New research confirms that drastic changes in ocean salinity from, for example, severe freshwater flooding, as recently experienced off the coast of north-east Queensland from abnormal monsoonal conditions, provoke a similar stress response in corals as extreme heating, resulting in “freshwater bleaching” and if unabated, coral death.
Researchers from the ARC Centre of Excellence for Coral Reef Studies at James Cook University (Coral CoE) and University of Technology Sydney (UTS) report that extreme and sudden changes in salinity, or the ocean salt concentration, cause a biochemical response in corals that is similar to marine heatwaves, but in some ways, more damaging to their cells ability to function.
“Corals are sensitive organisms, known to only tolerate slight changes in their environment. Thriving in clear, sunlit waters – the majority of reef-building corals are found in tropical and subtropical waters with a salinity between 32 to 42 parts per thousand,” said senior author Prof David Miller of Coral CoE.
“During the recent flooding, there are reports that nearshore reefs were exposed to roughly half the normal ocean salinity.”
Read more at ARC Centre of Excellence in Coral Reef Studies
Image: New research finds that extreme and sudden changes in salinity cause a biochemical response in corals (Acropora millepora) that is similar to marine heatwaves, but in some ways, more damaging to their cells. (Credit: ARC Centre of Excellence for Coral Reef Studies/Greg Torda)