Seasonal Estimation in Primary Productivity of Akilpur Lake in Dighwara, Saran (Bihar)

Abstract

The phytoplankton primary productivity forms the basis of the ecosystem functioning as it makes the chemical energy and organic matter available to the entire biological community. The primary productivity and its regulating factors were studied in Rasalpura pod during April 2019 to March 2021. Primary productivity of the pond was analyzed by light and dark bottle method introduced by Gardner and Grant (1927). The seasonal variation in primary productivity showed an increasing trend from 1.22±0.81 mg/l/hr then 1.99±0.65 mg/l/hr to 2.48±0.98 mg/l/hr in the monsoon, winter and summer season respectively. Investigation confirms the several variations do markedly affect pond productivity. The higher value of GPP and NPP during the summer season was due to penetration of more light intensity, suitable temperature, phytoplankton abundance which favors higher rate of photosynthesis and ultimately the pond productivity. The P/R ratio is an excellent functional index of the relative maturity of the system. The P/R ratio was highest during winter and lowest during summer season. The P/R≥1 value was observed during winter. During the monsoon, this ratio≤1 which could be on account less penetration of light into the water due to increased sediments resulting in lesser photosynthetic activity and thereby increase in productivity. Standing stock of phytoplankton is related to productivity which justifies its use as an index. Phytoplankton community and gross production showed significant relation at the sampling sites.