Wind-derived seiches as a means for detecting
and monitoring the unionid community in the
western basin of Lake Erie
Todd D. Crail
Philip M. Mathias, Johan F. Gottgens, Jon M. Bossenbroek
The University of Toledo
My Questions
• Increasing number of refuges…
• Are unionids found anywhere else, such as the
in-shore marshes and near-shore open lake
habitats?
• Can I sample them? And how?
• Richness? Recruitment?
• Historic sequence in shell material?
Sampling Sites
N
Lake Erie
• Eight sites
“qualitatively”
sampled 2003-2008
Luna Pier
• Sites open to lake,
with dreissenids
present
Bayshore
Maumee Bay SP
Turtle Creek
• Most sites also had
diked marshes
Ottawa NWR
Toussaint Creek
East Harbor
Winous
Point
• Recovered live
individuals of at
least two species at
all sites
Sampling Sites – “Marshes”
• First sites sampled were drowned
river mouths and hemi-marsh
• Methods were tactile and a modified
basket rake
• Timed searches, measured shell
length, and classified as live, fresh
dead, weathered and sub-fossil
• Mobility increased greatly using
snow shoes
Sampling Sites – “Marshes”
• Diked marshes had four species live
–
–
–
–
Pyganodon grandis – Giant Floater
Toxolasma parvus - Liliput
Uniomerus tetralasumus – Pondhorn
Utterbackia imbecillis – Pond Papershell
• Open sites had up to seven species
live
–
–
–
–
–
Leptodea fragilis - Fragile Papershell
Lasmigona complanata - White Heelsplitter
Potamilus alatus - Pink Heelsplitter
Giant Floater
Quadrula quadrula - Mapleleaf
• Refer to Bowers & de Szalay 2004,
American Midland Naturalist
• Noticed the profound effect of seiches
& how it simplified sampling
Example Seiche (2003)
6
Displacement (feet)
4
2
0
-2
-4
-6
-8
Time (hours)
http://en.wikipedia.org/wiki/Seiche
Example Seiche – Bayshore Road (2006)
One meter seiche during low water
Example Seiche – Bayshore Road (2006)
One meter seiche during low water
Bayshore - 2006
•
Four species recovered live
–
–
–
–
•
Amblema plicata – Threeridge
Fragile Papershell
Giant Floater
Pink Heelsplitter
In a 20 minute timed search, we
found, measured, recorded and
replaced 34 individuals (3 species)
– Roughly 35 seconds per individual
•
In an additional 25 minute search, we
found 5 live threeridge
•
Found 6 species fresh dead to lightly
weathered
•
Found 3 species sub-fossil
•
The farther the seiche went out, the
greater the abundance of live mussels
Bayshore - 2006
• Fragile Papershell
– 28 individuals
– Length was 29 – 114 mm
– Mean Length was 74 mm
• Threeridge
– 5 individuals
– Length was 59 – 80 mm
– Mean Length was 71 mm
Bayshore - 2006
• Rate of dreissenid infection was
< 10 dreissenids on any
individual except (1) 109 mm
fragile papershell (19)
Partitioning of Habitat?
RED – Fragile Papershell
BLUE – Threeridge
Green – Giant Floater
Time Series
1955 1960
1965
Sub-Fossil
1970
1975
1980
Weathered
1985
1990
1995
2000
Fresh Dead
More accurately account for time since death, since we can
age live dreissenids inside the shell?
2006
Time Series
1955 1960
1965
1970
1975
1980
1985
1990
1995
2000
?
Sub-Fossil
Weathered
Fresh Dead
Weathering is a spectrum depending on the system and species
2006
Time Series
1955 1960
1965
1970
1975
1980
1985
1990
1995
2000
?
?
?
?
Sub-Fossil
?
Weathered
Fresh Dead
Fossilization is a spectrum process as well but…
2006
Time Series
1955 1960
1965
1970
1975
1980
1985
1990
1995
2000
?
?
?
Sub-Fossil
?
?
Weathered
Fresh Dead
Fossilization is a spectrum process as well but…
Why aren’t sub-fossil species found in the current assemblage?
2006
Time Series
1955 1960
1965
1970
1975
1980
1985
1990
1995
2000
?
?
?
Sub-Fossil
?
?
Weathered
Fresh Dead
Fossilization is a spectrum process as well but…
Why aren’t sub-fossil species found in the current assemblage?
Why aren’t weathered, fresh dead & live species found in the
sub-fossil assemblage?
