Diving for 500-Year-Old Corals in Tobago
[MUSIC]
[A scientist sits on the edge of a moving boat moving past rocky islands.]
NATHALIE GOODKIN (Associate Curator, Division of Physical Sciences, American Museum of Natural History): I’m an oceanographer, and I study the history of the ocean’s role in climate.
[GOODKIN appears on screen in speaking to camera in front of a tropical seashore.]
GOODKIN: Climate systems don’t just impact one location; climate systems impact a large area.
[A yellow buoy with solar panels and instrumentation bobs in the water.]
GOODKIN: We have buoys that we can put in the ocean that can record environmental conditions, but we can’t cover the entire ocean with buoys.
[We swim over a mound of corals underwater. A school of fish nibbles at coral.]
GOODKIN: Corals serve as a natural buoy, where they are recording all of those conditions using the chemistry of their skeleton right where they’re growing over several centuries.
[BUBBLES]
[Title appears on screen: “Diving for Corals in Tobago. Constantine S. Niarchos Expedition 2019.” GOODKIN appears back on screen speaking to the camera.]
GOODKIN: So I’ve been working in the Pacific Ocean for a very long time,
[Text appears on screen: “Nathalie Goodkin, Associate Curator, Division of Physical Sciences”]
GOODKIN: but ever since I completed my Ph.D. thesis,
[GOODKIN sits on a boat with rocky islands in the background.]
GOODKIN: which was looking at the North Atlantic Oscillation in Bermuda, I’ve wanted to return to the Atlantic.
[GOODKIN sits on the edge of a boat smiling. A map of the Atlantic Ocean fades in, showing North and South America, Greenland, Europe, and Africa. At the bottom, text appears: “North Atlantic Oscillation (NAO)”]
GOODKIN: The North Atlantic Oscillation is a measure of the difference between sea level pressure at two points in the North Atlantic.
[Two dots appear in the ocean. The first dot is close to Iceland and reads “Low pressure”. The second is near the coast of Morocco and reads “High pressure.”]
GOODKIN: And what it’s telling you, effectively, is what the wind patterns are.
[The labels next to the two dots both change to “Similar pressure.”]
GOODKIN: When those pressure differences are similar, the winds slow down, they slacken.
[Arrows showing the wind paths flow from North America’s coast through the two points down towards Africa, away from Europe. The labels then change to their original labels of low pressure in the Iceland dot and high pressure in the Morocco dot.]
GOODKIN: When those pressure differences are larger, the winds speed up.
[Bigger, faster arrows fly through the two points from the coast of North America and instead curve up towards Europe.]
GOODKIN: As you change these winds and their directions, you change the storm tracks,
[An animated icon of a thunder cloud with lightning boltes appears on screen.]
GOODKIN: you change the wave height…
[An animated icon of rolling waves appears on screen.]
GOODKIN: It also changes surface temperature, both on land and in the water.
[An animated icon of a thermometer appears on screen. Swaths of color appear on the map to indicate warmer and cooler areas: the area between the two dots is red and warmer, stretching from North America to Europe, and the areas both North and South of this area both appear blue, and are cooler.]
[The icons and temperature coloration disappears. A circle appears around an area off the north coast of South America.]
GOODKIN: In the modern record, the NAO has the strongest impact here in Tobago.
[The map zooms in so we see the islands of Trinidad and Tobago with labels next to them. The map continues to zoom into Tobago while it fades and we see landscapes of blue ocean and rocky islands.]
GOODKIN: And so we’re trying to get coral cores to understand how the system is changing both through time and geographically.
[GOODKIN reappears on screen speaking to the camera.]
GOODKIN: The first thing you really need when you want to go work in a foreign country is a collaborator who wants to work with you–
[GOODKIN holds a coral core out over the edge of the boat to another scientist snorkeling in the water below. The same scientist, REIA GUPPY, sits on the edge of a boat in a wetsuit while tropical shores fly by in the background.]
GOODKIN: –and is interested in the science questions you’re asking.
[ENGINE RUMBLE]
[GUPPY appears on screen speaking to camera with islands in the background.]
REIA GUPPY (Assistant Professor, The University of Trinidad and Tobago): Because I work on coral reefs, she—good ol' Google—found me,
[Text on screen: “Reia Guppy, Assistant professor, The University of Trinidad and Tobago”]
GUPPY: and asked if we were interested in collaborating.
