Reproduction of the calanoid copepod Calanus propinquus in the southern Weddell Sea,Antarctica: observations in laboratory

Reproduction of the dominant Antarctic copepod Calanus propinquus was studied in February–April, 1989 aboard the R.V Dmitry Mendeleev during cruise N° 43 to the Weddell Sea. Single females were kept at 0 °C in the laboratory for 56 days with abundant food concentration (above 300 µg C l^–1 of Platymonas viridis). Females released clutches at night at 2–3 day intervals. Most clutches contained from 10 to 40 eggs, mean 37.3 eggs female^–1. Average carbon content of an egg was 0.37 ± 0.05 µg C. The maximum daily egg production rate of 30–50 eggs female^–1 d^–1 was observed for the first 3 days of the laboratory incubation, corresponding to 3.7–6.2% body C. The state of gonadal development of females showed the decline of the reproductive season in late February. The data suggest that egg laying in the region under study starts in December and lasts until March. The state of ovarian maturation, changes in vertical distribution and biochemical body composition of females suggest the possibility of two-year life cycle in C. propinquus in the southern Weddell Sea.