Seasonal and spatial variability in egg production, abundance and production of small copepods in and near Jiaozhou Bay, China

Abstract

Distribution, egg production rate (EPR) and abundances of four small copepods in genera Paracalanus and Acartia were studied monthly from October 2005 to September 2006 in and outside Jiaozhou Bay, China. Biomass and secondary production also were calculated to show the importance of these small copepods. As predominant species, Paracalanus parvus and Acartia bifilosa, occurred continuously in this bay throughout the year, with large abundance peaks from late spring to early summer. Acartia pacifica occurred sporadically in May, but in July, it reached higher maximum abundance than the other species. Parvocalanus crassirostris was relatively rare and occurred seasonally. Spatial distributions of these species differed according to the environmental variation inside and outside the bay. Egg production for each species mainly occurred in the warming period. The average female growth rates were higher for species with seasonal occurrence than those that were present continuously. The total secondary production rate of these four species was highest in June and lowest in April. These small copepods made greater contributions to the annual secondary production rate than did larger copepod species in Jiaozhou Bay. Comparisons are also made with other similar coastal waters worldwide.