Seasonal reproductive biology of Centropages tenuiremis (copepoda) in Xiamen waters, People's Republic of China

The egg production rate (EPR) and the effects of environmental variations on diapause induction in the copepod Centropages tenuiremis in Xiamen waters were studied in 2002 and 2003. The EPR ranged from 7.33 ± 8.14 (on 18 February 2003) to 91.08 ± 20.61 (on 6 June 2003) eggs female ^-1day^-1 (mean ± 95% confidence limits), and displayed a significant seasonal pattern. Before the period of maximum egg production, EPR increased with seawater temperature and chlorophyll a concentration; but after the maximum, no significant relationship was found between EPR and chlorophyll a concentration, and there was a negative linear relationship between EPR and temperature. Seawater temperature and photoperiod, respectively, played a primary role in the switch to diapause egg production by the females as shown by single-factor probit analysis. However, the difference in effect between the two factors was demonstrated by binary logistic multivariate analysis. These results suggest that this copepod rapidly increases subitaneous EPR by taking full advantage of conditions in favorable seasons (winter and spring). Subitaneous EPR decreases and there is a switch to the production of diapause eggs that survive in the bottom sediments during unfavorable seasons (summer and autumn) in Xiamen waters.