Coral Heat Tolerance: Nurture Beats Nature

Written by on May 13, 2014 in Coral Reefs, Marine Life
Rachael Bay puts an identification tag next to a coral colony.

Rachael Bay puts an identification tag next to a coral colony so that researchers can find the same colony later. Photo credit: Steve Palumbi.

Coral reefs provide coastal protection and a source of livelihood for millions of people around the globe, but these delicate ecosystems are increasingly threatened by climate change. Over the last 20 years, nearly half of the world’s reef-building corals have been decimated by overfishing, pollution, ocean acidification and warming water temperatures. A new study by Stanford researchers, however, provides a little bit of good news: some corals can withstand increasing temperatures better than previously thought.

The researchers, led by biology professor Stephen Palumbi, director of Stanford’s Hopkins Marine Station, looked at how corals may be able to increase their tolerance to heat and if those abilities are due to nature or nurture. Specifically, how much of corals’ ability to tolerate heat is due to genetics, and how much can be changed by the environment?

To find out, they transplanted corals between warm and cool pools in the National Park of American Samoa — where water temperatures can exceed 95 degrees Fahrenheit — and measured heat tolerance after a year. The found that about half of heat tolerance can be adjusted by the environment, meaning the other half is likely genetic.

Over the course of the study, corals transplanted from the cool pool to the hot pool became more heat tolerant. They were able to accomplish this by switching on or off certain genes, depending on temperature.

Portable stress tank systems used to measure thermal tolerance in reef-building corals.

Portable stress tank systems used to measure thermal tolerance in reef-building corals. These tanks allow scientists to carefully control the temperature of corals in order to measure heat stress response. Photo credit: Rachael Bay.

The study highlights how tolerance increase from environmental changes can occur much more quickly than tolerance from genetic changes. The researchers determined that some corals can adjust their internal functions to tolerate warmer water 50 times faster than by adapting through evolutionary changes alone. This may prove beneficial in providing corals with a ‘cushion’ of time during which they may be able to keep up with climate change, but this ability is certainly not unlimited.

“These results tell us that both nature and nurture play a role in deciding how heat tolerant a coral colony is,” Palumbi said in a news release. “Nurture, the effect of environment, can change heat tolerance much more quickly – within the lifetime of one coral rather than over many generations.”

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Copyright © 2014 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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