LULU GARCIA-NAVARRO, HOST:
The U.S. Virgin Islands were devastated by hurricanes Maria and Irma, leaving homes collapsed and trees toppled on land. But there was also a great deal of damage under the water. In St. John, the storms churned up parts of the lush coral reef, depositing chunks on the beaches. Joining us now to talk about it is marine biologist Peter Edmunds of California State University, Northridge. He's been studying those reefs in St. John for more than three decades. Welcome to the program, sir.
PETER EDMUNDS: Thank you very much. A pleasure to be here.
GARCIA-NAVARRO: You received National Science Foundation support to visit St. John in November. And you took a look at the coral. What did you see?
EDMUNDS: Well, storms bring massive waves that - 20, 25 feet in height to the surface. And those waves bring tremendous forces underwater that drag things across the bottom and break things off the bottom and cause a tremendous amount of scarring. And so in the Virgin Islands, we're accustomed to calm, sheltered waters, sunny days and spectacular underwater visibility. And then after a storm, everything has changed. And it's a remarkable game trying to imagine what it was like on that night of the storm.
GARCIA-NAVARRO: So you saw specifically, I think, in the shallower parts quite a bit of damage. Tell me what you saw there.
EDMUNDS: Most folks who visit the Virgin Islands and snorkel around the Virgin Islands will snorkel in water that is five, 10 to 20 feet deep. And those are the areas that are most prone to the damage. And sure enough, when we swam over those areas, we saw the damage, the toppling and the scarring. But once we got below about 20, 25 feet, it was a different story. And certainly, you can find broken corals and toppled sea fans and the damage. But I think what was remarkable was the amount of coral and soft coral that survived.
GARCIA-NAVARRO: We do know that there have been coral bleaching events and that there are pressures because of climate change. And add to that a storm like this. And is it harder for the reefs to recover?
EDMUNDS: Absolutely. It's a situation where you've got slow challenges playing out over decades and centuries. And you've got short-term challenges playing out overnight. And one playing out over the night were the hurricanes. And the longer-term things are rising sea water temperature and declining pH of the ocean. And so since there are now fewer corals on adjacent islands, it will slow the rate of which the reefs recover. And I think that is very worrying. But that's quite different from saying that they won't recover. And I think in addition, the kinds of coral that live there are changing dramatically, as well.
EDMUNDS: The classic corals of the Caribbean you might have seen there in the 1950s, 1960s would've been towering elkhorn and staghorn corals and beautiful, massive star corals. And unfortunately, those are the corals that have suffered particularly acutely from diseases and rising temperature and previous storms. But in their place are corals that are growing that are a more weedy species in the sense that - of a weed in your garden. They're small. They're perhaps a little drab. There's lots of them. They grow fast. And they die fast, as well. But they are a shadow of the kind of corals that used to be found there 50 years ago.
GARCIA-NAVARRO: Can you give us a sense of what percentage of the coral reef was damaged if you could quantify it and the timeline for recovery?
EDMUNDS: In some of the places where we were, by August of 2017, when we were last there before the hurricane, one-tenth of the sea floor or less was covered by live coral. And now 3 or 4 percent of that has been killed. And the rate of recovery will be slow. Corals grow very slowly. So probably by next summer, we'll start to see baby corals settling on the reef. And some of those will survive and produce the reefs of tomorrow. But whether they do that or not will depend on these progressive changes in the environmental conditions and whether or not there are further Category 5 storms in 2018 or 2019 or 2020.
GARCIA-NAVARRO: Marine biologist Peter Edmunds of California State University, Northridge, thank you so much.
EDMUNDS: Thank you very much. Transcript provided by NPR, Copyright NPR.