Whitford, Philip; Whitford, Kathryn (ed.) / Transactions of the Wisconsin Academy of Sciences, Arts and Letters
volume 74 (1986)
Keough, Janet R.
The Mink River- a freshwater estuary, pp. 1-11 PDF (4.8 MB)
10 Wisconsin Academy of Sciences, Arts and Letters [Vol. 74 More protected communities, such as the wet meadow around the edge of the wetland, are more species-rich. The wet meadow community develops on and around Carex stricta hummocks; this topographic diversity, located higher in the watershed, permits the establishment of more species. Keddy and Reznicek (1985) suggested that the zonation of communities may be related to the position of maximum and minimum high water. They suggest that certain communities—wet meadow and shallow marsh—depend upon periodically exposed substrate for seed establishment. This appears to be so in the Mink River system; only those species that can survive by reproducing vegetatively persist in deep water. Zizania aquatica requires mudflat conditions in spring to germinate. Woody species on the shrub carr do not establish on hummocks, but in the low spots on the wet meadow. They are repeatedly killed by high water. Regeneration of such communities seems to be in phase with the cycle of low water conditions in Lake Michigan. Little is known about the food web associated with Lake Michigan coastal wetlands. Harris et a!. (1977) and Roznik (1978) have suggested that certain birds may respond to the dynamic structure of these emergent plant communities as water level changes from year to year. Furthermore, little is known about how the chemical gradient along the river may influence the distribution of aquatic plants or animals. Many intriguing questions can be raised concerning long-term fluctuations in biomass production by the various plant communities, as well as the fate of biomass and its contribution to the food web of the river and bay. Much can be learned about the adaptations of organisms in such a frequently disturbed coastal environment. Examples include the adaptations to long-term waler level fluctuations by Carex stricta and Calamagrostis canadensis, by species of Scirpus (S. americanum, S. acutus, and S. validus), and by Zizania aquatica. While some coastal wetlands have been protected as natural reserves and are recognized as including unusual species associations or unique habitats, many biological and physical dynamics are still waiting to be explored. ACKNOWLEDGEMENTS Forest Stearns is gratefully acknowledged for support and encouragement during the entire course of this study, and, with Glenn Guntenspergen, offered many helpful suggestions on the manuscript. Many thanks are due the faculty and staff of the U.W. Center for Great Lakes Studies, whose equipment and expertise made the field work possible. U.W.-Green Bay generously provided lodging at Toft Point, under the administration of Keith White. Field assistance was provided by many persons, the most persistent of whom included Joyce Witebsky, Glenn Guntenspergen, and Steve Kroeger. Peter Salamun and Margaret Summerfield helped with identification of submergent species. The study was supported by a grant from the Wisconsin Coastal Management Program to Forest Stearns and by the Raymond Hatcher Fund through the U.W.-Milwaukee Botany Department. This is Contribution 289, U.W. Center for Great Lakes Studies. REFERENCES CITED Bosley, T. R. 1976. Green Bay's west shore coastal wetlands: a history of change. M.S. Thesis. University of Wisconsin-Green Bay. 92 pp. Bosley, T. R. 1978. Loss of wetlands on the west shore of Green Bay. Trans. Wis. Acad. Sci., Arts and Lett. 66:235-245. Brant, R. A. and C. E. Herdendorf. 1972. Delineation of Great Lakes estuaries. In Proc. 15th Conf. Great Lakes Research., I. A. G. L. R., Ann Arbor, MI. pp. 710-7 18. Curtis, J. T. 1959. Vegetation of Wisconsin. University of Wisconsin Press, Madison, WI. 657 pp. Dorr, J. A. Jr. and D. F. Eschman. 1977. Geology of Michigan. University of Michigan Press, Ann Arbor. 475 pp. Fahselt, D. and M. A. Maun. 1980. A quan
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