Tuesday, October 11, 2011

Coral bleaching: living through a train wreck and being unable to stop it

Have you ever seen a train wreck happen? I’m seeing one right now and it’s terribly sad and a preview of the future. I’m currently teaching my field biology course on a remote marine lab on a Caye off Belize and we’re literally watching the coral bleach. 

Coral, as you might know, has a symbiotic relationship with algae. The colors that coral have result from their algae (called zoozanthellae in the jargon of coral folks). These zoozanthellae are very sensitive to temperature and coral ‘bleaching’ events occur when the zoozanthellae jettison their coral head; something they should not do (imagine the parachute scene from the Woody Allen film “Everything you wanted to know about sex but were too afraid to ask”; Google it if you have to!).

Bleaching is bad: the reef dies if it bleaches and can’t be recolonized by new zoozanthellae. There have been Caribbean-wide bleaching events in the past few decades and some of these have led to widespread destruction of coral reefs. I wonder if we’re about to experience a new one.

I’ve been in the water the past four days. It’s HOT here and the water is warming up. We’ve not had rain in three days and yesterday the water temperature (not just in shallow areas) was over 90°F. This is a magic temperature range because many of these zoozanthellae jettison their coral around this temperature. 

My colleague, a coral reef biologist, pointed out last night that if we didn’t get rain or a wind that would mix in the cold water, we should expect to see a lot of bleaching today. And, while we had a nice sea breeze last night, and the water temperature went down a bit (the air temperature feels like it’s over 100°F), this morning I was shocked to see bleaching coral. Coral heads that were a brilliant yellow yesterday morning are now white. A fan coral, that should be a brilliant purple, is now beached skeletal white.

It’s a compelling sight; made worse because we know what’s going to kill the reef (hot temperatures). We also know what’s going to cause widespread destruction of oceans (acidification). We know that these are a direct result of anthropogenic atmospheric carbon. We know that over-fishing (this will be the subject of another post) eliminates fish populations. We know, yet we continue along our path to a train wreck. Would be fascinating to watch if the consequences were not so profound.

Reefs protect land from storms. Reefs are where fish larvae grow up and thus are important to maintain fisheries. Reefs are going to be the source of new antibiotics that are needed since our current crop of antibiotics is becoming ineffective because of overuse and evolution. Reefs harbor incredible biodiversity; a reason alone for their protection.

Train wreck. Happening. Not very nice to see.

You ever seen a train wreck? Talk about it over dinner. Better yet, discuss ways that we can work together to stop it.

No comments:

Post a Comment