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Are Seagrasses in Charlotte Harbor Migrating Landward in Response to
Expected Sea Level Rise?
Charlotte Harbor Watershed SummitMarch 27, 2008
Judy Ott FDEP South District Laboratory
Environmental Assessment & Restoration& Partners
Environmental Assessment & RestorationCharlotte Harbor Aquatic Preserves
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Background
Questions Relating to Sea Level Rise
Field & Analysis Methods
Results
Discussion
Conclusions
This Presentation Briefly DescribesSeagrass Transect Monitoring in
Charlotte Harbor:
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BACKGROUNDFDEP Charlotte Harbor Aquatic Preserves
Coordinates Seagrass Transect Monitoring:
To Assess Seagrass Conditions Throughout
Charlotte Harbor.
At 50 Fixed Transects.
Every Fall Since 1999.
Consistent with SWFWMD Protocols.
With Help From Many Partners.
Source: CHAPs
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CHAPs Seagrass Transects Compliment Other
Seagrass Monitoring & Aerial Mapping
Programs…
Source: SWFWMD
ON-GOING SEAGRASS TRANSECT MONITORING
# Times
Agency Sites Location Start /Year
FDEP/CHAPs 50 Charlotte Harbor APs 1999 1
FDEP/EBAP 5 Estero Bay AP 2002 2
SCCF 7 Caloosahatchee R 2004 6-12
San Carlos Bay (1999)
FDEP/EAR 6 Caloosahatchee R 2007 4
San Carlos Bay (2000)
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… & Water Quality Monitoring Programs…
FDEP, SCCF & WMDContinuous Data
LoggersCharlotte Harbor
Estuaries Volunteer Water
Quality Monitoring Fixed Sites
Coastal Charlotte Harbor
Monitoring Network
Random Grids
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... To Help Manage the
Estuaries for Long Term Health &
Balanced Uses.
Source: CHAPs
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Studies Show Seagrasses have been Relatively Stable in Charlotte Harbor in the Last Decade:
Seagrass Deep Edge Hasn’t Change Significantly. (Stearns et al 2007, Boswell et al 2006, Ott et al CEHR 2006)
0.0
0.5
1.0
1.5
2.0
Estuary
Sea
gras
s D
eep
Edg
e (m
)
(m)
1999 -2005 Mean Depth at Deep Edge of Seagrasses for Each Estuary
From: Ott 2006
7YearMean
1.61.8
0.8
1.3 1.3
1.7
1.3
1.8
1.0
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Studies Show Seagrasses have been Relatively Stable in Charlotte Harbor in the Last Decade:
Seagrass Deep Edge Hasn’t Change Significantly. (Stearns et al 2007, Boswell et al 2006, Ott et al CEHR 2006)
0.0
0.5
1.0
1.5
2.0
Estuary
Sea
gras
s D
eep
Edg
e (m
)
(m)
1999 -2005 Mean Depth at Deep Edge of Seagrasses for Each Estuary
From: Ott 2006
7YearMean 1999 2000 2001 2002 2003 2004 2005
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Seagrass Acreage Hasn’t Change Significantly. (Corbett et al 2006, Kaufman/SWFWMD 2007)
1982 – 2003 Change in Seagrass Acres in Charlotte Harbor
From: Corbett 2006
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Seagrass Acreage Hasn’t Change Significantly. (Corbett et al 2006, Kaufman/SWFWMD 2007 )
● 18,364 acres● 225 acres increase● 1% change
2004 – 2006 Change in Seagrass Acres in Charlotte Harbor
From: SWFWMD/Kaufman 2007
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But Seagrass Density is Declining in Some Estuaries.(Boswell et al 2006, Stearns et al 2007)
1999 – 2004 Change in Seagrass Density in Charlotte Harbor
From: Boswell et al 2006
Freq
uenc
y of
Qua
drat
s Su
rvey
ed
Estuary
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But Seagrass Density is Declining in Some Estuaries.(Boswell et al 2006, Stearns et al 2007)
From: Boswell et al 2006
1999 – 2006 Change in Seagrass Species Density in Charlotte Harbor
Mea
n B
B A
bund
ance
Mea
n B
B A
bund
ance
Mea
n B
B A
bund
ance
From: Stearns et al 2007
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Seagrass Transect Data is Used by CHNEP to Set Resource Based Water Quality Targets:
Based on Seagrass Deep Edge & Water Clarity.Allows Flexibility in Reaching Water Quality Targets.
