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>The effect of210Pb and stable lead on the induction of menta deformities inchironomus tentanslarvae and on their growth and survival
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The effect of210Pb and stable lead on the induction of menta deformities inchironomus tentanslarvae and on their growth and survival
AbstractTo determine whether menta deformities in chironomid larvae collected from Port Hope Harbour, Ontario, were the result of exposure to ionizing radiation or to heavy metals in the sediment,Chironomus tentanslarvae were exposed in the laboratory to concentrations of210Pb and stable lead representative of contaminant levels in the harbour. Exposure to 100, 1,000, and 2,000 Bq210Pb g−1dry sediment had no effect on larval survival, growth, or frequency of deformities. Likewise, exposure to 0.5 and 5.0 mg lead g−1dry sediment had no effect on the larvae, but exposure to 35.0 mg lead g−1dry sediment (the maximum levels observed in Port Hope Harbour) resulted in 100 mortality of the larvae. These results indicate that the observed mouthpart deformities in chironomid larvae of Port Hope Harbour are not the result of radiation exposure. They also indicate that heavy metals (lead) may be having an impact on the Port Hope Harbour population. Deformities were observed in all treatments and were confined mainly to the median tooth, with cleft or forked median teeth being the most common deformity. Restriction of the deformities to the median tooth is consistent with an inherited genetic effect, and we consider them to be natural abnormalities. These natural abnormalities must be considered when using chironomid mouthpart deformities as an index of environmental degrad
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