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Study from ODU-based GMSA Finds Mangrove Forests in Decline Worldwide

Beth Polidoro

More than one in six mangrove species worldwide are in danger of extinction due to coastal development and other factors, including climate change, logging, and conversion for aquaculture, according to the first-ever global assessment on the conservation status of mangroves.

Mangrove experts worldwide worked together on the assessment with the Global Marine Species Assessment (GMSA), which is headquartered at Old Dominion University and led by marine biologist Kent Carpenter of the ODU faculty. GMSA is part of the Biodiversity Assessment Unit, a joint initiative of the International Union for Conservation of Nature (IUCN) and Conservation International.

The study appears in the current issue of the scientific journal PLoS ONE.

As a result of the findings, 11 out of 70 species studied will be placed on the IUCN Red List of Threatened Species™. The Atlantic and Pacific coasts of Central America, where as many as 40 percent of mangrove species are considered threatened, are particularly affected.

"The potential loss of these species is a symptom of widespread destruction and exploitation of mangrove forests," said Beth Polidoro, research associate of the GMSA at ODU and principal author of the study. "Mangroves form one of the most important tropical habitats that support many species, and their loss can affect marine and terrestrial biodiversity much more widely."

The primary threats to mangroves are habitat destruction and removal of mangrove areas for conversion to aquaculture, agriculture, urban and coastal development, and overexploitation for timber, said Polidoro. "Climate change is also considered a threat to all mangrove species, particularly along the edge of their habitat, where sea temperature and other environmental changes may be greatest."

Mangrove forests grow where saltwater meets the shore in tropical and subtropical regions, thus serving as an interface between terrestrial, fresh-water and marine ecosystems. These forests provide at least $1.6 billion each year in ecosystem services.

Mangroves protect coastal communities from damage caused by tsunami waves, erosion and storms, and serve as a nursery for fish and other species that support coastal livelihoods. In addition, they have a staggering ability to sequester carbon from the atmosphere, and serve as both a source and repository for nutrients and sediments for other inshore marine habitats, such as seagrass beds and coral reefs.

"The loss of mangroves will have devastating economic and environmental consequences," said Greg Stone, senior vice president of marine programs at Conservation International. "These ecosystems are not only a vital component in efforts to fight climate change, but they also protect some of the world's most vulnerable people from extreme weather and provide them with a source of food and income."

Urgent protection is needed for two mangrove species that are listed as Critically Endangered, the highest probability of extinction measured by the IUCN Red List, Sonneratia griffithii and Bruguiera hainesii.

Sonneratia griffithii is found in India and southeast Asia, where 80% all mangrove area has been lost over the past 60 years. Bruguiera hainesii is an even rarer species and grows only in a few fragmented locations in Indonesia, Malaysia, Thailand, Myanmar, Singapore and Papua New Guinea. It is estimated that there are fewer than 250 mature trees of the species remaining.

This article was posted on: April 9, 2010

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