Life history and production of Hyalella azteca (Crustacea: Amphipoda) in a hypereutrophic prairie pond in southern Alberta

Abstract

The life history and production of the amphipod Hyalella azteca were studied over an 18-month period in a hypereutrophic prairie pond in southern Alberta, Canada. The population reproduced once a year, with breeding commencing in June and continuing until August. Population density was highest in June. The mortality rate of the adult population increased with the onset of reproduction, and remained high until the end of winter. The population density was lowest during winter and early spring (January to May). Biomass (B) fluctuated in a similar manner to population density, but the peak biomass occurred in August and September. Annual production (P) was 23.12 g∙m−2 (dry weight), estimated by the size-frequency method. The corresponding annual turnover ratio (P/B) was 5.68. The unusually high annual production and turnover ratio are attributed to the high density and large adult size of this population.