Report in BioScience details global decline of nonmarine mollusks

04/02/04

Experts find multiple threats and many extinctions

In the April, 2004, issue of BioScience, a team of 16 experts from around the world report on the diversity and plight of what may be the world's most endangered group of animals – nonmarine mollusks (that is, terrestrial and freshwater mollusks). The World Conservation Union lists in the IUCN Red List of Threatened Species a total of 1,930 threatened nonmarine mollusks, which is nearly half the number of all known amphibian species, more than twice the number of shark and ray species, and nearly seven times the number of turtle species.

Furthermore, nonmarine mollusks have the dubious honor of having the highest number of documented extinctions of any major taxonomic group. A staggering 42% of the 693 recorded extinctions of all animal species since the year 1500 are mollusks (260 gastropods and 31 bivalves).

Regrettably, nonmarine molluscan extinctions go largely unnoticed by the general public, most biologists, and many conservation agencies, which focus their resources and energy on more charismatic vertebrate species. The extraordinary decline of nonmarine mollusks is due directly to habitat destruction and disruption of natural ecosystem processes. As an integral component of healthy ecosystems, molluscan diversity is valuable both for its own sake and as an indicator of conditions that may affect other species, including our own.

Nonmarine mollusks are members of the second most diverse group of animals, the phylum Mollusca, which includes snails, slugs, clams, mussels and others. There are approximately 24,000 terrestrial and 7,000 freshwater mollusk species for which valid descriptions exist. There are probably 11,000 to 40,000 undescribed terrestrial species and 3,000 to 10,000 undescribed freshwater species. Even the lower estimates exceed the number of all known species of birds, and the higher figures exceed the number of all known species of vertebrates.

Journalists may obtain copies of the article by contacting Donna Royston, AIBS communications representative, or Charles Lydeard of the University of Alabama, lead author of the article.

Source: Eurekalert & others

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