Temperature-dependent development in Pseudocalanus species

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Abstract
The duration of embryonic development and that of well-fed older stages were determined for Pseudocalanus acuspes, P. minutus, P. moultoni, and P. newmani. Excluding abnormal individuals, the times for older stages were lognormally distributed, with similar variances among species, stages, and temperatures. Some residual variance occurred among families reared together. Copepod rearings should take these sources of variance into account. Development times (D) were described well by Bělehrádek's temperature (T) function, D = a(T − α)−b, with b = 2.05 for all species from previous studies, and α and a fitted for embryonic development. Only a needed to be fitted for older stages (i.e., "equiproportional" development). Relative times to given stages at all temperatures (i.e., relative values of a) were similar in three species, but P. minutus deviated from this pattern. Values of α were directly related to presumed environmental temperatures in the species' ranges. Values of a were directly related to egg and body sizes of the different species. The temperature functions can be used to predict the lengths of the generations in these four species in nature when food is adequate.