The production and respiration ecology of reservoir populations of zooplankton

Abstract

Field measurements of standing crop biomass and population numbers at weekly intervals and respiration rates of zooplankton at fortnightly intervals were determined in a London storage reservoir between January 1968 and June 1969. Biomass estimates fell within a range of 0.38 - 4.56 g dry weight.m for cladocerans and 0.08 - 2.66g.dry weight.m for copepods. Daphnia hyalina population numbers were highest in the spring, 601.35 x 10 .m in 1968 and 761.71 x 10 .m in 1969. Daily production rates were calculated to be between 0.0022 and 0.225gC.m .day and the annual production for 1968 was estimated at 12.70gC.m the main contribution coming from D. hyalina. Population respiration rates were between 2.35 and 27.28ug02.mg.dry weight 1. hr. -1 with the highest rates occurring in spring and autumn. A length weight relationship, growth rates of eggs and stages of life and respiration rates of D. hyalina were determined in the laboratory. These culture experiments at 10°C gave an egg duration rate of 7-10 days. Respiration determinations, measured by the Cartesian diver technique, were lower than the field measurements.