Studies on Fish Fauna of Certain Lakes in Relation to Seasonal Variations of their Productivity

Water physico chemical parameters and planktons density are an essential factors for fish productivity. In Lake Jakaram have been studied through seasonal surveys in two years 2015-16 and 2016-17.The present study was aimed to assess the seasonal variation on physico-chemical parameters such as temperature, pH, alkalinity, dissolved oxygen, BOD and COD and their relationship with zooplankton and phytoplankton community. The seasonal variation of nutrients like nitrate, phosphate was recorded to determine the utilization of nutrients by phytoplankton in aquatic environment. The results revealed that physico chemical parameters showed significant difference among the seasons. The statistical analysis of physico-chemical parameter showed well-defined seasonal variation, relatively high temperature, high value of dissolved oxygen and highest production range of alkalinity were observed which are favourable factors for the production of air breathing fishes. The maximum of temperature was recorded during summer season it showed a significant inverse relationship with dissolved oxygen positive relationship with PH. Dissolved oxygen shows a negative relation with alkalinity, total hardness, nitrate, phosphate, chlorides. The correlation analysis exposed that physico-chemical parameter and nutrients are effective dynamics to control the seasonal variations on plankton diversity therefore the present study reveals that Lake Jakaram has rich in plant and community due to presence of high nutrient content and consisting appropriate environmental factor zooplanktons (species) in lake Jakaram during the study period holds a key position in the food web as it was directly related to the consumption of organic energy produced by phytoplanktonic photosynthesis and then by transforming it to the higher trophic levels of heterotrophs such as fish. Some Zoo plankton population was decreased due to unfavourable condition. Plankton diversity and physico- chemical parameters of water or important criteria for evaluating the suitability of water for culture practices. Therefore, structure of different fish food organisms assumes greater significance to fishery management. Seasonal variation of the plankton population of Jakaram Lake Mulugu district was carried out during June 2015 to may 2017 .phytoplankton density was slightly higher during summer. Chlorophyceae appeared as the dominant group of phytoplankton in Lake Jakaram during both the study years. During the first year of study period this group exhibited maximum density of (2851 org/L) followed by Gynophycea ( 1805 org/ L) Bacillariophyceae (2726 org/ l) and Euglenophyceae (416 org/ l). Similarly chlorophyceae also registered maximum density of (3168 org/l) during second year period followed by Gynophyceae( 1516 org/L) Bacillariophyceae (2687 org/ l),and euglenophyceae( 180 org/ l). Annual densities of zooplanktons during the first year copepoda appeared as dominant group of zooplanktons with higher density (7619 org/ l) during the first year of the study period followed by cladocera( 3775 org/ l) Rotifera (4230 org/ l) and ostracoda (2202 org/l). During the second year of the study period copepod again contributed maximum density (9547 org/l) followed by Rotifera (4614 org/ l) cladocera (3498 org/L and ostracoda (2226 org/L). The minimum number of zoo planktons and was recorded in the rainy. Phytoplankton and zooplanktons have a nominal positive relationship. Phytoplankton was increased or decreased with the relation with zooplanktons.