Transcript salve regina_04 - U.S. GLOBEC Georges Bank

Globec Legacy- the SSC ideas
A.
B.
C.
D.
E.
Philosophy
Body of Knowledge
Innovative Methodologies
Management and information transfer
Education/Outreach
Philosophy
• Multi/interdisciplinary international
collaboration
• Coupled models as integrative tools
• Mult-scale (time,space, institutional)
analysis
• Enhanced understanding of role of higher
trophic levels
Innovative methodologies
• Coupled models (trophic, scale, time) to
investigate structure, function and
variability
• Sampling and technological advances
• Retrospective studes of past ecosystem
states
• Comparative approach among regions
Management and information transfer
• Policy (providing conceptual understanding
of ecosystem function)
• Managers (providing tools to incorporate
climate-driven variability)
• Communities (enhancing communication on
global ecosystem change and marine
sustainability
ESSAS: Ecosystem Studies of
Subarctic Seas
A new GLOBEC program
Science 304: 1463-1466 4June2004
•There is no single, fully integrated model that can
simulate all possible ocean ecosystem states
•The key steps in representing extended food webs
in complex marine systems are (i) to concentrate the
biological resolution, or detail of representation, in
the main target species and (ii) make increasing
simplifications, or decrease in resolution, with
distance both up and down the trophic scale from the
target species (the “rhomboid” or “middle out”
Model Resolution-Temporal/Spatial
Issues of Model Integration
THE SEA
SPECIES IN THE MODEL
Birds/mammals
Bacteria
Number of Species
Number of State
Variables
Detail of
Resolution
Residual currents and temperature field
The rhomboid approach in GB
GLOBEC
• NPZ type
• Copepod life cycle type
• Larval fish dynamics type
Modeling approach
Hydrodynamic model
(The Unstructured Grid
Finite Volume Costal
Ocean Model)
HydroFields
Zooplankton or fish
larvae population
dynamics model
(Individual Based Model)
Lagrange approach
Prey
HydroFields
Lower trophic level food
web model
(NPZD Model)
Eulerian approach
Ji and Chen
Model Structure
Ammonia
Nitrate
Uptake
Uptake
Silicate
Uptake
Remineralization
Dissolution
Small
Large
Phytoplankton
Phytoplankton
Grazing
Grazing
Mortality
Mortality
Small
Predation
Zooplankton
Mortality
Grazing
Detritus
Nitrogen
Large
Zooplankton
Mortality
Mortality
Fecal
Detritus
Silica
Ji, Chen and coworkers
Chlorophyll a (mg m-3)
0.10
1999 Day:73-80
0.32
1.00
3.16
10.00
1999 Day:81-88
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2
SeaWiFS data from GOMOOS website By Dr. Andrew Thomas, UMaine
1999 Day:89-96
3-D Model
Subtidal currents
Day 76
Surface
wind
20 m
3-D Model
Biological
Model
Ji, Chen and
coworkers
Day 63
Day 66
Day 71
Day 76
Day 81
Day 86
Copepod life history models: biological
resolution on target species
Population dynamics of Calanus finmarchicus
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Eggs    U .Eggs    K z  Eggs     Eggs .Eggs  Spawn.CVIfm  mEggs .Eggs
t
z  z







NI    U .NI    K z  NI     NI .NI   Eggs .Eggs  mNI .NI   WNI NI 
t
z  z
z
 



CI    U .CI    K z  CI     CI .CI   NVI .NVI  mCI .CI   WCI CI 
t
z 
z
z
 

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


CVIfj    U .CVIfj    K z  CVIfj  
t
z 
z


 (1  Diap )






.
CV


.
CVd


.
CVIfj

m
.
CVIfj

W
CVIfj
CV
CVd
CVIfj
CVIfj


2
z CVIfj

Diap (t )  1  exp  50 sin(  (t  LagT ) / 360)  1
Spawn(t )  1  Diap (t ).EPRmax
Wi  Wmi tanh  z  Z i 
2

