The estimation of secondary production in a natural population of Daphnia hyalina (Leydig) using alternative methods of computation

Abstract

A single set of population data for Daphnia hyalina was used to estimate production using four methods on a daily and annual basis . Estimates varied from 12 .94 to 50 .60 g dry weight m-2 y-1 . The differences obtained are attributed to faults in the method such as the ignoring of post embryonic development times and poor estimates of basic variables used for the calculations . The latter include poor estimations of specific parts of the population census, particularly egg estimates, and choice of values used for weight estimates and duration times of stages . The normally used birth rate model probably underestimates production whereas the growth increment method probably overestimates production .

Seasonality, population dynamics and production of planktonic rotifers in Lough Neagh, Northern Ireland

“…An additional problem seen in this area is the occurrence of negative death rates. Apparently nonsensical, because theoretically values of d' cannot become negative, their regular appearance here and in other zooplankton populations suggests an inadequacy of the model (Andrew, 1983;Bosch & Ringleberg, 1985). Bosch & Ringleberg (1985) attribute negative death rates, to understand values of b', caused by diurnal variations of the egg ratios -an effect that could be important when embryonic development times are very short or the water column is highly stratified and compartments remain unsampled.…”

Population dynamics and estimation of production in Bosmina longirostris (O. F. Müller) in the River Danube (Danubialia Hungarica, CVIII)

“…4), which is now written as b Taylor = b em (b DP) N,, N T = turnover time There is no agreement on the method of its estimation. Some persons calculate it as the reciprocal of finite birth rate, while others use the reciprocal of the P/B values obtained from production estimations with the growth increment method (Edmonson & Winberg, 1971;Andrew, 1983). In the present paper, the reciprocal of the instantaneous birth rate is adopted (Kwik & Carter, 1975;Romanovsky & Polishchuk, 1982).…”

Growth rates of natural tintinnid populations in Narragansett Bay

“…Numerous techniques have been proposed to deal with the problem of continuously breeding populations, the most common being application of laboratory-derived growth rate data to population estimates (Uye et al 1983), the population dynamics method (Durbin & Durbin 1981), and the use of such physiological measures as production/biomass (P/B) ratios (Tremblay & Roff 1983). Each approach is limited by the validity of inherent assumptions and the accuracy of basic growth variables and demographic statistics (Edmondson 1974, Andrew 1983. Large volume containment studies (Beers et al 1977) eliminate many census problems, but are expensive and labor-intensive.…”