| Badfish Creek, a stream receiving sewage effluent from the city of Madison, is dominated by submerged macrophytic vegetation that causes nighttime depression of dissolved oxygen. This study examines many facets of the ecology of the submerged macrophyte community in Badfish Creek during 1984, and attempts to understand important factors of this community and to provide insignt useful for potential control mechanisms. The dominant species is Potamogeton pectinatus; other species observed were Ceratophyllum demersum, Cladophora glomerata and Elodea canadensis. Maximum total biomass was 710 g m('-2), with shoot biomass peaking at 620 g m('-2). A study of the distribution of biomass throughout the stream indicated that light availability, mediated by tree shading, limited macrophyte biomass. Laboratory experiments using infrared gas analysis indicated that the optimal temperature for net photosynthesis for P. pectinatus is 25 C, with a maximum net photosynthetic rate of 1.39 mg C gAFDW('-1) h('-1). An analysis of the role of macrophytes in the nutrient budget of Badfish Creek indicated that the macrophytes were not a significant reservoir of N, P and K; conversely, nutrients were not limiting to macrophyte productivity. Studies on the germination of P. pectinatus tubers show that temperature is the most important factor controlling the germination of postdormant tubers, with a threshhold temperature of approximately 15 C. The presence of light slightly increases the germination of tubers. The adaptation of leaf morphology to the aquatic environment was examined in a theoretical context. Dissected leaves were found to be adaptive to both stagnant and turbulent flows, while entire leaves were adaptive to habitats with moderate flow velocities. Data on community composition support these observations.;The current control technique, cutting, was analyzed for its efficiency and effects on the environment, and other control techniques were discussed. Cutting was found to be inefficient; other long-term control techniques were suggested, including the establishment of shade trees along the banks to reduce light reaching the macrophyte community. |
