More than 40 percent of a sample of amphibians, reptiles, mammals, and birds that are restricted to mangrove ecosystems are globally threatened with extinction, according to an assessment published in the July/August issue of BioScience. The study, by David A. Luther of the University of Maryland and Russell Greenberg of the Smithsonian Migratory Bird Center, was based on an extensive literature search and expert consultations. The conclusions emphasize the vulnerability of animals that are dependent on a habitat rapidly being lost or degraded through coastal development, overexploitation, pollution, and changes in sea level and salinity.
Mangroves, which are salt-tolerant woody plants concentrated along coastal margins, generally in warm regions, have long been known to support many species of animals. Hundreds of vertebrates are sometimes found in mangroves, but Luther and Greenberg concentrated on the 69 terrestrial vertebrate species and subspecies that seem restricted to mangroves: 48 birds, 14 reptiles, 6 mammals, and 1 amphibian. These include several species with striking adaptations, such as specialized glands to excrete salt. The ground foragers among them feed primarily on crabs, but many of the birds feed on insects. For unclear reasons, mangrove-restricted species and subspecies are concentrated in Asia and Australia.
Between the early 1980s and 2001, between 19 and 35 percent of the world's mangrove forest area was lost. At this rate of loss--about 2 percent each year--mangroves could be extinct in 100 years. Only 27 of the terrestrial vertebrates that are dependent on mangroves have been assessed by the IUCN (International Union for the Conservation of Nature), and 13 of those are classified as threatened on the IUCN Red List, Luther and Greenberg report. They urge research aimed at predicting how continuing changes to mangrove forests are likely to affect the species found there: such information could guide attempts to conserve these specialized ecosystems.
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BioScience, published 11 times per year, is the journal of the American Institute of Biological Sciences (AIBS). BioScience publishes commentary and peer-reviewed articles covering a wide range of biological fields, with a focus on "Organisms from Molecules to the Environment." The journal has been published since 1964. AIBS is an umbrella organization for professional scientific societies and organizations that are involved with biology. It represents some 200 member societies and organizations with a combined membership of about 250,000.
The complete list of research articles in the July/August 2009 issue of BioScience is as follows:
Modern Molecular Methods for Amphibian Conservation.
Andrew Storfer, Jonathan M. Eastman, and Stephen F. Spear
Genes in Streams: Using DNA to Understand the Movement of Freshwater Fauna and Their Riverine Habitat.
Jane M. Hughes, Daniel J. Schmidt, and Debra S. Finn
The Activities and Importance of International Field Stations.
Richard L. Wyman, Eugene Wallensky, and Mark Baine
A Burning Story: The Role of Fire in the History of Life.
Juli G. Pausas and Jon E. Keeley
Mangroves: A Global Perspective on the Evolution and Conservation of Their Terrestrial Vertebrates.
David A. Luther and Russell Greenberg
Data-intensive Science: A New Paradigm for Biodiversity Studies.
Steve Kelling, Wesley M. Hochachka, Daniel Fink, Mirek Riedewald, Rich Caruana, Grant Ballard, and Giles Hooker