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Scientists in the Florida Keys haven't had great success revitalizing coral reefs


We're going to go to the Florida Keys now, where scientists have been planting cultivated corals in an effort to revitalize reefs that are threatened by heat and disease. Last summer, though, the waters at these keys reached hot tub temperatures, which dealt a severe blow to those restoration efforts. An underwater survey this month revealed that just one-fifth of the staghorn corals that scientists planted have survived, and only 5% of the elkhorn corals remain. Katey Lesneski has been diving on these surveys. She's with the Florida Keys National Marine Sanctuary and joins us now. Welcome back to the show.

KATEY LESNESKI: Good afternoon. Thank you so much for having me on to tell you the next part of the story of these corals in the keys.

CHANG: Yeah. Well, before we get to the next part, I just want to hear you describe, like, what have you been seeing recently on these dives that you've been doing?

LESNESKI: So during our research cruise, we started at our northernmost site, which is Carysfort Reef off of Key Largo. And there we were quite pleased to see a number of living colonies of elkhorn and staghorn coral, which, when they're healthy, are this really nice, rich, beautiful tan, orange and brown color. And they really stand out against the blue water and the rest of the reef that has purple and green and yellow sea fans. As we moved further south on our way to Key West, unfortunately, we found more and more dead corals that have died either within the last several months or maybe within the last six months. And that looks quite different. The colors are very drab. The coral skeletons are covered in brown and green algae, and it looks basically just like a field of rocks. And all of that color has gone.

CHANG: Wow. Like, so you can't even tell if it's coral.

LESNESKI: Exactly. It looks like a very monotonous landscape and just does not have that beautiful variety of colors that you see on a healthy reef.

CHANG: Well, then let me ask you this. What do these survival rates that we've been talking about mean for restoration efforts long term? I mean, is it still worth cultivating and planting new corals into these reefs, knowing that they're undergoing so much stress when they're trying to survive there?

LESNESKI: Yeah, so that's a great question, and it is one that a lot of people have posed. And while these survival rates are not where we would like them to be, when these corals were still alive on the reefs, they were providing ecological benefits and, subsequently, economic benefits. And we have quite a lot to learn from these survivors. Why did they survive? Where exactly in different reef habitats did they survive? And can we use that information to make even better decisions about reef restoration going forward?

CHANG: I feel like this conversation is pretty depressing, though. I mean, how do you keep these corals alive given the environment? Is there any sliver of hope that you can offer?

LESNESKI: (Laughter) Yes, so finding a sliver of hope is always so important for myself and my colleagues. The piece of hope that I can offer is that, of course, we did find individuals of these species living on our reef restoration sites. And as I mentioned, we have a lot to learn from them. But during these surveys, anecdotally, we looked at other species on these reefs and found that corals that we lumped together in the category of boulder corals, massive corals and brain corals, they looked very vibrant in color, as if nothing had fazed them. And so we have hope that those individuals in the reef community will continue to do well in the coming months and years.

CHANG: Diversity is always better.

LESNESKI: I absolutely agree.

CHANG: (Laughter) That is Katey Lesneski, a research coordinator for coral restoration at the Florida Keys National Marine Sanctuary. Thank you so much, Katey.

LESNESKI: Thank you so much, Ailsa. Transcript provided by NPR, Copyright NPR.

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Alejandra Marquez Janse is a producer for NPR's evening news program All Things Considered. She was part of a team that traveled to Uvalde, Texas, months after the mass shooting at Robb Elementary to cover its impact on the community. She also helped script and produce NPR's first bilingual special coverage of the State of the Union – broadcast in Spanish and English.
Ailsa Chang is an award-winning journalist who hosts All Things Considered along with Ari Shapiro, Audie Cornish, and Mary Louise Kelly. She landed in public radio after practicing law for a few years.
Christopher Intagliata is an editor at All Things Considered, where he writes news and edits interviews with politicians, musicians, restaurant owners, scientists and many of the other voices heard on the air.