Interaction between microalgal species richness and environmental variables in Peringalkuthu Reservoir, Western Ghats, Kerala.

Microalgae are the most diverse group of aquatic organisms and are the primary food source for animals of higher trophic levels in the aquatic food web. Biomonitoring the fresh water habitats in terms of phycological evaluation provide useful information about the pollution status of the water body. The present investigation aimed to delineate the interaction between microalgal species richness and environmental variables in Peringalkuthu Reservoir of Western Ghats, Kerala. Samples were collected during 2009-2011 for the analysis of environmental variables and microalgal community. Ninety four species of microalgae belonged to 42 genera under the classes Chlorophyceae, Desmidiaceae, Bacillariophyceae, Cyanophyceae and Euglenophycea were recorded from the samples. The dominant groups were desmids followed by diatoms. Factor analysis and multivariate analysis were applied to evaluate the extent of interaction between the microalgal species richness and the environmental variables. Temperature, total alkalinity, BOD, phosphate, silicate and chloride showed positive relationship with the species richness of the microalgae. While pH, total hardness, nitrate, fluoride, calcium and magnesium hinder the microalgal species richness. Elucidation of the interactions between microalgae and various environmental parameters suggested a control over the anthropogenic interventions to the reservoir to check the conversion of the lake oligotrophic to eutrophic condition.