Calanus finmarchicus diapause stock in the Gulf of Maine crashed during Autumn 1998

Calanus finmarchicusCalanus finmarchicus diapause stock diapause stock in the Gulf of Maine in the Gulf of Maine

crashed during Autumn 1998crashed during Autumn 1998

HYPOTHESIS:HYPOTHESIS:C. finmarchicusC. finmarchicus - an indicator of climate- - an indicator of climate-

driven changes in ocean circulation?driven changes in ocean circulation?

Since shelf populations of Since shelf populations of C. finmarchicusC. finmarchicus are are not self-sustaining and must be supplied every not self-sustaining and must be supplied every year or every few years from external sources, year or every few years from external sources, we hypothesize that their fluctuations in we hypothesize that their fluctuations in abundance reflect climate-driven changes in abundance reflect climate-driven changes in ocean circulation.ocean circulation.

The North Atlantic Oscillation (NAO)The North Atlantic Oscillation (NAO)

NAO +NAO +- Strong H and L pressure cells- Strong H and L pressure cells- Westerlies strengthen- Westerlies strengthen-Storm track shifts NorthStorm track shifts North

NAO -NAO --Weak H and L pressure cells-Weak H and L pressure cells- Westerlies weaken- Westerlies weaken- Storm track shifts South- Storm track shifts South

North Atlantic Ocean Circulation North Atlantic Ocean Circulation Responses to the NAOResponses to the NAO

NAO +NAO +- Enhanced production of LSW and - Enhanced production of LSW and intensification of DWBCintensification of DWBC- Labrador Current weakens- Labrador Current weakens- Gulf Stream north wall shifts North- Gulf Stream north wall shifts North

NAO -NAO -- Reduced production of LSW and- Reduced production of LSW and weakening of DWBCweakening of DWBC- Labrador Current intensifies- Labrador Current intensifies- Gulf Stream north wall shifts South- Gulf Stream north wall shifts South

Emphasis on NW AtlanticEmphasis on NW Atlantic

The Winter The Winter NAONAO Index Index

1860 1880 1900 1920 1940 1960 1980 2000

42 0

-2 -4

Progress of LSSW along Continental MarginProgress of LSSW along Continental Margin

Feb.98

Sep.97Oct.97

Feb.98

Jan.98

Mar.98

Intrusions of LSSW into Intrusions of LSSW into Gulf of MaineGulf of Maine

JanuaryJanuary AprilApril MayMay

SeptemberSeptember OctoberOctober NovemberNovember

The ‘98 EventThe ‘98 Event

JanuaryJanuary

AprilApril

The ‘98 EventThe ‘98 Event

MayMay

The ‘98 EventThe ‘98 Event

SeptemberSeptember

The ‘98 EventThe ‘98 Event

OctoberOctober

The ‘98 EventThe ‘98 Event

NovemberNovember

The ‘98 EventThe ‘98 Event

Complex LinkagesComplex LinkagesClimateClimate

CalanusCalanus

PhysicalPhysicalOceanographyOceanography

NW Atlantic’s NW Atlantic’s Coupled Slope Water SystemCoupled Slope Water System

Maximum Modal StateMaximum Modal State- Associated with NAO +- Associated with NAO +

Minimum Modal StateMinimum Modal State- Associated with NAO- Associated with NAO - -

1950 1960 1970 1980 1990 2000

3 0

-3

4 0

-4

NAO Index

RSW Temp. Index

Time Series of the NAO Index and the Regional Slope Water Temperature Index

Time-Series DataTime-Series Data Slope-Water SectorsSlope-Water Sectors

Coupled Slope Water System and the NAO

r

-8 -4 0 4 8

0.4 0

-0.4 -0.8

0.8

Lag (yr)

Cross-Correlation

RSW

T In

dex

-6 -4 -2 0 2 4 6

4

0

-4

-6

NAO

Relationship, Lag=1

RSWT changes 1 yr after NAO. R2=0.31

Predicting the Response Predicting the Response of the Coupled Slope Water of the Coupled Slope Water

System to the NAOSystem to the NAO

Observed and Predicted Observed and Predicted Time Series of the RSWT Time Series of the RSWT

Index for 1958-1999Index for 1958-1999

Predicted RSWTPredicted RSWTIndex for 2000-2003Index for 2000-2003

HindcastingHindcasting ForecastingForecasting

Continuous Plankton Recorder (CPR) Continuous Plankton Recorder (CPR) Survey of the North AtlanticSurvey of the North Atlantic

• SAHFOS supervises CPR surveys SAHFOS supervises CPR surveys throughout most of North Atlantic.throughout most of North Atlantic.

• Sister CPR surveys on Scotian ShelfSister CPR surveys on Scotian Shelf and Gulf of Maine provide comparableand Gulf of Maine provide comparable plankton time-series data.plankton time-series data.

• Gulf of Maine CPR surveys are Gulf of Maine CPR surveys are conducted by NMFS in Narragansett, RI.conducted by NMFS in Narragansett, RI.

Time Series of the NAO Index, theTime Series of the NAO Index, theRegional Slope Water Temperature Index, Regional Slope Water Temperature Index, and the and the C. finmarchicusC. finmarchicus Abundance Index Abundance Index

NAO Index

Regional Slope Water Temperature Index

C. finmarchicus Abundance Index

Calanus and the Coupled Slope Water Systemr

0.4 0

-0.4 -0.8

0.8

Lag (yr)

Cross-Correlation

Calanu

s

-6 -4 -2 0 2 4 6

1

0

-1

RSWT Index

Relationship, Lag=3Calanus changes 3 yrs after RSWT R2=0.25

1998-8 -4 0 4 8