More Algae Means Corals Have More to Lose

Written by on October 16, 2012 in Marine Life
Coral bleaching.

Example of bleached coral (white) with healthy coral in the Mariana Islands, Guam. Photo credit: David Burdick, NOAA.

A new study reveals that too much of a good thing is bad for corals.

Corals have a symbiotic (mutually beneficial) relationship with the single-celled algae, Symbiodinium.  The coral needs the algae to survive so it was thought that the more symbionts coral had, the better.  However, researchers from the University of Miami’s Rosenstiel School of Marine and Atmospheric Science (RSMAS) found that the opposite was true.

“We discovered that the more symbiotic algae a coral has, the more severely it bleaches, showing that too much of a good thing can actually be bad,” explained Ross Cunning, lead author and Ph.D. student at RSMAS.  “We also learned that the number of algae in corals varies over time, which helps us better understand coral bleaching risk.”

Cunning monitored cauliflower coral (Pocillopora damicornis), collected from the Pacific coast of Panama, for six months in RSMAS’s Experimental Hatchery.  The corals were slowly warmed up and they eventually bleached.  By analyzing DNA samples, they determined that corals with more algae bleached more severely than corals with fewer algae.

“Corals regulate their symbionts to match the environment in which they are found, and this study shows there is a real cost to having too many,” said co-author Andrew Baker, associate professor at RSMAS.

“There are real-world implications of this.  Corals will be more vulnerable to bleaching if they are found in environments which increase the number of symbionts, such as coastal reefs polluted by wastewater and runoff.”

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Copyright © 2012 by Marine Science Today, a publication of Marine Science Today LLC.

About the Author

About the Author: Emily Tripp is the Publisher and Editor of MarineScienceToday.com. She holds marine science and biology degrees from the University of Miami's Rosenstiel School of Marine and Atmospheric Science and a Master of Advanced Studies degree in Marine Biodiversity and Conservation from Scripps Institution of Oceanography. When she's not writing about marine science, she's probably running around outside or playing with her dog. .

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