Tuesday, June 29, 2010

Long-ignored freshwater molluscs in Cuba under threat

Long-ignored freshwater molluscs in Cuba under threat
Jeremy Hance
June 28, 2010

Among biologists, Cuba is famous for its diversity of molluscs with some
3,000 species, including the fact that over 90 percent of its land
snails live no-were else. Given this, it's not surprising that Cuba is
known as the 'paradise of malacologists' (scientists who study
molluscs). However, one type of mollusc has been largely ignored in
Cuba: freshwater. A new study in Tropical Conservation Science hopes to
remedy that.

According to the study there are 42 known species of freshwater
molluscs. Although the percentage of endemic freshwater molluscs
(occurring only in Cuba) is not nearly as high as its land snails, it is
still considerable. Ten species are only found in Cuba, or nearly a
quarter. Yet the study found that a number of these molluscs are in need
of protection.

"With the exception of some highly charismatic species of land snails,
such as those of the genus Polymita and Liguus, no other species of
molluscs are taken into consideration when selecting a protected area or
delimiting its borders," the authors write.

Currently, 24 of Cuba's freshwater molluscs are found in the nation's
over 200 protected areas, leaving 18 unprotected. Three of these are
only found in Cuba: Nanivitrea alcaldei, Nanivitrea helicoides, and
Pachychilus nigratus. In addition, there are already concerns that the
Nanivitrea species may have gone extinct.

"Biodiversity conservation and managing are key activities for the
health and existence of many ecosystems. However, mammals, birds or
reptiles receive most of the attention, leaving molluscs and other taxa
in a category that we might call neglected," the authors write.

Molluscs are threatened by loss of habitat, tourism construction, and
alien species. A rising population in Cuba means that many water areas,
once habitat for molluscs, have been turned to provide water to a
thirsty growing population. In addition, invasive species like thiarids
snails are linked to some population declines of endemic molluscs by
out-competing native species for food.

Saving local molluscs species, according to the authors, could lead to
important benefits for Cuban society.

"The preservation of the Cuban endemic freshwater molluscs will not only
help to sustain ecosystem functioning, but could also have an important
impact on public health. Many of the introduced species of molluscs are
usually considered as intermediary hosts of parasites responsible for
some tropical diseases. These opportunistic species can establish
themselves in disturbed ecosystems, reaching high densities in a short
period of time. However, some of the endemic species may serve as
biological control agents, which could outcompete the exotic molluscs
and prevent their successful establishment if the natural habitat
remains unaltered."


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