“…The lakes were heavily acidified by the 1970s (to pH <5; and have aqueous Cu and Ni concentrations that continue to exceed provincial water quality guidelines (Cooperative Freshwater Ecology Unit, Laurentian University, 2013). Each of the three Sudbury study lakes has undergone prior diatom-based reconstructions of pH (Dixit et al, 1987(Dixit et al, , 1990(Dixit et al, , 1996, analyses of sedimentary metals (Snetsinger, 1993;Tropea, 2008;Tropea et al, 2010), cladoceran assemblages and sedimentary chlorophyll-a (Labaj et al, 2015), and regular water chemistry monitoring since 1973 (Middle, Clearwater) or 1991 (Daisy; Cooperative Freshwater Ecology Unit, Laurentian University, 2013).…”