Successful Eelgrass Restoration: Case Studies

in Urban SystemsAshley Bulseco-McKim

November 19, 2012

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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

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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

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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

Short et al. 20028

Frame: “TERFSTM” – Transplating Eelgrass Remotely w/Frame Systems

11/19/2012

Short et al. 20029

Frame: “TERFSTM” – Transplating Eelgrass Remotely w/Frame Systems

11/19/2012

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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

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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

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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

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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-1Prelimina

ry(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

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Variable % Increase (+) or Decrease (-) at 5 yr

Recommended requirements for eelgrass

Total nitrogen (TN) (µmol L-1) -35 NADissolved inorganic nitrogen (DIN) (µmol L-1)

-55 < 0.15 (mg L-1)

Total phosphorus (TP) -28 NADissolved inorganic phosphorus (DIP)

-15 < 0.02 (mg L-1)

Total chlorophyll a (µg L-1) -26 < 15Total suspended solids (TSS) (mg L-1) 5 < 15Percent organic carbon (POC) as % TSS

-33 NA

Secchi depth (m) 4 NADissolved oxygen (DO) (mg µg L-1) 5 NA