Heat and cold damage corals in their own ways

Terra Daily via SPX: Around the world coral reefs are facing threats brought by climate change and dramatic shifts in sea temperatures. While ocean warming has been the primary focus for scientists and ocean policy managers, cold events can also cause large-scale coral bleaching events.

A new study by scientists at Scripps Institution of Oceanography at UC San Diego compared damage to corals exposed to heat as well as cold stress. The results reveal that cool temperatures can inflict more damage in the short term, but heat is more destructive in the long run.

...Climate change is widely known to produce warming conditions in the oceans, but extreme cold-water events have become more frequent and intense as well. In 2010, for example, coral reefs around the world faced one of the coldest winters and one of the hottest summers on record.

During a unique experiment conducted by former Scripps Oceanography student Melissa Roth and current Scripps scientist Dimitri Deheyn, corals subjected to cold temperatures suffered greater growth impairment and other measurable damage in just days compared with heat treated corals.

Yet the researchers found that corals were eventually able to adjust to the chilly conditions, stabilize their health and continue to grow. However, over the long term corals subjected to heat suffered more greatly than those in cold, with evidence of severe bleaching and growth stoppage, a trajectory that leads to death....

A reef in the Maldives, shot by J. Ollé, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license