Chironomid larvae (Chironomus spp.,Dicrotendipes conjunctus andProcladius paludicola) collected from Cox Creek and Aldgate Creek, South Australia, showed morphological abnormalities similar to those reported in other studies elsewhere in the world. The sediment of Cox Creek contained high concentrations of pesticides and there was a significant correlation between the occurrence of mouthpart and antennal deformities in larvae and the concentration of DDT and the herbicide, Dacthal®.
Laboratory experiments were conducted using a culture ofChironomus sp. to determine whether or not a causal relationship existed between exposure to pesticides and the occurrence of deformities in larvae. Results showed a positive relationship between the concentration of DDT and the percentage of deformed mouthparts (menta). The results for the effect of DDT on antennae and those for the effect of Dachthal® were less clear, but generally showed a higher incidence of deformity for treatments compared with controls.
To compare these results to a natural population (i.e. from an unpolluted area) the incidence of deformities was measured for larvae collected from Deep Creek Conservation Park, an area virtually free of pollution. The significance of this work is discussed with regard to its wider application as a useful environmental monitoring technique for freshwater systems.