RNA concentration of zooplankton: Relationship with size and growth1

The relationship between RNA concentration and dry weight (W) of zooplankton from the Korsfjord, western Norway, was best described by a power function, [RNA] = aW b . Dry weight explained about 75% of the intraspecific and 43% of the interspecific variation in RNA concentration. The intraspecific regression slope (average −0.74) was significantly steeper than the multispecific slope (−0.33). Published data on growth rate of zooplankton from Korsfjorden and other areas revealed a pattern with dry weight similar to that for RNA concentration, with an interspecific regression slope of −0.32. Combining the interspecific regressions of growth rate and RNA concentration vs. dry weight gives a relationship between growth rate (k, coefficient of daily exponential growth) and RNA concentration ( µ g·mg dry wt −1 ), k ·10 3 = 0.795 × [RNA], which can be used to estimate the average growth rate of macrozooplankton samples with RNA concentrations between 3 and 70 µ g·mg dry wt −1 .