WATER PRODUCTIVITY EVALUATION THROUGH MICROBIAL INDICES IN AQUATIC ECOSYSTEM

It is becoming more widely acknowledged that microbial indices are essential instruments for assessing water production in fisheries and aquaculture. These indicators represent the composition, dynamics, and role of microbial communities, which are critical to organic matter breakdown, nutrient cycling, and ecosystem health. Since the growth and health of aquatic creatures in aquaculture systems are directly impacted by the quality of the water, knowledge of microbiological factors is crucial for sustainable production. Heterotrophic Bacterial Count (HBC) and Total Bacterial Count (TBC) are important microbiological indices that provide information on the availability of organic materials and microbial biomass. Aquaculture waters' microbiological safety is evaluated by counting coliforms, especially total and faecal coliforms, which act as indicators of pollution. Microbial activity and nutrient turnover, which are essential for primary productivity and food web maintenance, are reflected in bacterial production rates and Microbial Biomass Carbon (MBC). Other significant indicators of microbial metabolic activity and ecosystem stress include the Biochemical Oxygen Demand (BOD), microbial respiration rate, and enzyme activities (such as urease and dehydrogenase). While nitrifying and denitrifying bacterial counts are used to evaluate nitrogen cycling efficiency, sophisticated indexes such as the Shannon-Weaver diversity index and Simpson's index offer a quantitative measure of microbial biodiversity. The energy efficiency of microbial communities is further revealed by the microbial quotient (qCO ). When taken as a whole, these indicators help evaluate the ecological balance, nutrient condition, and water quality of fishery habitats, wetlands, reservoirs, and aquaculture ponds. Aquaculture professionals can identify early indicators of eutrophication, pollution, or disease outbreaks and take prompt action by using microbiological indices. Furthermore, as compared to traditional physicochemical evaluations, these biological indicators are more economical and environmentally friendly instruments. This study provides a scientific basis for better aquaculture management and increased aquatic food security by highlighting the importance of microbial indices as essential elements of water productivity assessment.