Tuesday, June 5, 2007
469

The Effect of Road Salt (NaCl) on Life History Characteristics of Chironomus riparius

Mark F. Stauffer Jr., Shannon M. Rupprecht, and Pamela Silver. School of Science, Penn State University Erie, 5091 Station Road, Erie, PA 16563

Road salt, NaCl, has adverse effects on organisms in roadside wetlands. Road salt enters wetlands in winter, but the interactive physiological effects of salt and temperature on aquatic organisms are poorly understood. We measured survival of Chironomus riparius larvae in a factorial-design study to determine the joint effects of temperature (0.1, 5, 10, and 25°C) and salt (0, 5, 10, and 20‰) on benthic invertebrates. We reared 3rd-instar Chironomus larvae in laboratory mesocosms.  Chironomus larvae were acclimated in the mesocosms for 4 d before adding the salt and were fed a TetraMin suspension. Survival decreased as temperature (F2,26 = 18.53, p < 0.0001) and salinity (F3,26 = 11.43, p < 0.0001) increased.  At 5ºC, low concentrations of salt tended to increase survival, whereas at higher temperatures all concentrations of salt negatively affected survival. Low salt concentrations may protect larvae against freezing at winter temperatures and increase survival if it is flushed from the wetland before the spring thaw. Conversely, salt that reaches wetlands during early spring storms may be very detrimental.

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