Mote project may allow researchers to envision sea life decades from now

SUMMERLAND KEY — As part of the ongoing research into ocean acidification conducted at Mote Marine Laboratory’s Elizabeth Moore International Center for Coral Reef Research and Restoration, Heather Page has been examining the interaction of coral, seaweed and sponges.

In 56 tanks, split between pairing coral and seaweed, sponges and seaweed, and sponges and coral — half of which contain water conditions found now and half designed to resemble the temperature and acidity of water in 2100 — Page and a cadre of assistants and interns watched and learned.

The study was designed to test a hypothesis that as ocean acidification progresses, sponges and macro algae may dominate reef ecosystems.

It’s also the first of several studies that will eventually lead to Page and other researchers developing and monitoring complete underwater "mini-ecosystems" in large outdoor tanks, in an effort to predict the impact of global environmental changes, such as acidification and global warming.

That’s the type of detailed research that was nearly impossible to conduct before the opening of the $7 million center, which Mote officials refer to as the IC2R3, in May 2017.

Though programs at the center suffered a setback after Hurricane Irma made landfall in the Florida Keys on Sept. 10, 2017, the lab is up and running and scientists work around the clock in shifts, monitoring everything from coral growth and ocean acidification. In addition to researchers affiliated with Mote, visiting scientists from around the world book time on the key to pursue their own research projects.

Summerland Key is still a major focal point in the mission to restore coral reefs that are failing for a variety of reasons, including ocean acidification caused by global warming and disease.

For example, Christopher Page, is overseeing a breeding program that will, among other things, lead to more diversified genotypes of coral that can be planted in the reefs.

Once coral raised through lab spawning is large enough, it, too, would be subject to microfragmenting — a process that capitalizes on the natural healing process and allows corals to grow 25 times faster than normal.

“It’s basically a marriage between both techniques,” he said.

Erinn Muller, science director of the IC2R3 Coral Health and Disease Program, has been working with scientists from a variety of partners — including the National Oceanic and Atmospheric Administration, Florida Fish and Wildlife Conservation Commission, the Coral Restoration Foundation, Nova Southeastern University, Keys Marine Laboratory and the Florida Aquarium and Mote — to combat a coral whitening disease that started outside of Miami in 2014 and has since progressed south and west along the Florida Keys.

Meanwhile, scientists under the direction of Emily Hall have been researching the implications of ocean acidification.

At the same time, its unique location offers an opportunity for other research, such as the recent project started by Robert Nowicki, another postdoctoral fellow, who is studying how nurse sharks interact with the type of lobster traps used in the Dutch Caribbean.

Creating a small world

Page used Siderastrea Radians coral, also known as lesser starlet coral, a macro algae known as Dictyota, which is becoming more prevalent in the Caribbean waters, and an encrusting orange sponge.

The lesser starlet coral is a type of boulder, or reef-building coral that had all been rescued from dock pilings or PVC pipes around Key West.

The algae can grow over coral as can the sponges — which can also bore through the coral.

“They are all found on the reefs here normally,” Page said. “I really wanted to think about what organisms can interact in the natural environment, and can I actually see that interaction?”

For the coral, Page monitored the amount of skeleton that the coral could grow over a month, and measured photosynthesis and respiration — both in current water conditions and at the temperature the conditions anticipated in the future.

Going into the study — which has been done twice before by scientists at different laboratories — Page said she anticipated the algae to compete more with the coral for space on the reef after ocean acidification. She also expected to see coral tissue death two to three times greater under ocean acidification.

“We haven’t seen any evidence of that so far, which is interesting in and of itself,” Page said.

There hasn’t been a lot of work with sponges, so most of her findings will be new.

The study is more than just seeing which organism will dominate the other.

For example, Page hopes to learn how algae impacts pH, or acidity. So far, algae increases the pH — or decreases the acidity.

“That aspect can actually help the coral, which is why I’m so interested in these interactions because on one hand algae is competing for space and the same resources as coral, but on the other hand, it’s also buffering against these pH changes,” Page said. “I think, really if you have a separation between the two, perhaps the algae can be beneficial to the coral, but you have to think long term. What’s happening to this algae? Is it staying alive, doing photosynthesis forever? It eventually dies and decomposes. So when it starts decomposing, then you’re decreasing the pH and causing acidification, which would be bad for the corals.”

The next steps in the process involve both surveying the ecosystem in the Florida Reef Tract, to see what interactions already exist currently.

That will serve as a baseline for a year from now, when the scientists can see how much things have changed.

In the laboratory, the plan involves stable isotope tracers to see how the organisms interact.

To do that the researchers can trace carbon and nitrogen isotopes, to see where the organisms are in the food chain.

For example sponges might produce nitrogen that the macro algae can use and, Page said, recent evidence shows carbon that algae and coral produce can be used by the sponges.

Essentially, the algae and coral produce more nutrients through photosynthesis than they can use, and that gets released into the water column.

“We can’t see it, but we can measure it,” Page said.

For that experiment, 20 to 30 tanks will be set up with water conditions similar to the first experiment. That study should take four to six weeks.

The next step will be to set up larger mini reef environments, or mesocosms, in several of the larger tanks, then study those mini-reefs anywhere from six months to a year, learn their trophic interaction — or place in the food chain — and more accurately model and predict what will happen to coral reefs during ocean acidification.

“That will better inform policy and management,” Page said.

That may mean something like better management of the growth of seaweed by controlling the fishing of herbivore species — fish, sea urchins and such — to keep things in check.

“Getting a better understanding of how these ecosystems are actually functioning can only help us better understand the best way to actually protect them and manage them,” Page said.

It can also give the researchers a clue as to the type of sea life that reefs in 2100 may be able to sustain.

“Sponges still have structure, but can they support the amount of biodiversity a coral reef supports with their calcium carbonate skeletons?” Page said.

Sponges can support brittle star fish, tiny crabs and worms. But it’s not known how larger fish or apex predators like sharks may survive in that type of ecosystem.

“That’s ultimately where we want to get to with this whole research,” Page said. “How is this whole reef going to function?”