American Museum Of Natural History Scientists Help Demonstrate That Protecting Fish Species Can Help Coral Reefs Recover
Researchers have found that fishing bans in marine reserves lead to increased populations of parrotfish (pictured), which in turn help coral reefs re-establish and grow.
Credit: AMNH/Katherine Holmes
Threatened coral reefs could be given a helping hand by the establishment of marine reserves that limit fishing, according to a research team that included scientists from the American Museum of Natural History's Center for Biodiversity Conservation (CBC). Marine reserves have already proved to be a successful way of protecting fish and other marine life against overfishing. A study led by the University of Exeter and published this week in Proceedings of the National Academy of Sciences, shows for the first time how marine reserves could also help coral reefs re-establish and grow by promoting fish species that graze on harmful algae.
The research was carried out on the Exuma Cays Land and Sea Park (ECLSP), a marine reserve in The Bahamas, by a team that is part of the Bahamas Biocomplexity Project. At nearly 171 square miles (442 square kilometers), ECLSP is one of the largest and best-protected marine reserves in the Caribbean.
Marine reserves are areas of the sea that are protected against potentially damaging human activity such as fishing and prospecting. The research team found that the number of young corals doubled in areas where parrotfish and other native fish were protected by a fishing ban. They concluded that the reserve enabled young corals to survive exceptionally well because algae and seaweed, which often prevent coral from taking hold and growing on rocks and existing reefs, were controlled by grazing parrotfish.
"We know that if you stop killing fish you'll end up with more fish, but what hasn't been clear is what the ecological effects are of having more fish in a reef system," said Dr. Brumbaugh, a Senior Conservation Scientist at the CBC. "Some have worried that protecting too many predators would result in a decline in herbivores, which would subsequently cause an increase in algal cover. We've seen that you actually get less algae because there are enough herbivorous species like parrotfish to keep it in check despite the presence of more predators. This shows that not only is a marine reserve good for fishes, it's also good for corals."
To verify their conclusions, the team, which also included Katherine Holmes, a Biodiversity Specialist at the CBC, as well as scientists from Exeter; the University of California, Santa Barbara; Stanford University; the Perry Institute for Marine Science; the University of Miami; and the University of Sheffield, also tested their data against four other hypotheses. These included the possibility that nearby stands of parent coral were increasing the number of larva in the study area or that reef surface features, predator populations, or local circulation patterns were somehow promoting the survival rate of young coral in the park. After further analysis, the research team rejected each of these as an explanation of the effects they saw and that they ultimately ascribed to increases in populations of parrotfish.
"This is the first evidence we have that marine reserves benefit coral," said Peter Mumby, a professor in the Marine Spatial Ecology Lab at the University of Exeter and lead author on the paper. "Coral reefs are unique ecosystems that have supported thousands of fish and other marine species for millions of years. We estimate that humans have already destroyed around 30 percent of the world's coral reefs and climate change is now causing further damage to coral. These findings illustrate the need to maintain high levels of parrotfish on reefs in order to give corals a fighting chance of recovering."
The study was supported by grants from the National Science Foundation, the National Oceanic and Atmospheric Administration, the Environmental Protection Agency, The Royal Society, the Natural Environment Research Council, and the National Fish and Wildlife Foundation, and received additional support from the Bahamas Department of Marine Resources and the Bahamas National Trust.
Bahamas Biocomplexity Project (BBP)
The BBP is funded in part by a $2.5 million Biocomplexity in the Environment grant from the National Science Foundation (NSF) and is headed by Dr. Brumbaugh at the CBC. Scientists from the College of The Bahamas; the Perry Institute for Marine Science; Resources for the Future; Stanford University; the University of Arizona; the University of California, Davis; the University of Exeter; and the University of Miami are focusing their research efforts on coral marine ecosystems in The Bahamas, an archipelagic nation of hundreds of islands. The research team is trying to understand, through observation and modeling, how a network of ecologically connected and expanding marine reserves affect biodiversity, fisheries, and human welfare inside and outside the reserves. In addition to containing tremendous biodiversity, coral reefs throughout the Caribbean support local fisheries and important tourist industries. BBP researchers are building statistical and theoretical models of the natural and human processes that can influence the conservation and economic functions of a network of reserves and protected areas. Their research will both help to support decision-making in The Bahamas as well as provide new underpinnings to the science of conserving coral reef ecosystems worldwide. In 2000, the Bahamian government declared its intention to protect 20 percent of its marine environment within an ecologically connected network of marine protected areas, and is currently in the process of implementing five new reserves. At the same time, the Bahamas National Trust, a nongovernmental organization that manages the country's national park system, is in the process of enhancing management of its system of marine parks, including the ECLSP. This setting provides the real-world management context for the BBP's interdisciplinary efforts to synthesize theories, methods, and data from oceanography, marine ecology, population genetics, anthropology, and economics, as the researchers address important questions about the design of effective marine reserve networks.
Media Inquiries: Department of Communications, 212-769-5800