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Are Seagrasses in Charlotte Harbor Migrating Landward in Response to Expected Sea Level Rise?

Are Seagrasses in Charlotte Harbor Migrating Landward in Response to Expected Sea Level Rise?. Charlotte Harbor Watershed Summit March 27, 2008. Judy Ott FDEP South District Laboratory Environmental Assessment & Restoration & Partners. Environmental Assessment & Restoration

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Are Seagrasses in Charlotte Harbor Migrating Landward in Response to Expected Sea Level Rise?

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  1. Are Seagrasses in Charlotte Harbor Migrating Landward in Response to Expected Sea Level Rise? Charlotte Harbor Watershed Summit March 27, 2008 Judy Ott FDEP South District Laboratory Environmental Assessment & Restoration & Partners Environmental Assessment & Restoration Charlotte Harbor Aquatic Preserves

  2. This Presentation Briefly Describes Seagrass Transect Monitoring in Charlotte Harbor: Background Questions Relating to Sea Level Rise Field & Analysis Methods Results Discussion Conclusions

  3. BACKGROUND FDEP 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

  4. CHAPs Seagrass Transects Compliment Other Seagrass Monitoring & Aerial Mapping Programs… Source: SWFWMD

  5. … & Water Quality Monitoring Programs… Coastal Charlotte Harbor Monitoring Network Random Grids FDEP, SCCF & WMD Continuous Data Loggers Charlotte Harbor Estuaries Volunteer Water Quality Monitoring Fixed Sites

  6. ... To Help Manage the Estuaries for Long Term Health & Balanced Uses. Source: CHAPs

  7. Studies Show Seagrasses have been Relatively Stable in Charlotte Harbor in the Last Decade: 1999 -2005 Mean Depth at Deep Edge of Seagrasses for Each Estuary 1.8 1.8 1.7 1.6 1.3 1.3 1.3 (m) 1.0 0.8 7 Year Mean From: Ott 2006 Seagrass Deep Edge Hasn’t Change Significantly. (Stearns et al 2007, Boswell et al 2006, Ott et al CEHR 2006)

  8. Studies Show Seagrasses have been Relatively Stable in Charlotte Harbor in the Last Decade: 1999 -2005 Mean Depth at Deep Edge of Seagrasses for Each Estuary (m) 7 Year Mean 1999 2000 2001 2002 2003 2004 2005 From: Ott 2006 Seagrass Deep Edge Hasn’t Change Significantly. (Stearns et al 2007, Boswell et al 2006, Ott et al CEHR 2006)

  9. 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

  10. Seagrass Acreage Hasn’t Change Significantly. (Corbett et al 2006, Kaufman/SWFWMD 2007 ) 2004 – 2006 Change in Seagrass Acres in Charlotte Harbor • 18,364 acres • 225 acres increase • 1% change From: SWFWMD/Kaufman 2007

  11. 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 Frequency of Quadrats Surveyed Estuary From: Boswell et al 2006

  12. Mean BB Abundance Mean BB Abundance Mean BB Abundance But Seagrass Density is Declining in Some Estuaries. (Boswell et al 2006, Stearns et al 2007) 1999 – 2006 Change in Seagrass Species Density in Charlotte Harbor From: Stearns et al 2007 From: Boswell et al 2006

  13. Seagrass Transect Data is Used by CHNEP to Set Resource Based Water Quality Targets: Set Water Clarity Targets Based on Seagrass Light Requirements at Deep Edge. Calculate Levels of Color + Turbidity + Chl a Needed to Sustain Water Clarity. Color (PCU) Plane of Adequate Water Clarity Chlorophyll a Turbidity (NTU) Source: CHNEP/Corbett Based on Seagrass Deep Edge & Water Clarity. Allows Flexibility in Reaching Water Quality Targets.

  14. But Sea Level is Rising Water Resource Planning in Sarasota Bay (Clark et al.) Mangrove Restoration in Charlotte Harbor (Tattar et al). Oyster Research in Estero Bay (Volety et al). SWFRPC Analyses in Charlotte & Lee Co. & Anecdotal Observations….

