Production and turnover of Hyalella azteca in central Ontario, Canada compared with other regions

SUMMARY1   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°C.