Investigation of Aquatic Macrophytes Preference by Macro-invertebrates and Comparison of Physico-chemical and Biological Parameters of Godapitiya and Kadawara Tanks in Southern Province.

Abstract

Macrophytes are very important component in lentic as well as lotic systems. Macro-invertebrates are directly influenced by macrophytes as they provide refuge and food for macro-invertebrates directly or indirectly. Macro-invertebrates macrophyte relationship has been studied extensively in terrestrial ecosystem, but for aquatic system it is much less. The study was based on the preference of macro invertebrates for different macrophytes in two fresh water bodies in southern province of Sri Lanka. Physico-chemical and Biological parameters were observed in three sites in each tank. Study was carried out for 6 months of period. As physico-chemical parameters Temperature, Depth, Light penetration. Conductivity, Dissolved Oxygen, Biological Oxygen Demand, Primary productivity, Salinity, Alkalinity, Nitrate concentration and Phosphate concentration were observed data was collected for each parameter. As biological parameters data on aquatic plant associated macro-invertebrates per unit area from different sections of particular aquatic macrophyte were collected. Mean comparison of physico-chemical parameters and Biological parameters were carried out by one-way ANOVA to compare each site and different aquatic plants. Abundances of macro-invertebrates of each site were determined by graphically. In Godapitiya tank dominantly found Olu and Kumudu. But in Kadawara tank, found Nelum, Hydrilla, Salvinia as well as Olu and Kumudu. Physico-chemical parameters proved that the Godapitiya tank was in a moderately polluted state. The “I graphical inspection of data was revealed that P0 4 concentration of Godapitiya tank was higher because the farmers use phosphate fertilizers into the surrounding paddy cultivation and eventually drain these substances into the tank by rain. Graphical investigation also revealed that the abundance of Chironomidae is much high in each sites in two tanks which alarming the pollution state of the Godapitiya tank. It was observed that family Chironomidae, Pyralidae and Baetidae mostly prefer leaves, while Dytiscidae prefer roots. Biological parameters indicated that aquatic macro-invertebrates were directly affected by the macrophytes. It can be concluded that different aquatic macro-invertebrates colonize in the unique sections in order to their needs.