MEPS 154:155-165 (1997)  -  doi:10.3354/meps154155

Are in situ weight-specific growth rates body-size independent in marine planktonic copepods? A re-analysis of the global syntheses and a new empirical model

Hirst AG, Sheader M

The dependency of in situ weight-specific growth rates of marine copepods upon individual body size (weight) was examined by compiling literature values. Two predictive models were compared to the compiled values, one in which weight-specific growth rate of individuals is dependent upon body size and temperature, and another in which weight-specific growth rate is dependent upon temperature but independent of individual body size. By comparing predictions from the models with the compiled values, it is shown that the former model is a better predictor of weight-specific growth rates for marine copepods under most conditions. Temperature and body weight are of influence upon weight-specific growth 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 weight-specific fecundity and juvenile weight-specific growth are considered together, while the significant relationships give b values of 0.706 and 0.739 when juvenile growth was considered alone. These are similar to those describing other metabolic rates. No significant relationship 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 egg 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 rates of copepods from body weight and temperature. Given that many meso- and macrozooplankton samples are dominated by copepods, it is suggested that this equation may be the most appropriate for estimation of growth and production for suites of such organisms when there is a lack of growth rate data available.

Copepods · Weight-specific growth · Weight-specific fecundity · Allometry · Temperature · Generation time

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