Successful Eelgrass Restoration: Case Studies in Urban Systems Ashley Bulseco-McKim November 19,...
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Transcript of Successful Eelgrass Restoration: Case Studies in Urban Systems Ashley Bulseco-McKim November 19,...
Successful Eelgrass Restoration: Case Studies
in Urban Systems
Ashley Bulseco-McKim
November 19, 2012
2
Outline
Overview of restoration techniques Case studies in urban systems What worked? What didn’t work? Recommendations
11/19/2012
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Restoration Efforts
11/19/2012
Long Island:Churchill, Dennison,
Pickerell et al.Chesapeake
Bay:Orth, Marion,
Kemp, McGlathery,
Reynolds
NH/ME:Short(s), Davis,
Kopp et al.
Washington:Thom
Boston Harbor:Leschen, Evans, Estrella, Ford et
al.Rhode Island:Nixon, Granger,
Harris et al.
New Jersey:Campanella,
Bologna, Simmena et al.Heck, Duarte
North Carolina:Fonseca, Thayer
et al.
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Transplanting Techniques
11/19/2012
Hand planting Core/plug method Bare-root technique Horizontal rhizome method (Davis & Short 1997)
Framing TERFSTM
Checkerboard planting Seeds
Traditional Buoy Mechanized
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Hand-Planting
11/19/2012
Core/Plug method: extracts cores with sediment intact (instrusive)
Bare-root technique: removes shoots with small amount of rhizome
Horizontal rhizome method: Two shoots are aligned parallel, pointing in opposite directions, and are pressed horizontally in the top 2 cm of sediment (not good for silty clay)
http://projects.ups.edu http://morro-bay.com
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Transplanting Techniques
11/19/2012
Hand planting Core/plug method Bare-root technique Horizontal rhizome method (Davis & Short 1997)
Framing TERFSTM
Checkerboard planting Seeds
Traditional Buoy Mechanized
Short et al. 20027
Frame: “TERFSTM” – Transplating Eelgrass Remotely w/Frame Systems (UNH)
11/19/2012
60 x 60 cm frame that holds 50 eelgrass shoots each
Volunteers attached shoots to the frame using dissolving ties
Distributed by either wading or throwing over the side of a boat, held down to the sediment surface with bricks (roots in sediment, blades in water column)
Left for 3-5 weeks Too early: not enough time for roots to penetrate
sediment Too late: blades will entangle the frame
Re-use frames after removal
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Frame: PVC/jute
11/19/2012Leschen et al. 2010
Alternatives to TERFSTM
0.25 m2 square of PVC pipe with jute mesh streched over
Eelgrass shoots tied to intersections
Mesh cut away after establishment
Good for community-based efforts
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Frame: Checkerboard Pattern
11/19/2012 Leschen et al. 2010
Checkerboard plot 30-50 meters apart
Designed to cover more ground The void allows for
further growth of eelgrass
If too close together, you would increase initial effort
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Transplanting Techniques
11/19/2012
Hand planting Core/plug method Bare-root technique Horizontal rhizome method (Davis & Short 1997)
Framing TERFSTM
Checkerboard planting Seeds
Traditional Buoy Mechanized
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Seed:Manual Planting
11/19/2012Pickerell et al. 2005
Classic method of collecting reproductive shoots
Hold in seawater until seeds mature and are released
Broadcast over large areas relatively quickly, but unpredictable germination timing and high time commitment
(Leschen et al. 2010)
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Seed: Buoy-Deployment
11/19/2012Pickerell et al. 2005
Reproductive shoots are collected and immediately transferred to net 9 mm net Lobster buoy Cement block (anchor) Polypropylene line Garden hose Wire tie (adjust to water
depth) Efficient, but where do
seeds go?
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Seed: Mechanical Planting
11/19/2012Orth et al. 2009
Planter: Benthic sled Seed hopper Peristaltic pump Gel mixture of seeds
and Knox ® gelatin Injection nozzles
Buries seeds in the sediment
Variable effectiveness – is it worth the cost?
