocean each year is only expected to increase; researchers predict (using a generalized linear mixed model) that by 2025, 15.7 billion pieces of plastic will be caught on coral reefs in the Asia-Pacific region alone.  This estimation was based on a previous prediction of the amount of plastic trash entering the ocean, which used a model that considered population density and economic status of coastal regions.  Since coral reefs with complex structures, which provide the best habitats for fish and microorganisms, are especially likely to snag floating plastic, it is expected that the most valuable coral reefs will be especially prone to the growing threat of disease.

Estimated contributions of mismanaged plastic waste to debris levels on coral reefs, by country

Image credit:  Lamb et al., published in Science Magazine

The destruction of corals has many devastating consequences.  Coral reefs support extremely biodiverse ecosystems, and the loss of the rich habitat they provide can reduce the productivity of fisheries by two thirds.  Corals are also estimated to provide a yearly value of $375 billion “through fisheries, tourism, and coastal protection”, and are crucial to the wellbeing and livelihood of 275 million people worldwide.

The researchers behind this study hope that their findings, while distressing, will serve as motivation to reduce the amount of plastic debris entering the ocean in the future.  In an article by the Cornell Chronicle, Drew Harvell explains that “ ‘while we can’t stop the huge impact of global warming on coral health in the short term, this new work should drive policy toward reducing plastic pollution.’ ”

For more information on the effect of plastic pollution on coral reefs, see the original article in Science magazine, or a publication in the Cornell Chronicle.

Emily Markert is a Computer Science  undergraduate at Vanderbilt University supported by NSF Grant 1521672. The opinions expressed herein are Emily’s and not necessarily those of Cornell University or NSF. You can reach Emily at