Acute toxicity of six metals to the Rotifer Brachionus calyciflorus, with comparisons to other freshwater organisms

There are several advantages to the use of planktonic rotifers as freshwater bioassay organisms, yet few studies report toxicological data for these taxa. The goal of the present study was to evaluate the 24-h acute toxicity responses of Brachionus calycifiorus to six heavy metals, and to compare metal tolerance of this species to published results for other aquatic organisms. Metal toxicity to B. calyciflorus, in decreasing order, was Hg > Cu > Cd > Zn > Fe > Mn. This order follows the theoretical ranking by affinity for anionic radicals based on Lewis acid-base classification. While not quite as sensitive as Daphnia magna, B. calyciflorus is potentially useful as a bioassay species because it is easy to culture and manipulate, and is widely distributed in alkaline waters of eastern North America.