15 JUNE 1999
T.D. Williams, M.B. Jones-1999
Journal of Experimental Marine Biology and Ecology, 236(2): 273-290 (from Current Contents)
Abstract:
There are relatively few reports of the influence of environmental factors on the development and reproduction of harpacticoid copepods. In this study, we establish the effect of temperature (15, 20 and 25 degrees C) and food concentration (83-3250 mu g of carbon per litre of the alga Isochrysis galbana Parke) on the reproduction of the marine harpacticoid Tisbe battagliai Volkmann-Rocco. Reproductive lifespan, total number of broods and total number of offspring produced were recorded from females reared individually in the laboratory. Reduction in algal concentration from 3250 to 1300 mu g C/1 resulted in significant decreases in the number of broods and offspring produced at 15 and 20 degrees C, but not at 25 degrees C. Algal concentrations lower than 1300 pg C/1 elicited significant reductions in reproductive output throughout the temperature range. There was an inverse relationship between female lifespan and temperature; females reared at 15 degrees C lived approximately twice as long as those reared at 25 degrees C. Increases in temperature (15-25 degrees C) and algal concentration (520-3250 mu g C/1) resulted in a reduction in the time interval between hatching of successive broods. Larger brood sizes were observed with increased algal concentration, however, there was no clear trend of temperature on brood size. The implication of these results to the development of harpacticoid populations in the natural environment is discussed.
(ZENECA Ltd, Brixham Environm Lab, Freshwater Quarry, Brixham TQ5 8BA, Devon, England, UK, e-mail: tim.williams@brixham.zeneca.com)