Fat Coral Survives Climate Change?
Fat makes you live longer? When it comes to coral in heat stress environments, the answer is yes. Researchers from the School of Earth Sciences at The Ohio State University have found that coral species with higher fat percentages survive heat stress over the long term.
A 2014 bleaching study by the same team of researchers revealed that fat helps coral recover faster in the short term. Now, the same high-fat coral species that showed swift resiliency one year ago are bouncing back more fully than the corals that store less fat, according to the study published in the Proceedings of the Royal Society B: Biological Sciences.
When corals become strained as a result of high water temperatures, they expel algae from their tissue and turn a stark white. Coral and algae, known as zooxanthellae, work in symbiosis by sharing nutrients. The coral provides the algae with compounds to undergo photosynthesis and the algae supplies the products of photosynthesis to the coral, which are used to create fats, protein, carbohydrates and form calcium carbonate. A bleached coral has less nutrients to grow because it's primary food source-the algae-is missing, and, therefore the coral is more susceptible to disease and storm damage.
Three global bleaching events have taken place since the 1980s, including one that is going on right now, as a result of climate change increasing acidity levels and temperatures in the world's oceans. According to lead study author Verena Schoepf, annual bleaching as a result of global warming is expected to start later this century. By better understanding how corals react and recover from bleaching events, scientists can comprehend how climate change will impact the coral ecosystems that so many marine organisms depend on.
"Already, bleaching events have resulted in significant amounts of coral dying and causing impact to ocean ecosystems, but up until now it was largely unknown whether coral could recover between annual bleaching events," Schoepf said in a statement.
The main investigator on both studies was Ohio State professor Andrea Grottoli. Grottoli, Schoepf and other scientists exposed three distinctive coral species to two rounds of annual bleaching and then tested the corals six weeks after exposure to see how the species fared. Finger coral, which had the most fat of the three species tested, recuperated the best. One year later, finger coral still has recovered the most fully while mustard hill coral, which had the least amount of fat, has still not fully rebounded. If annual bleaching becomes a frequent occurrence, a low-fat coral such as mustard hill may not ever have the opportunity to bounce back to normal health.
While all three corals regained a symbiotic relationship with algae, those with more fat were able to recover faster because they were able to depend on their stored up energy reserves to survive during the time they were without the algae.
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