international conference on shellfish restoration 2006 - charleston, sc oyster reef restoration...
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International Conference on Shellfish Restoration 2006 - Charleston, SC
Oyster Reef Restoration Using “Spat Seeding”: Early Reef Development and Performance at Sites
in New Hampshire, USA
http://oyster.unh.edu
Ray Grizzle, Jennifer Greene, and Mark Capone
Current Status of the Eastern Oyster, Crassostrea virginica
(P. Trowbridge)
• Extreme population declines in many areas from disease (MSX, Dermo), predators, over-harvesting, pollution, habitat degradation
• New Hampshire Estuaries Project goals: 20 restored acres, and 50,000 bushels standing stock by 2010
Nova Scotia
Maine
Cape Cod
Great Bay
A ‘pristine’ NH oyster reef
• few dead shells
• many live oysters (500/m2 in some areas)• extensive vertical structure in some areas
Badly Degraded Reef Reef With Some ‘Structure’
• mostly dead shells• sparse live oysters (~20/m2)• minimal vertical structure
• few dead shells• many live oysters (~100/m2)• some vertical structure• excessive sedimentation
How do we restore oyster reefs?
1. Identify potential causes for population declines on site-by-site basis
2. Design site-specific construction/restoration protocol
3. Assess initial construction/restoration
4. Maintain “restored” area
5. Assess long-term development and performance
Life Cycle of the Eastern Oyster, Crassostrea virginica
Trochophore LarvaVeliger Larva
Straight-hinge stage
Juvenile/SpatAdult
Egg
Oyster Life Cycle
Sessile, Benthic
Oyster Restoration = Facilitating the Life Cycle
Remote Setting, Early Grow-out (Nursery), & Reef Construction
Shellfish Restoration Sites, Dates of Construction:
• Salmon Falls River, 2000
• South Mill Pond, 2001
• Adams Point, 2003
• Nannie Island, 2004
• Bellamy River, 2005, 2006
Salmon FallsRiver
BellamyRiver
AdamsPoint
NannieIsland
South MillPond
Adams Point – An Experimental Scale Adams Point – An Experimental Scale Restoration ProjectRestoration Project
•Experimental design (2 x 2 factorial) to test: 1) two cultch types, and 2) two spat seeding densities
•Each treatment replicated 3 times 12 mini-reefs (2m x 3m) constructed
•Mini-reef bases built up to ~30 cm height with crushed granite
•Spat-on-cultch (shell or rock) spread over surface of granite bases
How many spat should be expected from the remote setting process?
• Spat setting success has ranged from <5% to >50% in our trials
• Important factors:
cultch
food
water quality
condition of the larvae
We can’t believe they all died!We can’t believe they all died!
Nursery Raft Survival and Growth
• ~75% survival is typical for 6 – 8 weeks on nursery raft
• Growth typically averages 2 - 3 mm/week
• Some animals ~1 mm/day
Development of Constructed Mini-Reefs
Adams Point, 2003-2006
• Consistent density decline
• Similar (but elevated compared to natural reef) densities after ~3 years post-construction
• Some originally seeded oysters in 2nd year of maturity
• Substantial development of vertical structure…
Performance of Constructed Mini-Reefs
Adams Point, Summer 2006
• Maximum ~6% water filtration (seston removal) after 3.2 years
Two New Programs: Oyster Conservationists and Shell RecyclingDo you want to participate in oyster restoration in New Hampshire?
http://oyster.unh.edu
Acres
Site/Construction Year(s) Larvae Source/Experimental Test Restored Current Status
Salmon Falls River/2000 XBreed larvae vs. native transplant 0.1 ~100% mortality
South Mill Pond/2001 ME larvae; oysters with blue mussels <0.1 ~100% mortality
Adams Point/2003 ME larvae; low vs. high density 0.05 >50% mortality
Nannie Island/2004 ME larvae; large vs. small reefs 1.25 >50% mortality
Bellamy River/2005 NH larvae; multiple mini-reefs 1.5 >50% mortality
2006 NH larvae; multiple mini-reefs 1.5 ?
TOTAL: 4.4 acres
Summary of New Hampshire Shellfish Restoration Projects
ACKNOWLEDGMENTS• UNH: Ryan McDonnell, Kaitlin Graiff, Dave Shay, Deb UNH: Ryan McDonnell, Kaitlin Graiff, Dave Shay, Deb
Lamson, Ben Winslow, Sarah Mikulak, Michelle GraffamLamson, Ben Winslow, Sarah Mikulak, Michelle Graffam
• Interns: William Walker, Winnie Wong, Sarah Morrison, Interns: William Walker, Winnie Wong, Sarah Morrison, Alicia June, Blake BowickAlicia June, Blake Bowick
• Oyster Conservationist Volunteers, Active Shell RecyclersOyster Conservationist Volunteers, Active Shell Recyclers
• Toni Simmons/Muscongus Bay AquacultureToni Simmons/Muscongus Bay Aquaculture
• Davis FoundationDavis Foundation