Physical-biological interactions:Physical-biological interactions:regional to basin scalesregional to basin scales

I. Pseudocalanus spp.: MARMAP data 1977-1987

II. P. moultoni and P. newmani: U.S. Globec Georges Bank broadscale surveys in 1997

III. Calanus finmarchicus: U.S. Globec Georges Bank broadscale surveys 1995-1999

IV. Toward a basin scale approach: lessons from the JGOFS program on physical-biogeochemical interactions at large scales

General circulation during the stratified seasonGeneral circulation during the stratified seasonBeardsley et al. (1997)

A finite-element model A finite-element model of the Gulf of Maine / of the Gulf of Maine / Georges Bank region Georges Bank region (Lynch et al., 1996)(Lynch et al., 1996)

PseudocalanusPseudocalanus spp. spp. MARMAP 1977-1987MARMAP 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

A first attempt to A first attempt to simulate the simulate the

observed observed PseudocalanusPseudocalanus spp. spp.

distributions…distributions…

P. moultoni

P. newmani

1997 Broadscale Survey Data1997 Broadscale Survey Data

Species-specific PCR(Bucklin et al., 2001)

Observations:P. Moultoni

Models

Observations:P. newmani

Are the inverse solutions ecologically realistic?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]

C5 moulting potential:Mean C5 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

Are the inverse solutions ecologically realistic?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 predatorabundance and feeding rates

http://userwww.sfsu.edu/~bioocean/research/gbpredation/gbpredation1.html

Physics-- assumes perfect knowledge of the circulation-- 2-D transport (no vertical shear)

Biology-- density dependence vs. “geographic” formulation-- multistage models, behavior, etc.

Observational limitations-- only adults sampled-- upper 40m

Caveats to interpretation of these solutionsCaveats to interpretation of these solutions

C. finmarchicusC. finmarchicus climatology: climatology:

Globec Broadscale Globec Broadscale surveys 1995-1999surveys 1995-1999

N3

N4

N5

N6

C6

C5

C4

C3

C2

C1

Jan Feb Mar Apr May Jun

Time

Log

(abu

ndan

ce)

Durbin et al.http://globec.gso.uri.edu/

1 1 1( ) ( )(1 )ii i i i i i i i

Cv C K C R F F C

t

Fi: molting flux Fi(T,Chl) computed (Campbell et al. 2001) R: sources of N3 Inferred (monthly)μi: mortality Inferred (monthly)Ci off-bank Inferred (initial conditions)

N3 N4 N5 N6 C1 C2 C3 C4 C5 C6

R μN4 μN5 μN6 μC1 μC2 μC3 μC4 μC5 μC6

C. finmarchicus modelX. Li et al.

Inferred off-bank initial conditions

N3 N4 N5 N6 C1

C2 C3 C4 C5 C6

C. finmarchicus solution: January- June

Inferred Mortality

N3

N4

N5

N6

C6

C5

C4

C3

C2

C1

Jan-Feb Feb-Mar Mar-Apr Apr-May May-Jun

Spatially averaged mortality rate:seasonal variation

Spatially averaged mortality rate:January-June average

Term-by-term analysis

Transport terms: large magnitude, but net effect is smallPrimary balance: tendency/molting/mortality

Spatially averaged mortality rateSpatially averaged mortality rate

Black: central caseGray: off-bank sources=0 (including ICs)

Mor

tali

ty (

d-1)

Stage

Biological control of the vernal population increase of C. finmarchicus on Georges Bank

1i

i i i i

CF F C

t

1 ˆii i i i

CF F C

t

iˆi only slightly smaller than

Advectivedelivery

Advectiveloss

Georges Bank

Advectivedelivery

Advectiveloss

Georges Bank×

National Science FoundationNCAR: Scientific Computing Division

Eddy-driven sources and sinks of nutrients in the upper ocean:Eddy-driven sources and sinks of nutrients in the upper ocean:results of a 0.1results of a 0.1° resolution model of the North Atlantic° resolution model of the North Atlantic

McGillicuddy, D.J., Anderson, L.A., Doney, S.C. and M.E. Maltrud

2222 OOCHOHCO

tonPhytoplank

4443 SiOH , PO , NO

Nutrients

Fish) nZooplankto(

0I

0I 1%

New Production in theNew Production in theOpen OceanOpen Ocean

12yrm N mol 0.5

An eddy-resolving nutrient transport modelAn eddy-resolving nutrient transport model

Euphotic Zone: NP=NP(I,NO3,T)Aphotic Zone: Relaxation to clim.

NO3(σT)

Simulated Annual New ProductionSimulated Annual New Production

BATS EUMELI

NABE

OWSI

Verticaladvection

Horizontaladvection

New Prod Conv + Diff

Total Mean Eddy

Annual Annual New New

ProductionProductionTerm Term

BalancesBalances

Observed Annual New Production = 0.5 mol N m-2 yr-1

New Production at BATS:New Production at BATS:Three Models, Three Different Nutrient Transport Pathways

Coarse (1.6º) Eddy-resolving (0.1º)

Sea SurfaceTemperature

log (NewProduction)

Toward a basin-scale model of Toward a basin-scale model of C. finmarchicusC. finmarchicus

Planque et al. (1997)

END

References

McGillicuddy, D.J., Lynch, D.R., Moore, A.M., Gentleman, W.C., Davis, C.S., and C.J. Meise, 1998b. An adjoint data assimilation approach to diagnosis of physical and biological controls on Pseudocalanus spp. in the Gulf of Maine - Georges Bank region . Fisheries Oceanography, 7(3/4), 205-218.

McGillicuddy, D.J. and A. Bucklin, 2002. Intermingling of two Pseudocalanus species on Georges Bank . Journal of Marine Research, 60, 583-604.

McGillicuddy, D.J., Anderson, L.A., Doney, S.C., and M.E. Maltrud, 2003. Eddy-driven sources and sinks of nutrients in the upper ocean: results from a 0.1 degree resolution model of the North Atlantic. Global Biogeochemical Cycles, 17(2), 1035, doi:10.1029/2002GB001987.

See http://www.whoi.edu/people/mcgillic “publications” link for more information