Limnology and Fisheries of Georgian Bay and the North Channel Ecosystems

Abstract

Field investigations during the ice-free period of 1980 confirm that the dominant attached filamentous algae in the Canadian waters of Lake Huron are the green algae Ulothrix zonata and Cladophora glomerata, and the red alga Bangia atropurpurea. It is believed that nutrient availability limits the distribution of these algae, while temperature controls their seasonal periodicity. Because of favourable physical characteristics, the study area represents a vast potential habitat for attached filamentous algae, It is expected that eastern Georgian Bay, in particular, will suffer significant environmental degradation from the growth of Cladophora unless existing phosphorus levels are maintained indefinitely (i.e., < 0.005 mg total P 1-1). Attached filamentous algae accumulate (103 to 105 x) a variety of elements primarily in proportion to availability in the surrounding water. The occurrence of maximum algal metal concentrations at municipal waste water outfalls, river mouths and harbour areas (e.g., in utg g-', Cr 29.0, Cu 46.4, Ni 34.0, Pb 55.0) is indicative of discrete source loadings, while elevated levels at remote sites in eastern Georgian Bay (e.g., in lsg g-1 , Cr 12.0-15.5, Cu 18.0, Ni 15.0-16.0, Pb 8.5-8.8) are suggestive of generalized loadings from the Canadian Shield, possibly due to the effects of acidic precipitation.