Nearshore fluctuations in water chemistry, microcystins and coliform bacteria during the ice-free season in Lake Winnipeg, Manitoba, Canada

The aim of this study was to identify empirical relationships among 12 water chemistry parameters, microcystins, and coliform bacteria at four beaches in Lake Winnipeg, Canada. While microcystin fluctuations were not synchronized among the different sites, concentrations were marginally correlated with concurrent nitrate levels at individual sites, but lagged more significantly behind soluble inorganic phosphorus, and inversely behind the nitrate-N/soluble phosphorus ratio (NPR). Microcystins were also inversely correlated with copper, which was used as an algaecide in the lake. Total coliform bacterial counts (TC) were significantly greater at times of increased turbidity, temperature, and higher inorganic phosphate and dissolved organic matter. TC were also inversely correlated with NPR.