Andrew Refkin of Dot Earth presented ecologist Roger Bradbury's view (portions included in my previous post) that we are in denial regarding the fate of the world’s coral reefs. For a hopeful, though cautious, opposing view, Refkin cites marine ecologist John Bruno of the University of North Carolina at Chapel Hill. As in other critical issues in which the science is not fully settled, the two specialists see the future differently.
Quoted by Refkin, Bruno writes:
It is scary, but is it true? I don’t think so. I have been called a pathological optimist, but on the other hand, I’ve watched reefs change radically from the dangerous wild places I experienced as a kid in the Florida Keys, to simplified systems with few corals and fewer predators. And this is in just 30 years.
One aspect of my research is focused on documenting and understudying the degradation of coral reef ecosystems, mainly in terms of the loss of reef-building corals. The story is more grim in the Caribbean, where there has been a decline of at least 50 percent (and probably more than 75 percent) of coral populations.
But the picture of coral loss is roughly the same globally. More recently, we’ve been working on the extent of overfishing and predator loss on Caribbean reefs. A healthy unfished reef is inhabited by top predators like sharks and grouper and total fish biomass is roughly 500 grams per square meter. Yet, the average reef has only 20 grams per square meter — obviously an extreme decrease in fish biomass.
So that aspect of Rogers Bradbury’s Op-Ed in today’s New York Times is generally accurate. The world’s coral reefs have indeed changed, are under enormous pressure, and their future is threatened.
But are they really “on a trajectory to collapse within a human generation”? No.
Is there really “no hope of saving the global coral reef ecosystem”? No, there is hope.
And is the “scientific evidence for this is compelling and unequivocal”? No, not remotely.
I think these are valid opinions, but they are not science, nor are they supported by science. What does the science say? It is a complicated picture and there isn’t any way to scientifically test the idea that “reefs are doomed.” Like everything else in conservation (and life) it depends. It depends on when greenhouse gas emissions are reduced and eventually halted. It depends on how big the human populations gets. It depends on when we start managing coral reef fisheries with a modicum of intelligence.