[GUPPY snorkels in the water.]
GUPPY: By trade I'm really a coral reef biologist. I'm very much interested in environmental health and disease,
[We see a bright brownish orange coral with fish swimming around it, a closeup of a coral with anemone-like tendrils, and a brain coral on the edge of a reef.]
GUPPY: how they are influenced by changes that are going on.
[GUPPY reappears on screen speaking to camera.]
GUPPY: Throughout my time, I've seen going from pretty resilient, healthy reefs
[Cut to a barren, dead section of reef.]
GUPPY: to really disastrous densities and diversity.
[We swim through some sea fans on top of dead coral.]
[A scuba diving scientist, KONRAD HUGHEN, makes the “OK” symbol at the camera underwater.]
GOODKIN: We decided we would involve Dr. Konrad Hughen at the Woods Hole Oceanographic Institution,
[HUGHEN points to a coral core laid out on a table. GOODKIN reappears on screen speaking to camera.]
GOODKIN: and then two students that would start at roughly the same time–
[GOODKIN sits next to her student on a boat. The same student labels a coral core.]
GOODKIN: one in the U.S. really working on the climate questions,
[A different student sits on the bow of a boat, pulling in the anchor. He examines a coral core along with HUGHEN.]
GOODKIN: and one here in Trinidad working on human impacts on reefs.
[GUPPY reappears on screen speaking to camera.]
GUPPY: We had chosen Speyside as our primary site, which is where we are at now. You can actually see in the background
[GUPPY turns to indicate two islands behind her. Closeup of the islands: one smaller in front and one much larger behind.]
GUPPY: two of the infamous islands which is Goat Island, and Little Tobago.
[GUPPY reappears on screen speaking to camera.]
GUPPY: Both of these islands are known for their large corals,
[We swim up to a large, striking brain coral underwater, followed by an overhead view of a different large brain coral.]
GUPPY: which is what you really want to be able to get these long-term climate records.
[GOODKIN reappears on screen speaking to camera.]
GOODKIN: At any given location, what we’re doing is we’re drilling a coral core.
[The scientists load scuba gear onto a boat from a small pier.]
GOODKIN: We’re getting up each morning, we have an enormous amount of equipment. We’re loading it onto boats and heading out to sea.
[The small boat, named “Fish Machine 2”, floats on the water as a few scientists arrange gear and jump off into the water.]
GOODKIN: We’re identifying those corals, and then we’re going ahead and sampling them.
[We dive from the surface and look down on three scuba divers surrounding a coral. We swim up on HUGHEN, in scuba gear, drilling into a coral with a pneumatic drill. One of the students drills a different coral, and hands the core underwater to HUGHEN.]
GOODKIN: Our main goal for this trip was to collect a core from the largest coral we found last spring when we were here surveying.
[HUGHEN swims over a huge coral – it’s as long or longer than his whole body as he swims overtop it.]
GOODKIN: This was a very difficult core to drill. We estimated that the coral was about three meters in height.
[We see the huge coral from the side as a few scuba divers swim around it.]
GOODKIN: It was in about 45-feet depth, which is very deep for drilling.
[GUPPY reappears on screen speaking to camera.]
GUPPY: I've been diving this site since the '90s—it is known for the strong currents where the surface currents go in one direction and under the water the currents go in a different direction.
[GOODKIN reappears on screen speaking to camera.]
GOODKIN: When we showed up in the morning, we expected to be there three, maybe four days.
[Camera pans over a blue sky, islands, and calm seas.]
GOODKIN: We showed up, there were no currents at the surface,
[Scuba divers swim next to a huge coral.]
GOODKIN: there were no currents at the bottom. The visibility was crystal clear,
[Close up of HUGHEN drilling a hole in the top of the huge coral.]
GOODKIN: and we were able to get the bottom of that core in one day.
[GOODKIN holds up a white coral core on the boat, smiling.]
GUPPY: It is a very short term injury. It’s not lethal to them.
[A gloved hand pushes a cement plug into the drill hole at the top of a coral.]
GUPPY: When we cover the hole with an inert substance,
[An older cement plug in a coral, covered with bits of coral growth and algae.]
GUPPY: the coral eventually grows over it.
[The five scientists and students stand around a table, each picking up a section of coral core and holding it up end to end. It stretches almost the length of the table.]
