Relation between biomass and body weight of plankton in a steady state oceanic ecosystem1

In the size range from 10−4 to 103 µg (carbon) body weight, the biomass of plankton in the euphotic layer of the North Pacific Central Gyre decreases as an allometric function of body weight. Even in a steady state ecosystem such as that analyzed here, there is variability in space and time; this suggests that one must be careful in extrapolating the relation to less predictable marine areas. In obtaining dynamic information from biomass spectra, one must distinguish changes due to the flow of energy within the spectrum (growth, predation, reproduction) from changes due to emigration from or immigration into the spectrum of the particular area sampled, such as those due to the diel vertical migration of macrozooplankton in the largest size classes.