THE BENTHIC MACRO-ALGAE OF GEORGIAN BAY, THE NORTH CHANNEL AND THEIR DRAINAGE-BASIN

Thirty-nine subgeneric taxa of macroalgae have been collected from 83 sites in Georgian bay, the North Channel and their drainage basin. There were 15 species in the Bay and Channel and 32 species in streams, rivers and impoundments in the basin. Only 8 of the Bay and Channel species were also found in the watershed. Cladophora glomerata was the most important species in Georgian Bay and the North Channel, having an estimated 640 .times. 103 m2 cover and 19 .times. 104 kg fresh weight standing crop. However, this species was largely concentrated on the southwestern shorelines of these water bodies. Its distribution along the northeastern shoreline appears to be limited by total ion and phosphorus levels. Chara globularis/vulgaris was the subdominant taxon in Georgian Bay and the North Channel with an estimated 70 .times. 103 m2 cover and 15 .times. 103 kg fresh weight biomass. This species was more widely distributed than C. glomerata. No other taxon contributed significantly to the standing crop including the frequently occurring Ulothrix zonata, zygnema spp. and Spirogyra spp. The maximum benthic macroalgal biomass was estimated to be approximately 10% of the phytoplankton biomass.