B.S. Cheng and K.A. Hovel
Authors: Brian S. Cheng and Kevin A. Hovel
Manuscript Title: Biotic resistance to invasion along an estuarine gradient
Contact Information: Brian Cheng, bscheng@ucdavis.edu, 925-876-7988
Supplementary Material 1. Proportional chalk block loss (mean ± SE) across the estuarine
gradient. Sites are listed from left to right with increasing distance away from bay mouth for riprap (R) and soft-sediment (S) sites.
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B.S. Cheng and K.A. Hovel
Supplementary Material 2. Scatterplots of eelgrass habitat principle components (X and Y
axis) against mussel counts (color) in a) 2006 and b) 2007. Interpretation can be made by
comparing changes in color along each X and Y axis (for main effects). Interactive effects are
evident if changes in color proceed along the diagonal. Color scale is the same for both years.
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B.S. Cheng and K.A. Hovel
Supplementary Material 3. Pooled Asian mussel recruitment at R1 and R2 sites in 2007 (mean
mussel counts per core ± SE, left axis) and shell height (mean ± SE, right axis).
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B.S. Cheng and K.A. Hovel
Supplementary Material 4. Length frequency histograms of all Asian mussel recruits collected
at R1 and R2 during the recruitment pulse in 2007.
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B.S. Cheng and K.A. Hovel
Supplementary Material 5. Results from fully caged artificial seagrass units deployed along the
estuarine gradient. Proportional mussel survival (mean + SE) in a) 2006 (n = 22) and b) 2007 (n
= 12). c) Dry weight (mean + SE) in 2007 and d) gonad index (mean + SE). Gonad index is
calculated as gonad weight divided by total body weight. Letters indicate group designations
from Student-Newman-Keuls post-hoc tests in C & D (P < 0.05). ND = no data, data excluded
due to predator intrusion into plots. Sites are listed from left to right by increasing distance away
from bay mouth.
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B.S. Cheng and K.A. Hovel
Supplementary Material 6. Eelgrass habitat structure along the estuarine gradient. Shoot
density (mean number per core +SE, closed circles) and shoot length (mean +SE, open circles) in
a) 2006 and b) 2007.
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B.S. Cheng and K.A. Hovel
Supplementary Material 7. ANOVA table for the restricted analysis on open plots at sites less
than 3.5 km from the bay mouth testing the effects of distance and habitat and their interaction
on proportional mussel mortality. Adjusted r2 = 58.2%.
Source
SS
df
MS
F-ratio
P
Distance
3.812
1
3.812
50.440
<0.001
Habitat
0.716
1
0.716
9.48
0.003
Distance * Habitat
1.054
1
1.054
13.953
<0.001
Error
3.930
52
0.076
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B.S. Cheng and K.A. Hovel
Supplementary Material 8. Proportional Asian mussel mortality (mean + SE) in all cage
treatments after seven day deployments across the estuarine gradient. Data from years 2006 and
2007 have been pooled for brevity.
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