Assessment of Epilithic Microalgae along Longitudinal Gradient in Freshwater Bodies of South India

Epilithic microalgae are associated with hard substrates of freshwater environments and they play a vital role in primary production, nutrient cycling and contributing habitat for other organisms in aquatic environments. Thus, the present study was focused to assess the diversity and distributional pattern of epilithic microalgae along longitudinal gradient in lentic freshwater bodies, Tamil Nadu, India. Nine freshwater bodies (lakes, ponds and temple tanks) were examined in Madurai district. Microalgae were collected from submerged substrates of bedrock, boulders and pebbles in lentic waters. In total, 14 genera of microalgae were collected. Fragilaria was the highest percentage. The high diversity was observed in site 9 revealed by Shannon diversity index. Abundance of microalgae was high in lakes when compared to temple tanks and ponds. Of twelve environmental variables, total dissolved solids, conductivity and salinity were significant factors for the distribution of microalgae. This finding suggests that microalgae in lentic freshwater bodies are not influenced with longitudinal gradient whereas chemical parameters of water such as total dissolved solids, dissolved oxygen, electrical conductivity and salinity are the determining factors.