Road Salt Impacts Freshwater Zooplankton at Concentrations below Current Water Quality Guidelines

Abstract

Widespread use of NaCl for road deicing has caused increased chloride concentrations in lakes near urban centers and areas of high road density. Chloride can be toxic, and water quality guidelines have been created to regulate it and protect aquatic life. However, these guidelines may not adequately protect organisms in low-nutrient, soft water lakes such as those underlain by the Precambrian Shield. We tested this hypothesis by conducting laboratory experiments on six Daphnia species using a soft water culture medium. We also examined temporal changes in cladoceran assemblages in the sediments of two small lakes on the Canadian Shield: one near a highway and the other >3 km from roads where salt is applied in the winter. Our results showed that Daphnia were sensitive to low chloride concentrations with decreased reproduction and increased mortality occurring between 5 and 40 mg Cl–/L. Analysis of cladoceran remains in lake sediments revealed changes in assemblage composition that coincided with the initial application of road salt in this region. In contrast, there were no changes detected in the remote lake. We found that 22.7% of recreational lakes in Ontario have chloride concentrations between 5 and 40 mg/L suggesting that cladoceran zooplankton in these lakes may already be experiencing negative effects of chloride.

Effects of chloride and nutrients on freshwater plankton communities

“…The CWQG should be re-evaluated to address these shortcomings. Our results are in agreement with recent laboratory-and field-based studies that demonstrate zooplankton sensitivity to chloride at concentrations below CWQG (Arnott et al 2020;Valleau et al 2020;Isanta-Navarro et al 2021). Together, these results suggest that interactive stressors should be considered.…”

Linking changes in sedimentary Cladocera assemblages to limnological variables in 67 Sudbury (Ontario, Canada) lakes reflecting various degrees of metal smelter impacts

“…were more abundant in sulfatedominated lakes (Bos et al 1999). In our ordinations, Alona circumfibriata was negatively related to Cl, which is consistent with recent paleolimnological investigations into the effects of road salting on soft-water Canadian lakes (Arnott et al 2020). In addition, our forward-and backward-selected RDA and pRDA results suggest that Acantholebris curvirostris, Alona quadrangularis, Alona rustica, and Camptocerus rectirostris, though present at low relative abundances (<6%), also have negative relationships with Cl.…”

Water Sampling Module for Collecting and Concentrating Legionella pneumophila from Low-to-Medium Contaminated Environment

“…Saline samples that provide appropriate physiological conditions do not inhibit L. pneumophila recovery as it was reported that such solutions can be considered for L. pneumophila suspensions. Normal environmental conditions might be closer to distilled water, but river water has some salts in it [59], and CTW will often have salts and sometimes even high levels of salts [60]. The quality of processed water influenced significantly the ability to carry out uninterrupted filtration.…”