The co-evolution of oceanic ecosystems and physical

circulation

Paul G. Falkowski

Environmental Biophysics and Molecular Ecology Program

Institute of Marine and Coastal Sciences

And Department of Geology

Rutgers University

New Brunswick, New Jersey

Email: falko@imcs.rutgers.edu

WOCE San Antonio November 20, 2002

THE GLOBAL SCALE

OCEAN CIRCULATIONINFLUENCE ON

Photosynthetic Biomass, Primary and Export Production

FROM A POOL TO A FLUX

MODELS OF NET PRIMARY PRODUCTION

“Figure 9.10 A plot showing the correlation between external nutrient concentration (represented, in this case, by NO 3) and the maximum quantum yield for photosynthetic carbon fixation. The data were obtained from three regions in the North Atlantic: circles are from an upwelling region off norhwest Africa, squares are from a transition region, and triangles are from an oligotrophic region. (Data courtesy of Marcel Babin and Andre Morel)

EXPORT PRODUCTION

ADDING UNCERTAINTY

TURBULENCE, EDDY PUMPING AND PRIMARY

PRODUCTIONTHE MESOSCALE MATTERS!

QuickTime™ and a decompressor

are needed to see this picture.

FAST REPETITION RATE FLUOROMETRY

A peek into the photophysiological response of phytoplankton to

mesoscale turbulent mixing processes

Depth (m

)

Distance

Distance

Distance

Distance

Figure 1 A schematic representation of the eddy upwelling mechanism. The solid line depicts the vertical deflection of an individual isopycnal caused by the presence of two adjacent eddies of opposite sign. The dashed line indicates how the isopycnal might be subsequently perturbed by interaction of the two eddies. I 0 represents incident solar

radiation, and 1% I 0 the base of the euphotic zone.

PHYSICAL SELCTION OF PHYTOPLANTKON TAXA

NOT ALL CHLOROPHYLL IS THE SAME: THE ‘FUNCTIONAL GROUP’ ARGUMENT AND

MARGALEF’S MANDALA

 

 

 

 

 

 

2´ 10- 7 4´ 10- 7 6´ 10- 7 8´ 10- 7 1´ 10- 6

0.25

0.5

0.75

1

1.25

1.5

1.75

Cell N quota

Growth rate, d-1

Diatom

Cocco

Droop model

0max,iiiiiQQQμμ⎛⎞−=⎜⎟⎝⎠

iiiiidNNmNdtμ=⋅−⋅

max,iiiRkRρρ⋅=+

()0max,iiiidQQQdtρμ=− −⋅

0()iidRDRRNdtρ=⋅−−⋅

max,*0max,max,max,max,iiiiiiiiiiiKmRmµQmμρμρ⋅⋅=⋅−⋅−⋅⋅

Symbol Units Meaning

State variablesN cell L-1 Population density R µmol L-1 Resource availability Q µmol cell-1 Cell quota

Physiological functionρ µmol cell-1 h-1 Uptake rate

ParametersD h-1 Dilution rate R0 µmol L-1 Constant nutrient inflowing rate µmax h-1 Maximal growth rate

K µmol cell-1 Growth rate half saturation constQ0 µmol cell-1 Minimal cell quota

Notational conventions i Subscript to distinguish terms pertaining to a given species

t h Time

Droop Model

When equilibrium is reached between loss and growth rates, there will be a superior competitor, which has the smaller resource requirement (R i*) (Tilman 1977).

THE OCEANIC FAX MACHINE

TURBULENCE ON GEOLOGICAL TIME SCALES

CIRCULATION AS A GENETIC ISOLATING

PROCESSSPECIATION AND SELECTION IN

THE MODERN OCEAN

PCR amplification (SSU rDNA) ofCoccolithus pelagicus

from 500 to … 1 cell.

Crtl+

1 105 50 100 500

Calcidiscusleptoporus

100200

300...

11 12 27 28 78 131 43 NZ SA

0.01

B28

27

78

12

43

131

SA

11

NZ

A

C

Fig. 6

CONCLUSIONS

• THE OCEAN IS FUNDAMENTALLY A “BOTTOM UP” SYSTEM, HENCE,

• TO THE EXTENT THAT THERMOHALINE CIRCULATION BRINGS NUTRIENTS INTO THE UPPER OCEAN, TO FIRST ORDER IT DCONTROLS THE DISTRIBUTION AND MAGNITUDE OF PHYTOPLANKTON BIOMASS, AS WELL AS NET AND EXPORT PRODUCTION

• ON LONGER TIME SCALES, GLOBAL OCEAN CIRCULATION DISTRIBUTES AND GENETICALLY ISOLATES PHYTOPLANKTON – IT IS AN EVOLUTIONARY SELECTION MECHANISM ON TIME SCALES OF CENTURIES TO MILLIONS OF YEARS

• POPULATIONS OF PHYTOPLANKTON NEVER SEE OCEAN CIRCULATION; THEY EXPERIENCE MESOSCALE MIXING PROCESSES, INCLUDING EDDIES, FRONTS, AND COASTAL UPWELLING.

• MESOSCALE PROCESSES EXERT STRONG CONTROLS ON LOCAL SELECTION INDIVIDUAL TAXA – WE ARE STILL LEARNING HOW THESE CONTROLS WORK.

CHALLENGES FOR THE FUTURE

1. THE MESOSCALE

2. PALEOPHYSICAL OCEANOGRAPHY

3. INTEGRATING OCEAN CIRCULATION WITH EARTH SYSTEMS PROCESSES

OUR FUTURE

HUMANS HAVE ESCAPED THE RED QUEEN CONTROL– BUT

ARE WE IN CONTROL OF OUR DESTINY?

THANKS TO

DENNIS MCGUILLICUDDY

SCOTT DONEY

SASHA TOZZI

ELENA LITCHMAN

MICHAEL BEHRENFELD

ZBIGNIEW KOLBER

EDWARD LAWS

NASA, NSF, ONR AND DOE