Investigation of chloride concentrations and littoral invertebrate community structure in stormwater and non-stormwater ponds (Ontario, Canada)

There is evidence that road salt generated chloride levels encountered in some Canadian water bodies are toxic to aquatic organisms. Little is known about the effect of chloride input on invertebrate communities, particularly in ponds. This study was conducted on 19 stormwater and 63 non-stormwater ponds in Ontario, Canada. Chloride concentrations in stormwater and non-stormwater ponds ranged from 104 to 2497 mg/L and 36 to 495 mg/L, respectively. For all ponds studied land use of the surrounding area was more important than, although correlated with, chloride concentration in determining pond invertebrate community structure. The relationship between environmental factors and non-stormwater pond communities was non-significant, however, CCA identified chloride concentration as important in determining community structure. Stormwater pond community structure was largely determined by chloride concentration however other correlated variables might be important. The results of this study indicate that community level effects of road salts are evident in the natural environment.