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The paper describes the modelling ofeg g production in Acartia spp. under changing environmental conditions in the southern Baltic Sea (Gdańsk Deep). The hypothesis (Sekiguchi et al. 1980) that the food-saturated rate of egg matter production is equivalent to specific growth rate ofco pepods is applied. The average number ofeggs produced per day by one Acartia female is obtained as a function ofg rowth rate, i.e. by multiplying exp gN3 − 1 from the growth rate of the nauplius stage equation by Wfemale/Wegg. The copepod model, reduced to a zerodimensional population model calibrated for Acartia spp. under the environmental conditions typical ofthe southern Baltic Sea, was used to determine the effects of temperature and food concentration on the growth rate ofeac h oft he model stages (see Part 1 – Dzierzbicka-Głowacka et al. 2009 – this issue). In this part, egg production as a function of the above parameters is evaluated. The rate of reproduction during the seasons in the upper layer ofthe Gdańsk Deep is also determined.
Quantitative expressions are presented to describe the effects of temperature and food concentration on stage duration and growth rate of Temora longicornis for each of the model stage groups (N1–N6 – naupliar stages, C1, C2, C3, C4, C5 –the five copepodid stages). The calculations were made on the basis of experimental data from the literature for T. longicornis from the south-eastern and the southern North Sea. Relationships were obtained between the growth parameters and temperature for the 5–10◦C temperature range and food concentrations from 25 mgC m−3 to excess. Also computed was the total mean development time as a function of the above-mentioned parameters, temperature and food availability. The simulations computed here are similar to the experimental results. The growth rates for successive stages were obtained according to the correction of the ‘Moult Rate’ method, which allows the use of mean weights and stage durations. The calculations also suggest that three complete generations of T. longicornis from the Gdańsk Deep (the southern Baltic Sea) can develop during a single year.
The copepod model (see Dzierzbicka-Głowacka 2005b),red uced to a zero-dimensional population model (Fennel 2001,S tegert et al. 2007),i s calibrated for Acartia spp. under the environmental conditions typical of the southern Baltic Sea. Most of the coefficients used in the model are taken from the literature,co ntaining values from various published studies and parameters derived for similar species. The parameters for growth are presented in Part 1; those for population dynamics are given in Part 2. Ingestion rates,whic h are dependent on developmental stage, food supply,temp erature and weight of the animals, are estimated for Acartia bifilosa at 15◦C from the Gdańsk Deep after the experimental data of Ciszewski & Witek (1977). In Part 1 the model presents the change in mean individual mass in successive stages. Quantitative formulae are obtained describing the effects of temperature and food concentration on the development time of Acartia spp. for each of the model stage groups. The generation time during the seasons in the upper layer of the Gdańsk Deep is also determined. The simulations computed here are similar to the experimental results. Part 2 (Dzierzbicka-Głowacka et al. 2009 – this issue) will evaluate egg production as a function of the above-mentioned parameters,temp erature and food availability.
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