A Recipe for Ocean Productivity, with Variations

John MarraJohn MarraLamont-Doherty Earth ObservatoryLamont-Doherty Earth Observatory

Palisades, NYPalisades, NY

USAUSA

What I’m going to talk about An alternate (sort of) algorithm for An alternate (sort of) algorithm for

remotely-sensed primary remotely-sensed primary productivity productivity

Absorption and Pigments in Absorption and Pigments in phytoplankton, and in the phytoplankton, and in the algorithmalgorithm

Variations caused by mesoscale Variations caused by mesoscale phenomenaphenomena

An alternate (non-B&F) model of remotely-sensed primary

productivityP(z) = (E,N)a*ph [Chla(z)] E(z)

Agreement found between pigment and Agreement found between pigment and irradiance and irradiance and 1414C uptake in several studies C uptake in several studies

Coupled: based on absorption properties of Coupled: based on absorption properties of the ocean, and has some stabilitythe ocean, and has some stability

Allows for physiological adaptationAllows for physiological adaptation Challenge is to understand how quantum Challenge is to understand how quantum

yield and absorption vary with environmental yield and absorption vary with environmental propertiesproperties

Agreement found between calculations based on pigment and irradiance, with 14C uptake in different areas

0.01

0.1

1

10

0.01 0.1 1 10 100

C assim. (calculated)

C a

ssim

. (o

bse

rved)

Units: mmols C m-3 d-1

Boreal NA

Gulf of Maine

Sargasso Sea

Productivity Algorithm: What we need to know, minimum

Variability in Quantum Variability in Quantum Yield?Yield?

Chlorophyll-a as a Chlorophyll-a as a function of depth?function of depth?

Chlorophyll-specific Chlorophyll-specific absorption as a function absorption as a function of depth?of depth?

Spatial variability of Spatial variability of Chlorophyll-specific Chlorophyll-specific absorptionabsorption??

Function of irradiance; constant maximumFunction of irradiance; constant maximum

Gaussian (sub-surface Gaussian (sub-surface max) up to a thresholdmax) up to a threshold

Assumed constant with depth; Assumed constant with depth; averaged over averaged over

Varies with SST?Varies with SST?

Current version of the model

How the algorithm is (somewhat) stabilized and coupled.

Productivity

(Euphotic Depth)

Irradiance

Absorption

Chlorophyll

increasedecrease

increase

increase

decrease (all else

being equal)

increase

…but basing an algorithm on absorption means also knowing absorption from water and other components

Phytoplankton Absorption and Environmental Variables

Community composition

Environmental variables Absorption spectra

Absorption in Phytoplankton

Objective is to create rules for the geographic and Objective is to create rules for the geographic and temporal variability in a*temporal variability in a*ph ph (sensu Hoepffner and (sensu Hoepffner and Sathyendranath, 1992)Sathyendranath, 1992)

Avoid using relationships based on the [Chl-a] (e.g., Avoid using relationships based on the [Chl-a] (e.g., Bricaud et al., 1995; Cleveland, 1995) Bricaud et al., 1995; Cleveland, 1995) Up to now it seems that aUp to now it seems that a**

ph ph (() is only considered in ) is only considered in terms of the biological effects: pigment packaging and terms of the biological effects: pigment packaging and species composition, cell size.species composition, cell size.

Chlorophyll-a: as biomass, as an adaptable property, Chlorophyll-a: as biomass, as an adaptable property, as a trophic indicator?as a trophic indicator?

Assume that a*Assume that a*phph does not vary within the first two optical does not vary within the first two optical depths (literature supports, but not unanimous)depths (literature supports, but not unanimous)

How we might expect absorption properties to vary with SST

Absorption

Sea-Surface Temperature

a*p?

a*ph?

a*ps?

(Not a physiological relationship!)

Chlorophyll-specific absorption and SST

Sea Surface Temperature (ºC)

a*p

h (

m2 m

g c

hl-1

)

0.00

0.02

0.04

0.06

0.08

0.10

-5 0 5 10 15 20 25 30

Arabian SeaGulf of MaineMLML60NAESOPSGOMtotal pigmentPS pigment

(Marra and Trees, submitted)

PBopt and Temperature?

-1

1

3

5

7

9

11

13

15

-5 0 5 10 15 20 25 30 35

Temperature (ºC)

PBopt

[(m

gC

)(m

gC

hl)

-1 h

-1)]

(thanks to J. Cullen’s presentation at the Bangor Productivity Conference, March 2002)

(Based on physiology)

A Sample View of Algorithm Output: January, 1998

gC

m-2 d

-1

The Oceanic Mesoscale and Phytoplankton Variability

Two studies, two anti-cyclonic eddies, both Two studies, two anti-cyclonic eddies, both hemisphereshemispheres

Eddy Haulani off the island of HawaiiEddy Haulani off the island of Hawaii An eddy spawned by the Leeuwin Current (off An eddy spawned by the Leeuwin Current (off

W. Australia)W. Australia)

Vaillancourt, Marra, Bidigare, and Seki., submitted

The birth of the eddy, Haulani, near Hawaii I in Fall, 2000

Eddy Haulani as Ocean Color

Vaillancourt et al., submitted19 November, 2000(Dotted line indicates SST feature for same date)

SeaWiFS image, courtesy NASA GFSC and Orbital Sciences Corp.

Community composition in and out of the Hawaii eddy

Larger forms are found in greater numbers inside the eddy. (Picoplankton do not change much.)

Eddies in the Leeuwin Current

…Thomas Moore, LDEO and CSIRO, Hobart

The anti-cyclonic (“convergent”) eddy with the ocean color signal

From Moore et al., 2001

Anti-cyclonic eddy

We then compared the pigment composition of coastal water and that in the eddy….

Pigment analysis of coastal (Sta 52) and eddy (Sta 62) samples

Total quantity of pigment is the sameTotal quantity of pigment is the same Pigment composition nearly the same (loss of Pigment composition nearly the same (loss of

alloxanthin, fucoxanthin, Chl c1+c2)alloxanthin, fucoxanthin, Chl c1+c2)

Coastal Offshore eddy, 3 months later

From Moore et al., 2001

So, in conclusion… The Productivity Algorithm: promising, but needs workThe Productivity Algorithm: promising, but needs work

How does phytoplankton absorption vary with How does phytoplankton absorption vary with environmental properties?environmental properties?

What about other absorbing components?What about other absorbing components? Quantum yield parameterization?Quantum yield parameterization?

Non-absorption based observations (e.g., FRRF)Non-absorption based observations (e.g., FRRF) Environmental determinants to Environmental determinants to maxmax

Instead of PvsE parameters (like PInstead of PvsE parameters (like PBBoptopt), focus on a), focus on aphph and and

pigments pigments Go from satellite reflectances -> productivity?Go from satellite reflectances -> productivity? We need to understand the differences caused by We need to understand the differences caused by

vertical as opposed to horizontal processes in eddiesvertical as opposed to horizontal processes in eddies

Variations in Quantum Yield

Vaillancourt et al., in press, DSR II