Zakardjian et al. 2003. JGR.
Vol. 108. No.C11, 8016.
Zakardjian et al. 1999: CJFAS
56:2420-32
Zakardjian et al. 2003
Examples of copepod models in Georges
Bank GLOBEC
Miller, Lynch, Carlotti, Gentleman, Lewis, 1998
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3-D finite element model and climatology
Individual based model
Growth and reproduction as f (temperature)
Supply to GB from all GoM basins and Scotian Shelf
Jordan and Georges must be restocked from upstream
sources; role of local production in Wilkinson
unresolved
Examples of copepod models in Georges
Bank GLOBEC
• Lynch, Gentleman, McGillicuddy, Davis, 1998
– 3D finite element hydrodynamic model, mean climatological
circulation
– Advective- diffusive-reactive equation, stage-based
development
– Food limitation represented as linear decline below 150 µgC l-1
– Surface only and depth-averaged transport
– Base model has low mortality and abundant food
– Spatial and temporal pattersn of Calanus recruitment in first
generation consistent with observations only when model
included food limitation of populations in low chlorophyll GoM
in late winter/early spring
Examples of copepod models in Georges
Bank GLOBEC
• McGillicuddy, Lynch, Moore, Gentleman,
Davis, Meise 1998
• McGilluddy, Bucklin et al. papers
– Adjoint data assimilation
– 3D finite element, climatological circulation
– Assuming advective fields correct, calculate
biological terms (R) that fit the observations
Calanus finmarchicus: Relationship of egg
production to phytoplankton biomass
Durbin et al. 2003: Gulf of Maine
Runge et al. (in prep.): Georges Bank
Calanus finmarchicus
Stage-specific Mortality
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Jan. - Jun.
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Jan. - Jun.
-Developmental
stages
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-N6/C1
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N5/N6
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N3/N4
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Jan. - Jun.
1999
N4/N5
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Jan. - Jun.
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0.30
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1998
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1997
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1996
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Egg/N3 (old)
Instantaneous mortality rate ( d-1)
0.15
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0.30
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Developmental stages
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--C5/Male
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Feb. - Jun.
C5/Female
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C4/C5
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1995
C3/C4
0.30
C2/C3
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C1/C2
0.45
Start
x0,y0,z0,t0
Yolk
?
Y
Yolk Sac
Contribution
Y
Encounter
Rate
Larval Age
Larval Size
Larval Behavior
N
Light
?
Prey Conc
Prey Type
Larval Size
Light Level
Turbulence
Temperature
Next Time
Step
Prey Biomass
Encountered
Y
Reduce Prey
Biomass
Advect, Behave
xt,yt,zt,tt
Successful
Pursuit
Satiated
?
N
Growth
Length,Weight
Metabolic
Costs
Consume
Prey
Werner et al, 1996
Werner et al, 1996
Simulated larval
cod growth rates
(% d-1) on Georges
Bank based on
observed copepod
prey
concentrations
Top: April, 1995
Bottom: April, 1998
(Runge et al. in prep.)
3D Physical model
u,v,w,Kz,T...
3D-coupled NPZD model
(primary and secondary production)
(Prey fields)
3D-coupled CLCM
(distribution and abundance of
copepods)
(Prey fields)
3D-coupled fish larvae
trophodynamic model
(growth and survival of fish larvae)
Environmental conditions for recruitment
Local Growth vs Retention/Exchange
• Due to the circulation gyre, the residence time of water over the Bank is long
relative to biological time scales so that in situ growth rather than lateral
exchange is the dominant process controlling population abundance on the
Bank
• Fine-scale horizontal exchange causes significant leakage of nutrients,
plankton and fish larvae across the frontal boundaries of the Bank, thus
causing a chronic input and exchange/loss of nutrients, plankton and fish
larvae
• Secondary circulation associated with the tidal mixing fron causes a surface
convergence near the well-mixed area boundary, providing a mechanism for
concentrating target species in the tidal front zone. Transport towards the
center of the Bank should be greatest for plankton in the upper layer of the
water column in this zone, or for those species that undertake vertical
migrations.
• Periodic vertical migration of zooplankton and juvenile fish into and out of the
sheared bottom-boundary layer can lead to horizontal movement against the
mean flow
Stratification
• Seasonal density stratification over the southern flank of the Bank
causes prey aggregation in the pycnocline and increased survival of
predator populations
• Differences in phytoplankton abundance and species composition
mediated by differences in water column stability result in
measureable differences in copepod recruitment and growth rates.
This leads to greater abundances in one region over another, due
solely to high growth rates in situ
• Turbulent mixing, generated by wind and tidal forcing, has a
significant impact on rates of ingestion, respiration and predation;
the processes of turbulent mixing and seasonal density stratification
influence predator-prey encounter rates and thus growth and
survival of individual organisms
Episodic gains and Exchanges/Losses
• The residual mean flow is important in horizontal transport of
zooplankton and fish larvae onto and off of Georges Bank, thus
causing major sources and sinks for Bank populations
• The seeding of copepod populations from the Gulf of Maine during
winter has a significant impact on the level of prey biomass for
larval fish during late spring and early summer. A corollary is that
the population genetic makeup of the prey on Georges Bank
reflects the generic makeup of the source populations
• Storms, especially during winter and early spring, as well as
impingement of warm-core rings, can cause large exchanges/losses
of zooplankton and fish larvae from Georges Bank, thus increasing
the apparent mortality rate of Bank populations
• Population size is continuously regulated by incremental rather
than episodic events, i.e. the time scale of the variability of the
driving forces is of the same order as the generation time of the
population.
Mortality
• Predation rather than starvation is the
dominant source of mortality of fish larvae;
predation rather than advective exchange is
ths dominant source of mortality of
copepods
Science 304: 1463-1466 4June2004
•An important challenge in the development of a new generation
of ocean basin scale models is the incorporation of uncertainty
•Simulations should be probabalistic rather than deterministic,
such that our endemic lack of knowledge of processes and
structure can be acknowledged.