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USGS · 1013873

Effects of chronic exposure to simazine on the cladoceran, Daphnia pulex

K. M. Fitzmayer·J. G. Geiger·Michael J. Van Den Avyle
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Abstract

The effects of chronic exposure to simazine, an s-triazine herbicide, on the cladoceran Daphnia pulex were evaluated under laboratory conditions. The daphnids were exposed to simazine concentrations corresponding to previously calculated 48-hr LC5 and LC20 values and the effects on survival, growth, reproduction, and behavior were monitored daily for 26 days. Survival of D. pulex in 20 mg/L simazine averaged 9.6±1.7 days. Most mortality in 4 mg/L occurred between days 21 and 25, and 65% of the daphnids were dead by day 25. Simazine interfered with molting, and growth was reduced in both concentrations tested. Reproductive maturation was delayed by about one molt cycle (3 days at 20°C) in D. pulex exposed to 4 mg/L simazine and was prevented in daphnids exposed to 20 mg/L. Numbers of live young and broods produced by daphnids in 4 mg/L were significantly lower than those produced by controls.

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K. M. Fitzmayer, J. G. Geiger, Michael J. Van Den Avyle. 1982. Effects of chronic exposure to simazine on the cladoceran, Daphnia pulex. https://doi.org/10.1007/bf01056369

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