Coral bullies aren’t as mean as we thought

Degradation of coral reefs due to such threats as pollution, climate warming, disease, overfishing and tourism has made them a poster child for destruction of diverse, wild ecosystems suffering at the hands of human-made problems. There is a little bit of good news, though, according to researchers publishing in the June issue of Ecology. Seaweed, which can suffocate corals on massive reefs, isn’t as big a problem as once thought.

Seaweed — or, to be more specific, macroalgae — can not only crowd out baby corals for room on the reef, but also reduce a coral population’s potential for recovery after natural disturbances, such as hurricanes or disease. Without baby corals to continue the population, seaweed can take over, much like it did on several Jamaican reefs during the 1980s: originally 70 percent corals, the reefs now contain less than 10 percent corals, with seaweed being the dominant life form.

John Bruno of the University of North Carolina at Chapel Hill and his colleagues did a meta-analysis on previously published studies of so-called phase shifts on reefs. It turns out, the researchers say, that the transition from coral-dominated to seaweed-dominated reefs is not nearly as common as once thought.  Said Bruno in a press release:

“Until now, many scientists have concluded that the world’s coral reefs are being overrun by seaweed. Our findings show that’s not the case. Seaweed have taken over and are dominating some reefs, but far fewer than assumed.”

Of course, we shouldn’t just forget about protecting reefs from seaweed.  The researchers stress that  case studies (such as the degradation of Jamaican reefs) are still important warnings of the potential threat to wildlife posed by marine disturbances, and shouldn’t be ignored.

Read more in the ESA/UNC press release.

Author: Christine Buckley

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