hydrodynamic limitations and the effects of living ... · hydrodynamic limitations and the effects...
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Hydrodynamic Limitations and the Effects of Living Shoreline Stabilization on Mangrove Recruitment Christian Pilato1, Kelly Kibler2, Melinda Donnelly1, Linda Walters1
1Department of Biology2Department of Civil, Environmental, and Construction EngineeringUniversity of Central Florida
Stabilization and Mangrove Restoration
Lewis, 2005; Samson and Rollon, 2008
Replace pic
• Success = self sustaining
• Sensitive to local hydraulic conditions
• Hydrodynamic thresholds not well defined or considered
• Often fails• Mostly due to hydrologic issues• 50% average survival in “developed” countries,
11% survival in “developing” countries
De Soto National Memorial: 2017
De Soto National Memorial: 2017
150 meters of shoreline restored:• 270 mangroves• 1800 oyster shell bags
Contributors:• Coastal and Estuarine Ecology Lab• National Park Service• Coastal Conservation Association• 80 local volunteers
Shell bags as wave breaks
Pro
pag
ule
s p
er 0
.25
m2
±(S
.E.)
Seasonal propagule release begins
Res
tora
tion
Hur
rican
e Irm
a
NaturalRestoredRevetment
Seasonal propagule release begins
2017-2018 Monitoring
Seed
lings
per
0.2
5m
2 ±
(S.E
.)
2017-2018 Monitoring 2017-2018 Monitoring
Hydrodynamic Thresholds to Recruitment
Photo: Bywater et al., 2015
Are hydrodynamic forces limiting recruitment?
~3 month old black mangrove
Limitations to Recruitment
Ɵ
Hand-
powered
winch
FD (drag force)
Avicennia germinans
Rhizophora mangle
Avicennia germinans
Rhizophora mangle
Hand-winch
Load cell
Seedling5cm 5cm
Greenhouse test
Greenhouse Results
R. mangleA. germinans
Forc
e to
Rem
ova
l (kg
*m/s
2)
Below-ground biomass (g)
50 kg*m/s2 = ~11 pound-force
R. mangleA. germinans
Forc
e to
Rem
ova
l ±S.
E. (
kg*m
/s2)
Month
Mean Force to Removal through Time
R. mangleA. germinans
Bel
ow
-gro
un
d B
iom
ass
±S.
E. (
g)Month
Mean Below-ground Biomass through Time
Greenhouse Results
CANA 1
CANA 2
De Soto 1
De Soto 2
De Soto 1
Avicennia germinans
Rhizophora mangle
Field Results
Below-ground Biomass (g)
Forc
e to
Rem
ova
l (kg
*m/s
2)
Force to removal (95% CI)
R. mangleA. germinans
50 kg*m/s2 = ~11 pound-force
Sediment Graph
Field ResultsFo
rce
to R
emo
val ±
S.E.
(kg*
m/s
2)
R. mangleA. germinans
R. mangleA. germinans
Forc
e to
Rem
ova
l (kg
*m/s
2)
Surrounding Vegetation Cover (%)
Sediment Grain Size: D84 (mm)
Effects of Vegetation Cover (95% CI)Effects of Sediment Grain Size
0.5 m
Calculating Velocities
Drag force
Drag coefficient
Frontal area
Velocity of the fluidDensity of
the fluid
Uprooting Critical Velocities:• Mazda et al., 1997: 1.41-7.07 m/s• Tanino and Nepf, 2008: 1.62-3.31 m/s• J. Struve et al., 2003: 4.19-4.52 m/s, Extreme: 2.01 m/s• Ni, Y., 2014: 4.08-8.94 m/s
Avicennia germinans Rhizophora mangle
Mean frontal area= 10.69 cm2
Mean frontal area= 53.47 cm2
Caveats:• Erosion not considered• Grouped estimates for both species• Account for plant flexibility• Test more drag coefficients
Grouped Mean Frontal area= 32.08 cm2
=
Avicennia germinans
Rhizophora mangle
Uprooting Critical Velocities (red mangrove):••••
Acknowledgements