PRODUCTION AND TURNOVER OF HYALELLA-AZTECA IN CENTRAL ONTARIO, CANADA COMPARED WITH OTHER REGIONS

1. Hyalella azteca (Amphipoda) inhabiting macrophyte beds in eight Canadian Shield lakes were sampled during the ice-free seasons of 1984 and 1985. These amphipods were found to be predominantly univoltine in contrast to suggestions from a previous study. 2. Annual production determined by the size-frequency method ranged from 1.21 to 2.77g dry wt m(-2) year(-1), and are the highest rates recorded for this species in temperate waters. 3. Turnover rates (P/B ratios) ranged from 2.27 to 3.48 and are among the lowest values that have been measured. A synthesis of these data indicates that H. azteca turnover rates increase sigmoidally with degree-days above 5 degrees C.