Overriding questions

• What are the relevant time and space scales to study plankton diversity?

• Are the time and space scales that regulate diversity the same as those that control biogeochemical cycling?

The Hawaii Ocean Time-series (HOT)

• Established in 1988 as part of the U.S. JGOFS program.

• Primary objectives: characterize time-dependent dynamics in carbon, nitrogen, and phosphorus inventories and fluxes.

What have we learned?• Prokaryote dominated ecosystem.

• Ocean biology regulates nutrient stoichiometry and carbon export.

• Chronically oligotrophic upper ocean (NO3

- + NO2- <10 nM, PO4

3- <100 nM).

• N2 fixation plays an important role in nutrient dynamics and carbon export.

• Organization of plankton populations may be controlled by ocean-climate teleconnections.

Time scales and processes driving biological variability in the oceans

Global-scale climate variability

PDO / NAO ~ 10-30 year period

ENSO ~ 1-3 year period

Millennia

Decadal

Interannual

Intraannual Seasonal (light, temperature, nutrients)

Diurnal Tidal, light, predation

Are ocean-climate teleconnections reflected in

plankton dynamics?Prochlorococcus

(cel

ls m

-2)

1x1013

2x1013

3x1013

4x1013

ALOH

A M

LD anom

aly

-1.0

-0.5

0.0

0.5

1.0

Euka

ryot

es(c

ells

m-2

)

1x1011

2x1011

3x1011

4x1011

ALOH

A M

LD anom

aly

-1.0

-0.5

0.0

0.5

1.0

Year

1989 1991 1993 1995 1997 1999 2001 2003

Zoop

lank

ton

dry

wei

ght

(g m

-2)

0.00.30.60.91.2 ALO

HA

MLD

anomaly

-1.0

-0.5

0.0

0.5

1.0

ALO

HA

M

LD anom

aly

-1.0

-0.5

0.0

0.5

1.0

Div

inyl

Chl

a(m

g m

-2)

5

10

15

20

25

19'-H

ex.

(mg

m-2

)

1

4

7

10

ALO

HA

M

LD anom

aly

-1.0

-0.5

0.0

0.5

1.0

Year

1990 1992 1994 1996 1998 2000 2002 2004

19'-B

ut.

(mg

m-2

)

1

4

7

ALO

HA

M

LD anom

aly

-1.0

-0.5

0.0

0.5

1.0

Interdecadal and decadal scale dynamics in pigment biomarkers

Summary• Plankton populations at Station ALOHA vary

over a broad continuum of time scales ranging from seasonal, to decadal.

• Plankton population structure in the central North Pacific Ocean appears linked to ocean-climate dynamics.

• Understanding the mechanisms regulating temporal dynamics in plankton populations requires an integrated biogeochemical approach.