Freshwater environments are some of the most fragile and highly threatened ecosystems in the world. These ecosystems have been constantly manipulated by humans to satisfy their needs with little or no thought to the long term effects on them (Kaufman 1992). Molluscs are an important group for freshwater biodiversity, and where abundant play an important role in ecosystem functioning (Vaughn et al. 2004). They form an important component of most biological monitoring programmes that rate water quality and status of aquatic systems based on invertebrate assemblages (Ponder 1994, Seddon 1998, Strong et al. 2008). Bivalves in particular, as they accumulate toxic substances to a greater extent than other organisms, are used to monitor water quality (Salanki et al. 2003). Molluscs show a great specialization of ecological niches in freshwater environments, making them more vulnerable to modifications in their environment (Bouchet 1992, Lydeard et al. 2004). Consequently, freshwater molluscs have suffered a severe decline in diversity, distribution and abundance due to human induced alteration of habitats, pollution, siltation, deforestation, poor agricultural practices, the destruction of riparian zones and invasion by introduced species (Biggins et al. 1995, Pimm et al. 1995). Non-marine molluscs, which includes land and freshwater molluscs, comprise the largest number of recorded extinctions in the last 300 years (Groombridge 1992). Hence, conservation efforts are urgently needed to maintain and recover these unique components of aquatic biodiversity.