Distribution of Aquatic Macrophytes Related to Paper Mill Effluents in a Southern Michigan Stream

Cover, volume and dry weight of the aquatic macrophytes of Portage Creek in Kalamazoo Co., Michigan, were studied. Two series of water analyses 4 years apart were made for the length of the stream. The stream began in an unpopulated, uncultivated area and flowed into an urban area where it received paper mill wastes, after which the aquatic macrophytes were completely absent. The second series of analyses, made 1 year after the cessation of paper mill effluents, showed a tenfold reduction of turbidity in the polluted portion, suggesting that turbidity was the most probable cause for the absence of macrophytes in previous years. The substrate cover by macrophytes in the upstream unpolluted portion was 41%. On the basis of the total plant cover, the two dominant species were Potamogeton pectinatus (44%) and Sparganium americanum (18%). The portion of the water volume occupied by aquatic macrophytes was 0.043%. Four of the 10 species found occupied 82.8% of the total plant volume (Nasturtium officinale, 25.4%; Potamogeton crispus, 22.0%; P. pectinatus, 18.4%; Elodea canadensis, 17.0%). The same four species comprised 83.3% of the dry weight (E. canadensis, 23.7%; P. crispus, 21.8%; N. officinale, 19.9%; P. pectinatus, 18.5%).