JOURNAL OF PLANKTON RESEARCH | VOLUME 8 | NUMBER 5 | PAGES 973-983 | 1986
© Oxford University Press
research-article |
Gut evacuation rates and ingestion rates of Eudiaptomus graciloides measured by means of the gut fluorescence method
Freshwater Biological Laboratory, University of Copenhagen 51 Helsingørsgade, DK-3400 Hillerød, Denmark
Received on September 1, 1985; accepted on April 1, 1986 Diel variation in feeding rates of Eudiaptomus graciloides was measured in situ with the gut fluorescence method during May and June in the eutrophic Frederiksborg Slotssø Pronounced diel periodicity occurred in both periods with highest feeding rates during the night. The food concentration as well as the periodicity was almost constant with depth, indicating that the feeding activity represents a behavioral periodicity. The gut evacuation measured in the laboratory on field-collected copepods was exponential and temperature-dependent. The exponential decline in gut content was found for both copepods feeding continuously and when feeding had ceased. Considering spatial and temporal variation in feeding activity, daily ratios were 6168° body carbon per day, and higher than if calculated from existing laboratory data of short-term feeding dates.