Acute toxicity tests on the freshwater isopod, Asellus aquaticus using FeSO4. 7H2O, with special reference to techniques and the possibility of intraspecific variation

Techniques are described for assessing the toxicity of Fe(II), an important component of the effluent from mines, to the freshwater isopod, Asellus aquaticus. These techniques either involve buffer systems or working at low pH. Both techniques indicate that A. aquaticus is very tolerant of Fe(II). Furthermore, the low-pH technique suggests that animals from sites exposed to mine-waste pollution are more tolerant than those from sites not so exposed. This difference is masked in the buffer experiments, possibly due to the formation of less toxic buffer-Fe(II) complexes.