1. Unionid research in Lake Erie coastal wetlands
Ferenc A. de Szalay, Richard Bowers, and Doug Kapusinski
Department of Biological Sciences

2. Since 1980s, Zebra mussels invaded lower Great Lakes
Since 1980s, Zebra mussels invaded lower Great Lakes
caused drastic declines of unionids
Surveys by Zanatta, Nichols, Schloesser et al. found remnant unionid populations in some Great Lakes CW and nearshore areas

3. Crane Creek Marsh, Ottawa NWR

4. Sampled 77 random locations in 2001
Crane Creek Marsh, Ottawa NWR
Sampled 77 random locations in 2001
Tactile searches for 4 person hours per 50 x 50 m plot
Collected zebra mussels on PVC plates at 4 locations

5. Abundant ZM at all locations
Most in deep areas (>35 cm)

6. Collected 1129 unionids in 15 species
Dominant species: Q. quadrula, P. grandis, L. fragilis, A. plicata
Aged years

7. Unionids clustered in deep areas (>35 cm) not exposed during late season seiches
Attached Zebra mussels highest in deep areas

8. GIS analysis – patchy distribution of unionids
Most in stream channel, deep pools
Few in areas dewatered during seiches

9. Thick shell species inhabited deepest areas (>35 cm)
Thin shell species inhabited deep & shallow areas (>15 cm)

10. 2001-2008 surveys similar unionid communities at other sites at Ottawa NWR

11. 63% with up to 1/4 of shell covered with byssal threads
77% had no live zebra mussels on shell

12. Why are unionids surviving in Crane Creek Marsh?
Zebra mussel mortality when unionids burrow in sediments (e.g. Nichols and Wilcox 1997)
Predation of zebra mussels by fish and waterfowl (e.g., Petrie and Knapton 1999, Magoulick and Lewis 2002)

13. Predator Exclosure Experiment
5-m diameter Exclosures with:
3 X 3 cm mesh sides - Fishless
3 X 3 cm mesh sides with 1 m X 1 m holes - Open
Stakes only - Sham

14. Added live Quadrula quadrula, Leptodea fragilis in June 2007
Collected in July & September 2007
Counted attached zebra mussels

15. Q. quadrula - Fishless >> Open = Sham
L. fragilis - N.S.

16. Implications Predators limit zebra mussels on unionids
Which predators are impacting zebra mussels?

18. Carp Enclosure Experiment
5-m diameter Exclosures with:
3 X 3 cm mesh sides - Fishless
Stakes only - Sham
3 X 3 cm mesh sides with 1 carp - Carp
Added live and dead Q. quadrula in June 2008
Collected live and dead Q. quadrula in July, Sept. 2008
Counted attached zebra mussels

19. Live Q. quadrula - Fishless >> Sham = Carp
Dead Q. quadrula - Fishless >> Sham = Carp

20. Conclusions Zebra mussel survive in Great Lakes coastal marshes
Zebra mussel reduced by fish predation
Common Carp are key predators of zebra mussel on unionids
Unionid burrowing during summer does not eliminate attached zebra mussels

21. Thanks to:
Dan Frisk, Doug Brewer, Ron Huffman, USFWS; Chris Dwyer, Ohio DNR
Field and laboratory help by D. Kapusinski, J. Clark, N. Yaussy, J. Bowers, A. Brager. M. Rubin, K. Gee, Robert Christy, KSU photgrapher
Funded provided by Ohio Department of Natural Resources, Lake Erie Protection Fund, A.&M. Herrick Aquatic Ecology Research Facility Fund