April 19, 2018

expert reaction to research on the resilience of coral to climate change

Researchers publishing in PLoS Genetics examine the potential and limits for rapid genetic adaptation to warming in a Great Barrier Reef coral.

Dr Stephen Simpson, Associate Professor in Marine Biology & Global Change at the University of Exeter, said:

“Understanding the adaptive capacity of organisms is essential to predict likely impacts of climate change. Adaptation can be through range shifts and relocation of locally-adapted genotypes, selection on existing diversity, and novel mutations. The first two require continuous habitat for genotypes to move over generations, and the Great Barrier Reef is a great example of a 2,300 km chain of neighbouring reefs spanning 14° of latitude.

“Acropora millepora is a fast growing species of coral that bounces back well after ecological disturbance (cyclones, bleaching, etc.), and lives at a range of depths including very shallow waters, so is likely to have locally-adapted colonies that tolerate different water temperatures. Thus it is heartening, but not surprising, that this species has substantial genetic diversity with genotypes that could tolerate another century of warming (albeit with more frequent bleaching events).

“But corals live in a symbiotic relationship with zooxanthellae, which are plant-like cells hosted in surface tissues that provide up to 90% of the energy to the colony. Whether there is also sufficient genotypic variation in the zooxanthellae to tolerate further warming remains to be seen. While the fact that one species may do well is good news, there are many other reef organisms that may fare far worse, so it is easy to envisage a future with a few winners but many losers, threatening the functional integrity of reef ecosystems.

“Genetic diversity favouring heat tolerance may not be the same as the diversity needed by corals to tolerate ocean acidification, increased turbidity and provide resilience to other manmade local stressors (plastics, noise, overfishing, etc.).

“To understand the resilience of an ecosystem to future change requires multi-species studies conducted with multiple stressors. Scientifically, this is asking for the moon on a stick, but it is the reality for the tens of thousands of environmentally-sensitive species in iconic places such as the Great Barrier Reef in this rapidly changing world.”

* ‘Potential and limits for rapid genetic adaptation to warming in a Great Barrier Reef coral’ by Mikhail V. Matz et al. published in PLoS Genetics at 7pm UK time on Thursday 19 April 2018.

Declared interests

None received.