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The Reef That Built Itself Back: Coral Recovery After Bleaching · How To Protect The Ocean

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  About 1,000 miles south of Hawaii, there's this reef of coral so remote
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  that almost nobody lives there.
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  In 2023, the water around it heated up so much and stayed hot for
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  so long, more than half a year, the reef essentially bleached.
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  And the man who monitors it described feeling the suffering in his own body.
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  And what he found when he went back is the most hopeful thing I'd
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  ever read about a coral all year.
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  Now, there's a tiny ring of coral in the North Pacific, and for more
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  than six months the water stays really, really hot, almost too hot.
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  And some of the brightest most vibrant corals on the reef turn
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  completely white, so they bleach.
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  And the scientist who monitors that reef later said he honestly
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  didn't know if it'd ever come back.
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  When he went back three years later, he put his face in the water and he
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  found it was covered with baby corals.
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  Now, today I'm going to show you why this happened, because the
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  reason has a lot to do with you.
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  Welcome back to the How to Protect the Ocean podcast.
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  I'm your host, Andrew Lewin, a marine biologist and science
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  communicator, here to talk to you about marine science, marine news,
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  and marine conservation or ocean conservation, however you wanna say it.
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  Because it's, really important that we get to know more about
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  what's happening with the ocean.
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  I covered this story a little while ago on our YouTube channel.
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  But I wanted to cover it a little bit here 'cause I wanted to share the good
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  news, because there's hope for coral, and I think that's really important
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  when people have hope for coral.
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  Now, yesterday we talked about marine protected areas as nature
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  reserves of the sea, and why most people couldn't name one.
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  If you listened to it, I gave you a bit of an exercise to find out, like, what the
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  marine protected area nearest you is and what was in it and all that kind of stuff.
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  But today it's all about what those reserves actually do when things go wrong,
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  And especially when coral bleaching and we have, like, heat waves and stuff.
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  And now let's, be honest like, the feeling around corals first, Every time you see a
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  headline about coral bleaching, there's a little voice inside you that says, " Well,
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  that's it for reefs," like, "They're done.
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  We're never really gonna see it." Chasing Coral was probably one of the
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  most depressing documentaries I've ever seen on Netflix and just in general.
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  And it made people, like, emotional after, and it didn't really give
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  people hope for what the corals can do.
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  All right?
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  And of course the numbers don't help.
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  Like, living coral around the world has dropped about 10% since 1980,
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  and mostly from repeated bleaching.
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  And right now, with a strong El Niño pushing ocean temperatures
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  up, and of course we had an El Niño not too long ago as well.
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  This round of bleaching could end up being among the worst ever recorded.
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  So if you quietly give up on coral, I get it.
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  I understand where you're taking this.
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  I get it.
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  But I've had those days too.
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  Like, it's not something that we should keep close.
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  We should realize that these corals are tough.
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  They've been around for millions of years.
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  And I've been studying the ocean my whole career.
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  I want you to give me the next 15 minutes just to be able to
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  tell you about this interesting story that we're gonna talk about.
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  Because this tells us that corals can be really resilient, especially when
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  left by themselves and on their own.
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  I think it's really important.
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  So let's talk about what coral bleaching is, Coral is an animal.
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  It shares its body with tiny algae that lives inside the tissues, kinda like
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  roommates if you think about it, those roommates make food from sunlight, and
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  they hand most of that food over to the coral so they can build the skeleton.
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  And that's where the corals get most of their energy, and it's where their
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  colors come from a lot of the times.
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  So when the water gets too hot for too long, that relationship breaks
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  down, and the coral just kicks the algae out of the coral skeleton.
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  Without them, you see straight through the tissue, and you see
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  the white skeleton behind that.
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  That white skeleton is always there, but the tissue hides the
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  white skeleton because it's got the color, and it's, like, the fleshy.
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  And that's bleaching, when that color disappears from the fleshy coral.
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  Now, a bleached coral it's starving.
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  It's not dead, but it's starving.
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  it still has a chance.
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  So if the water cools down in time, the algae can move back in, probably
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  different algae, it's not the same algae, and the coral can recover.
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  If the heat lasts too long, the coral dies, and something, like, else moves
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  in that takes place, whether it's algae or something like that, we don't know.
