Population structure and some biological parameters of Daphnia similis, an important fish food organism

Abstract

Population structure of Daphnia similis was analysed in a local perennial pond at Kot-Bhalwal, Jammu for a period of one year (January –December, 2013). Throughout the experimental period, density of D. similis remained quite high (12-15 ind/ml) with a maxima recorded to be 30 ind/ml during March (temperature 21 °C) and minima recorded during August (5 ind/ml) and September (2 ind/ml). Physico-chemical parameters during the entire study were recorded to be well within the tolerable range of the species. Field observations, as authenticated by laboratory studies reveal the mean length (1.66 mm), mean brood size (19.1mm) to be maximum during spring as compared to extreme summers (June onwards) and winter (January) when the mean length, mean brood size and incubation period was recorded to be minimum.