Cool water from internal waves can protect corals during heat stress

Corals are sensitive organisms; even minor increases in temperature can harm the photosynthetic algae living inside, prompting the host coral to reject the symbiotes. A new study in the Andaman Sea, site of largest coral bleaching incident to date, shows that internal waves can protect coral reefs with an influx of cool water, according to a GEOMAR press release.

Large-amplitude internal waves travel along the thermocline separating the oceans’ warmer upper layer from cooler deep water. Upon hitting the continental shelf, these waves can break and bring cooler water to shallower regions where coral reefs form. Low temperatures usually have a negative impact on coral, but during times of heat stress, the cooler water is beneficial to the organisms.

In the studied region, internal waves are most common between January and March. Further research using in-situ measurements is necessary to determine how internal waves affect other reefs around the world, one researcher said.