Production and Loss of Eggs in the Calanoid Copepod Centropages abdominalis Sato in Fukuyama Harbor, the Inland Sea of Japan
福山港におけるカラノイダ目橈脚類Centropages abdominalis Satoの卵の生産と減耗
the Inland Sea of Japan
The calanoid copepod Centropages abdominalis occurred in the plankton from November 1986 to May 1987 (temperature range: 8.9 - 19.7 °C) in Fukuyama Harbor, in the central part of the Inland Sea of Japan. Its fecundity was estimated by two methods: the incubation method and the egg-ratio method. The incubation fecundity ranged from 39 to 142 eggs female^<-1> d^<-1>, with a corresponding carbon weight specific rate ranging from 0.19 to 0.70 d^<-1>. The specific egg production rate (SEPR, d^<-1>) can be estimated from temperature (T, °C) and chlorophyll (P, μg 1^<-1>) with the multiple regression equation: SEPR=0.330 lnT+0.125 lnP - 0.678. The egg-ratio fecundity, however, was extremely low (0.6 - 45 eggs female^<-1> d^<-1>) compared to the incubation fecundity. The difference between these two fecundities was regarded as loss of eggs caused by various factors. This loss was higher in March-May (mean: 94.2%) than that in November - February (mean: 81.0%). We attribute it mainly to sinking from the water column and predation, including cannibalism, by omnivorous copepods (i.e.late copepodites of C. abdominalis and Acartia omorii). Higher loss of eggs in April and May may also be related to the production of diapause eggs.
Copyright (c) 1994 The Plankton Society of Japan