The toxicity of paired metal mixtures to the nematode Monhystera disjuncta (Bastian, 1865)

Abstract

The toxicity of bipartite Hg, Cu, Zn and Ni metal mixtures was studied to the free-living marine nematode Monohystera disjuncta. Observed mortality and developmental inhibition responses could not be predicted by independent dissimilar nor simple similar action. The toxic unit concept was also used to evaluate overall mixture toxicity. With regard to mortality all paired metal mixtures act in a less than additive manner. The developmental inhibition response was not so clear-cut: the ZnNi mixture acts synergistically; similarly the joint effect of ZnCu combinations and CuNi mixtures, containing small amounts of Cu (1 mg litre −1), act synergistically and the response type with regard to the HgCu mixture is not very clear.