Beautiful and Depressing: Shifting Baselines and Dying Reefs
by John Hocevar
August 15, 2010
Greetings from Mile Zero, the Conch Republic. Key West, Florida – former home of Ernest Hemingway, and, as much as it kills me to say it, what will someday all too soon be referred to as the former home of the most extensive coral reef network in the continental United States.
Greenpeace just finished two days documenting the reefs here in the lower Keys as part of our three month long expedition to respond to the disaster in the Gulf of Mexico, and it was lovely. We saw giant brain corals, galaxies of star corals, and schools of brightly colored snapper, grunts, and parrotfish. There were angelfish, wrasses, soldierfish, damselfish, and dozens – even hundreds – more. We all felt lucky to be out in the water.
And they were probably the most depressing dives I’ve ever had.
The problem is that my background is in coral reef ecology, and I’ve been diving since the early 80s. I’ve read descriptions of how productive these reefs were 100 years ago, I’ve looked at pictures of what these reefs looked like 60 years ago, and I’ve seen with my own eyes what they looked like 25 years ago. I’ve read the reports that predict that 60% of the world’s reefs will be gone within the next 20 years.
Our coral reefs are being wiped off the face of the earth, and there seems to be little we can do about it. The problems are enormous. Global warming causes corals to expel the symbiotic algae in a phenomenon known as bleaching, which is typically fatal in most areas. Acidification, caused when the ocean directly absorbs carbon dioxide released by burning fossil fuels, is slowing coral growth rates and adding new stresses to reefs. Pollution, particularly high nutrient runoff from sewage and agriculture, is spurring plankton blooms and enabling algae to out-compete corals for space on the reef. Overfishing has changed
the delicate balance of reef fish assemblages and removed many of the fish that help keep reefs healthy.
So while we all enjoyed having a chance to dive here, it was heart breaking to see how many coral heads were dead and overgrown with algae, how few sharks, jacks, grouper or other predators there were, and how poor the water quality was miles offshore.
There is some good news, I suppose, in that we know what needs to be done to save the reefs. Establishing large scale fully protected marine reserves helps increase the resilience of coral reefs and rebuild fish populations. Shifting from fossil fuels to clean, renewable energy will tackle global warming and acidification, two of the biggest threats. And we can reduce the amount of fertilizer we use, changing the odds back in favor of corals.
Perhaps the best news of all is that despite early fears that the oil from the BP Horizon disaster was going to be sucked into the loop current and funneled through the Keys, the reefs appear to have been spared – at least so far. It’s still quite possible that low concentrations of oil and toxic dispersants have made it into this area, but more study is needed. Tonight we’re heading for the Dry Tortugas with two scientists from Nova University to help look at how the tropical coral reefs closest to the BP Horizon site are doing.
Before we leave though, I’d like to share one final bit of good news from the Conch Republic. Heavily overfished, conchs were severely depleted and in danger of disappearing from the Keys entirely. A ban on taking conchs was implemented, and a program was established to help re-build the population. On our dives over the past two days, I’m happy to report that we saw dozens of conchs. I’m sure we have a long way to go before the population is fully restored, but it seems clear that conchs are rebounding, another example of what we can do if we give nature a chance to heal itself.