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Several large or several (more) small: designing marine reserve networks for oyster restoration Brandon Puckett and David Eggleston North Carolina State University, Center for Marine Sciences and Technology
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Conceptual approach: metapopulations Discrete populations Spatially dynamic demographics Connected by migration Two spatial scales: 1)Local 2)Regional Sources (λ c > 1) v sinks (λ c < 1) Growth Survival Reproduction Demographics
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Conceptual approach: metapopulations Discrete populations Spatially dynamic demographics Connected by migration Two spatial scales: 1)Local 2)Regional Sources (λ c > 1) & sinks (λ c < 1)
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Conceptual approach: SLOSS Conserve Single Large Or Several Small areas? Terrestrial systems: single large Marine systems (limited): several small Single Large Several Small OR
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Conceptual approach: SLOSS Conserve Single Large Or Several Small areas? Terrestrial systems: single large Marine systems (limited): several small base Several Large Several (more) Small
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gametes fertilized eggtrochophoreveligerpediveliger spat ~ 2-3 weeks ~ 1-3 years weak swimmers adults Focal species: eastern oyster Peaks: June & August
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Deep Bay Ocracoke Crab Hole Bluff Point Mounds of limestone rip-rap Then: Reserve(s), Now: Reserve networks Must be SELF-SUSTAINING Reserves contain artificial reefs Distances: 10-125 km Areas: 3-24 ha Study system: oyster reserves
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1)Reserve network self-sustaining? 2)Optimal network design? Questions Stopher Slade
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Stage-based matrix model Time step: 2 mo. Initial population = density x area 10 reserves and 6 size-classes Parameters P ij : probability of remaining in size class i in reserve j G ij : probability of growing into size class i + 1 in reserve j F ij : per capita number of offspring in stage i in reserve j m jk : probability of dispersal from reserve k to reserve j Methods: 1) Reserve network self-sustaining? reserve 1 reserve 2 F 21 F 22 P 12 P 22 P 32 P 11 P 21 P 31 i 1 3 2 1 3 2 G 12 G 22 G 11 G 21 m 22 m 11 m 21 m 12 F 32 F 31 Larval pool
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Model inputs: growth and survival June 2006 cohort Aug 2006 cohort 0 40 80 120 00.51.01.52.02.5 Age (yrs) LVL (mm) 00.51.01.52.02.5 Age (yrs) 0 0.2 0.4 0.6 0.8 1.0 00.51.01.52.02.5 Age (yrs) Survivorship (%) 00.51.01.52.02.5 Age (yrs) 30% 40% 45% 30%
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Model inputs: growth and survival June 2006 cohort Aug 2006 cohort 0 40 80 120 00.51.01.52.02.5 Age (yrs) LVL (mm) 00.51.01.52.02.5 Age (yrs) 30% 40% 30% 45%
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Model inputs: reproductive output 0 5 0-1515-3030-4545-6060-7575+ 0 25 50 75 100 0-1515-3030-4545-6060-7575+ 0-1515-3030-4545-6060-7575+ Size class Per capita larval output 70% 90% June 2006August 2006
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Model inputs: connectivity Connectivity < 5% < 25%> 25% Few consistent connections in space or time Mean larval retention ~ 6%
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6-8/06 N < 500k < 5 mil > 5 mil λcλc < 0.7 < 1.0 > 1.0 0 25 50 75 100 6/066/076/086/096/10 Metapopulation size (x10 6 ) Results: 1) Reserve network self-sustaining?
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8-10/06 0 25 50 75 100 6/066/076/086/096/10 Metapopulation size (x10 6 ) Results: 1) Reserve network self-sustaining?
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10/06-6/07 0 25 50 75 100 6/066/076/086/096/10 Metapopulation size (x10 6 ) Results: 1) Reserve network self-sustaining?
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6-8/07 0 25 50 75 100 6/066/076/086/096/10 Metapopulation size (x10 6 ) Results: 1) Reserve network self-sustaining?
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8-10/07 0 25 50 75 100 6/066/076/086/096/10 Metapopulation size (x10 6 ) Results: 1) Reserve network self-sustaining?
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10/07-6/08 0 25 50 75 100 6/066/076/086/096/10 Metapopulation size (x10 6 ) Results: 1) Reserve network self-sustaining?
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6-8/08 0 25 50 75 100 6/066/076/086/096/10 Metapopulation size (x10 6 ) Results: 1) Reserve network self-sustaining?
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8-10/08 0 25 50 75 100 6/066/076/086/096/10 Metapopulation size (x10 6 ) Results: 1) Reserve network self-sustaining?
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10/08-6/09 0 25 50 75 100 6/066/076/086/096/10 Metapopulation size (x10 6 ) Results: 1) Reserve network self-sustaining?
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6-8/09 0 25 50 75 100 6/066/076/086/096/10 Metapopulation size (x10 6 ) Results: 1) Reserve network self-sustaining?
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8-10/09 0 25 50 75 100 6/066/076/086/096/10 Metapopulation size (x10 6 ) Results: 1) Reserve network self-sustaining?
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0 25 50 75 100 6/066/076/086/096/10 Metapopulation size (x10 6 ) 10/09-6/10 Results: 1) Reserve network self-sustaining? Metapopulation size declined ~ exponentially (λ = 0.7 ± 0.1)
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Methods: 2) Optimal design? Simulations Several large: area x2, x4, x6, x8, x10 Several (more) small: number x2, x4, x6, x8, x10 Site selection algorithm Pool of 187 cultch planting sites Maximize connectivity to and from existing network several large several (more) small base
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Connectivity < 5% < 25% > 25% 10x 4x 2x Connectivity does not scale up Large connections primarily self-recruitment Connections more consistent Results: 2) Optimal design?
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Connectivity < 5% < 25% > 25% Connectivity scales initially Increased number and magnitude of inter-reserve connections 100 40 20 Results: 2) Optimal design?
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0 5 10 15 20 02004006008001000 Area (ha) Larval retention (%) 020406080100120 # of reserves Several large Several (more) small * * Several (more) small increases larval retention Law of diminishing returns SLASS hybrid optimal
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Conclusions Spatiotemporal variation in demographics w/ (limited) connectivity Proof of metapopulation concept Current reserve network not capable of persisting Sources, Sinks, and “the metapopulation stoplight” Several (more) small reserves preferred SLASS—Several Large AND Several Small
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Acknowledgements Funding: NMFS/Sea Grant Population Dynamics Fellowship NC Sea Grant American Recovery and Reinvestment Act (NOAA/NCCF) NSA Michael Castagna Student Grant for Applied Research Raleigh Salt Water Sportfishing Club Field/Technical Assistance: NC DMF: Stopher Slade and Craig Hardy Ray Mroch Amy Haase Gayle Plaia Ryan Rindone Christina Durham Geoff Bell Erika Millstein Josh Wiggs Michelle Moorman
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‘Growers’ ‘Survivors’ ‘Spawners’ ‘Connectors’ Demographic and connectivity summary ‘Spawners’ ‘Survivors’ ‘Growers’
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