Seagrass Restoration. or Restoration in Wetsuits. Michael Hannam Joel Breems

Transcription

1 Seagrass Restoration or Restoration in Wetsuits Michael Hannam Joel Breems

2 References Guidelines for the Conservation and Restoration of Seagrasses in the United States and Adjacent Waters (Fonseca et al. 1998) NOAA Coastal Ocean Program, Decision Analysis Series No. 12

3 Seagrass Restoration Lecture Objectives: Outline the importance and criteria of site selection in seagrass restoration Introduce the main restoration categories Outline specific methodologies and contexts in which they are appropriate Time for questions

4 Mitigation vs. Restoration Summarized from Fonseca et al. (1998) Mitigation: A permit requirement to compensate for the destruction of existing habitat, when the agent of loss and the responsible party are known Restoration: When the agent of loss is known, but there is no responsible party identified. Summarized from Lewis (1989) Mitigation: The legal compensation for loss resulting from permitted activities. Restoration: The return of an altered or modified site to one that is comparable to the site condition before alteration or modification occurred.

5 Site Selection Does the site have a history of seagrass? Is the donor population from the same depth? Is there adequate light? Is there bioturbation pressure? Is this a depositional/erosion zone? Is the sediment quality acceptable?

6 Site Selection Golden Rule: If seagrass does not grow there now what makes you think it can be successfully restored (Feredette et al 1985)

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8 Categories of Approach Sod/core Bare root and rhizome Seed

9 General benefits of each Sod Less disturbance to the roots and rhizome Resistant to erosion or wave pressure Bare Root Less impact on donor site High success low cost Seed Potentially low impact activity Time and cost efficient.

10 Sod (ECOSUB)

11 ECOSUB I Developed Murdoch University in Western Australia for a large scale mitigation project m 2 Capable of collecting and installing m 2 (75 for ECOSUB II) per day. Protocol: The machine is operated by two divers and is positioned over the seagrass. The ECOSUB then cuts a 0.5 m 2 sod of seagrass and stores it in an onboard hopper. The ECOSUB is then floated to the surface using tanks and towed to the rehabilitation site where the cutter head clears a spot for the sod and it is transplanted.

12 ECOSUB Photo: D. A. Lord and associates 2005

13 Plug method Photo: Fonseca et al 1998 Photo: Seddon 2004 Photo: Seddon 2004

14 Plug Method Methods A PVC or metal core is used to remove a seagrass ramet and surrounding sediment The corer is caped to create a vacuum allowing the removal of the core The core and ramet must be stored properly in transit An equivalent sized hole is excavated or softened at the restoration site Complete ramet and core are installed in the new location Monitor! Photos: Fonseca et al 1998

15 Plug method Benefits Less disturbance to roots and rhizomes Less impact from sediment chemistry Resistant to erosional forces 3.53 work min per plant Drawbacks Impact to donor site Increased costs Applicable uses Mitigation/ salvage harvest Intertidal

16 Bare Root Photo: Orth et al 1999

17 HRM/rhizome Methods To Anchor or not to anchor The Methods developed by Davis and Short (1997) and Orth et al. (1999) are very similar. Benefits Decrease donor requirement Efficient min/unit for both >70% survival at 1 month and equivalent density to control populations at 20 months

18 HRM/rhizome Methods To Anchor or not to anchor Photo: Fonseca et al. (1998) Drawbacks SCUBA requirement Donor site impact Lack of success in intertidal zones Applicable uses Mitigation or Restoration To augment natural recolonization Photo: S. Wyllie-Echeverria

19 Altering Sediment Chemistry to Perry Gayaldo 2002 enhance survival Demonstrated the impact of oxidation/ reduction (E h) on survival of seedlings Shock of transplant Impact of E h on plant survival Increasing Redox potential leads to increased survival.

20 O 2 Oxidation Sulfate Sulfide Anaerobic Bacteria

21 TERFS Transplanting Eelgrass Remotely with Frames Systems 50 eelgrass plants/frame (Battelle) Transplants a 0.25 m 2 eelgrass patch (Short et al. 2002)

22 Terfs

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25 Terfs Sort of

26 Seeds Benefits Low Cost Potential low impact Ideal for site testing Mimic natural processes Harvest and deployment in one day Drawbacks Slower establishment Appropriate uses Ideally suited for Restoration

27 BuDS: Buoy Deployed Seeding (Battelle) (Battelle) (Battelle) (CCE) (Pickerell et al. 2006)

28 Gel Seeding Method Photo: Nixon et al. (2002)

29 Gel Seeding Method Developed by Scott Nixon at the University of Rhode Island Methods A sled is towed behind a boat creating a furrow Seagrass seeds suspended in gel are injected into the furrow A trailing weight fills the furrow and covers the seeds

30 Gel Seeding Method Benefits Speed of planting Control over seeding densities No divers (or wetsuits) Increased germination rates Drawbacks Seed sorting Potential impact on donor population Experimental

31 No one really knows the cost of lost habitat functions Seagrass Transplanting Costs Planning Restoration Monitoring Adaptive management budget for these expenses but hope not to use them 1 ac (0.4 ha) ~ $15K (Fonseca et al. 1998) 1 ac ~ $100K (RKK 2001) 1 ac (TERFS method) ~ projected at $3.2M (Walker 2003) 1 ac (staple method) ~ projected at $4.1M (Walker 2003)

32 Conclusion Many different methods which are more or less appropriate based on: Costs Resouces available Context of effort (mitigation/restoration) Not all restoration is successful Site selection key!!