2006
Winous Point Marsh Conservancy - 2006
• 6 species live (white heelsplitter, fragile papershell, pink heelsplitter,
giant floater, lilliput, pond papershell)
• 4 species fresh dead (threeridge, Obliquaria reflexa - threehorn
wartyback, mapleleaf, pimpleback)
Bayshore & Maumee Bay SP - 2008
• ~0.5 meter seiche event
• At Bayshore Road
– 32 individuals / 3 species
– 28 were fragile papershell
• mean length of 55 mm
• mean length of 74 mm in 2006
• At Maumee Bay SP
– 22 individuals / 2 species
– 17 were fragile papershell
• range 16 – 112 mm
• mean length was 38 mm
• mode was 29 mm
– Continuous distribution
– 6 weathered species
More Partitioning of Habitat?
RED – Fragile Papershell
BLUE – Threeridge
Green – Giant Floater
More Partitioning of Habitat?
RED – Fragile Papershell
BLUE – Threeridge
Green – Giant Floater
YELLOW – Papershell, Floater
and Pink Heelsplitter Juveniles!
Is this evidence of ontogenic shifts?
Or is it just a population sink?
Bayshore - 2008
• (4) 100 meter transects
with a modified BR-12
basket rake
– www.shellfishing.com
• No live species
• Is the Missouri
Trawl the
answer?
Substrates
Higher Quality Substrate?
Potamogeton crispus, Lyngbia sp. and Dreissenia building substrate deep
enough for Unionids to burrow
Higher Quality Substrate?
140 mm white heelsplitter in Dreissenid fortified fine silt
(other Unionid species present as well)
Ponar Sampling at Bayshore 2010
Our Ponar Rig
Ponar Sampling at Bayshore 2010
Sediment Dry Mass from Bayshore Outlet to Maumee Bay State Park
700
R2 = 0.43
Sediment Dry Mass
600
500
400
300
200
100
0
0
5
10
15
Site Number
20
25
Ponar Sampling at Bayshore 2010
Sediment Dry Mass from Bayshore Outlet to Maumee Bay State Park
700
R2 = 0.43
Sediment Dry Mass
600
500
400
300
200
100
0
0
5
10
15
Site Number
20
25
Ponar Sampling at Bayshore 2010
Sediment Dry Mass from Bayshore Outlet to Maumee Bay State Park
700
R2 = 0.43
Sediment Dry Mass
600
500
400
300
200
100
0
0
5
10
15
Site Number
20
25
Ponar Sampling at Bayshore 2010
Sediment Dry Mass from Bayshore Outlet to Maumee Bay State Park
700
R2 = 0.43
Sediment Dry Mass
600
500
400
300
200
100
0
0
5
10
15
Site Number
20
25
Ponar Sampling at Bayshore 2010
Sediment Dry Mass from Bayshore Outlet to Maumee Bay State Park
700
R2 = 0.43
Sediment Dry Mass
600
500
400
300
200
100
0
0
5
10
15
Site Number
20
25
Ponar Sampling at Bayshore 2010
Ponar Sampling at Bayshore 2010
Site 2
Ponar Sampling at Bayshore 2010
Site 11
Ponar Sampling at Bayshore 2010
Site 18
Lake-Influenced Maumee River 2010
• Live fragile papershell, deertoe, threehorn
wartyback, threeridge, mapleleaf, pimpleback, pink
heelsplitter, white heelsplitter, giant floater, liliput,
wabash pigtoe, fat mucket
Lake-Influenced Maumee River 2010
• Live fragile papershell, deertoe, threehorn
wartyback, threeridge, mapleleaf, pimpleback, pink
heelsplitter, white heelsplitter, giant floater, liliput,
wabash pigtoe, fat mucket
X
X
XXX
X
X
X
Port Clinton 2010
• Fresh Dead shell from fragile papershell, giant
floater, threeridge, white heelsplitter, pink
heelsplitter, threehorn wartyback, deertoe and
pond mussel on a public beach.
Port Clinton 2010
• I hypothesize the success of the community has to
do with sediment conveyance
• This resolves fouling, food, and stability
My Questions with Answers
• Unionids are found elsewhere, such as the inshore marshes and near-shore open lake
habitats.
• I can sample them… with luck or hard work
• There’s richness. There’s recruitment.
• There’s an historic sequence in shell material,
but it’s different at two times.
More Questions Than Answers
• What is the mechanism?
• Veliger density dependent? Reduction of
dreissenid health? Dreissenid predator density?
Dreissenid air exposure? Or is it about substrate?
• Or all of the above? Are there factors not
considered?
• Where else are they? And how can we find them?
Acknowledgements
• Fellowship with the National Science
Foundation GK-12 Program DGE-0742395
• Funding from the Winous Point Marsh
Conservancy
• Lake Erie Center & Department of
Environmental Sciences
• Field help from Maria Tumeo
• Thoughtful comments from Tom Bridgeman