Factors affecting the respiration/ETS ratio in marine zooplankton

Respiration (R) and electron transport system (ETS) activity were studied in marine zooplankton of different size classes (100-200, 200-500 and 500-1000 mu m) in order to determine the factors affecting the variability of the relationship between the two parameters. The WETS ratio varied within the range of values observed in the literature. The variability was more pronounced in the smaller size fraction. We found this ratio and primary production to vary in parallel during the development of the late winter bloom in the Canary Island waters. Higher ratios were observed to coincide with higher values of primary production. When the data from different oceanic environments were pooled, we found the ratios to be inversely related to temperature. The WETS ratio seemed to reflect the scope of metabolic activity in the zooplankton. Using a how-through system, we observed short-term respiration rates and ETS activities to be related to the activity level of the organisms. This suggests that variability in the relationship between both measurements could be due to the inadequacy of assessing respiration rates using the classical balance method and the problem of measuring enzymes at V-max.