Composition and Trophic categorization of aquatic insects in Sothuparai reservoir

Abstract

Aquatic insects are an indispensable part of the food web of nutrient cycle and it also a bioindicator in freshwater ecosystems. The use of aquatic insects as bioindicators provides data to estimate the degree of environmental impact and its potential effects on other living organisms. Sothuparai Dam enriches the entire area of Periyakulam that has an annual supply of surplus rainfall by monsoons that brings good quantum of water. The Sothuparai reservoir supplies water to the nearby villages of Periyakulam Taluk. Thus the present investigation was undertaken to study the ecological parameters and assessment of abiotic and biotic potential of the reservoir with special reference to aquatic insect diversity. Water and soil analysis was carried out every month in upstream and downstream of the Sothuparai Reservoir during June, 2013 to May, 2015. In the present investigation two sampling sites were selected for the study in Sothuparai Reservoir. The study Site 1 is located at 2km away from the reservoir and is towards the origin, called Upstream and Site 2 is located 2km away from the outlet of the reservoir, where the water runs through an irrigation canal and it is called Downstream. Water current, depth and width of the reservoir fluctuates seasonally and this was influenced by rainfall in the study area. Turbidity was high and it exceeded the standard permissible limit and it increased to five folds than the optimum range. TDS values were lower than the permissible limit. Electrical conductivity was found to be within the permissible limit in upstream and downstream of the reservoir. pH value of Sothuparai water samples were found to be 5.5 to 8.9 and the values were within the permissible limit as prescribed by EPA. The value of total alkalinity in Sothuparai reservoir water falls within the standard limit. Total hardness of the present investigation was much lower than the prescribed limit .Calcium and Magnesium concentration in Sothuparai reservoir was below the permissible limit.