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

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

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)

Conceptual approach: SLOSS  Conserve Single Large Or Several Small areas?  Terrestrial systems: single large  Marine systems (limited): several small Single Large Several Small OR

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

gametes fertilized eggtrochophoreveligerpediveliger spat ~ 2-3 weeks ~ 1-3 years weak swimmers adults Focal species: eastern oyster Peaks: June & August

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: km  Areas: 3-24 ha Study system: oyster reserves

1)Reserve network self-sustaining? 2)Optimal network design? Questions Stopher Slade

 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 G 12 G 22 G 11 G 21 m 22 m 11 m 21 m 12 F 32 F 31 Larval pool

Model inputs: growth and survival June 2006 cohort Aug 2006 cohort Age (yrs) LVL (mm) Age (yrs) Age (yrs) Survivorship (%) Age (yrs) 30% 40% 45% 30%

Model inputs: growth and survival June 2006 cohort Aug 2006 cohort Age (yrs) LVL (mm) Age (yrs) 30% 40% 30% 45%

Model inputs: reproductive output Size class Per capita larval output 70% 90% June 2006August 2006

Model inputs: connectivity Connectivity < 5% < 25%> 25%  Few consistent connections in space or time  Mean larval retention ~ 6%

6-8/06 N < 500k < 5 mil > 5 mil λcλc < 0.7 < 1.0 > /066/076/086/096/10 Metapopulation size (x10 6 ) Results: 1) Reserve network self-sustaining?

8-10/ /066/076/086/096/10 Metapopulation size (x10 6 ) Results: 1) Reserve network self-sustaining?

10/06-6/ /066/076/086/096/10 Metapopulation size (x10 6 ) Results: 1) Reserve network self-sustaining?

6-8/ /066/076/086/096/10 Metapopulation size (x10 6 ) Results: 1) Reserve network self-sustaining?

8-10/ /066/076/086/096/10 Metapopulation size (x10 6 ) Results: 1) Reserve network self-sustaining?

10/07-6/ /066/076/086/096/10 Metapopulation size (x10 6 ) Results: 1) Reserve network self-sustaining?

6-8/ /066/076/086/096/10 Metapopulation size (x10 6 ) Results: 1) Reserve network self-sustaining?

8-10/ /066/076/086/096/10 Metapopulation size (x10 6 ) Results: 1) Reserve network self-sustaining?

10/08-6/ /066/076/086/096/10 Metapopulation size (x10 6 ) Results: 1) Reserve network self-sustaining?

6-8/ /066/076/086/096/10 Metapopulation size (x10 6 ) Results: 1) Reserve network self-sustaining?

8-10/ /066/076/086/096/10 Metapopulation size (x10 6 ) Results: 1) Reserve network self-sustaining?

/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)

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

Connectivity < 5% < 25% > 25% 10x 4x 2x  Connectivity does not scale up  Large connections primarily self-recruitment  Connections more consistent Results: 2) Optimal design?

Connectivity < 5% < 25% > 25%  Connectivity scales initially  Increased number and magnitude of inter-reserve connections Results: 2) Optimal design?

Area (ha) Larval retention (%) # of reserves Several large Several (more) small * *  Several (more) small increases larval retention  Law of diminishing returns  SLASS hybrid optimal

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

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

‘Growers’ ‘Survivors’ ‘Spawners’ ‘Connectors’ Demographic and connectivity summary ‘Spawners’ ‘Survivors’ ‘Growers’