The Effects of Road Salt and Nutrient Runoff on Freshwater Ecosystems

Schimmel/Conrades Science Center 163

Runoff from human activities can have harmful effects on freshwater ecosystems. Road salt and agricultural pollutants can enter bodies of water, potentially disrupting their stability. Runoff can lower biodiversity and abundances of zooplankton species, which can result in increases in phytoplankton concentrations and algal blooms. Using both a controlled mesocosms experiment and a survey of local ponds, we investigated how road salt and agricultural nutrient runoff affect freshwater ecosystems. Increased salt concentrations had an effect on all zooplankton species and led to increased algae due to decreased herbivory. Increased nutrients enhanced zooplankton growth overall, but we did not see a synergistic effect of salt and nutrients on zooplankton abundance as expected. The survey of ponds in Delaware, OH showed that some ponds had high concentrations of salts and nutrients, indicating an unhealthy ecosystem, but we did not observe correlations between salt concentrations, nutrients, and zooplankton communities. This was most likely due to the seasonal differences in zooplankton populations between the experiment and the survey, as well as much smaller range of salt concentrations in the ponds compared to the range of the mesocosms. These findings suggest that if the use of road salt continues, changes should be implemented in order to conserve freshwater ecosystems.