Use%20of%20regularly%20migrating%20non-biological%20platforms%20as%20vehicles%20for%20spatio-temporal%20sampling%20of%20Southern%20Ocean%20systems

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Use of regularly migrating non-biological
platforms as vehicles for spatio-temporal
sampling of Southern Ocean systems
Simon Wright, Brian Griffiths, Bronte
Tilbrook,Steve Rintoul, Alain Poisson
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26 Feb 2003
25 Jan 2003
10 Feb 2003
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How to model microbial populations?

• Recognize different types of communities
• Key species and associations
• When and where do they occur?
• Time of season
• Oceanographic conditions
• MLD, nutrients, ice, etc
• Parameterize the community properties
• Primary production, respiration
• Aggregation
• Sedimentation
• Size distribution

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• What would a Southern Ocean Observing System look
  like?

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Regularly Migrating Non-Biological Platforms
(RMNBPs)
Seagoing Hydro-Investigative Platforms (SHIPs)
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Aurora Australis
LAstrolabe
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Programmable Ecological Observing Package (Live
Elements)
(PEOPLE)
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Three pronged approach

• Monitoring on repeat transects lAstrolabe
• Intensive oceanographic surveys Aurora
  Australis
• Process studies in minicosms
• Coupled with laboratory experiments

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Aurora Australis
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ASF
Pycnocline
Tmin
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ASF
Pycnocline
Tmin
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Disadvantage of Aurora Australis erratic
migratory route
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Three pronged approach

• Monitoring on repeat transects lAstrolabe
• Intensive oceanographic surveys Aurora
  Australis
• Process studies in minicosms
• Coupled with laboratory experiments

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Sokolov Rintoul 2002
Regular monitoring of Hobart - Dumont
dUrville 3 4 repeat transects per season
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Astrolabe lab in hold
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Astrolabe lab interior
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lAstrolabe repeat transects

• Oceanography
• XBT sections, nutrients Steve Rintoul, CSIRO
• alkalinity
• Alain Poisson IPEV, Paris
• Phytoplankton
• Chlorophyll fluorometry , FRRF
• Brian Griffiths, CSIRO
• HPLC pigments, Species ID and counts (whole and
  net), coccolithophorid counts
• Australian Antarctic Division
• Carbon dioxide pCO2
• Bronte Tilbrook, CSIRO

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Astrolabe 2002/03
CO2 drawdown
Chlorophyll a
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Astrolabe 2002/03
CO2 drawdown
Chlorophyll a
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Oct Nov Dec
Jan Feb Mar
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Date of bloom at mid latitude (53- 60ºS)
Season Bloom peak
1997-98 3 Dec
1998-99 19 Dec
1999-00 01 Jan
2000-01 09 Jan
2001-02 25 Jan
2002-03 10 Feb
2003-04 10 Jan
2004-05 15 Dec
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Oct Nov Dec
Jan Feb
Mar
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Oct Nov Dec
Jan Feb
Mar
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Bloom dynamics at mid latitude (53- 60ºS)

• 2002 - 2003
• Bloom in Feb
• about 1 ug Chl a/ L
• Dominant species
• F. kerguelensis, Phaeocystis, Trichotoxon,
  Thalassiothrix, Pseudonitzschia

• 2003 2004, 2004 2005 (Typical)
• Bloom in Dec - Jan
• about 0.8 - 1 ug Chl a/ L
• Dominant species
• F. kerguelensis, Pseudonitzschia, Trichotoxon,
  Chaetoceros dichaeta

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Oct Nov Dec Jan Feb Mar
Oct Nov Dec Jan Feb Mar
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Oct Nov Dec Jan Feb Mar
Oct Nov Dec Jan Feb Mar
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Bloom dynamics at mid latitude (53- 60ºS)

• The late bloom in 2002-2003 was associated with
  relatively warm, very low salinity water
• This water had low nutrient concentrations.
• A bloom developed only after nutrient
  concentrations increased

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Conclusions

• Regular sampling of Southern Ocean from
  lAstrolabe identified seasonal patterns in
  microbial populations
• relationship to carbon dioxide uptake
• Relationship to nutrient drawdown
• Substantial interannual differences in bloom
  dynamics appeared to be driven by seawater
  chemistry
• An anomalous late bloom developed only after
  nutrient concentrations increased in a large area
  of warm low salinity water.

A small subset of total data made possible by
repeated sampling of many parameters in a
collaborative program
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lAstrolabe repeat transects

• Organization
• Alain Poisson IPEV, Paris
• Bronte Tilbrook, CSIRO
• Acknowledgements
• Captain and crew S.V. lAstrolabe
• Many volunteer samplers

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What should a SOOS look like?

• Regular transects along the same transect

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What should a SOOS look like?

• Oceanography
• Thermosalinograph
• XBT sections, nutrients
• Alkalinity
• Carbon dioxide pCO2
• Atmospheric
• Carbon dioxide, oxygen, DMS
• Dust
• Environment
• Temperature, radiation, wind speed, wave height,
  ice
• Plankton
• Chlorophyll fluorometry, FRRF
• HPLC pigments, Species ID and counts (whole and
  net)
• Continuous plankton recorder