Mangroves Key to Health of Coral Reef Fisheries

WASHINGTON, DC, February 5, 2004 (ENS) - A strong and direct link exists between the number of fish on coral reefs and the health of nearby mangrove forests, according to a new study released today. Researchers say the finding is further evidence of the need to conserve mangrove forests, which are disappearing at a rate that alarms conservationists.

Mangrove forests once covered some 75 percent of the coastlines of tropical and sub-tropical countries, but some 35 percent of the world's mangroves are already gone. In the Americas mangrove forests are being cleared at a rate faster than the tropical rainforests.

The new study, published in the journal "Nature," finds coral reef fish twice as abundant at reefs with nearby healthy mangrove forests compared to reefs far from any mangroves.

The researchers measured 164 fish species at reefs in the Central American country of Belize.

Mangrove forests have been called the rainforests of the sea. (Photo courtesy United Nations Environment Program)

"There is nothing subtle about these numbers," said Dr. Peter Mumby, a researcher from the University of Exeter in England and the study's lead author. "This research shows a direct link between mangroves and the number of fish on coral reefs including several species of snapper that are heavily fished."

Mangrove forests are groves of salt tolerant marine trees that serve as the interface between land and sea, subject to the twice daily ebb and flow of the tides. They serve several key environmental roles, buffering against the effects of violent storms and filtering pollutants.

Mumby and his colleagues say their study adds to evidence that mangrove forests play a key role for many fish species, serving as a middle habitat between seagrass nurseries and the adult habitat of the reef.

Without mangroves, smaller fish are forced to seek shelter in reefs, where they are exposed to more predators.

The researchers say their study indicates the need for strong conservation efforts to protect mangroves forests, for economic as well as environmental reasons.

"There is a strong economic rationale for protecting mangroves since coral reef fisheries have an estimated annual value of $5.7 billion and many people also depend on them for subsistence," said Dr. Kenyon Lindeman, a co-author of the report and a senior scientist with Environmental Defense, a U.S. environmental research and advocacy organization.

For centuries mangrove forests were considered by many as useless swamps and many mangroves have been cleared to make way for development.

Many mangroves have been clearcut to make way for shrimp farms. (Photo courtesy Environmental Justice Foundation)

The authors say conservation efforts should include the creation of marine protected areas - a key issue at next week's meeting of the Convention of Biological Diversity.

The 11 day meeting, which marks the 10th anniversary of the global biodiversity agreement, begins February 9 in Kuala Lumpur, Malaysia.

"Networks of marine protected areas work for both people and fish," says Dr. Ghislaine Llewellyn, a marine scientist with World Wildlife Fund and a co-author of the report. "This study is yet more evidence that systems of marine parks are urgently needed to safeguard biodiversity and secure food resources."