Diving into the deep ocean to find hope for threatened coral reefs

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JOHN YANG: Now to our latest ScienceScope episode.

A third of the planet’s coral reef ecosystems are at risk of being damaged by warming sea temperatures and the subsequent coral bleaching, but can these creatures adapt and survive?

NewsHour’s science producer Nsikan Akpan and producer Matt Ehrichs take us on a voyage deep into the Atlantic Ocean, looking for answers.

NSIKAN AKPAN: I’m in a plastic pod in the middle of the ocean off Bermuda’s southeast coast. This thing is smaller than a Volkswagen Beetle.

As six-foot swells toss our tiny submersible, I think, this was a terrible idea. Then, suddenly, the pod tips forward. The descent begins. The rocking slowly stops, as the ocean swallows us.

All that’s left is peace. No more e-mails. No claustrophobia. Just the whole ocean spread in front of us and a scientific quest.

ScienceScope visited Bermuda to travel hundreds of feet underwater with the privately funded Nekton mission and to see the threats harming more than a third of the planet’s coral reefs, because some coral may adapt by going deeper.

ALEX ROGERS, Chief Scientist, Nekton: Nekton is a brand-new project aimed at exploring and documenting life in the deep ocean, but also showing the public what lives in the deep ocean, and what it does for humankind, and also what impacts humans are having on the deep sea.

NSIKAN AKPAN: The project plans to measure biodiversity and ocean chemistry at three sites in the Atlantic. The team uses a variety of tools, among them, two Triton submersibles called Nemo and Nomad. They’re the same type used by filmmaker and ocean explorer James Cameron.

Capable of diving 1,000 feet, these minisubs are equipped with the latest filming and scientific equipment. They will document the vast, uncharted void that is the deep sea.

ALEX ROGERS: Well, at present, about .0001 percent of the deep sea has been explored by scientists like myself. Our goal is to set up a standard protocol for investigating the deep sea.

NSIKAN AKPAN: Over the course of four hours, we glide across huge portions of the seafloor. This is called a transect. The scientists videotape and ultimately identify as many species as possible.

ALEX ROGERS: On the limestone, we have coral garden habitat. The bright white corals are hydrocorals. The yellow corals are gorgonians, and the wire corals are black corals.

NSIKAN AKPAN: Oodles of fish dart back and forth in this abyss, while moray eels stick out their neon green necks from the sea bed. But the team can identify species even when they’re not physically around using environmental DNA.

ALEX ROGERS: So, you can imagine if you put your hand in a big glass of water, and a few cells fall off your hand with your DNA on them, then we would be able to take that water and sequence it, and find out that you have been there, and you have put your hand in the water.

NSIKAN AKPAN: The scientists collect water samples to do the same with ocean critters, which shed cells with DNA in many forms, scales, shells.

ALEX ROGERS: Poop as well.


ALEX ROGERS: Poop is a great source of DNA.

NSIKAN AKPAN: Closer to the surface, Nekton conducts similar surveys by relying on research divers from Project Baseline, a global citizen science initiative.

These divers film the biodiversity, but also collect physical specimens for researchers like Gretchen Goodbody-Gringley. She studies how corals migrate from shallow water into the deeper, darker mesophotic zone.

Located 131 to more than 500 feet underwater, this deeper region may one day serve as a refuge for corals affected by bleaching and other threats.

GRETCHEN GOODBODY-GRINGLEY, Reef Ecologist: Many of the anthropogenic or human-caused threats that are impacting shallow water coral reefs, such as increases in seawater temperature, increases in pollution, sedimentation and runoff from the land, these all impact the shallow water reef more than they are impacting the mesophotic reef.

NSIKAN AKPAN: Warming waters cause coral bleaching, as seen here with mushroom coral. The coral expels its colorful, symbiotic algae, which have become toxic due to the heat. This coral also expands to 340 percent of its size.

If this event occurs too frequently, the coral won’t only bleach. It’ll die. All corals start as little larvae that get swept around by currents before attaching in a single spot. So, Gringley, Rogers and the Nekton team use these underwater surveys and environmental DNA to see which shallow water corals can also live in the mesophotic zone and maybe one day use this deeper ocean as a hideout.

GRETCHEN GOODBODY-GRINGLEY: So if you have high levels of genetic diversity across geographic range or across depth range, this would be indicative of mixing, and so the larvae are in fact migrating between zones.

NSIKAN AKPAN: So, from these teeny-tiny samples, her team can unlock how generations of corals have migrated. The results will clear up which coral species can migrate and which can’t.

Conservation scientists in the future can use this information to best protect these critical critters, maybe by preserving them in aquariums or physically transplanting them from shallow water to the mesophotic zone.

OLIVER STEEDS, Mission Director, Nekton: The deep ocean is the most critical frontier for humanity, and is also the least known. The deep ocean is our beating heart, and if you didn’t know how healthy your heart was, wouldn’t you want to know?

NSIKAN AKPAN: Until next time, I’m Nsikan Akpan, and this is ScienceScope from the PBS NewsHour.

JOHN YANG: Online, you can watch additional episodes of ScienceScope and get five important news stories you might have missed last week.

All that and more is on our Web site, pbs.org/newshour.

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