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J essica Sherman Central Michigan University

This study explores the existence of refuge populations of unionids (freshwater mussels) in Great Lakes coastal wetlands and the impact of water level fluctuations on their habitat. Conducted by Jessica Sherman at Central Michigan University, the research employs water quality measurements and surveys across various sites, including Saginaw Bay and North Maumee Bay. Results indicate the presence and fouling status of unionid species, as well as the extent of dreissenid colonization, highlighting ecological dynamics in these critical wetland ecosystems.

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J essica Sherman Central Michigan University

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  1. Jessica Sherman Central Michigan University Great lakes coastal wetlands: What is a refuge for unionids?The effects of water level fluctuations

  2. Introduction • Jessica Sherman • B.S. in Biology and Pre-Veterinary Medicine from the University of Findlay • Currently at CMU for M.S. in Conservation Biology • Advisor: Don Uzarski • Committee: Dave Zanatta, DaelynWoolnough, and Brent Murry

  3. Objectives • Locate refuge populations of unionids in Great Lakes coastal wetlands • Measure chemical and physical parameters • Determine if any support unionids or inhibit dreissenid colonization

  4. Methods • Project began in early June • Initial set up phase • Sites revisited at six and 12 weeks • Inner and outer wetland surveyed • Emergent stem densities

  5. Grand Traverse Bay Study Sites

  6. Beaver Island

  7. Garden Island

  8. The Les Cheneaux Islands

  9. Saginaw Bay

  10. Lake St. Clair Delta

  11. North Maumee Bay

  12. Methods • Water Quality Measurements • Multiparameter Water Quality Sonde • Water gauges

  13. Methods • Water Quality Measurements • Multiparameter Water Quality Sonde • Water gauges

  14. Methods • Dreissenid Colonization • Unglazed clay tiles • 16x16 cm

  15. Methods • Unionid Surveys • Initial 1 p-h visual search for live mussels • Staked location • Snorkeled searches

  16. Methods • Unionid Surveys • Initial 1 p-h visual search for live mussels • Staked location • Snorkeled searches • Except… • North Maumee Bay

  17. Methods • Unionid Surveys • Clam rake surveys • Haphazard starting location

  18. Results • Live Unionids found • Les Cheneaux Islands • 1 species • 100% fouled • Lake St. Clair Delta • 10 species • 85% fouled • North Maumee Bay • 2 species • 50% fouled

  19. The Les Cheneaux Islands Lake St. Clair Delta = Unionids present = Unionids absent North Maumee Bay

  20. Results • Dreissena colonization on tiles only at Saginaw Bay and North Maumee Bay • Highest 20,741 and 31,007 per m2 , respectively • Present in open water of all sites studied • Saginaw Bay historically contained 13 unionid species Ricciardi et al. 1995, Goodrich and Vander Schalie 1932

  21. Saginaw Bay Results 5,087 per m2 46 per m2 = No colonization = Colonization 20,741 per m2 North Maumee Bay 821 per m2 31,007 per m2 0 per m2 * Highest Recorded Dreissenid Colonization Outer wetland higher than inner

  22. Results 18.5% 28%

  23. Results

  24. Results

  25. Results

  26. Conclusions • Physicochemical variables in Saginaw Bay & North Maumee Bay appear to support Dreissena colonization • Low productivity could inhibit Dreissena colonization • No correlations between unionid populations and physicochemical factors

  27. Thank you!

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