Southern Ocean GLOBEC Program

Southern Ocean GLOBEC Program

Eileen E. HofmannThird GLOBEC PRSW

Boulder, February 2009

SO GLOBEC Program

• Understand physical and biological factors that contribute to enhanced growth, reproduction, recruitment, and survivorship of krill - include predators and competitors

• Overwintering strategies and role of sea ice and circulation are primary focus

SO GLOBEC Program

• SO GLOBEC is part of International GLOBEC and US SO GLOBEC is a contribution to the international effort

• Field studies began in 1999-2000 • Field studies finished in 2007/08• SO GLOBEC program is now in synthesis

and integration phase

UK

AustraliaUS, Germany

Germany

Korea

SO GLOBEC Field Study Sites

Target Species

Approach

Two special issues of Deep-Sea Research IIdevoted to SO GLOBEC results

Third volume is in progress and should be done by end of 2009

Synthesis approach

Research Highlights

• Understanding of circulation• Connections of circulation to top

predator distributions• Connection of SO GLOBEC region to

larger system• Innovative use of seal-derived

hydrographic data

Stratification, retention and frontal exchanges

Sea ice modifies all of theseIce shelf effects on circulation (Klinck et al.,

2004)

(Beardsley et al., 20)04

(Thiele et al., 2004)

Humpback WhaleLocations

Extensive observationsof predator abundanceand distribution

Habitat use, predator andprey interactions

Food web interactions

Biological Hot Spots

Snow petrel andAdélie Penguindistribution in relation to watermasses

(Chapman et al., 2004)

Not all parts of the shelf are biologically similar

Biological Hot SpotsBiological Hot Spots

(Costa et al., 2007)

Bellingshausen Sea

Drake Passage

MB

MB : Marguerite Bay

MT : Marguerite Trough

AI : Alexander Island

CS : Crystal Sound

LF : Laubeuf Fjord

MT

AI

CS

LF

Predator Hot Spots

Role of circulation and biology in producing hot spot regions?

No. krill /m2

0

< 2

2-4

4-8

8-16

16-32

32-64

64-128

128-256

>256

no data

Atkinson et al (2004)

Circumpolar distribution of Antarctic krill

(Lawson et al., 2004)(Ashjian et al., 2004)

Zooplankton Population Variability

Shifts in Abundance and Distribution

Reconsider Krill Dominated Food Web

Alternative pathways buffer change - reflect/support long-term change?Need better quantification of alternative pathways

Alternative Food Web Pathways

High krill Low krill

Three-dimensional rendering of Crabeater sealMovements obtained from satellite tags

Studies of habitat use, behavior, predator- prey interactions

Studies ofanimalphysiologyand biology

Summary

• Large scale connectivity in zooplankton populations - combination of local retention and import from other regions

• Considerable interannual variability in zooplankton composition and relative abundance

• Variability related to chlorophyll values• Bottom up control? Implications for food

web structure?

Summary

• Technology that has been advanced through SO GLOBEC

• Seal-derived hydrographic measurements are important data

• Large-scale applications for understanding circulation and ice shelf dynamics

• Important data for evaluation of numerical circulation models

• Important for understanding habitat use

Concluding Remarks

• SO GLOBEC provides comprehensive biological and physical data sets from several sites in the Antarctic

• Provide the basis for investigating physical controls of Antarctic marine food web, alternative food web structures, e2e food webs structures, and climate variability

• Poised for comparative studies with GLOBEC and related programs outside of the Antarctic