By Cat Lazaroff
SAN FRANCISCO, California, February 22, 2001 (ENS) - There is now compelling scientific evidence that marine reserves conserve both biodiversity and fisheries, and could help to replenish the seas, says a scientific consensus statement signed by 150 of the world's leading marine scientists. The statement was released this week at the annual American Association for the Advancement of Science (AAAS) meeting.
"Dying coral reefs, toxic algal blooms, massive fish kills and the collapse of fisheries are symptoms of fundamental changes in ocean life that are caused, in part, by overfishing," said Stephen Palumbi of Harvard University. "Overfishing, pushed by a hungry world's demand for seafood, has moved species of fish toward extinction and permanent marine parks may be the only answer to save them." "All around the world there are different experiences, but the basic message is the same: marine reserves work, and they work fast," agreed past AAAS president Dr. Jane Lubchenco. "It is no longer a question of whether to set aside fully protected areas in the ocean, but where to establish them. We urge the immediate application of fully protected marine reserves as a central oceans management tool."
Lubchenco is co-chair of the National Center for Ecological Analysis and Synthesis (NCEAS), a federally funded think tank on questions of ecology, based at the University of California, Santa Barbara. The new scientific theory of marine reserves presented at the meeting is the culmination of three years of study by an international group of leading marine scientists working through NCEAS.
At the 1997 AAAS meeting in Seattle, Washington, scientists reviewed the state of the oceans and identified research priorities. In response, an international team of scientists was established at NCEAS, and charged with developing a better scientific understanding of marine reserves. This new analysis now provides the scientific evidence necessary to establish additional reserves that scientists can be confident will work.
The declining state of the oceans and the collapse of many fisheries creates a critical need for more effective management of marine biodiversity, populations of exploited species and the overall health of the oceans, marine scientists believe. While marine protected areas (MPA's) and Marine Sanctuaries have been designated to enhance conservation, they often allow activities such as fishing and mining, whereas marine reserves do not.
Population densities were on average 91 percent higher than those outside reserves biomass was 192 percent higher average organism size was 31 percent higher species diversity was 23 percent higher "The results are startling and consistent," said Dr. Robert Warner of the University of California, Santa Barbara. "We now have strong evidence that reserves work. Within and around marine parks, fish population doubles, fish size grows by 30 percent and reproduction triples."
"Furthermore, it all happens within two to four years and it lasts for decades," Warner said.
The size and abundance of exploited species also increases in areas adjacent to reserves, the study found. Reserves serve as natural hatcheries, replenishing populations throughout the region as young fish and other species spill over beyond reserve boundaries. Dr. Callum Roberts of Harvard University has worked closely with fishers around the world and cited numerous case studies of successful marine reserves. In New Zealand, despite violent opposition at the outset, fishers have now become the champions of reserves where they have seen populations of snappers increase 40 fold.
In 1994, three large areas totaling 17,000 square kilometers in the Gulf of Maine were closed to all fishing methods that put groundfish at risk. Scallops flourished in the undisturbed habitat. Within five years their populations rebounded to nine to 14 times their density in fished areas.
Monitoring showed scallop fishers hugging the edge of the closed areas, benefiting from high catches as a result of adults and their offspring moving outside the reserves.
Marine reserves differ from parks on land because most marine species disperse through the water as larvae or spores, moved by tides and currents. Dispersal distances of 20 to 50 kilometers are not uncommon and 500 to 1000 kilometers is possible in some cases due to currents.
"You want to design reserves so that they have a spillover effect in helping replenish the ocean beyond the protected area," said Dr. Steve Palumbi of Harvard University. "Well designed networks are the key." Using new knowledge of larval dispersal patterns, scientists can determine the optimal span, spacing and size of the reserves. The NCEAS studies demonstrate that networks of fully protected marine reserves linked both ecologically, through larval dispersal, and physically, through ocean currents, are much more likely to achieve the full array of benefits that marine resource managers are being called upon to deliver.
Single isolated reserves, which have been favored by resource managers in the past, are much less likely to provide meaningful protections, the researchers concluded.
The scientists also presented a new computer based tool that can map and design reserve systems for fishery managers across the U.S. and the world. Fisheries managers will be able to map out reserves based on specific conservation goals such as how representation of 20 percent of all habitats might translate in the water in ways that make stakeholders happy.
This new technology has the potential to revolutionize the design of future protected areas, as in the Channel Islands where it is being applied in efforts to establish fully protected marine zones.
Staghorn corals in the Florida Keys National Marine Sanctuary. Pollution leaking from septic tanks and nutrients in runoff from the Florida mainland have reduced corals in this marine protected area in recent years. (Photo courtesy Marine Conservation Biology Institute) Yet even with the new scientific consensus emerging, the future of reserves in the U.S. is uncertain. Questions about the efficacy of marine reserves are being raised again by the new administration in response to former President Bill Clinton's executive order directing federal and state agencies to work together to develop a national system of marine protected areas (MPAs). The new science should allay concerns voiced in a letter to President George W. Bush by the new chair of the Senate Resources Committee, Utah Republican James Hansen, the scientists said.
"No goals or purposes of the MPA for a system of MPA's have been identified; and no research has been identified to determine whether the goals of MPAs are being achieved," Hansen wrote. "MPAs must be done in a scientifically defensible manner."
"Conservationists can be reassured that marine reserves are protecting biodiversity, and while fishermen may lose access to some areas, they will reap the benefits outside the reserves," said Dr. Lubchenco. "The overall lesson is that all stakeholders can be served by well designed networks of marine reserves."