Polychlorinated biphenyls and organochlorine pesticides in the freshwater mussel Hyridella menziesi from the Waikato River, New Zealand

The Waikato River is the longest and most heavily utilized river in New Zealand. At eight sites along the river system, mussels, Hyridella menziesi, were collected, and the concentrations of PCBs and organochlorine pesticides were determined. trans-Chlordane was detected in six of the eight locations, while lindane, dieldrin, cis-chlordane, DDE, and DDT were detected in all samples. The distribution of lindane and dieldrin was fairly uniform throughout the river system, indicating the absence of discrete sources. Total chlordane was highest in Taupo, declining with distance downstream, while total DDT peaked at Ohakuri and Karapiro, both of which are agricultural regions. Total PCBs ranged 75-fold, with a peak at Karapiro, and the congeners were dominated by penta-, hexa-, and hepta-chlorinated compounds. Generally, the lipid content or condition of the mussels were not correlated significantly with total chlordane, DDTs, or PCBs, but chlordane showed a strong inverse relationship with condition.