In situ feeding of the planktonic copepod Calanus sinicus in the Inland Sea of Japan, examined by the gut fluorescence method
Inland Sea of Japan
We investigated in situ feeding of adult females of the planktonic copepod Calanus sinicus in the Inland Sea of Japan by the gut fluorescence method. Unlike many empirical observations of food-dependent feeding in copepods, no correlation was found between in situ gut pigment of C. sinicus and ambient chlorophyll a concentration. This might partly be due to the large (up to 13-fold) variability in individual gut content, which persisted thrdughout the day. The C. sinicus population showed a diel feeding periodicity; mean gut pigment was significantly higher at night than during the day. Gut evacuation rate increased linearly with increasing temperature. Daily pigment ingestion rates were estimated at 3 stations where gut pigment data over 24 h were available. They varied from 209 to 842 ng pigment indiv.^<-1> d^<-1>. Assuming that the population biomass of C. sinicus at these stations was 32 mg C m^<-3> (the average biomass in Osaka Bay), the population would have consumed 13 to 85% of the phytoplankton standing crop per day.
Copyright (c) 1995 The Plankton Society of Japan