Inter-specific scaling of phytoplankton production and cell size in the field

Abstract

This study tests the hypothesis that the interspecific scaling ofphytoplankton production and cell size in the field follows the 3/4-powerscaling law. Published data of cell size and in situ, cell-specificcarbon production rates by single phytoplankton species, collectedin surface waters of lakes, rivers, estuaries and oceans, are reviewed.Across more than nine orders of magnitude in cell volume, 98% ofthe variability in carbon production rates was explained by cellsize. The slope (b) in the log-log relationship between carbon productionrate and cell volume did not differ significantly from 1, eitherfor diatoms (b = 1.01) or for dinoflagellates (b = 0.89). For allphytoplankton species considered together, which included also cyanobacteriaand haptophytes, b took a value of 0.91, which is significantly higherthan 3/4. The observed nearly isometric scaling relationships betweenproduction rate and cell volume suggest that there is no relationshipbetween phytoplankton growth rate and cell size. The present analysisconfirms recent evidence showing that phytoplankton metabolism innatural conditions does not follow the 3/4-power scaling rule. Itis argued that allometric models of plankton growth and metabolismshould incorporate scaling parameters measured in situ on naturalphytoplankton assemblages, rather than those obtained in the laboratorywith monospecific cultures.