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GREAT LAKES COASTAL WETLANDS: WHAT IS A REFUGE FOR UNIONIDS? THE EFFECTS OF WATER LEVEL FLUCTUATIONS Jessica Sherman Central Michigan University
GREAT LAKES COASTAL WETLANDS: WHAT IS A REFUGE FOR UNIONIDS?
THE EFFECTS OF WATER LEVEL FLUCTUATIONS
Jessica ShermanCentral Michigan University
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, Daelyn
Woolnough, and Brent Murry
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
Methods Project began in early June
Initial set up phaseSites revisited at six and 12 weeks
Inner and outer wetland surveyedEmergent stem densities
Grand Traverse Bay
Study Sites
Beaver Island
Garden Island
The Les Cheneaux Islands
Saginaw Bay
Lake St. Clair Delta
North Maumee Bay
Methods Water Quality Measurements
Multiparameter Water Quality SondeWater gauges
Water Quality MeasurementsMultiparameter Water Quality SondeWater gauges
Methods
Methods Dreissenid Colonization
Unglazed clay tiles○ 16x16 cm
Unionid SurveysInitial 1 p-h visual search for live
mussels○ Staked location○ Snorkeled searches
Methods
Unionid SurveysInitial 1 p-h visual search for live
mussels○ Staked location○ Snorkeled searches○ Except…
North Maumee Bay
Methods
Unionid SurveysClam rake surveys
○ Haphazard starting location
Methods
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
North Maumee Bay
Lake St. Clair DeltaThe Les Cheneaux Islands
= Unionids present
= Unionids absent
Results Dreissena colonization on tiles only at
Saginaw Bay and North Maumee BayHighest 20,741 and 31,007 per m2 ,
respectivelyPresent in open water of all sites studied
Saginaw Bay historically contained 13 unionid species
Ricciardi et al. 1995, Goodrich and Vander Schalie 1932
Saginaw Bay
5,087 per m2
46 per m2
20,741 per m2
* Highest Recorded Dreissenid Colonization Outer wetland higher than inner
North Maumee Bay
0 per m2
821 per m231,007 per m2
Results = No colonization = Colonization
ResultsPhysicochemical Parameters by Region
PC 1
-6 -4 -2 0 2 4 6 8
PC
2
-6
-4
-2
0
2
4
Temperature
Conductivity
Oxygen
Turbidity
TDS
pH
Alkalinity
Water Depth
Substrate Depth
NH3
SRP
NO4
Saginaw BayLes Cheneaux IslandsBeaver IslandLake St. Clair DeltaNorth Maumee BayGarden IslandGrand Traverse Bay
ConductivityAlkalinityTDS
pH
pHTemperatureTurbidity
Water Depth
28%
18.5
%
Results
ResultsLow Water Level Measurements by Region
PC 1
-6 -4 -2 0 2 4 6 8
PC
2
-6
-4
-2
0
2
4Saginaw BayLes Cheneaux IslandsBeaver IslandLake St. Clair DeltaNorth Maumee BayGarden IslandGrand Traverse Bay
0-0.08 m
0.09-0.2 m
> 0.2 m
Low Water Measurements
28%
18.5
%
ResultsWater Level Fluctuations by Region
PC 1
-6 -4 -2 0 2 4 6
PC
2
-6
-4
-2
0
2
4Saginaw BayLes Cheneaux IslandsBeaver IslandLake St. Clair DeltaNorth Maumee BayGarden IslandGrand Traverse Bay
Water Level Fluctuations
0- 0.25 m
0.25- 0.5 m
0.5- 0.75 m
0.75-1.0 m> 1.0 m
28%
18.5
%
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
Thank you!
