The dependence of body weight in copepodite stages of Pseudocalanus spp. on variations of ambient temperature and food concentration

Quantitative expressions are presented describing the effects of temperature and food concentration on the mean body weight of copepodite stages of Pseudocalanus spp. The calculations were made on the basis of experimental data from the literature for three geographically separate populations of Pseudocalanus from Puget Sound (Washington, USA), from the southern North Sea and the Baltic Sea. Relationships were obtained between the coefficient of daily exponential growth of body weight of Pseudocalanus sp. from Puget Sound and temperature in the 8–15.5◦C range and food concentrations from 10 mgC m−3 to excess, as well as for Pseudocalanus elongatus from the southern North Sea at high food concentrations and in the 4–15◦C temperature range. Also computed was the mean body weight for stages CII to CV of P. elongatus from the southern Baltic Sea at 5◦C. The empirical models presented here can be used with good precision in mathematical models of pelagic communities. The results presented here indicate that Pseudocalanus sp. from Puget Sound (a species resembling Pseudocalanus minutus) is similar to P. elongatus from the southern North Sea and the English Channel with respect to growth parameters in the studied range of temperatures for excess food. P. elongatus collected in the Baltic Sea (Gulf of Gdańsk) differs from P. elongatus from the southern North Sea.