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  Like, a different type of algae, like a hairy algae that goes along the outside.
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  Something like seaweed or something like that.
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  It will kill the fleshy material for sure, and it'll prevent it from growing back.
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  So the real question is what decides which way a reef goes after that heat breaks?
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  Because there's a bit of a transition after that.
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  Now, to answer that, we need to go to a place where nothing has been taken away.
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  So about 1,000 miles south of Hawaii, middle of the Pacific,
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  there's an atoll called the Palmyra.
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  And Palmyra is a ring of tiny islands built by coral itself.
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  So sitting on top of an old volcano that wore away under the
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  sea a very, very long time ago.
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  During World War II, the US military built a runway and a few buildings on there
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  just to kinda have this home, because as they needed these islands to make
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  land in these islands for positioning.
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  Now, after that, most people just left it alone.
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  No towns, no permanent residences.
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  Today, it's a US National Wildlife, Refuge, and with a small research
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  station on it, and a few dozen people working there at any one point in time.
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  Well, now when you get in the water, it's like a city at lunch hour,
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  schools of fish moving between coral the size of cars, like massive, massive coral.
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  A grouper parked on the coral head with, like, a tiny cleaner fish that picks
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  parasites off its skin, basically like a spa appointment, like you get these
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  cleaning stations is what we call them.
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  And then, of course, an octopus watching from the crack, just kinda
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  hiding out of the way, and black tip reef sharks cruising around the edges.
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  Now, Joe Pawlik is a senior reef strategy lead at The Nature
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  Conservancy, and he monitors the reefs.
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  And he describes corals so packed together that they're growing on top of one
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  another, fighting over space, that happens a lot when you have a healthy reef.
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  On most reefs around the world, that's a memory.
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  We don't see that anymore.
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  But on Palmyra, it's a normal Tuesday Then, of course, 2023 arrived, and a
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  marine heatwave rolled over Palmyra and stayed for more than half a year.
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  Pawlik watched some of the most vibrant corals of the reef turn completely white.
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  He later described it as devastating.
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  He goes, "The kind of thing you feel in your body." And he admitted he didn't
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  know if the reef would ever come back.
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  it's tough when you see it bleach for so long, and then you wonder like, "Is this
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  ever gonna recover? We have no idea."
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  There's no control over it at that point.
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  Three years later, he goes back to Palmyra.
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  He's back in the water, and some of the damage is still there.
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  He still sees it.
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  Some reefs recovered faster than others.
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  But around the scarred corals, there are hundreds of little bumps
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  that look like tiny cauliflowers.
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  He called it an absolute sea of baby, tiny baby corals.
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  Those babies became the corals that survived.
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  Research shows corals that make it through a bleaching often can handle
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  heat better, and that tolerance can be passed down to the next generation.
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  So the reef that came back may be tougher than the one that was bleached.
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  Now, I should put a caveat in here.
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  It's pretty much natural selection.
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  There are certain types of algae that can handle the heat a little better,
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  so if they repopulate within the coral, that can have a higher heat tolerance.
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  They won't leave as quickly as others.
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  It doesn't necessarily mean that all different types of
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  corals are going to survive.
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  There could be some that are more prone to attracting the sp-specific algae,
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  like Zoantella is what they call it.
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  But it still shows that they're a little bit tougher when it
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  comes to this type of bleaching.
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  But the question is, it's not just the corals.
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  Why did Palmyra get a second chance when so many reefs don't?
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  And it comes down to the crew of three.
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  And the crew of three is kind of interesting.
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  You have the cleaners, the parrotfish.
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  All over Palmyra, parrotfish graze the reef all day, scraping
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  off algae off the corals.
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  After bleaching, that job becomes life or death.
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  Seaweed grows faster in warm water, and it's always looking for open real estate.
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  So if it takes over dead or, bleached patches on corals, it's very hard for the
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  corals to ever get a chance to grow back.
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  And parrotfish keep that space clear of that algae because that's what they do.
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  They eat algae.
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  They're herbivores Now, of course, there's always the landing pad of
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  the actual coral, You need coral colonies to be able to come back
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  if that flesh kinda goes away.
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  So you have this crustose coralline algae.
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  It's a specific type of algae, and it's one of my favorite things.
