Just "Beet" It? A Comparison of Road Salt Effects on the Life History of Daphnia magna

In areas that experience snow and ice, deicing reagents such as road salts are often used on roads to promote safer driving conditions. However, road salts run off into local vegetation, soil systems, and (my focus) freshwater systems. The impacts of excess salt and chloride in freshwater have been studied extensively on a broad diversity of organisms under different conditions, but previous studies have rarely used different types of road salts. Zooplankton are primary consumers in many freshwater systems, feeding on phytoplankton and serving as prey for predator species higher in the trophic chain. These animals generally are impacted negatively under high salinity conditions, which can lead to population declines and alter community composition. Additionally, phytoplanktonic producer populations may experience loose regulation by zooplankton and other primary consumers, which can contribute to ecological disasters when zooplankton populations decline, such as algal blooms, which cause mass die-offs of fish and other aquatic species. In this study, I used the indicator species Daphnia magna and three road salt compounds to compare the negative effects of road salt on D. magna reproduction and mortality across salt treatments in two different concentrations. Overall, there was no significant difference among salt treatments on the mortality and reproduction of D. magna. Notably, the advertised “eco-friendly” salt with beet extract was no less impactful on these life history traits than its competitors, highlighting the need for manufacturers to provide evidence for these claims.