  15. …& the NEPs are Incorporating Sea Level Rise in CCMPs & Goals.

  16. 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?

  17. METHODS CHAPs Seagrass Monitoring Protocols: Monitored Each Fall. 50 Fixed Sites in Charlotte Harbor Estuaries. Sites Grouped by Estuary. Source: CHAPs

  18. 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). Few = + < 5% = 1 6-25% = 2 26-50% = 3 51-75% = 4 > 75% = 5 Braun Blanquet Abundance Categories

  19. Water Depths are Corrected to Mid-Tide using Observed Tides Stages & Tide Ranges from Nearest NOAA Tide Gauge. 1.3’ 1.3’ 1.0’ 1.2’ 0.9’ 0.9’ 1.3’ 1.5’ 1.3’ 1.4’ 1.7’ 1.5’ 1.5’

  20. X X X X X X 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

  21. 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. ?

  22. ICW05 Waterward 5 m GAS01 Shoreward 5 m GAS05 Shoreward 4 m PIS01 Shoreward 15 m PIS05 Shoreward 4 m PIS03 Waterward 12 m PI04 Waterward 2 m MP05 Shoreward 2 m

  23. Water Depth Did Not Increase Significantly From 1998 – 2007. MEAN DEPTH AT SHALLOW EDGE REFERENCE POINT

  24. 41 cm SE=1.6 R2=.060 P=.08 48 cm SE=1.4 R2=.014 P=.31 48 cm SE=4.8 R2=.022 P=.40 51 cm SE=1.1 R2=.239 P=.15 52 cm SE=2.5 R2=.002 P=.80 52 cm SE=2.3 R2=.000 P=.97 54 cm SE=3.8 R2=.000 P=.89 58 cm SE=2.7 R2=.018 P=.24 No Estuaries Showed Significant Changes in Water Depth at Shallow Edge Reference Point.

  25. But 1 Estuary & Region as a Whole Showed Significant Increases in Water Depth at Deep Edge of Seagrasses. 87 cm SE=2.1 R2=.01 P=.43 124 cm SE=4.6 R2=.01 P=.54 128 cm SE=5.2 R2=.03 P=.36 147 cm SE=2.3 R2=.01 P=.05 158 cm SE=5.3 R2=.030 P=.22 169 cm SE=5.5 R2=.03 P=.15 176 cm SE=6.7 R2=.05 P=.12 186 cm SE=4.8 R2=.37 P=.00

  26. DISCUSSION Improved Accuracy of Seagrass Transect Locations Each Year with GPS. 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. Improved Analysis & Availability of Seagrass Data Access Data Base & Summary Reports.

  27. CONCLUSIONS Based on Preliminary Analysis of Seagrass Transect Data, Seagrasses Do not Appear to have Moved Shoreward since 1998. Depth Measurements Collected with Seagrass Transect Data Did Not Find a Significant Increase in Water Levels in Charlotte Harbor since 1998. More Precise Tide Measurements During Seagrass Monitoring will Enhance the Ability to Detect Smaller Changes in Water Depth. More Rigorous Statistical Analyses are Needed to Relate Seagrass Changes to Sea Level Rise..

  28. CONCLUSIONS 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. Continuing Seagrass Transect Monitoring & Improving Tide Estimations will Enhance Links between Seagrass Health, Water Quality Targets & Sea Level Rise.

  29. 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 CHNEP: Catherine Corbett CHEC:Renee Duffey & Jason Hale & 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

  30. For More Information, Please Contact: FDEP in Punta Gorda: South Distinct Laboratory Environmental Assessment & Restoration (941) 575-5810 & Charlotte Harbor Aquatic Preserves (941) 575-5861 or Judy Ott Until April 2: judith.ott@dep.state.fl.us Starting April 3: jott@swfrpc.org (239) 338-2550 Ext 230

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