Tough reefs and doing nothing
On 7 March, this blog noted that the GCRA had made a classic paper available again. On 13 March, Doug Fenner wrote this to the coral list:
The Goreau paper is indeed a classic and a great introduction to coral reefs. I have used it in teaching many times and highly recommend it. It's great to have it available again. Many thanks! (interesting about the publication delay, didn't know that!)His response continues in the comment attached to this post
I wanted to just comment on the two paragraphs in the message about resilience. First, I don't think anyone suggests that coral reefs will always bounce back from any disturbance, no matter what we do. That's ridiculous. If people produce a chronic disturbance that badly damages a reef, then is the reef going to bounce back after an acute disturbance? No way. But, if a reef is totally undisturbed by humans, will it bounce back from a natural disturbance? Almost surely.
posted by Caspar Henderson at
10:28 am
1 Comments:
Doug Fenner continues:
I live in American Samoa, on an island that is 1.5 million years old. Hurricanes hit the island an average of about once per 5 years. So it has had about 300,000 hurricanes during the island's lifetime, and the reefs are still here (about 28% coral cover at the moment). Guam usually has several hurricanes each year, and is old too. In one of my first trips to the Philippines, I saw a reef that had been hit by a hurricane a month earlier. One area had had coral growing on rocks small enough for the hurricane to move. The rolling rocks had crushed over 99.9% of the coral, everything was dead rubble. I came back a few years later, and couldn't find the spot, even though it was right in front of the dive shop. Then I realized it was an area now covered by about 80% live coral- a riot of gorgeous healthy coral of a wide varitey of species! Incredible, saw it with my own eyes. And the Philippines is not known for the world's most pristine reefs.
In Cozumel, after Hurricane Gilbert, the second most powerful hurricane on record before it made landfall, I saw a temporary algae bloom that went away, and corals recovering, even though the reefs there had about 2000 dives a day, and this was after the Diadema dieoff. But then the reefs are in a park, in strong clear oceanic currents, and are swarming with fish including herbivores, and have very limited macroalgae, and bleaches little or not at all during mass bleachings in the Caribbean. It was one of the few resilient reefs left in the Caribbean.
The claim that "Those touting 'resilience' claim that we should do nothing at all and the reefs will recover all by themselves", " is itself pretty amazing. Who said that. Where is that quote from?...The resilience people are saying that if chronic human impacts are kept to low enough levels, this will help reefs recover on their own from disturbances. Working to reduce chronic human impacts is certainly doing something. Anybody who has tried it knows it's darn hard work and most of the time we're not very successful. He is right we are saying that if a reef is healthy enough we don't need to do restoration after a disturbance. Nobody was helping American Samoa reefs after those 300,000 hurricanes, and the reefs recovered.
But if we do nothing as Goreau is claiming resiliance people are saying, and just let the chronic impacts, such as overfishing, sedimentation, and nutrient imputs, go on and get worse, the reefs will very likely undergo a phase shift after a disturbance, just as I recounted for SW Madagascar, and which happened in Jamaica years ago.
In fairness, when Tom's talking about "doing nothing", what he means is "doing nothing to actively restore the reef." He just didn't say it that way, and it sounds like resilience people are saying "don't do anything, just watch the reefs die." Which they aren't saying at all.
Tom Goreau has a company with a patent for biorock, a form of active reef restoration using electric current. So what he's advocating is active restoration of reefs using his method. That's another option. We can use all the options we can get, its going to take everything we can do to make a dent in the ongoing loss of coral reefs. Personally, I tend to think we need to stop the things that are causing the problem in the first place. That would be the best solution. But as we all know that's a lot easier said than done, and we haven't managed so far very well, as the huge decline in coral cover in the Caribbean shows. Active reef restoration is definitely needed in some places.
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