EMPIRICAL-MODELS OF ANNUAL PRODUCTION AND PRODUCTIVITY-BIOMASS RATIOS OF BENTHIC INVERTEBRATES IN RUNNING WATERS

Published data on secondary production of running water invertebrates are analyzed by multiple regression to quantify the relationship between productivity (P, in grams dry mass per square metre per year) and biomass (B, in grams dry mass per square metre), mean individual mass (M, in grams dry mass), and annual mean water temperature (T, in degrees Celsius) to compare productivity of major taxonomic groups and to compare to invertebrate populations from other aquatic ecosystems. The equation P = 0.18 B1.01 M-0.34 10(0.037T) explains 87% of the variability in log P in the 291 lotic invertebrate populations analyzed. Significant differences were detected among major taxonomic groups, but these differences account for only about 4% of the variability in log P. Once the effect of biomass, mean individual mass and water temperature are taken into account, productivity of lake and stream invertebrate populations is quite similar, although productivity is a linear function of biomass in streams and not in lakes. Comparison of models for running waters, lake and marine ecosystems suggests that marine invertebrates are less productive than freshwater populations.