Effect of manuring rate on in situ production of zooplankton Daphnia carinata

Abstract

Using life history parameters as criteria, production of the cladoceran, Daphnia carinata was estimated in situ using seven different manure dosage treatments in quadruplicate. Doses of manures (cow manure, poultry manure, mustard oil cake = 1:1:1) increased in a two fold manner from 75 (12.5%) to 600 g (100%) every 16 days in four treatments, whereas, both dose and frequency of application varied to achieve a total dosage of 600 g every 16 days in the remainder of the treatments. Frequent application of low doses of manure (12.5% every 2 days or 25% every 4 days) resulted in significantly higher number and biomass of Daphnia than any of the treatments employed. This condition was attributed to the high primary productivity and favourable water quality and resulted in an increased growth rate, early reproduction, relatively long life span and more production of offspring. High dose treatment every 16 days showed the lowest population for all treatments. Minor food and/or water quality differences in treatments were well reflected in changes in life history characteristics of test cladocerans.