>>NATHALIE GOODKIN (Associate Curator, Division of Physical Sciences): I'm an oceanographer
and I study the history of the ocean’s role in climate.
Climate systems don’t just impact one location; climate systems impact a large area.
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.
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.
So I’ve been working in the Pacific Ocean for a very long time, but ever since I completed
my Ph.D. thesis, which was looking at the North Atlantic Oscillation in Bermuda, I’ve
wanted to return to the Atlantic.
The North Atlantic Oscillation is a measure of the difference between sea level pressure
at two points in the North Atlantic.
And what it’s telling you, effectively, is what the wind patterns are.
When those pressure differences are similar, the winds slow down, they slacken.
When those pressure differences are larger, the winds speed up.
As you change these winds and their directions, you change the storm tracks, you change the
wave height…
It also changes surface temperature, both on land and in the water.
In the modern record, the NAO has the strongest impact here in Tobago.
And so we’re trying to get coral cores to understand how the system is changing both
through time and geographically.
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 and is interested in the science questions you’re asking.
>>REIA GUPPY (Assistant Professor, The University of Trinidad and Tobago): Because I work on
coral reefs, she—good ol' Google—found me, and asked if we were interested in collaborating.
By trade I'm really a coral reef biologist.
I'm very much interested in environmental health and disease, how they are influenced
by changes that are going on.
Throughout my time, I've seen going from pretty resilient, healthy reefs to really disastrous
densities and diversity.
>>GOODKIN: We decided we would involve Dr. Konrad Hughen at the Woods Hole Oceanographic
Institution, and then two students that would start at roughly the same time– one in the
U.S. really working on the climate questions, and one here in Trinidad working on human
impacts on reefs.
>>GUPPY: We had chosen Speyside as our primary site, which is where we are at now.
You can actually see in the background two of the infamous islands which is Goat Island,
and Little Tobago.
Both of these islands are known for their large corals, which is what you really want
to be able to get these long-term climate records.
>>GOODKIN: At any given location, what we’re doing is we’re drilling a coral core.
We’re getting up each morning, we have an enormous amount of equipment.
We’re loading it onto boats and heading out to sea.
We’re identifying those corals, and then we’re going ahead and sampling them.
Our main goal for this trip was to collect a core from the largest coral we found last
spring when we were here surveying.
This was a very difficult core to drill.
We estimated that the coral was about three meters in height.
It was in about 45-feet depth, which is very deep for drilling.
>>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: When we showed up in the morning, we expected to be there three, maybe four
days.
We showed up, there were no currents at the surface, there were no currents at the bottom.
The visibility was crystal clear, and we were able to get the bottom of that core in one
day.
>>GUPPY: It is a very short term injury.
It’s not lethal to them.
When we cover the hole with an inert substance, the coral eventually grows over it.
>>GOODKIN: We were able to collect a core that was 2.8 meters long, so that could be
up to 500 years of environmental record.
So once we get the samples back to the lab, the first thing that we do is that we slice
them into rectangular pieces.
>>GUPPY: When we cut the corals, we would be able to see these growth rings, very similar
to what you would see in tree growth rings.
>>GOODKIN: And from there we’ll start with our chemical analysis.
Strontium is one element we’re very interested in.
If it gets colder, the corals incorporate more strontium into their skeleton.
And when it gets warmer, they incorporate less strontium.
And with records of sea surface temperature from the last 20 years, we’re able to calibrate
each coral to have a thermometer back in time.
One of the concerns of the next 50–100 years is that as our climate system changes, the
NAO will change.
This will impact shipping routes.
It will impact energy supply through hydroelectric dams and wind farms.
This will impact droughts and water supply for large populations.
And, so, the first thing we really need to do is to understand how this system has operated
in the past and what might happen as we change the system around it.
>>GUPPY: As a Caribbean person, we're all about trying to move towards sustainable development.
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.
I'm, you know, very optimistic that, if we can continue to do land management, 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.
>>GOODKIN: The cores hold so much information.
We can study ocean currents.
We can study ocean physical conditions.
We can study the biological conditions on the reef.
We can study the nutrients that the corals and the other plankton are living off of,
all recorded within the coral skeleton.
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 to better understand
the corals and the climate of this region.