The Loss of Species: Mangrove Extinction Risk and Geographic Areas of Global Concern

Abstract

Mangrove species are uniquely adapted to tropical and subtropical coasts, and although relatively low in number of species, mangrove forests provide at least US $1.6 billion each year in ecosystem services and support coastal livelihoods worldwide. Globally, mangrove areas are declining rapidly as they are cleared for coastal development and aquaculture and logged for timber and fuel production. Little is known about the effects of mangrove area loss on individual mangrove species and local or regional populations. To address this gap, species-specific information on global distribution, population status, life history traits, and major threats were compiled for each of the 70 known species of mangroves. Each species’ probability of extinction was assessed under the Categories and Criteria of the IUCN Red List of Threatened Species. Eleven of the 70 mangrove species (16%) are at elevated threat of extinction. Particular areas of geographical concern include the Atlantic and Pacific coasts of Central America, where as many as 40% of mangroves species present are threatened with extinction. Across the globe, mangrove species found primarily in the high intertidal and upstream estuarine zones, which often have specific freshwater requirements and patchy distributions, are the most threatened because they are often the first cleared for development of aquaculture and agriculture. The loss of mangrove species will have devastating economic and environmental consequences for coastal communities, especially in those areas with low mangrove diversity and high mangrove area or species loss. Several species at high risk of extinction may disappear well before the next decade if existing protective measures are not  enforced.

Download PDF: Polidoro et al. 2010a

In April 2010, Global Marine Species Assessment (GMSA) findings on the conservation status of the mangroves of the world were published in PLoS One, an open-access online journal published by the Public Library of Science. This 21-author manuscript, entitled “The loss of species: mangrove extinction risk and geographic areas of global concern,” highlights species-specific information on global distribution, population status, life history traits, and major threats that were compiled for each of the 70 known species of mangroves. Habitat destruction and removal of mangrove areas for aquaculture, agriculture, and coastal development threaten 16 percent of mangroves around the world.

Figure 1: A distribution map of the proportion of Threatened (Critically Endangered, Endangered, and Vulnerable) Mangrove Species worldwide.
Figure 1: A distribution map of the proportion of Threatened (Critically Endangered, Endangered, and Vulnerable) Mangrove Species worldwide.

With some exceptions, mangrove areas and species of concern are generally not adequately represented within protected areas. By identifying geographic areas with high proportions of threatened species, such as the Eastern Tropical Pacific, future conservation efforts can be concentrated in those areas where it is needed most. In addition to legislative actions, initiatives are needed on the part of governments, NGOs, and private individuals to acquire and protect privately owned parcels of coastal land, especially those that contain viable populations of threatened mangrove species.