Title: Circulation and trophodynamic modeling of larval fish populations: a case study of Georges Bank cod
1Circulation and trophodynamic modeling of larval
fish populations a case study of Georges Bank cod
- Cisco Werner
- Marine Sciences Department
- U of North Carolina at Chapel Hill
- cisco_at_unc.edu
Supported by NSF and NOAA
2Colleagues
- Canadian DFO Ian Perry, Fred Page, Charles
Hannah, Mike Sinclair, Dave Greenberg, John
Loder - Dartmouth College Dan Lynch, Chris Naimie
- NMFS Greg Lough, Larry Buckley, Jim Manning
- UNC-CH Brian Blanton, John Quinlan
3Outline
- Physical-biological coupling in marine ecosystems
- GLOBEC and Georges Bank
- Key physical processes on GB
- Modeling retention
- Trophodynamics and IBMs
- Next steps and Conclusions
4GBank
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12GBank
13GBank
14Cod fluctuations
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16 Phases of Georges Bank GLOBEC
- Onset of stratification (1995)
- Exchange (1997)
- Fronts (1999)
- Synthesis Integration (2002-06)
- Broadscale Cruises (1995-1999)
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18 U.S. Cruises Canadian Cruises
Year Cruises Days Cruises Days
______________________________________________
1993 1 6 1994 8 82 1 7
1995 23 272 2 18 1996 11 115 1 8
1997 23 252 1 8 1998 12 122 1999
27 331 4 3 Totals 104 1,174 10 77
19Physical forcing and flow features- tides-
winds- heating-cooling
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21Finite Element Mesh Georges Bank /
Northwest Atlantic Model
22Model equations
Quoddy
- Nonlinear prognostic, finite element model
(Lynch Werner,1991) - 3-D shallow water equations
23- Higher order turbulent closure
- wherein
- E1 and B1 are experimental constants (Mellor
Yamada, 82) - W is a wall proximity function (Blumberg et al.
1992) - and the vertical turbulent mixing coefficients
- (Nm,Nh,Nq) (qlsm,qlsh,qlsq)
- are given in terms of the stability functions
sm,sh and sq as in Galperin et al. (1988)
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25Tidal ellipses Residual
(time-averaged) currents
26Wind
Wind effects
10 meters
1 meter
Decreased wind effects
50 meters
30 meters
27Retention/Loss from Advective effects only
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34Spawning, circulation and retention (Page et al.
1999)
Sept-Oct
March-April
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36Larval behavior
37Model generated larval behavior
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39What about feeding?
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41Individual level
42Hydrodynamics and Individual Based Modeling
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45Turbulence distribution on Georges Bank
46Basic growth flowchart
47Larval Age Larval Size Larval Behavior
Start x0,y0,z0,t0
Yolk ?
Yolk Sac Contribution
Y
N
Encounter Rate
Successful Pursuit
Y
Light ?
Prey Biomass Encountered
Prey Conc Prey Type
Larval Size
Light Level Turbulence Temperature
Y
Next Time Step
Reduce Prey Biomass
Satiated ?
Advect, Behave xt,yt,zt,tt
N
Metabolic Costs
Consume Prey
Growth Length,Weight
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50- on-bank retention
- advective losses
- starvation
- growth
- distribution
Surviving larvae are located at depth in
retentive regions!!
51Examine growth of cod larvae during 95 98
3D Representations of observed prey and
temperature fields modeled turbulence and light
fields
Will produce 3D maps of potential growth
zones. Can this technique be used to define
regions of high and low growth or survivorship?
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53Oithona Naups
Oithona Copes
- March 1995
- Objective analysis
- of zooplankton biomass on Georges Bank from
broadscale MOCNESS sampling.
01m
10m
20m
40m
60m
?g/liter
54March Temp
May Temp
- March 1995
- Objective Analysis
- of temperature
- on Georges Bank
- from Broadscale CTD
- sampling.
01m
10m
20m
40m
60m
C
5512mm May
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58Interannual variability of larval growth may be
related to zooplankton abundance
59Modeling zooplankton dynamics (Calanus fin.)
60How to couple larval fish models and zooplankton
models?
61Predators?
62What about links to basin-scales?
63Fish and apex predators which depend directly on
the target taxa
Cod, haddock, herring, capelin, baleen whales
Cod, haddock, herring, salmon capelin, baleen
whales
Cod, haddock, herring, redfish, salmon,
baleen whales
Cod, haddock, herring, salmon mackerel, blue
whiting, baleen whales
Cod, haddock, whiting, herring,
mackerel, sandeel, pout
Cod, haddock, herring, capelin, baleen whales
Cod, haddock, herring, mackerel, sandlance, baleen
whales
64NW Atlantic cod
North Sea cod
65B. Dickson
66Gulf of Maine/Georges Bank Region
A hydrographic and faunal transition zone
especially vulnerable to changes in climate.
C. Greene
67 Circulation Increased Labrador
Current Transport
NAO (-)
NAO ()
(Drinkwater et al., 2001)
68Advance of Labrador Slope Water in 1997-1998
(Drinkwater et al., 2001)
69C. finmarchicus in the northern North Sea, and
the North Atlantic Oscillation
As reported by Fromentin and Planque, 1996
70Calanus abundance map compiled from data supplied
by SAHFOS to NERC Marine Productivity project
GR2/2749 and data from the EU-TASC project
1950-1999 mean abundance
71NORTH ATLANTIC OCEAN
SHELF SEAS
Climate forcing of ocean circulation
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73Conclusions
- Physical models are capable of providing
realistic flow fields on appropriate space-time
scales - Feeding environment/trophodynamics can provide
insight into key processes and their location
w/IBMs - Interannual variability, coupling to
basin-scales, predators, etc. still missing