Col
or (P
CU
)
Turbidity (NTU) Chlorophyll a
Calculate Levels of Color + Turbidity + Chl a Needed to Sustain Water Clarity.
Plane of Adequate
Water Clarity
Set Water Clarity Targets Based on
Seagrass Light Requirements at
Deep Edge.
Source: CHNEP/Corbett
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But Sea Level is Rising
Oyster Research in Estero Bay (Volety et al).
Mangrove Restoration in Charlotte Harbor (Tattar et al).
& Anecdotal Observations….
SWFRPC Analyses in Charlotte & Lee Co.
Water Resource Planning in Sarasota Bay (Clark et al.)
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…& the NEPs are Incorporating Sea Level Rise in CCMPs & Goals.
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QUESTIONS
BIGGY: How will Sea Level Rise Affect Seagrass Depths, Acres, Abundance &
Water Quality Targets in Charlotte Harbor?
SPECIFICALLY: Have Seagrasses in Charlotte Harbor Migrated Landward in Since 1999?
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Source: CHAPs
METHODSCHAPs Seagrass Monitoring Protocols:
Monitored Each Fall.
50 Fixed Sites in Charlotte Harbor Estuaries.
Sites Grouped by Estuary.Estuary
# Sites
Lemon Bay 6
Gasparilla Sound 7
Myakka River 5
Peace River 5
Charlotte Harbor West 5
Charlotte Harbor East 5
Pine Island Sound 9
Matlacha Pass 4
San Carlos Bay 4
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Few = + < 5% = 1 6-25% = 2 26-50% = 3 51-75% = 4 > 75% = 5
Braun Blanquet Abundance Categories
Fixed Transects from Shore to Seagrass Deep Edge.1 m2 Grids at Defined Intervals Along Each Transect.
5 Seagrass & 6 Physical Parameters.Use Braun Blanquet Abundance Categories.
Tide Stage Observed Relative to MHWL (Barnacles).
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Water Depths are Corrected to Mid-Tide using Observed Tides Stages & Tide Ranges from
Nearest NOAA Tide Gauge.
1.3’
0.9’
0.9’
1.0’1.3’ 1.3’1.2’
1.3’
1.5’
1.4’1.7’
1.5’1.5’
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CHAPs Data Analyses Use Access & SPSS.
Today’s Analyses made with Excel.
Based on 44 Stations, Excluding those with No Seagrass or Data
for > 3 Years:
MYR01 & MYR02
PR01 & PR02
MC01 & PIS08
XX X
X
X
X
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RESULTS
Location of Shoreward Edge of Seagrasses Did Not Move Significantly from 1998 – 2007.
Only 4 of 44 Seagrass Transect Sites Showed the Shallow Edge of Seagrasses Moved
Significantly Shoreward.
?
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CHANGE LOCATION OF SHALLOW EDGE OF SEAGRASS 1998 - 2007
Total # # Sites # Sites # Sites
Estuary Sites Changing Shoreward Waterward
Lemon Bay 6 2 GAS01 ICW05
(R2=.410 P=.05) (R2=.991 P=.000)
Gasparilla Sound 6 1 GAS05
(R2=.738 P=.00)
Myakka+Peace R 6 0
Charlotte Harbor 9 2 PIS01 PIS03
(R2=.869 P=.00) (R2=.690 P=.00)
Pine Island Sound 9 2 PIS05 PI04
(R2=.390 P=.05) (R2=.657 P=.01)
Matlacha Pass 4 0
San Carlos Bay 4 1 MP05
(R2=.722 P=.00)
Total 44 8 4 4
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GAS01 Shoreward 5 m
GAS05 Shoreward 4 m
MP05 Shoreward 2 m
PIS01 Shoreward 15 m
PIS05 Shoreward 4 m
ICW05 Waterward 5 m
PI04 Waterward 2 m
PIS03 Waterward 12 m
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Water Depth Did Not Increase Significantly From 1998 – 2007.
