Production ecology of the amphipod Hyalella azteca (Saussure) in a Northern Ontario lake

Abstract

Annual production of the amphipod Hyalella azteca was estimated in the upper littoral zone of Dock Lake, Ontario, over a 2 year period (1980-1981). Population density (negligible below 1 meter) differed among the three habitats sampled. Cohort production by the size frequency method was 1.39 g/m[superscript 2] (dry weight), mean annual biomass was 0.36 g/m[superscript 2] , and the P/B ratio was 3.9 for the 1980 year class. Six other methods for estimating production were applied to this cohort, providing comparable estimates ranging from 1.21 (instantaneous growth) to 1.65 (cohort G) g/m[superscript 2] . Size frequency estimates of annual production for 1980 and 1981 were 1.24 and 1.40 g/m[superscript 2] respectively. The annual P/B ratios of 3.9 and 4.0 for these two years agree with the cohort value. A comparison of production estimates for Hyalella azteca in the literature shows a gradient of production correlating with habitat temperature regime.