SNAILS AS BIOLOGICAL MONITOR (BIOINDICATOR)

A biological monitor reveals the qualitative status of the environment that are present in many water bodies can be monitored for biochemical or behavioural changes that may indicate a problem within their ecosystem. Bioindicators can tell us about the cumulative effects of different pollutants in the ecosystem. Due to their ubiquitous distribution and enormous species number, molluscs play important ecological roles in the different aquatic and terrestrial ecosystems of the world. They provide key species for ecosystem functioning because they contribute to huge amounts of the biomass on the different trophic levels in ecosystems. Gastropods represent the only molluscan class in terrestrial ecosystems and consequently, snails are the only molluscs which can be used for bioindication and biomonitoring purposes in these environments. Most species of the snails play a dominant role in the fresh waters by providing food for other organisms like fish and improve water quality by consuming large quantities of detritus and algae. The heavy metal accumulates in the body of the soft parts of the animal, as well as in the shell Gastropoda. Bioaccumulation of heavy metals by gastropods are influenced by environmental factors such as water flow, water availability, pH, sediment, salinity, and other.