Some species of invertebrates, particularly benthic infauna, show extreme metabolic fluctuations, from a truly basal metabolic rate while quiescent in anaerobic mode to higher rates as a result of physical activity whether they are anaerobic or aerobic. The fluctuations may be random or cyclic, endogenous, induced by experimental conditions, or by natural changes in environmental conditions; they are readily seen and quantified by direct calorimetry.
Biochemists studying anaerobic metabolism sometimes find large quantitative variations in metabolite concentration between individual test organisms. One source of variability may be the variability in the metabolic activity of the control and experimental animals. Information contained in heat flow recordings could be useful in normalizing data and making more precise correlations between actual metabolic rates and chemical measures of metabolism.
Theoretical enthalpy changes from known anaerobic end products and results of direct calorimetry do not agree at present. Continual comparisons, leading to consistent agreement or satisfactory explanation of their discrepancy, are necessary to demonstrate full understanding of anaerobic metabolism. Key words direct calorimetry, metabolic heat flow, anaerobic metabolism, benthic infauna, bivalves Address reprint requests t o Mario M. Pamatmet, P.O. Box 855, Tiburon, CA 94920.