Why I still have hope for coral reefs | Kristen Marhaver

84,532 views ・ 2017-08-11

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The first time I cried underwater
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was in 2008,
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the island of Curaçao,
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way down in the southern Caribbean.
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It's beautiful there.
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I was studying these corals for my PhD,
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and after days and days of diving on the same reef,
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I had gotten to know them as individuals.
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I had made friends with coral colonies --
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totally a normal thing to do.
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Then, Hurricane Omar smashed them apart and ripped off their skin,
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leaving little bits of wounded tissue that would have a hard time healing,
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and big patches of dead skeleton that would get overgrown by algae.
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When I saw this damage for the first time,
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stretching all the way down the reef,
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I sunk onto the sand in my scuba gear
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and I cried.
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If a coral could die that fast,
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how could a reef ever survive?
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And why was I making it my job to try to fight for them?
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I never heard another scientist tell that kind of story
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until last year.
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A scientist in Guam wrote,
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"I cried right into my mask,"
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seeing the damage on the reefs.
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Then a scientist in Australia wrote,
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"I showed my students the results of our coral surveys,
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and we wept."
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Crying about corals is having a moment, guys.
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(Laughter)
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And that's because reefs in the Pacific
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are losing corals faster than we've ever seen before.
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Because of climate change,
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the water is so hot for so long in the summers,
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that these animals can't function normally.
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They're spitting out the colored algae that lives in their skin,
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and the clear bleached tissue that's left usually starves to death
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and then rots away.
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Then the skeletons are overgrown by algae.
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This is happening over an unbelievable scale.
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The Northern Great Barrier Reef lost two-thirds of its corals last year
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over a distance of hundreds of miles,
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then bleached again this year,
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and the bleaching stretched further south.
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Reefs in the Pacific are in a nosedive right now,
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and no one knows how bad it's going to get,
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except ...
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over in the Caribbean where I work,
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we've already been through the nosedive.
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Reefs there have suffered through centuries of intense human abuse.
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We kind of already know how the story goes.
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And we might be able to help predict what happens next.
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Let's consult a graph.
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Since the invention of scuba,
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scientists have measured the amount of coral on the seafloor,
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and how it's changed through time.
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And after centuries of ratcheting human pressure,
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Caribbean reefs met one of three fates.
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Some reefs lost their corals very quickly.
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Some reefs lost their corals more slowly,
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but kind of ended up in the same place.
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OK, so far this is not going very well.
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But some reefs in the Caribbean --
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the ones best protected
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and the ones a little further from humans --
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they managed to hold onto their corals.
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Give us a challenge.
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And, we almost never saw a reef hit zero.
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The second time I cried underwater
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was on the north shore of Curaçao, 2011.
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It was the calmest day of the year,
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but it's always pretty sketchy diving there.
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My boyfriend and I swam against the waves.
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I watched my compass so we could find our way back out,
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and he watched for sharks,
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and after 20 minutes of swimming that felt like an hour,
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we finally dropped down to the reef,
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and I was so shocked,
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and I was so happy
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that my eyes filled with tears.
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There were corals 1,000 years old lined up one after another.
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They had survived the entire history of European colonialism in the Caribbean,
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and for centuries before that.
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I never knew what a coral could do when it was given a chance to thrive.
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The truth is that even as we lose so many corals,
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even as we go through this massive coral die-off,
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some reefs will survive.
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Some will be ragged on the edge,
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some will be beautiful.
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And by protecting shorelines and giving us food to eat
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and supporting tourism,
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they will still be worth billions and billions of dollars a year.
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The best time to protect a reef was 50 years ago,
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but the second-best time is right now.
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Even as we go through bleaching events,
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more frequent and in more places,
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some corals will be able to recover.
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We had a bleaching event in 2010 in the Caribbean
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that took off big patches of skin on boulder corals like these.
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This coral lost half of its skin.
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But if you look at the side of this coral a few years later,
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this coral is actually healthy again.
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It's doing what a healthy coral does.
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It's making copies of its polyps,
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it's fighting back the algae
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and it's reclaiming its territory.
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If a few polyps survive,
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a coral can regrow;
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it just needs time and protection and a reasonable temperature.
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Some corals can regrow in 10 years --
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others take a lot longer.
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But the more stresses we take off them locally --
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things like overfishing, sewage pollution, fertilizer pollution,
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dredging, coastal construction --
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the better they can hang on as we stabilize the climate,
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and the faster they can regrow.
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And as we go through the long, tough and necessary process
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of stabilizing the climate of planet Earth,
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some new corals will still be born.
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This is what I study in my research.
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We try to understand how corals make babies,
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and how those babies find their way to the reef,
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and we invent new methods to help them survive
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those early, fragile life stages.
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One of my favorite coral babies of all time
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showed up right after Hurricane Omar.
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It's the same species I was studying before the storm,
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but you almost never see babies of this species --
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it's really rare.
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This is actually an endangered species.
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In this photo, this little baby coral, this little circle of polyps,
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is a few years old.
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Like its cousins that bleach,
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it's fighting back the algae.
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And like its cousins on the north shore,
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it's aiming to live for 1,000 years.
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What's happening in the world and in the ocean
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has changed our time horizon.
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We can be incredibly pessimistic on the short term,
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and mourn what we lost
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and what we really took for granted.
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But we can still be optimistic on the long term,
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and we can still be ambitious about what we fight for
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and what we expect from our governments,
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from our planet.
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Corals have been living on planet Earth for hundreds of millions of years.
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They survived the extinction of the dinosaurs.
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They're badasses.
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(Laughter)
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An individual coral can go through tremendous trauma and fully recover
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if it's given a chance and it's given protection.
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Corals have always been playing the long game,
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and now so are we.
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Thanks very much.
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(Applause)
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