GOODKIN: We were able to collect a core that was 2.8 meters long,
[The camera pans across the long coral core.]
GOODKIN: so that could be up to 500 years of environmental record.
[One student labels a coral core. GOODKIN and GUPPY wrap up cores in towels.]
GOODKIN: So once we get the samples back to the lab,
[WHIRR OF A SAW]
[Back in cooler climates, GOODKIN and a student slice open coral cores outside with a circular saw table.]
GOODKIN: –the first thing that we do is that we slice them into rectangular pieces.
[GOODKIN looks at a sliced core.]
GUPPY: When we cut the corals, we would be able to see these growth rings,
[Close-up of some of the growth bands inside a sliced coral core.]
GUPPY: –very similar to what you would see in tree growth rings.
[A pointed machine takes a tiny sample from a piece of a coral core.]
GOODKIN: And from there we’ll start with our chemical analysis.
[GOODKIN places a tiny container on a scale back in the lab.]
GOODKIN: Strontium is one element we’re very interested in.
[GOODKIN reappears on screen speaking to camera.]
GOODKIN: If it gets colder, the corals incorporate more strontium into their skeleton. And when it gets warmer, they incorporate less strontium.
[An x-ray of a coral slice, showing dark bands of growth.]
GOODKIN: And with records of sea surface temperature from the last 20 years,
[Circles appear next to the dark bands with “Sr” for strontium inside. The “Sr”’s are replaced with temperatures varying from 25°C to 28°C.]
GOODKIN: we’re able to calibrate each coral to have a thermometer back in time.
[A stormy rainy seascape appears, with an overlay of the map showing the path of the North Atlantic Oscillation and its effects.]
GOODKIN: One of the concerns of the next 50–100 years is that as our climate system changes, the NAO will change.
[Beneath the map, we see a cargo ship.]
GOODKIN: This will impact shipping routes.
[The cargo ship is replaced by a wind turbine.]
GOODKIN: It will impact energy supply through hydroelectric dams and wind farms.
[The wind turbine is replaced by a puddle with rain on it, and then a rainy window looking out onto city traffic.]
GOODKIN: This will impact droughts and water supply for large populations.
[GOODKIN reappears on screen speaking to camera.]
GOODKIN: And, so, the first thing we really need to do is to understand how this system has operated in the past
[A sunny seascape with a boat floating on the waves.]
GOODKIN: and what might happen as we change the system around it.
[A triggerfish swims through the water. A Christmas tree worm sucks its bristles back into its hole. GUPPY reappears on screen speaking to camera.]
GUPPY: As a Caribbean person, we're all about trying to move towards sustainable development.
[Angelfish swim on the reef. Overhead shot of a large branching coral.]
GUPPY: We're starting to see a shift in some of those earlier species that had disappeared. They’re actually starting to come back, which is very exciting.
[Closeup of the surface of a brain coral. Striped fish swim through the reef.]
GUPPY: I'm, you know, very optimistic that, if we can continue to do land management,
[GUPPY reappears on screen speaking to the camera.]
GUPPY: in time that we'll be able to preserve our reefs and let them come back to something that they were like in the '80s and '90s.
[Swimming from the bottom to the surface, we see the Fish Machine 2 boat with the scientists on board.]
GOODKIN: The cores hold so much information.
[GOODKIN reappears on screen speaking to camera.]
GOODKIN: We can study ocean currents. We can study ocean physical conditions. We can study the biological conditions on the reef.
[HUGHEN and GOODKIN speak and look at the coral cores laid out on a table in front of them.]
GOODKIN: We can study the nutrients that the corals and the other plankton are living off of, all recorded within the coral skeleton.
[GUPPY hands a small chunk of a coral core from the water where she’s snorkeling up to the scientists on deck. The camera zooms in on the coral core.]
GOODKIN: It would take us decades to extract all of the information from them. It looks that there’ll be years to come of work here in Tobago–
[Swimming from the sea floor up to the surface, we see the boat and the scientists working on it.]
GOODKIN: –to better understand the corals and the climate of this region.
[Credits roll.]
In October 2019, Museum oceanographer Nathalie Goodkin and colleagues traveled to Tobago hoping to retrieve hundreds of years of data about ocean conditions and coral reef health by sampling the region’s giant corals.