A modeling study on processes controlling the biogeographic boundary of
Calanus finmarchicus in the north Atlantic – Arctic region
Outline:
Abstract
1. Introduction (Carin, Bob C., Ji, Cabell)

Climate change might cause the shift of the biogeographic boundary of Calanus
finmarchicus. The Arctic ecosystem could be changed dramatically if C.
finmarchicus become dominant over other Calanus species (C. glacialis and C.
hypoboreas). Understanding the processes that control the boundary is critical.

There are different hypotheses regarding the processes that might control the
boundary, including 1) low temperature can cause low development rate and
reproduction failure (Jaschnov, 1970; Sameoto, 1984; Tande, 1985); and 2) late
food availability can cause reproduction failure (Hirche 2007).

Our questions: What is the possibility of C. finmarchicus to colonize the Arctic
Ocean if temperature and food only affect development rate (no impact on
reproduction process)? i.e. If no reproduction failure (Can the temperature and
food-dependent development (+ flow fields) explain the observed boundary in
the north Atlantic-Arctic region (see Fig. 1 for the map of the region)?
2. Material and methods
2.1. Physical model (Chen, Bob R., Gao)
2.2. Biological model (Ji, Geoff, Carin, Bob C., Cabell)
Belehrádek’s function
Food-dependency
Coupling with physical model
2.3. Numerical experiments (Ji, Carin, Bob C., Cabell)
An example of temperature field output from the model (Fig. 2)
Starting of growth season based on SeaWiFS climatology (Fig. 3)
Growth Season Length (GSL) determined from Chl-a climatology (Fig. 4)
Model case runs:
Case 1a: Temperature-dependent development only, surface (0-m)
Case 1b: Temperature- and food- dependent development, surface (0-m)
Case 2a: Temperature-dependent development only, subsurface (50-m)
Case 2b: Temperature- and food- dependent development, surface (50-m)
Case 3: Continued advection of the individuals that reached C5 at Case 1b until
July 1 of the next year.
3. Results
3.1. Physical model results (Chen, Bob R., Gao)
Describe the modeled hydrography and circulation patterns in the north Atlantic
– Arctic region; compare model and observed T/S, and flow.
3.2. Biological model results (Ji, Carin, Bob C., Cabell)
Case 1a (successful and failed) (Fig. 5)
Case 1b (successful and failed) (Fig. 6)
Case 2a (successful and failed) (Fig. 7)
Case 2b (successful and failed) (Fig. 8)
Case 3 (Fig. 9)
4. Discussion (All)
4.1. Greenland Sea distribution
Match/mismatch with observed pattern
Interaction with circulation and temperature/food environment
4.2. Barents Sea distribution, match/mismatch with observed pattern
Match/mismatch with observed pattern
Interaction with circulation and temperature/food environment
4.3. Penetration to the Arctic Ocean and speculations on possible warming scenario
5. Conclusion