Potential Approaches

• Empirical downscaling: Ecosystem indicators for stock projection models are projected from IPCC global climate model simulations.

• Dynamical downscaling: IPCC simulations form the boundary conditions for regional bio-physical numerical models with higher trophic level feedbacks.

• Fully coupled bio-physical models that operate at time and space scales relevant to regional domains (impractical at present).

PredationSpatial

distribution

BiomassConsumption

ratePrey

composition

Spring conditions (Late) summer conditions

Prey

Timing of ice

retreat

SpringSST

Prey

Summer SST

Wind mixin

gStabilit

y

Estimated effects of summer SST & predation on log-recruitment

R2 =0.44P = 0.001

Prediction interval

Simulate effect of increase in average SST on recruitment at three levels of predation

Low Med High

Dynamical Modeling

Physical Forcing(Wind, temp, sun)

NutrientsNO3, NH4…

Primary Producers(Phytoplankton)

Secondary Producers(Zooplankton)

Higher trophic levels(Pollock etc.)

•Horizontal resolution: ~10km, vertical resolution: 60 layers•Computes physical properties i.e. temperature, salinity currents•BEST-NPZ model coupled to ROMS at every grid point and time-step

ROMS Physical Oceanography Model

EUPHAUSIIDS

LARGE COPEPODS

MICROZOOPLANKTON

SMALL PHYTOPLANKTON

LARGE PHYTOPLANKTON

NITRATE AMMONIUM

Slow sinkingDETRITUS

IRON

SMALL COPEPODS

Excretion + Respiration

WATERMortalityPredationEgestion

JELLYFISH

Fast sinkingDETRITUS

Inexplicitfood source

ICE ALGAE

NITRATE AMMONIUM

BENTHIC FAUNA BENTHIC DETRITUS

ICE

BENTHOS

Model Validation: Data availability

Location of nitrate data used: All months, all years

Model Validation: Primary Production

Observations from Rho, Whitledge and Goering (1997)

Simulated

Observed

Monthly mean daily primary production: Middle Shelf

SimulatedObserved

1999 2004

Zooplankon Biomass

Day 220 1999 2004

Microzooplankton 5.9 16

Small Copepods 2.8 4.5

Large Copepods 8.9 1.29

Euphausiids 0.57 3.9E-5

Compares ‘reasonably’ well to Coyle data … – but will the fish have enough to eat ?

Model Predictions:Ecosystem Projections

Euphausiid production: Annual average for shelf break A single projection

CCCMA

1999 2001 2003 2005 2007 2009 2011 2013 2015 2017 2019

Ensemble of runs will define upper and lower limits of projection

g C

m-2

15

25

35

45

Zooplankton biomass: Depth integrated at M2 mooring

FEAST model for forage species and predators

• Bioenergetics of feeding, growth, spawning• Focus on data-driven functional response between

predator and prey• Use allometric relationships for rates• Diet preferences based on stomach data• Movement (towards prey concentrations, away from poor

conditions, migration for spawning)• Currently includes pollock, cod, and arrowtooth flounder

Diet fitting by regionPrey Type (proportion in diet) by pollock body length (0-80cm)

regi

on

3 size classes of copepod in model summed for fittingamphipods, shrimp

stomachs sampled by pollock length by region

Combined BTS+Acoustic survey vs FEAST

2004

2008

FEAST age-0 seasonal forage potential and stock-assessment estimate of year-class strength

Colors: stock-assessment year-class strength

Blue weakestRed strongest

Domain 8 (outer northwest shelf)

Week of year

Ag

e 0

fo

rag

ing

p

ote

ntia

l