KOLLAM: Several among the 70 known species of mangroves are at high risk of extinction and may disappear well before the next decade if protective measures are not enforced, warns the first global study by U.S. researchers.

Eleven of these have been placed on the red list of threatened species kept by the International Union for Conservation of Nature (IUCN).

The study, led by Beth A. Polidoro attached to the Global Marine Species Assessment unit based at Old Dominion University, Virginia, shows that about 80 per cent of the mangrove areas in India and Southeast Asia have been lost over the past 60 years.

In India alone, over 40 per cent of the mangrove area on the west coast has been destroyed for aquaculture, agriculture, coastal development and urban development.

Disappearing at 2%-8%

The global mangrove area loss since 1980 stands at between 20 and 35 per cent. The areas are disappearing at 2-8 per cent per year and the rates are expected to continue unless mangrove forests are protected as a valuable resource, says the study recently published in PloS One, journal published by the Public Library of Science.

In addition, 40 per cent of the animal species that are restricted to mangrove habitat are at an elevated risk of extinction due to extensive habitat loss.

Given the accelerating rate of loss, mangrove forests may at least functionally disappear in around 100 years, the study states.

Mangrove forests are the economic foundations of many tropical regions providing at least $1.6 billion per year in ecosystem services worldwide.

It is also estimated that almost 80 per cent of the global fish catches are directly or indirectly dependent on mangroves. These are provided by mangroves, occupying only 0.12 per cent of the world's total land area.

Implementation of conservation plans for mangroves have largely been done in the absence of species-specific information, says the study. Tree felling, aquaculture and overexploitation of fisheries in mangrove areas are expected to be the greatest threats to mangrove species over the next 10-15 years.

Unlike other forests, mangrove forests consist of a relatively few species with 30-40 in the most diverse sites. Another big threat to mangroves is climate change, says the study.