1. Intermingling of two Pseudocalanus species on Georges Bank D.J. McGillicuddy, Jr. Woods Hole Oceanographic Institution A. Bucklin University of New Hampshire Journal of Marine Research 60, pp. 583-604, 2002.

2. P. moultoni P. newmani 1997 Broadscale Survey Data Species-specific PCR (Bucklin et al., 2001)

3. The forward model: an advection-diffusion-reaction equation C concentration v velocity K diffusivity Advection Tendency Diffusion Reaction (biological sources and sinks) C obs (t 0 ) C obs (t 1 ) time The forward problem

5. Observations: P. Moultoni Models Observations: P. newmani

9. Are the inverse solutions ecologically realistic? R(x,y,t) bounded by –100 to +100 individuals m -3 day -1 [most fall between -10 to +10] C 5 moulting potential: Mean C 5 abundance 2500 individuals m -3 (Incze pump samples: April 1997, May 1997, June 1995) Stage duration in GB conditions: 5 days (McLaren et al., 1989) Implied moulting flux of 500 individuals m -3 day -1

10. Are the inverse solutions ecologically realistic? Predation potential: Model predicted rates of 3-10% day -1 Bollens et al. specific rates of predation on C. finmarchicus and Pseudocalanus spp. copepodites based on observed predator abundance and feeding rates http://userwww.sfsu.edu/~bioocean/research/gbpredation/gbpredation1.html

11. Inverse method results in convergent solutions Geographically specific regions of growth/mortality These vary seasonally according to animal abundance patterns, the circulation, and their orientation Two main balances: –Tendency / source (weak currents or aligned gradients) –Tendency / source / advection Conclusions (I)

12. Resulting biological sources and sinks ecologically realistic -- R(x,y,t) bounded by independent rate estimates C 5 moulting flux Predation by invertebrates and vertebrates Emerging conceptual model: -- Distinct source regions in late winter P. moultoni on NW flank P. newmani on NE peak and Browns Bank -- During the growing season, GB circulation blends these reproducing (not interbreeding) populations such that their distributions overlap by early summer. Conclusions (II)

13. Physics -- errors in the circulation -- vertical shear Biology -- density dependence vs. “geographic” formulation -- multistage models, behavior, etc. Observational limitations -- only adults -- upper 40m Caveats

15. Are the inverse solutions ecologically realistic? R(x,y,t) bounded by –100 to +100 individuals m -3 day -1 [most fall between -10 to +10] C 5 moulting potential: Mean C 5 abundance 2500 individuals m -3 (Incze pump samples) Stage duration in GB conditions: 5 days (McLaren et al., 1989) Implied moulting flux of 500 individuals m -3 day -1 Predation potential: Hydroid ingestion rate: 0.25 cop. hydr -1 day -1 (Madin et al., 1996) Characteristic abundance: 10,000 hydranths m -3 Potential consumption rate: 2500 copepods m -3 day -1 Pseudocalanus adults ~15% of total postlarvae (Davis, 1987) Hydroid predation on Pseudocalanus: 200 individuals m -3 day -1

17. Pseudocalanus spp. MARMAP 1977-1987 Concentration (# m -3 ) Two population centers: Western Gulf of Maine Georges Bank Davis (1984) hypothesis: Western Gulf of Maine is a source region for the Georges Bank population

18. General circulation during the stratified season Beardsley et al. (1997)

19. A first attempt to simulate the data…

20. Derivation of the adjoint model (1) Problem: Given observations C 0 (t 0 ) and C 1 (t 1 ), find R(x,y) that minimizes J Define a cost function J: Where λ=λ(x,y,t) are Lagrange multipliers

21. Derivation of the adjoint model (2) Adjoint model: We require R at the minimum of (and therefore J) where It can be shown that:

22. Convergence of the iterative procedure

23. Example results: Mar-Apr to May-Jun Red: source Blue: sink

24. Term-by-Term Diagnosis Observations Biological Source/Sink Advection Diffusion Tendency JF-MA MA-MJ MJ-JA

25. Chlorophyll-a MARMAP 1977-1987 O’Reilly and Zetlin (1996) Jan-Feb Mar-Apr May-JunJul-Aug Sep-Oct Nov-Dec Davis (1984) Cutoff for food limitation 0.6 – 1.2 μg Chl l -1 Cutoff range

26. Chaetognaths MARMAP 1977-1987 Sullivan and Meise (1996) Jan-FebMar-Apr May-JunJul-Aug Sep-OctNov-Dec

27. ECOHAB-GOM Observations Townsend et al. (2001) 1)Gulf-wide distribution 2) Association with coastal current 3) Center of mass shifts west-to-east as season progresses

28. Some thoughts on model design for HAB applications Forward models Inverse approaches McG et al. (1998) Fisheries Oceanography, 7(3/4), 205-218. McG and Bucklin (2002) Journal of Marine Research, 60, 583-604. http://science.whoi.edu/users/mcgillic/software/scotia_1.0/

29. END

30. Term-by-Term Diagnosis Continued… Observations Biological Source/Sink Advection Diffusion Tendency JA-SO SO-ND ND-JF

32. Pseudocalanus spp. MARMAP 1977-1987 Concentration (# m -3 )

33. Term-by-Term Diagnosis Obs Src Adv Dif Ten JF-MA MA-MJ MJ-JA JA-SO SO-ND ND-JF

34. Term-by-Term Diagnosis Obs Src Adv Dif Ten JF-MA MA-MJ MJ-JA JA-SO SO-ND ND-JF

35. A first attempt to simulate the data…

36. Term-by-term diagnosis Red: source Blue: sink

37. Observations: P. Moultoni Models Observations: P. newmani