Year: 1988
Type: article
Abstract: An allometric model is used to estimate the productivity of natural phytoplankton assemblages.The 14C fixation rates of > 5 ~m phytoplankton cells, measured over a 5 yr period in the Celtic Sea, are used to test the relationship between cell size and productivity of natural phytoplankton assemblages.Phytoplankton biomass, as estimated from cell volume, explains between 85 and 90 % of the variance in 14C fixation rate under optimum growth conditions; in comparison, chlorophyll a concentration explains only 59 % of the variance.An allometric model, applied to the estimated phytoplankton biomass, is used to calculate the potential productivity of the phytoplankton under optimum growth conditions; this estimate of phytoplankton productivity explains 93 % of the variance in the in situ 14C fixation rate.When applied to data obtained over a 4 d period in the Celtic Sea, differences are found in the growth rate of individual species as well as in presumed losses due to grazing and sedimentation.This approach has the potential to estimate the productivity of each of the individual phytoplankton species which comprise a natural assemblage.where rate is growth rate or some other metabolic function: W = a measure of the mass of the organism; and (a) and (b) are constants (Peters 1983).Fenchel (1974) was the first to demonstrate that this relationship applied to the growth rate of microbes up to the size of ciliates, and the concept has been extended by Banse natural assemblage.The 14C productivity estimate approximates to a median value for the productivity of all the organisms present.Many workers have attempted to circumvent these limitations by applying size fractionation techniques to the 14C method.The approach has been successful, particularly in estimating the productivity of nanoplankton and picoplankton (Joint 1986).However, only minimal information has been extracted from 14C estimates on the microphytoplankton that frequently 'dominate natural assemblages.A parallel development in ecological research has concerned allometry, that is, the relationship between the size of an organism and some function of its metabolism such as respiration or growth rate.It is well known that the rates of metabolic processes of living organisms are inversely related to size and that sizedependence in the growth rate of micro-organisms can be described by an allometric relation.
Source: Marine Ecology Progress Series
DOI: 10.3354/meps047161
Language: English
Subfield: Oceanography
Field: Earth and Planetary Sciences
Domain: Physical Sciences
SDG: Life below water
Open Access status: bronze
OpenAlex ID: W2162960044