Haywood, Carl N. (ed.) / Transactions of the Wisconsin Academy of Sciences, Arts and Letters
volume 75 (1987)
Bouchard, Roy; Madsen, John D.
The aquatic macrophyte community of Black Earth Creek, Wisconsin, pp. 41-56 PDF (6.4 MB)
The Aquatic Macrophyte Community of Black Earth Creek, Wisconsin Roy Bouchard and John D. Madsen Abstract. The aquatic macrophyte community of Black Earth Creek, Wisconsin, was studied in June and July of 1985 and compared to data collected in 1981. Macrophyte distribution was examined by the line intercept method, with macrophyte cover negatively correlated to light reduction by tree canopy. The dominant species in the stream was Potamogeton cnispus. Other species included P. pectinatus, P. vaginatus, Elodea canadensis, Ranunculus longimostnis, Hypemicum boneale and filamentous algae, namely Rhizoclonium sp. Average total cover of all macrophytes was 55.6%. Cover of macrophytes was only slightly lower in 1985 than in 1981, which was thought to be due to random population fluctuations rather than directional change in the community. Macrophyte biomass was estimated at three unshaded stations. Maximum macrophyte biomass was 789 g dw m2, with no relation found between biomass and the inflow of a sewage treatment plant. Samples of Potarnogeton cnispus and Rhizoclonium sp. analyzed for tissue phosphorus indicated that plants are not near limiting concentrations for P; rather, present data indicate that light availability limits the growth of macrophytes in Black Earth Creek. Oxygen mass balance was used to estimate community photosynthesis and respiration, and the macrophyte/epiphyte contribution to community respiration estimated by in situ incubations. Macrophyte/epiphyte respiration contributed 47% to 68% of community respiration. The PIR ratio was 0.62, indicating a heterotrophic stream community. quatic macmophytes are an important and habitat for macmoinventebmates and component of stream ecosystems, other small organisms, as well as protecinfluencing physical, chemical and bio- tion for large fish species. Macmophytes logical processes. Aquatic macmophytes increase stream productivity beyond stabilize the stream substrate, reducing energy gained by allochthonous inputs. In turbidity and erosion. They also increase addition to these benefits, macmophytes deposition of suspended solids, further provide surface area for microbes, which reducing turbidity, and oxygenate the contribute significantly to many chemical water by means of photosynthesis. Stream processes in the stream, such as nitnificachannels deepen and current increases tion, respiration, and decomposition. between adjacent plant beds, improving However, excess growths of macrohabitat diversity. Aquatic macmophytes phytes can also create problems for the and attached epiphytic algae provide food stream ecosystem. Bank-to-bank growths of aquatic macmophytes will slow current John D. Madsen, formerly at the University of , Wisconsin-Madison, is now a research associate at velocities, causing flooding and siltation. the Fresh Water Institute, Rensselaer Polytechnic Homogeneous growths of macmophyte Institute, Troy, New York. species reduce habitat heterogeneity. Roy Bouchard is a member of the Maine Depart- Most importantly, excessive plant ment of Environmental Protection. growths create large daily dissolved oxy 41
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