Download - Paul Falkowski
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: [email protected]
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