Several large or several (more) small: designing marine reserve networks for oyster restoration...
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Several large or several (more) small: designing marine reserve networks for oyster restoration
Brandon Puckett and David EgglestonNorth 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 (λc > 1) v sinks (λc < 1)
• Growth
• Survival
• Reproduction
Demographics
Conceptual approach: metapopulations
Discrete populations Spatially dynamic demographics Connected by migration
Two spatial scales:1) Local
2) Regional
Sources (λc > 1) & sinks (λc < 1)
Conceptual approach: SLOSS
Conserve Single Large Or Several Small areas? Terrestrial systems: single large Marine systems (limited): several small
Single Large Several SmallOR
Conceptual approach: SLOSS
Conserve Single Large Or Several Small areas? Terrestrial systems: single large Marine systems (limited): several small
baseSeveral Large
Several (more) Small
gametes
fertilized egg trochophore veliger pediveliger
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: 10-125 km Areas: 3-24 ha
Study system: oyster reserves
1)Reserve network self-sustaining?
2)Optimal network design?
Questions
Stopher Slade Stopher Slade
Stage-based matrix model Time step: 2 mo. Initial population = density x
area 10 reserves and 6 size-classes Parameters
Pij: probability of remaining in size class i in reserve j
Gij: probability of growing into size class i + 1 in reserve j
Fij: per capita number of offspring in stage i in reserve j
mjk: probability of dispersal from reserve k to reserve j
Methods: 1) Reserve network self-sustaining?
reserve 1
reserve 2
F21
F22
P12 P22 P32
P11 P21 P31
i
1 32
1 32
G12 G22
G11 G21
m22
m11
m21
m12
F32
F31
Larval pool
Larval pool
Model inputs: growth and survivalJune 2006 cohort Aug 2006 cohort
0
40
80
120
0 0.5 1.0 1.5 2.0 2.5Age (yrs)
LVL
(m
m)
0 0.5 1.0 1.5 2.0 2.5Age (yrs)
0
0.2
0.4
0.6
0.8
1.0
0 0.5 1.0 1.5 2.0 2.5Age (yrs)
Sur
vivo
rshi
p (
%)
0 0.5 1.0 1.5 2.0 2.5
Age (yrs)
30% 40%
45%
30%
Model inputs: growth and survivalJune 2006 cohort Aug 2006 cohort
0
40
80
120
0 0.5 1.0 1.5 2.0 2.5Age (yrs)
LVL
(m
m)
0 0.5 1.0 1.5 2.0 2.5Age (yrs)
0
0.2
0.4
0.6
0.8
1.0
0 0.5 1.0 1.5 2.0 2.5Age (yrs)
Sur
vivo
rshi
p (
%)
0 0.5 1.0 1.5 2.0 2.5
Age (yrs)
30% 40%
30%
45%
Model inputs: reproductive output
0
5
0-15 15-30 30-45 45-60 60-75 75+
0
25
50
75
100
0-15 15-30 30-45 45-60 60-75 75+ 0-15 15-30 30-45 45-60 60-75 75+
Size class Size class
Per
cap
ita la
rval
ou
tput
70%
90%
June 2006 August 2006
Model inputs: connectivity
2006 2007 2008 2009
Connectivity
< 5% < 25% > 25%
Few consistent connections in space or time Mean larval retention ~ 6%
6-8/06
N
< 500k< 5 mil
> 5 mil
λc
< 0.7
< 1.0
> 1.0
0
25
50
75
100
6/06 6/07 6/08 6/09 6/10
Met
apo
pu
lati
on
siz
e (x
106 )
Results: 1) Reserve network self-sustaining?
8-10/06
0
25
50
75
100
6/06 6/07 6/08 6/09 6/10
Met
apo
pu
lati
on
siz
e (x
106 )
Results: 1) Reserve network self-sustaining?
10/06-6/07
0
25
50
75
100
6/06 6/07 6/08 6/09 6/10
Met
apo
pu
lati
on
siz
e (x
106 )
Results: 1) Reserve network self-sustaining?
6-8/07
0
25
50
75
100
6/06 6/07 6/08 6/09 6/10
Met
apo
pu
lati
on
siz
e (x
106 )
Results: 1) Reserve network self-sustaining?
8-10/07
0
25
50
75
100
6/06 6/07 6/08 6/09 6/10
Met
apo
pu
lati
on
siz
e (x
106 )
Results: 1) Reserve network self-sustaining?
10/07-6/08
0
25
50
75
100
6/06 6/07 6/08 6/09 6/10
Met
apo
pu
lati
on
siz
e (x
106 )
Results: 1) Reserve network self-sustaining?
6-8/08
0
25
50
75
100
6/06 6/07 6/08 6/09 6/10
Met
apo
pu
lati
on
siz
e (x
106 )
Results: 1) Reserve network self-sustaining?
8-10/08
0
25
50
75
100
6/06 6/07 6/08 6/09 6/10
Met
apo
pu
lati
on
siz
e (x
106 )
Results: 1) Reserve network self-sustaining?
10/08-6/09
0
25
50
75
100
6/06 6/07 6/08 6/09 6/10
Met
apo
pu
lati
on
siz
e (x
106 )
Results: 1) Reserve network self-sustaining?
6-8/09
0
25
50
75
100
6/06 6/07 6/08 6/09 6/10
Met
apo
pu
lati
on
siz
e (x
106 )
Results: 1) Reserve network self-sustaining?
8-10/09
0
25
50
75
100
6/06 6/07 6/08 6/09 6/10
Met
apo
pu
lati
on
siz
e (x
106 )
Results: 1) Reserve network self-sustaining?
0
25
50
75
100
6/06 6/07 6/08 6/09 6/10
Met
apo
pu
lati
on
siz
e (x
106 )
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) smallbase
Connectivity
< 5%< 25%> 25%
10x4x2xBase
Connectivity does not scale up Large connections primarily self-recruitment Connections more consistent
Results: 2) Optimal design?
Connectivity
< 5%< 25%> 25%
Base
Connectivity scales initially Increased number and magnitude of inter-reserve
connections
1004020
Results: 2) Optimal design?
Results: 2) Optimal design?
0
5
10
15
20
0 200 400 600 800 1000
Area (ha)
Lar
val r
eten
tio
n (
%)
0 20 40 60 80 100 120
# of reserves
Several largeSeveral (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’