Climate change threatens Pacific Ocean mangroves
August 7, 2006
Action is needed to conserve mangroves in the Pacific amid concern that rising sea levels, linked with climate change, are set to drown large areas of these precious and economically important ecosystems.
Studies, announced by the United Nations Environment Programme (UNEP), indicate that some islands in the region could see over half of the mangroves steadily lost by the end of the century, with the worst hit being American Samoa, Fiji, Tuvalu, and the Federated States of Micronesia.
The study, which has assessed the vulnerability of the 16 Pacific Island countries and territories that have native mangroves, finds that overall as much as 13 per cent of the mangrove area may be lost.
It makes a series of recommendations to coastal planners. These include reducing pollution from land-based sources in order to make existing mangroves more healthy and resilient, alongside restoring lost or degraded mangroves wetlands.
Setting back coastal infrastructure and development to allow mangroves to spread inland may also be possible along some sections of Pacific island coastlines, says the report.
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”.
“Industrialized nations must meet their commitments under the Kyoto Protocol, the international emission-reduction treaty, as a first step to the even deeper cuts needed to stabilize the atmosphere,” he added.
“But there is also an urgent need to help vulnerable communities adapt to the sea level rise which is already underway. This report provides sensible and sound advice on management regimes needed to boost the health and resilience of coastal zones and coastal ecosystems like mangroves in the face of current and future threats,” said Mr. Steiner.
The new report, Pacific Island Mangroves in a Changing Climate and Rising Seas [pdf file 2.4mb], has been compiled by the Regional Seas Programme of UNEP, the Secretariat of the Pacific Regional Environment Programme (SPREP) based in Apia, Samoa, the Western Pacific Regional Fishery Management Council in Honolulu, United States, and well over a dozen additional agencies and organizations from the Pacific Islands region.
Kitty Simonds, Executive Director of the Western Pacific Regional Fishery Management Council, explained, “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 Council has recently begun to replace its existing suite of Fishery Management Plans with integrated ecosystem-based plans for each island archipelago. The results and recommendations stemming from this study are contributing to the development of these new place-based Fishery Ecosystem Plans.”
The true economic value of ecosystems like mangroves is now starting to emerge as a result of landmark reports such as the Millennium Ecosystem Assessment, the work of some 1,300 scientists and experts.
Other recent assessments show that:
- Mangroves are important nurseries for fish, act to filter coastal pollution and 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.
- The health of mangroves also affects the health of other economically and biologically important ecosystems, including coral reefs and seagrass beds.
- Mangroves provide important shoreline protection. Wave energy may be reduced by 75 per cent during a wave’s passage through 200 metres of mangrove forest.
- 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.
- An estimated 75 per cent of commercially caught prawns in Queensland, Australia, depend on mangroves.
- A 400 square kilometer managed mangrove forests in Matang, Malaysia, 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. 35 per cent of this loss has occurred in the past two decades.
Eric Gilman of the University of Tasmania and the report’s lead author 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 also offers the elements of site-specific strategies that managers of coastal zones can implement to minimize and offset anticipated mangrove losses from climate change affects. These focus on community-based approaches and integrated coastal zone management as well as increased public awareness and outreach,” he added.