Impact of heavy metals (cadmium and copper) stress on the bioturbation potential of polychaete Perinereis aibuhitensis (family Nereididae)

Abstract

The change of macrofaunal bioturbation potential (BP) under environmental stress has application value in ecological restoration and ecological models. Single and combined toxic effects of metals cadmium and copper on the BP of polychaete Perinereis aibuhitensis were studied. The distribution of tracer sand showed a negative correlation between the transportation capacity of P. aibuhitensis and the Cd concentration; Cu stress indicated a stronger ability of promoting downward transportation, and the linear relationship with concentration was not so obvious as Cd. The toxicity stress of Cd and Cu also showed a significant effect on the oxidation-reduction potential (ORP) in the sediment matrix. There was a certain synergistic effect between cadmium and copper, and toxicity effects were associated with metal concentration and stress duration. In the later stage of the combined experiment, P. aibuhitensis avoided living in depth near the bottom, especially when the concentrations of Cd and Cu were high. For the bioturbation model, it was suggested that the two parameters of mobility and reworking would be reduced by half or one category scale depending on the cadmium and copper concentration and stress duration. The results can be used for ecological restoration prediction and ecological risk assessment; it is necessary to carry out more studies with a variety of environmental factors and indicators, since a variety of coexisted pollutants would show complex influence on the BP of macrobenthos.