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  It's a bubblegum pink crust that grows over the rock and dead coral.
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  So it's not the same algae as what you would think of, like the hairy
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  algae that would grow over top and prevent other corals from growing.
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  But it's on the corals team, this one.
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  Baby corals floating in the water column go looking for somewhere to
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  settle, and many of them prefer to land right on top of this pink crust.
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  And it holds space for them until, like, the conditions are right
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  for those corals to move back in.
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  Now, of course, then you got, like, the bosses, You got the sharks.
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  And Palmyra has one of the highest densities of predators
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  ever recorded by scientists.
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  And that matters for the corals in a bit of a roundabout way.
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  Sharks eat the mid-sized predatory fish, and those mid-sized fish eat
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  the grazers, like the parrotfish.
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  So with plenty of sharks around, the mid-sized predators stay in check, and
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  the parrotfish and other grazers like, they stay around, they stay abundant.
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  Pull out the sharks, and the whole cleaning crew shrinks,
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  and that, can be difficult.
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  And that's what is the difference in terms of why Palmyra survives so well.
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  It's an intact food web.
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  That's what it looks like.
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  You have predators, you have grazers, and you have the coralline algae that kind
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  of sits there to hold that space open because the algae can't grow on top of it.
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  And it's rare.
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  You don't see it a lot.
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  Around the world, sharks and rays have declined by 71% since 1970, mostly
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  from overfishing Now, you might be thinking like, "Sure, that works
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  in the middle of nowhere with no people, but what about places where
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  people live and fish every day?"
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  And for that, we have to go to the southern tip of Africa one of the oldest
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  marine protected areas on the continent.
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  On South Africa's southern coast, there's a stretch of
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  rocky shoreline called Siksikama.
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  I think I'm pronouncing that properly.
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  It's been protected for decades and the oldest marine protected area
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  in Africa, and fishing has been banned there for a long, long time.
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  Now living on those rocky reefs is a fish called the red roman.
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  It's a bright red sea bream, and it's, it's a homebody.
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  It likes to stay around.
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  That red roman tend to stay in the same small patch of
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  the reef their entire lives.
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  That makes them perfect for an experiment because red roman born inside a marine
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  protected area is likely to live its whole life inside that marine protected area.
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  So researchers at Rhodes University wanted to know whether the protected waters
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  handle extreme conditions differently from the fish in fished waters.
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  So they fitted these red romans with small acoustic tags that record how
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  much the fish moves, which is a good proxy for how active and healthy it is.
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  Now, they tagged one population that's fished and one population that's not
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  inside the marine protected area.
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  Then nature ran the test for them.
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  First there was an intense upwelling when cold water surges upward towards
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  the coast, then the marine cold spell.
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  When the temperature crashed, the fish population slowed down, so the fish became
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  a little sluggish because it was too cold.
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  The protected population they kept moving.
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  Now the research explanation is really important here.
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  Fishing tends to take certain kinds of fish, and it may be
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  removing the individuals that are the best at handling temperature
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  extremes, so the bold, active ones.
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  So inside a protected area, those tough individuals stay in the
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  population and keep breeding.
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  It's not even just, like, the tough species, it's the tough individuals
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  from that specific species.
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  So climate change means more extremes in both directions, so
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  hotter heat waves and sharper cold snaps depending on where you are.
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  And the researchers concluded that the networks of marine protected areas
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  can help build the fish populations that are ready for those conditions.
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  So we got two stories here, a coral reef in the Pacific and a reef in South
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  Africa pointing to the same type of idea.
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  When you leave the ecosystem whole, that means no fishing, no bothersome,
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  it keeps its best tools for bouncing back Now, I wanna be straight with
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  you here because you deserve the entire picture, the full picture.
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  Protected areas allow restoration by time and resilience, so that's great.
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  On their own, they can't save reefs just like from unlimited warming.
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  that eventually will take a toll.
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  The UN's climate panel estimates that at 1.5 degrees of warming, somewhere
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  between 70% of coral reefs could be lost.
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  Based on current national pledges, the world is heading towards roughly
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  2.6 degrees by the end of the century.
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  So researchers at Rhodes have made the same point over and over again.
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  If climate change overwhelms its ecosystem's resilience, cutting
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  carbon emissions is the primary fix.
