ARE IN-SITU WEIGHT-SPECIFIC GROWTH-RATES BODY-SIZE INDEPENDENT IN MARINE PLANKTONIC COPEPODS - A REANALYSIS OF THE GLOBAL SYNTHESES AND A NEW EMPIRICAL-MODEL

The dependency of in situ weight-specific growth rates of marine copep ods upon individual body size (weight) was examined by compiling liter ature values. Two predictive models were compared to the compiled valu es, one in which weight-specific growth rate of individuals is depende nt upon body size and temperature, and another in which weight-specifi c growth rate is dependent upon temperature but independent of individ ual body size. By comparing predictions from the models with the compi led values, it is shown that the former model is a better predictor of weight-specific growth rates for marine copepods under most condition s. Temperature and body weight are of influence upon weight-specific g rowth rates for the whole data set (which includes adult, juvenile and mixed growth types), rates declining with increasing size. Allometric scaling coefficients of b = 0.581 to 0.737 were found when adult weig ht-specific fecundity and juvenile weight-specific growth are consider ed together, while the significant relationships give b values of 0.70 6 and 0.739 when juvenile growth was considered alone. These are simil ar to those describing other metabolic rates. No significant relations hip was found for weight-specific fecundity and body weight, although the data set was very Limited. Copepod generation times were shown to be weight dependent when compared to the combined geometric mean of eg g and adult weights rather than adult weight alone. By combining data from the literature, a new globally applicable empirical equation was constructed which allows predictions of the weight-specific growth rat es of copepods from body weight and temperature. Given that many meso- and macrozooplankton samples are dominated by copepods, it is suggest ed that this equation may be the most appropriate for estimation of gr owth and production for suites of such organisms when there is a lack of growth rate data available.