Net cadmium flux in Hyalella azteca (crustacea: amphipoda) populations from five central Ontario lakes

Abstract

Cadmium concentrations in Hyalella azteca from five soft-water lakes in central Ontario (Heeney, Dickie, Red Chalk, Blue Chalk, Harp) were independent of animal dry mass. Mean concentrations varied seasonally from 12 to 54μg Cd/g dry mass in Heeney Lake, and from 3 to 8 μg Cd/g dry mass in Harp Lake. Peak concentrations were recorded in the spring, and may reflect high aqueous [Cd]. Mean cadmium concentrations in H. azteca from the five study lakes increased in the order Red Chalk < Harp < BlueChalk < Dickie < Heeney, and were inversely correlated ( p = 0.042) with lake water calcium concentrations. Secondary production estimates for these populations ranged from 0.178 (Heeney L.) to 1.571 g dry mass m −2 year −1 (Dickie L.). Net annual cadmium flux through the populations ranged from 2.29 to 13.46 μg Cdm −2 year −1, and was highest in Dickie Lake, which had both high secondary production of, and high cadmium concentrations in, H. azteca. Net maximum daily cadmium flux was also highest in Dickie Lake (0.496 μg Cd m −2 day −1). Cadmium concentrations in, and net flux through, benthic invertebrate populations from soft-water lakes without point sources of cadmium contamination may be elevated before lakes are considered acidified.