Gauging the Impact of Marine Reserves
Scripps Grad Students Traveling Through Caribbean
to Learn What Conditions Allow Fish and Reefs to Thrive
By Ioana Patringenaru | November 27, 2006
A graduate student at UCSD’s Scripps Institution of Oceanography dove off the Yucatan Peninsula a few weeks ago in an unprotected area not far from Cancun. He hardly saw a fish. On some parts of the reef, corals were sick or missing altogether missing. Then he dove in protected waters off the island of Cozumel. A completely different landscape awaited him. Large schools of snappers were swimming around a healthy reef. He saw plenty of large groupers too.
This contrast can be found all around the Caribbean, said Gustavo Paredes, a graduate student at the Center for Marine Biodiversity and Conservation at Scripps. Without protection, the ocean’s ecosystems are struggling, while in well-managed, large reserves entire marine communities are thriving.
Paredes and fellow graduate student Marah Newman spent more than two years collecting and analyzing data about corals and fish from all over the Caribbean. They visited Jamaica, Mexico, Belize and Florida. They stayed at each site anywhere from two to six weeks and dove two to three times a day. Parades counted fish, taking down their size and type. Newman counted and measured corals and invertebrates.
Researchers are usually working on specific reefs or species, Paredes said. He and Newman wanted to look at the whole picture. “These are important questions and they need to be addressed on a large scale,” Newman said. Setting up reserves and protecting fish is important, Paredes said. It provides badly needed income for countries that rely on tourism as their main industry. Also, healthy reefs might do a better job at protecting coasts from water surges caused by hurricanes.
Newman, Paredes and their advisors recently published some of their findings in Ecology Letters. In a nutshell, they found that large reserves that prohibit all fishing and are set up over a long period of time allow fish to recover and thrive.
Follow these rules and you get Cozumel, a spot well known for spectacular diving conditions and bountiful fish. Without them, you get Akumal, a small community on the mainland just a few miles away. In Akumal, snappers were about 10 inches long. In Cozumel, some measured two feet. Newman said she didn’t know some of the fish she saw there could be that big.
The bad news is that during their two-year trek through the Caribbean, Newman and Paredes saw a lot of places that were just as desolate as Akumal. A trip to the Dry Tortugas National Park near the Florida Keys was particularly depressing, Newman said. The islands are protected and really remote, so the two grad students hoped they’d see a healthier ecosystem. Then they got into the water. “It was incredibly disappointing,” is how Newman put it, adding she became really concerned. If the United States with all its resources couldn’t protect its marine ecosystems, what could poorer developing countries do, she wondered. She also wondered why that ecosystem failed to thrive even though it was protected. “That’s when I took a step back and thought, man, this is really complicated,” she said.
But there’s good news too. Paredes and Newman’s data show that inside large, no-take, well-established reserves, fish are coming back in great numbers. That’s the first step toward getting corals to come back, too, Newman said. Fish eat algae, which compete with corals and try to take over reefs. The catch here is that marine reserves need to be at least about 39 square miles and set up for at least a decade. In small reserves, it’s too easy for fish to leave and be caught by fishermen right away, Paredes said.
The two grad students now hope their work will actually have an impact on the ground. They’re writing reports for local authorities in the areas they visited. The idea is to praise reserves that do a good job and make some suggestions for those that don’t, said Newman. In places like Akumal, the need for action is urgent, Paredes said.
“I don’t know what’s going to happen there, if they don’t protect it right now,” he said.