Pacific Mangrove Forests Vulnerable to Rising Sea Levels

APIA, Samoa, July 21, 2006 (ENS) - Rising sea levels linked with climate change are predicted to drown large areas of mangroves that line the shores of Pacific island nations. Mangrove forests provide shoreline protection by reducing wave energy, they act to filter coastal pollution, and the long underwater roots of the salt-loving trees shelter fish nurseries.

Some islands in the Pacific region could lose more than half of their mangroves by the end of the century and overall as much as 13 percent of the Pacific mangrove area may be lost, according to new research released by the United Nations Environment Programme (UNEP) on Tuesday.

Achim Steiner, UNEP’s executive director, said, "There are many compelling reasons for fighting climate change - the threats to mangroves in the Pacific, and by inference across other low lying parts of the tropics, underline yet another reason to act."

The study, "Pacific Island Mangroves in a Changing Climate and Rising Seas," assessed the vulnerability of the 16 Pacific Island countries and territories that have native mangroves. It finds that American Samoa, Fiji, Tuvalu, and the Federated States of Micronesia are likely to lose the most mangroves.

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Mangrove forest at Kosrae Village Dive and Eco Adventure Resort on Kosrae Island, Micronesia (Photo courtesy Kosrae Village)
To cope with rising sea levels, Steiner urged industrialized nations to meet their commitments under the Kyoto Protocol, which requires that 35 developed nations cut their greenhouse gas emissions an average of 5.2 percent by 2012.

Greenhouse gases trap the Sun's rays close to the Earth, raising the planetary temperature. As polar ice caps and glaciers melt, sea levels around the world are rising.

There is "an urgent need to help vulnerable communities adapt to the sea level rise which is already underway," Steiner said.

The report was compiled by UNEP's Regional Seas Programme, the Secretariat of the Pacific Regional Environment Programme (SPREP) based in Apia, the Western Pacific Regional Fishery Management Council in Honolulu, and more than a dozen additional agencies and organizations from the Pacific Islands region.

Lead author Eric Gilman of the University of Tasmania said, "The report not only spells out the threats, but also identifies national and regional priority needs for technical and institutional capacity building."

The report offers elements of site-specific strategies that managers of coastal zones can implement to minimize and offset anticipated mangrove losses from climate change.

"These focus on community-based approaches and integrated coastal zone management as well as increased public awareness and outreach," Gilman said.

Pollution from land-based sources can be reduced in order to make existing mangroves more healthy and resilient, the report recommends.

Author Vainuupo Jungblut works with SPREP as associate Ramsar officer, facilitating protection for Pacific Islands wetlands of international importance under the Ramsar Convention on Wetlands.

"One of the major challenges the Pacific Islands region faces is climate change and sea level rise, and adjusting to the responses of coastal ecosystems to these forces," Jungblut said. "The challenge for the region is to implement appropriate and affordable adaptation measures with limited resources."

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Mangroves along a tidal stream on the Pacific island of Kiribati (Photo by Richard Mieremet courtesy NOAA)
Lost and degraded mangrove wetlands can be restored, the report's authors suggest, and coastal development can be set back to allow mangroves to spread inland along some sections of Pacific island coastlines.

Kitty Simonds, executive director of the Western Pacific Regional Fishery Management Council, said, "Mangrove wetlands’ functional links with other coastal ecosystems and their important contribution to near shore fisheries production make it critical for Pacific Island governments and local communities to act now to ensure the sustainable provision of mangrove ecosystem services."

The health of mangroves affects the health of other economically and biologically important ecosystems, including coral reefs and seagrass beds.

Mangroves are important sources of timber and construction materials for local communities. Pacific islanders also harvest dyes from mangroves to treat textiles, nets and fish traps.

According to some estimates, the goods and services generated by mangroves may be worth an average of $900,000 per square kilometer, depending on their location and uses.

Studies in Thailand put the figure at up to $3.5 million per square kilometer and in American Samoa at just over $100,000 per square kilometer.

The report estimates that 75 percent of commercially caught prawns in Queensland, Australia, depend on mangroves.

The water-dependent trees are valuable in Matang, Malaysia, where a 400 square kilometer managed mangrove forest supports a fishery worth $100 million a year. Forestry products from the Matang mangroves are worth $10 million annually, it is estimated.

Roughly half the world’s mangrove area has been lost since 1900 as a result of clearances for developments like shrimp farms, and 35 percent of this loss has occurred in the past 20 years.

Author Hanneke Van Lavieren of UNEP’s Regional Seas Programme said, "The 2002 World Summit on Sustainable Development set an ambitious target - to achieve a significant reduction in the current rate of loss of biodiversity by 2010 - as one contribution to fighting poverty and delivering prosperity. We hope this new report and its recommendations on mangroves and climate change can play its part towards achieving the biodiversity goal in the Pacific."

The report "Pacific Island Mangroves in a Changing Climate and Rising Seas" is online at: www.unep.org.