A 14-year study by the Wildlife Conservation Society in an atoll reef lagoon in Glover's Reef, Belize has found that fishing closures there produce encouraging increases in populations of predatory fish species. However, such closures have resulted in only minimal increases in herbivorous fish, which feed on the algae that smother corals and inhibit reef recovery.
Conservationists are hopeful that Belize's nation-wide fishing ban on parrotfish -- an important herbivorous species (pictured here) -- may help degraded reef systems rebound. Credit: Wildlife Conservation Society
The findings will help WCS researchers in their search for new solutions to the problem of restoring Caribbean reefs damaged by fishing and climate change.
The study appears in an online version of Aquatic Conservation: Marine and Freshwater Ecosystems. The authors include: Tim McClanahan, N.A. Muthiga, and R.A. Coleman of the Wildlife Conservation Society.
Specifically, the fishing closures have resulted in the recovery of species such as barracuda, groupers, snappers, and other predatory fish. Herbivorous fish such as parrotfish and surgeonfish, however, managed only slight recoveries, along with a small amount of the herbivory needed to reduce erect algae and promote the growth of more hard corals. This modest recovery of herbivorous fish has not been sufficient in reversing the degradation of the reefs by algae that have overgrown the reef and replaced the coral that once occupied 75 percent, but now represent less than 20 percent, of the seafloor cover. The authors note that a recent national-level ban by the Belizean government on the fishing of parrotfish—a widespread herbivorous species—may be the key to reef recovery, provided that the fishing ban is enforced and met with compliance. WCS provided valuable data through its monitoring program at Glover's Reef to justify the landmark measure to protect reef grazers.
"The fishing ban in the fully protected portion of the lagoon was expected to result in an increase in predatory fish and—more importantly—herbivorous fish such as parrotfish that in turn reverse the degraded condition of algal dominance in this reef," said Dr. Tim McClanahan, lead author of the study and head of WCS's coral reef research and conservation program. "What happened was a recovery of predatory fish, but not of the herbivorous fish, a finding that is forcing us to come up with a more effective model of reef management and recovery. If the nation-wide ban on parrotfish is successful, then we can see if this type of large-scale management is the only effective solution for protecting coral reefs."
According to the authors, a number of factors could be contributing to the unpredicted responses of fishing closures, which considerably complicates the understanding of coral reef ecology and management. The complex web of species interactions may produce unexpected cascading effects because of underestimates in the possible responses to bans on fishing. Other possible reason: the size of the closure may be too small to produce the desired effect, or there may be a failure of compliance with fishers following the ban. The authors also mention that environmental factors such as oceanographic oscillations and warming waters complicate any attempt to establish cause-and-effect relationships in these systems, as they noted a loss in coral cover across the 1998 El Niño that killed many corals worldwide.
"It is encouraging to see the recovery of large predatory fish such as groupers and snappers under significant pressure elsewhere in Belize, but the lagging herbivorous fish is a warning that there is no single solution to coral reef conservation," said Dr. Caleb McClennen, Director of WCS's Marine Program. "While no-take zones are critical, more comprehensive ecosystem-based management is essential throughout the range of targeted species for long term recovery of the entire Meso-American Barrier Reef."
From Fiji to Kenya to Glover's Reef, Dr. Tim McClanahan's research examines the ecology, fisheries, climate change effects, and management of coral reefs at key sites throughout the world. This work has been supported by the John D. and Catherine T. MacArthur Foundation and The Tiffany & Co. Foundation. WCS wishes to acknowledge the Oak Foundation and The Summit Foundation for their generous support of this study and our marine conservation work throughout Belize.
John Delaney | EurekAlert!
Further reports about: > WCS
From the Arctic to the tropics: researchers present a unique database on Earth’s vegetation
20.11.2018 | Martin-Luther-Universität Halle-Wittenberg
Fading stripes in Southeast Asia: First insight into the ecology of an elusive and threatened rabbit
20.11.2018 | Forschungsverbund Berlin e.V.
Max Planck researchers revel the nano-structure of molecular trains and the reason for smooth transport in cellular antennas.
Moving around, sensing the extracellular environment, and signaling to other cells are important for a cell to function properly. Responsible for those tasks...
Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.
Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...
Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.
Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...
Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.
In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...
On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.
19.11.2018 | Event News
09.11.2018 | Event News
06.11.2018 | Event News
20.11.2018 | Life Sciences
20.11.2018 | Life Sciences
20.11.2018 | Physics and Astronomy