The use of biomass spectra and allometric relations to estimate respiration of planktonic communities

In this paper we compared two different approaches to estimate plankton energy consumption: (i) combination of the observed biomass-size spectrum and empirical allometric relationships between respiration and body size, and (ii) the experimental measurement of ETS (electronic transfer system) activity. The first approach was carried out through both discrete and continuous models. Results indicated a good agreement between predicted and observed metabolism in both a freshwater and an oceanic plankton assemblage from bacteria to zooplankton. The discrete integration of the spectrum accounts better for changing systems than continuous integration, which is more appropriate for theoretical approaches to studying the metabolism of the community. The combination of biomass spectrum slopes and allometric exponents was critical in metabolism sensitivity to size structure: flatter biomass slopes (as found in microbial assemblages) allow for greater variations in this size range to the total metabolism contribution of the planktonic community. For future studies, the fast progression in technical discrimination and measurement of particles makes this approach a promising tool for the analysis of energy budgets in planktonic ecosystems.