Environment

Bring on the sharks! 'Super reefs' could support more marine life with a little TLC

Predatory fish depletion and recovery potential on Caribbean coral reefs

A study published on Wednesday, March 1, 2017, details a new way of measuring the ability of reefs to draw sharks, rays and other large predators that could improve conservation efforts.
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A study published on Wednesday, March 1, 2017, details a new way of measuring the ability of reefs to draw sharks, rays and other large predators that could improve conservation efforts.

Not all reefs are created equal, a distinction that fish seem to recognize but until now scientists largely overlooked.

In a study published Wednesday in the journal Science Advances, researchers found that if managed properly, Caribbean reefs could support from 60 to 90 percent more sharks, rays and other large predators than now inhabiting them. They also found that some, with a perfect combination of caves and coral for habitat, prey and the right temperatures, have the potential to become Seaquariums of the sea in the form of ‘super’ reefs.

It’s immensely valuable from a tourism perspective.

University of North Carolina marine ecologist John Bruno

“It’s immensely valuable from a tourism perspective,” said University of North Carolina marine ecologist John Bruno. “The next step is to employ this kind of approach in designing conservation across the landscape and figure out the reefs with the greatest restoration potential.”

Large predators have largely disappeared from reefs across the Caribbean, along with parts of Florida, Bruno said. Scientists know pressure from over-fishing and coastal development have helped wipe out fish, but they’re not sure by how much and have little data to determine the number of predators that historically inhabited specific reefs. In devising goals to revive reefs, marine managers typically look at Pacific atolls, where fish are still abundant, to design cookie cutter conservation plans, he said.

A three-year NASA field expedition to examine Earth’s coral reefs is now underway, giving scientists the opportunity to study reefs' ecology and condition.

But in a survey of 39 reefs in the Caribbean, including the Dry Tortugas, Bruno and the team found that not all reefs are alike, nor can they all support larger predators. To figure out the reef’s true potential, they looked at critical variables. Those include things like caves and coral that provide shelter, the abundance of prey and temperature swings.

“One of the things we can do is … measure all the variables and determine carrying capacity and then we can decide if this reef is worth protecting or not,” said co-author Abel Valdivia, a former National Oceanic and Atmospheric Administration contractor who studies coral in the Florida Keys now with the Center for Biological Diversity.

39 The number of reefs surveyed over three years to determine measures for a reef’s potential to draw sharks and other large predators

Their research also showed that reefs with some kind of management plan, whether in Cuba or the U.S., fared better and that unprotected reefs in Belize and Mexico have the potential to draw far more predators.

“Ultimately reef predators are far more valuable alive than dead,” Bruno said. “A single shark worth only a hundred bucks in a market can be worth over a million dollars in tourism revenue over it’s lifetime.”

Follow Jenny Staletovich on Twitter @jenstaletovich

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