Attached Filamentous Algae of Northern Lake Superior: Field Ecology and Biomonitoring Potential During 1983

Abstract

A survey of attached filamentous algae along the Canadian shoreline of northern Lake Superior was carried out in late August, 1983. Consistent with earlier surveys of the American northwestern shoreline, Ulothrix zonata was identified as the dominant taxon, although most substrata were largely free of attached algae, as is characteristic of highly oligotrophic conditions. A variety of minor green and blue-green algae were also identified. It is expected that the basinwide distribution of U. zonata will directly reflect any future increases in nearshore nutrient status. In contrast, it is not expected that Cladophora will ever widely occur in Lake Superior, irrespective of nearshore enrichment, because water temperatures are apparently prohibitively low. U. zonata samples from three Lake Superior shoreline sites were analyzed for elemental and polychlorinated biphenyl (PCB) concentrations. In general, Lake Superior water-to-algae elemental concentration factors (10 -2-10 -5 ×) were similar to those from other locations in the Great Lakes. Elevated concentrations of Fe (1.40 mg/g), Al (0.54 mg/g), and V(16.0 μg/g) in the vicinity of Thunder Bay Harbour and the mouth of the Kaministikwia River are indicative of point source loadings, while detection of PCBs (<20–40 ng/g) at all three Lake Superior sites is suggestive of widespread low-level contamination.