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  It's not restoration of corals.
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  That can help.
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  It can give it a little bit of time, but that heating and that
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  climate change, that's just what's gonna be the big downfall.
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  Cutting emissions turns down the heat.
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  keeps the survivors in the game, so there's something left
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  over to recover when it does.
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  And we need both.
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  So we need both, One of them is something you can push for
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  in your own region this year.
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  And, like, the lessons of Palmyra are already traveling, which is great.
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  Woods Hole Oceanographic Institution, Stanford University, and the Nature
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  Conservancy built a framework called Super Reefs, and it looks at water
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  conditions, currents, and coral genetics to find the reefs most likely to
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  survive a hotter future, then focuses on protection and restoration in those areas.
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  Now, they're working with local partners in places like Maui and
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  Belize, which is kinda cool to see.
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  And in Florida, Mote Marine Laboratory has started releasing hatchery-raised
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  Caribbean king crabs onto reefs because those king crabs eat seaweed.
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  And in Puerto Rico, restoration teams are bringing back sea urchins
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  for the same type of job, to eat the algae, and they're rebuilding the
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  cleaning crew that Palmyra never lost.
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  So it's all different types of species, but it has the same function.
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  You have your grazers.
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  You have the coralline algae that you can find in a lot of places around
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  the world, and then you have your predators, which will be different
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  and unique in every situation.
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  So here's the one thing I want you to take home from this, Because every, episode we
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  try to have a CTA, like a call to action.
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  So the next time a marine protected area consultation opens up in your region,
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  like submit one comment of support.
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  You wanna support that.
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  You wanna show the government, "Hey, this is something that I
• 13:21
  really wanna have in my area."
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  These consultations happen more often than people realize, so check
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  them out at different places, and they're usually open to anyone.
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  In Canada, Fisheries Oceans Canada post them online.
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  And in the US, look at NOAA or your state agencies.
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  Most countries have something similar.
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  Like, they all have, like, on their government website.
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  Now, your comment doesn't have to be long.
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  It can be two sentences.
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  It could be, " I support protecting this area because intact ecosystems
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  recover faster from heat waves.
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  Please give science-based protections full weight," and that's enough,
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  officials count those comments.
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  And as we talked about yesterday, the other side always shows up, the people
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  who don't want the marine protected areas.
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  And if you wanna just take what I just said and post it into a comment period,
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  I'm gonna put this in the show notes so you can get access to it and just copy
• 14:05
  and paste it into your next comment.
• 14:07
  And if you want help finding an open consultation near you, like, message me.
• 14:11
  You can hit me up as a Spotify comments, or if you are listening to your favorite
• 14:15
  podcast app and you don't have access to comments, then all you have to do is just
• 14:18
  look in the show notes and, you'll have, access to my socials there, and you can
• 14:21
  just DM me, I love to hear from you guys.
• 14:24
  Now, I want you, like, as you know this, as you now learn this, I want
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  you to picture that reef in Palmyra, Three years after it turned white,
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  the floor is covered with little baby corals, each one the child of
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  a survivor and tougher than before.
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  And parrotfish are cleaning spaces for more to be able to colonize on it, and
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  pink crusts are holding that door open to make sure algae doesn't grow on top, and
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  sharks are keeping the whole system in balance to make sure that it just stays
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  as is, and it grows back those corals.
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  And Joe Pollock put it this way, pretty much more or less: "We're
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  nowhere near ready to write the obituary on coral reefs.
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  They're not gone.
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  And when the ecosystem is whole, it starts to fight back.
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  And our job is to keep more of them whole so that they can fight."
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  now tomorrow we're talking about the people side of all of this.
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  Those parrotfish and red roman, someone somewhere fishes
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  them to feed their family.
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  So why telling people fishing is bad backfires and what works better is what
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  we're gonna be talking about tomorrow.
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  So I want you to hit that follow button so you don't miss it and you can catch it.
• 15:22
  And this has been another wonderful episode, I think wonderful episode.
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  We got to talk a lot about coral reefs in a positive way.
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  but I am your host, Andrew Lewin, and you've been listening to the
• 15:31
  How to Protect the Ocean podcast.
• 15:32
  I want you to have a great day.
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  We'll talk to you tomorrow morning, and happy conservation.