The Freshwater Mollusks of Mexico: Can We Still Prevent Their Silent Extinction?

Abstract

In this chapter, we provide an overview of the diversity of the Mexican freshwater mollusks (gastropods and bivalves). We outline their current status as one of the most imperiled group of animals in Mexico and we discuss necessary changes to stop their decline. The Mexican freshwater molluscan fauna is composed of 292 species, of which 195 are gastropods and 97 bivalves. Like many other aquatic invertebrates worldwide, members of both molluscan classes are rapidly declining in most regions of Mexico. These losses constitute a silent extinction during the Anthropocene resulting from water pollution, large diversions for irrigation of arid regions, hydropower production, and introductions of non-native species. The lack of historical data about molluscan distributions, especially of bivalves, makes it difficult to determine the full extent of these local and regional extinctions. However, a few case studies that include the methods of conservation paleobiology are used to show an alarming picture: the comparison of local sub-fossil records with recent data documents a dramatic loss of freshwater snail diversity of more than 80% in only a century. In light of this, it is becoming increasingly clear that current conservation efforts alone will not be enough to stop more extinctions. Climate change, especially increased frequency and intensity of regional drought, is known to decrease habitat quality. Dam removal along with more and larger protected areas and ecosystem restorations can reverse the trend of some of these potential species losses. We advocate a shift in consciousness so that natural scientific efforts are part of an integrated holistic solution that includes the ecological, economic, philosophical, and theological values for society.