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Seed: Genetic Diversity
11/19/2012Orth et al. 2012
Hand-planting and frames rely on adult eelgrass shoots which may lead to loss of genetic diversity (Williams 2001)
Genetic diversity is important in ecosystem restoration because genetically diverse assemblages may be more resistant to disturbances and climate change
In Chesapeake Bay/Virginia Bay, found both donor beds and restoration sites had the same level of genetic diversity
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Other Restoration Techniques
11/19/2012
Community-based restoration Emphasis on site-selection Long-term monitoring – important to assess
success & failures, structural attributes, and functional attributes Structural attributes: biotic and abiotic
components Functional attributes: ecosystem services e.g.
energy flow, biogeochemical cycling, trophic relationships, growth rates, materials exchange
Important to understand how restoration sites compare to natural sites in regards to these factors
Short et al. 2002b18
UNH Community-based Restoration
11/19/2012
Make eelgrass restoration more accessible
The success of a community project relies on community involvement
Volunteers leave with an interest in coastal restoration and will advocate for it in the future
Short et al. 2002a19
Site Selection Model
11/19/2012
PTSI, test-transplants, TSI Multiplicative Index
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Case Study: Boston Harbor, MA
11/19/2012Leschen et al. 2010
Goal: to restore eelgrass from spring ‘04 to fall ’07 to mitigate impacts from HubLine pipeline
Deer Island secondary wastewater treatment facility
Natural repopulation unlikely due to wind-driven current patterns (seeds wouldn’t reach estuary)
= good candidate
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Methods
11/19/2012Leschen et al. 2010
Short et al. 2002 site-selection model
Used frames (checkerboard pattern), hand-planting (horizontal rhizome), and seeds (manual) to test effectiveness – Lynn Harbor
Monitoring
• Short model (2002)
• Groundtruth• 12 potential sites
Site Selection
• Used TERFSTM
• 200 shoots site-1
Preliminary
(12 sites)
• PVC/jute• Horizontal
rhizome• 1000 shoots site-
1
Medium-scale
(subset)
• PVC/jute• Hand-planting• 3,600 to 7,200 shoots
site-1
• 300,000 seeds
Large-Scale
(Subset)
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Results
11/19/2012Leschen et al. 2010
Preliminary: sites > 57% silt/clay failed & < 35% silt/clay successful
Medium-scale: TERFSTM attracted burrowing crabs so adapted to PVC/jute – four sites to test
Large-scale: planted sites comparable to or exceeded natural beds in biomass and density
Within 1 year, impossible to differentiate between plots planted with different methods
Overall: successfully restored over 2 ha of eelgrass to Boston Harbor
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What worked? What didn’t work?
11/19/2012Leschen et al. 2010
Horizontal rhizome method worked well but required SCUBA
PVC/jute frames good for community involvement (> 150 volunteers) but less efficient
Checkerboard planting minimized human effort
TERFSTM attracted crabs Seeds distributed on
sediment surface were not successful (but better if scratched into the sediment)
Not enough information on sediment requirements for eelgrass – wide range in literature!
What we’ve learned (Leschen et al. 2010)
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Recommendations (Leschen et al. 2010)
11/19/2012
Need better information on physical requirements (e.g. wave exposure and sediment characteristics) to be used in site selection model
Because of imbalance between amount of eelgrass lost and eelgrass restored, we need to consider other management at the same time (4 ha gained, 760 ha lost) = “watershed approach”
Areas with compromised water or sediment quality may not be ready for eelgrass transplantation, and alternative mitigation strategies might be more far-reaching (e.g. minimizing boat impacts)
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Recommendations (Neponset)
11/19/2012
Adapt Short et al. 2002 model for site selection
Use a combination of transplant methods (or experiment before large-scale transplant)
Gain a better understanding of sediment characteristics
Gain a better understanding of wave exposure Survey types of bioturbators Involve the community Long-term monitoring
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References
11/19/2012
Leschen et al. 2010 Orth et al. 2008 Orth et al. 2012 Pickerell et al. 2005 Short et al. 2002a Short et al. 2002b
Note: literature cited in text includes hyperlinks to PDFs
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Recommended Requirements for Eelgrass
11/19/2012
Variable % Increase (+) or Decrease (-) at 5 yr
Recommended requirements for eelgrass
Total nitrogen (TN) (µmol L-1) -35 NA
Dissolved inorganic nitrogen (DIN) (µmol L-1)
-55 < 0.15 (mg L-1)
Total phosphorus (TP) -28 NA
Dissolved inorganic phosphorus (DIP)
-15 < 0.02 (mg L-1)
Total chlorophyll a (µg L-1) -26 < 15
Total suspended solids (TSS) (mg L-1) 5 < 15
Percent organic carbon (POC) as % TSS
-33 NA
Secchi depth (m) 4 NA
Dissolved oxygen (DO) (mg µg L-1) 5 NA