Regional and Seasonal Variation in the Respiratory Rate of Marine Copepods1

Abstract

The respiratory rate of seven species of marine calanoid copepods was measured at the same temperature, and an attempt was made to find a basis for comparison of respiration in zooplankton crustaceans of different size. When the log of the respiratory rate was plotted against either log length or log dry weight, a positive linear correlation was obtained, but in each case the correlation coefficient was greater than would be expected if metabolism were related to surface area. When the respiratory rate was plotted against dry weight without logarithmic transformation, a linear correlation coefficient r = 0.978 was obtained. When dry weight was used to correct for size differences between populations, Acartia clausi from Southampton water had a statistically higher metabolic rate in laboratory experiments during the cooler months of the year than those from Long Island Sound at the same season. Seasonal variation in metabolism independent of temperature was demonstrated for several species of copepods, and some of the factors that might be responsible for this variation are discussed.