All Estuaries
Mean SE
1999 -49 4.12
2000 -51 3.83
2001 -47 3.78
2002 -50 2.75
2003 -47 2.63
2004 -53 2.59
2005 -57 2.71
2006 -50 2.73
2007 -55 3.34
All Years -51 1.06
R2 0.239
P 0.15
MEAN DEPTH AT SHALLOW EDGE REFERENCE POINT
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No Estuaries Showed Significant Changes in Water Depth at Shallow Edge Reference Point.
Mean Depth (cm) at Seagrass Shallow Edge Refrence Location ("0 Stake") 1999 - 2007
-70
-60
-50
-40
-30
-20
-10
0
Estuary
Dep
th (cm
)
41 cmSE=1.6R2=.060P=.08
54 cmSE=3.8R2=.000P=.89
52 cmSE=2.3R2=.000P=.97
48 cmSE=1.4R2=.014P=.31
58 cmSE=2.7R2=.018P=.24
52 cmSE=2.5R2=.002P=.80
48 cmSE=4.8R2=.022P=.40
51 cmSE=1.1R2=.239P=.15
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But 1 Estuary & Region as a Whole Showed Significant Increases in Water Depth at
Deep Edge of Seagrasses.
Mean Depth (cm) at Seagrass Deep Edge 1999 - 2007
-200
-150
-100
-50
0
Estuary
Dep
th (cm
)
158 cmSE=5.3R2=.030P=.22
176 cmSE=6.7R2=.05P=.12
87 cmSE=2.1R2=.01P=.43
124 cmSE=4.6R2=.01P=.54
169 cmSE=5.5R2=.03P=.15
128 cmSE=5.2R2=.03P=.36 186 cm
SE=4.8R2=.37P=.00
147 cmSE=2.3R2=.01P=.05
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DISCUSSION
Improved Accuracy of Seagrass Transect Locations Each Year with GPS.
Improved Analysis & Availability of Seagrass Data Access Data Base & Summary Reports.
Improved Precision of Seagrass Transect Locations Improved Each Year with More Stakes.
Improved Description of Seagrass Abundance Since 2005 with Addition of Shoot Counts &
Total Abundances.
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CONCLUSIONS
Based on Preliminary Analysis of Seagrass Transect Data, Seagrasses Do not Appear to
have Moved Shoreward since 1998.
More Precise Tide Measurements During Seagrass Monitoring will Enhance the Ability to Detect
Smaller Changes in Water Depth.
Depth Measurements Collected with Seagrass Transect Data Did Not Find a Significant Increase in
Water Levels in Charlotte Harbor since 1998.
More Rigorous Statistical Analyses are Needed to Relate Seagrass Changes to Sea Level Rise..
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CONCLUSIONS
Continuing Seagrass Transect Monitoring & Improving Tide Estimations will Enhance Links
between Seagrass Health, Water Quality Targets & Sea Level Rise.
Based on this & Recent Seagrass Reports, Mean Deep Edge of Seagrass Growth is An
Effective Tool for Evaluating Water Quality Targets.
Seagrass Distribution & Abundance Reflect Seasonal Changes in Seagrass Conditions Related
to Rainfall & Changes in Salinity Regimes.
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Thank You to All the Many People Who Helped with “Seagrassing” Since 1998:
FDEP: Neil Ayers, Erin Dykes, Stephanie Erickson, Trink Fletcher, Debbie Horner, Carla Kappmeyer, Ray
Leary, Jennifer Nelson, Mindy Schneider-Brown, Heather Stafford, Jennifer Thera & Celia Stearns
CHEC: Renee Duffey & Jason Hale
CHNEP: Catherine Corbett
& MANY OTHERS INCLUDING: Rick Bartleson, Jaime Boswell, Brian Cotterill, Ken Cummins,
Katie Fuhr, Kris Kaufmann, Ray Kurz, Jim Lacascio, Ronda McKenzie, Bob Repenning, Tom Ries, Karen Shudes, Betty Staugler, Kendra Willett,
Peggy Wilzbach & Bill Van Oyen
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FDEP in Punta Gorda:
South Distinct LaboratoryEnvironmental Assessment & Restoration
(941) 575-5810
&
Charlotte Harbor Aquatic Preserves(941) 575-5861
or
Judy OttUntil April 2: [email protected]
Starting April 3: [email protected] (239) 338-2550 Ext 230
For More Information, Please Contact: