Spatial distribution and abundance of marine picoplankton across the

Patagonian shelf-break

Heather A. Wright, Lisa R. Moore University of Southern Maine, AGU Feb. 22,2010

• Background and motivation

• COPAS08 cruise - Coccolithophores of the Patagonian Atlantic Shelf

• Analysis of Picoplankton distribution and abundance: Prochlorococcus, Synechococcus,Picoeukaryotes, Heterotrophic bacteria

• Conclusions

Outline

Quantifying populations

Sid

e S

ca

tte

rChlorophyll fluorescence

Ch

loro

ph

yll

flu

ore

sc

en

ce

Side Scatter

Station 10 19m depth

Cyanobacteria:

Prochlorococcus

SynechococcusPicoeukaryotes:

Mixed populations

Chlorophyll fluorescenceC

hlo

rop

hyll

flu

ore

sc

en

ce

Station 50 18m depth

Side Scatter

Johnson, et al. 2006. Science 311: 1737-1740

Picoplankton distributions

Cruise motivation

Observe and quantify picophytoplankton distribution In this unique hydrographic region during an austral

summer coccolithophore bloom

• What are the dominant picoplankton populations?

• What are the distribution and abundance patterns?

• Are there physico-chemical correlations?

COPAS08

http://oceancolor.gsfc.nasa.gov/S. Painter, unpub.

Cruise track and hydrographic

features

Sea SurfaceTemperature

Chlorophyll

Depth profiles of picoplankton and chlorophyll at Station 20

PicoeukaryotesCyanobacteria

picoplankton Heterotrophic bacteria

1.5e13

1.0e13

5.0e12

2.5e12

1.0e12

8.0e11

6.0e11

4.0e11

2.0e11

1.5e13

1.0e13

7.5e12

5.0e12

2.5e12

1.5e14

1.0e14

7.5e13

5.0e13

2.5e13

Dep

th in

tegrated ab

un

dan

ce

[cells/m

2]

Section A

Section A crosses shelf break waters of Malvinas Current into deep, warmer waters of the Brazilian current.

Temperature C

Picoeukaryotes

Cyanobacteria

Section B

Cyanobacteria

Hydrographic Regions shift East to West as transect crosses shelf-break into the Malvinas water and Shelf.

Temperature C

Picoeukaryotes

Temperature and Nutrients

Positive correlation with temperature Negative correlation with TDN

Conclusions

• Picophytoplankton distribution corresponds with hydrographic features of the Patagonian Shelf-break region

• Cyanobacteria are numerically dominant above 48S whereas picoeukaryotes are more abundant further south

• Heterotrophic biomass is greater throughout all stations and an order of magnitude higher than total picophytoplankton

• Cyanobacterial abundance is correlated with temperature, anti-correlated with nutrients whereas Picoeukaryotes are not strongly correlated with temperature

Acknowledgments

The Moore lab for sample collection and technical assistance:

Kate Callnan, Kay Roache-Johnson

The Balch lab and Bigelow Laboratory for Ocean Sciences:

Dr. William Balch, Emily Lyczkowski, Dave Drapeau, Bruce Bowler

The Captain RV Revelle and UCSD shipboard technical staff for cruise logistics, sample collection, and nutrient processing:

Captain Desjardins, Rob Palomares, Matt Durham, and Dan Schuller

Graduate thesis committee at University of Southern Maine:

Dr. Lisa Moore, Dr. Terry Theodose, Dr. Jeff Walker

This research project is funded through NSF grant #0847890 and Bio-OCE NSF #0851288