EXPERIMENTAL RECORDS OF THE EFFECTS OF FOOD PATCHINESS AND PREDATION ON EGG-PRODUCTION OF ACARTIA-TONSA

The effects of predation and spatial patchiness in food distribution o n egg production of the marine calanoid copepod Acartia tonsa were inv estigated in the laboratory. A postexperiment egg production method wa s developed to override the decline in number of copepods due to preda tion. The copepods were able to remain in food patches about 41-47% of the time, and consequently egg production rates were higher than expe cted from the average food concentration. Predation by the calanoid co pepod Labidocera aestiva tended to increase egg production rates of A. tonsa. The interaction of patchiness and predation resulted in relati vely less time spent by A. tonsa in the food patches, probably as a co nsequence of conflict between hunger level and predation risk.