Growth and development rates of the copepod Calanus finmarchicus reared in the laboratory

Development rates, nitrogen- and carbon-specific growth rates, size, and condition were determined for the copepod Calanus finmarchicus reared at 3 temperatures (4, 8, and 12 degreesC) at non-limiting food concentrations and 2 limiting food concentrations at 8 degreesC in the laboratory. Development rates were equiproportional, but not isochronal. Naupliar stage durations were similar, except for non-feeding stages, which were of short duration, and the first feeding stage, which was prolonged, while copepodite stage durations increased with increasing stage of development. Under limiting food concentrations at 8 degreesC, development rates were prolonged but similar relative patterns in stage durations were observed. Body size (length and weight) was inversely related to temperature and positively related to food concentration. Condition measurements were not affected by temperature, but were positively related to food concentration. Growth rates increased with increasing temperature and increased asymptotically with increasing food concentration. At high food concentrations, growth rates of naupliar stages were high (except for individuals molting from the final naupliar stage to the first copepodite stage, in which growth rates were depressed), while growth of copepodites decreased with increasing stage of development, Neither nitrogen nor carbon growth rates, the former a proxy for structural growth, were exponential over the entire life cycle, but rather sigmoidal. Carbon-specific growth rates were greater than nitrogen-specific growth rates, and this difference increased with increasing stage of development, reflecting an augmentation in lipid deposition in the older stages. However, nitrogen and carbon growth rates were more similar under food-limited conditions. Based on this study, we recommend that secondary production rates of Calanus finmarchicus and possibly other lipid-storing copepods not be estimated from egg production measurements alone, as has been suggested for other species of copepods, because growth, including structural growth, is not equivalent for all stages.