Effects of water column depth and sediment base area on the bioturbation efficacy of freshwater operculate snails

The bioturbation potential of three freshwater operculate snails, Filopaludina bengalensis, Gabbia orcula and Melanoides tuberculata, was compared, using water column depth and sediment surface area as the explanatory variables. Assessment of nutrient fluxes from sediment to overlying water was estimated in glass microcosms, that varied in height (tall, medium, short) and base (narrow, wide), resulting in six habitat conditions. In course of movement and grazing, all the three snail species modified surface architecture of the sediment. Besides, the snails modulated NOX ˉ (NO2 ˉ-N + NO3 ˉ-N), NH4+-N and PO43--P concentrations and other parameters (TDS, conductivity) of the water column in significantly varying proportions. Snail-induced changes in the rate of nutrient flux were highest for F. bengalensis. Periphytic chlorophyll-a concentration was reduced in all snail-treated microcosms compared to the control. Grazing, scraping and movement of snails on sediment facilitated the release of the nutrients in a species-specific manner depending on sediment surface area and water column depth of the microcosm. Apparently, snails may be useful in mobilizing the sediment content in freshwater lakes and ponds, facilitating ecosystem processes.

Automated summary

By comparing the bioturbation potential of three freshwater operculate snails, it was found that snails can modify the surface architecture of sediment, regulate nutrient concentrations in the water column, and release nutrients under different conditions. The grazing and movement of snails contribute to ecosystem processes in freshwater lakes and ponds.