Southern Ocean GLOBEC Program Eileen E. Hofmann Third GLOBEC PRSW Boulder, February 2009.
Globec Legacy- the SSC ideas
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Transcript of Globec Legacy- the SSC ideas
Globec Legacy- the SSC ideas
A. Philosophy
B. Body of Knowledge
C. Innovative Methodologies
D. Management and information transfer
E. 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” approach).
Model Resolution-Temporal/Spatial Issues of Model Integration
Bacteria
Birds/mammals
THE SEA
Number of Species
SPECIES IN THE MODEL
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
Hydrodynamic model(The Unstructured Grid Finite Volume Costal Ocean Model)
Lower trophic level food web model(NPZD Model) Eulerian approach
Zooplankton or fish larvae population dynamics model(Individual Based Model) Lagrange approach
Modeling approach
Prey
Hydro-Fields
Hydro-Fields
Ji and Chen
Ammonia Silicate
SmallPhytoplankton
LargePhytoplankton
SmallZooplankton
LargeZooplankton
DetritusNitrogen
DetritusSilica
Predation
Mortality
Remineralization
UptakeUptake Uptake
Dissolution
Fecal
Mortality
Grazing Grazing
Mortality
Mortality
Nitrate
Grazing
Mortality
Model Structure
Ji, Chen and coworkers
Chlorophyll a (mg m-3)
0.10 0.32 1.00 3.16 10.00
1999 Day:73-80
1
2
1999 Day:81-88 1999 Day:89-96
SeaWiFS data from GOMOOS website By Dr. Andrew Thomas, UMaine
Day 76
Subtidal currents
wind
Surface
20 m
3-D Model
3-D Model
Biological Model
Day 63 Day 66
Day 71 Day 76
Day 81 Day 86
Ji, Chen and coworkers
Copepod life history models: biological resolution on target species
Population dynamics of Calanus finmarchicus
EggsmCVIfmSpawnEggsEggsz
Kz
EggsUEggst EggsEggsz ....
NIWz
NImEggsNINIz
Kz
NIUNIt NINIEggsNIz
....
CIWz
CImNVICICIz
Kz
CIUCIt CICINVICIz
....
CVIfjW
zCVIfjmCVIfjCVdCV
DiapCVIfjCVIfjCVIfjCVdCV
....2
)1(
CVIfjz
Kz
CVIfjUCVIfjt z.
21)360/)(sin(50exp1)( LagTttDiap
max.)(1)( EPRtDiaptSpawn iii ZzWmW tanh
Zakardjian et al. 1999: CJFAS 56:2420-32
Zakardjian et al. 2003. JGR. Vol. 108. No.C11, 8016.
Zakardjian et al. 2003
Examples of copepod models in Georges Bank GLOBEC
Miller, Lynch, Carlotti, Gentleman, Lewis, 1998– 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
Durbin et al. 2003: Gulf of Maine Runge et al. (in prep.): Georges Bank
Calanus finmarchicus: Relationship of egg
production to phytoplankton biomass
Feb. - Jun.
Inst
ant
ane
ous
mor
talit
y ra
te (
d-1)
0.00
0.15
0.30
0.45 --
----
-- -- --
----
-- ----
--
---- -- --
-- ---- -- --
--
Jan. - Jun.
0.00
0.15
0.30
0.45
--
--
-- -- --
--
-- -- -- -- ----
--
---- -- --
-- -- -- ----
Calanus finmarchicusStage-specific Mortality
1996
1995
Developmental stages
0.00
0.15
0.30
0.45
--
----
-- --
---- -- -- --
--
--
-- --
-- ----
-- -- -- ----
1997 Jan. - Jun.
0.00
0.15
0.30
0.45
--
-- --
--
---- -- --
-- -- --
--
-- --
----
---- -- -- --
--
Developmental stages
Egg
/N3
(old
)
N3/
N4
N4/
N5
N5/
N6
N6/
C1
C1/
C2
C2/
C3
C3/
C4
C4/
C5
C5
/Fem
ale
C5
/Mal
e
0.00
0.15
0.30
0.45
--
--
---- --
--
---- -- --
--
---- --
-- -- -- ---- -- --
1999
1998 Jan. - Jun.
Jan. - Jun.
Startx0,y0,z0,t0
Yolk?
Yolk SacContribution
Light?
EncounterRate
SuccessfulPursuit
Prey BiomassEncountered
Next TimeStep
Advect, Behavext,yt,zt,tt
MetabolicCosts
Reduce PreyBiomass
Satiated?
ConsumePrey
Y
Y
Y
N
N
GrowthLength,Weight
Larval Size
Light LevelTurbulence
Temperature
Larval AgeLarval Size
Larval Behavior
Prey ConcPrey Type
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 modelu,v,w,Kz,T...
3D-coupled NPZD model(primary and secondary production)
3D-coupled CLCM(distribution and abundance of
copepods)
3D-coupled fish larvae trophodynamic model(growth and survival of fish larvae)
Environmental conditions for recruitment
(Prey fields)
(Prey fields)
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.