When the Arctic Becomes Subarctic

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• When the Arctic Becomes Subarctic
• Seabirds Respond to
• Three Decades of Climate Change

George J. Divoky Institute of Arctic
Biology University of Alaska Fairbanks
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Arctic
Subarctic

• Seasonal first-year ice cover and well mixed
  water column
• Moderate to high productivity from phytoplankton
  bloom
• Diverse and abundant forage fish (i.e. sand
  lance, capelin, herring) important to higher
  trophic levels
• Nearshore supports diverse fauna and flora little
  to upper trophic levels

• Multi-year ice cover for nearly entire year
  reduces access and upwelling
• Low water column productivity
• Ice-associated diatoms and algae support
  cryopelagic fauna important to higher trophic
  levels
• Ice scour of nearshore scoured by ice providing
  little to upper trophic levels

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Cooper Island
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Changes in annual temperature
Annual temperature anomaly for1975-2004 vs.
1951-1974
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Percentage difference in ice cover1990-2000
vs.1979-1989
Cooper Island
J.C. Comiso, NASA/GSFC and Rob Gersten, SSAI
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Arctic Terns Mid-1970s 60 breeding pairs Breeding
success primarily dependent on presence of
multi-year pack ice Nearshore important to
thousands of migrant terns
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Black Guillemots trapped here
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Point Barrow
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Arctic Cod
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Bluhm and Gradinger
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Colony Growth 1975-1990
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June 1984
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Missing 1998
NOAA/CMDL BRW Melt Date Guillemot First Egg
(minus 14 days) X-Correlation gt 0.73 (excluding
1998)
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August 1988
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August 1988
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Number of days the ground is snowfree at Barrow
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Number of days the ground is snowfree at Barrow
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First time in 400 years Black Guillemots could
breed in northern Alaska
Tree ring record from northern Alaska
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Breeding pairs and nest sites by year
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Rapid colony growth during negative Arctic
Oscillation (AO) and decreased population after
AO shift
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Cooper Island
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Distance of ice edge from Point Barrow on 10
August
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Breeding success (fledges per egg)
Before AO shift (1975-89) 0.52 fledges per
egg After AO (1989-2004) 0.23 fledges per egg
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Ice 2003
July 17
July 27
Aug 10
Aug 25
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Reproductive success Pre-AO shift and 2003
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Four-horned Sculpin
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Snailfish
Snail Fish
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Wolf Fish
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isopod
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Horned Puffins begin to breed in northern Alaska
in 1986
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Cooper Island
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Percentage difference in ice cover1990-2000
vs.1979-1989
Cooper Island
J.C. Comiso, NASA/GSFC and Rob Gersten, SSAI
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Number of days the ground is snowfree at Barrow
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Horned Puffins compete with Black Guillemots for
cavities One third of all Black Guillemot chicks
killed by puffins in 2004 (most would have
starved anyway)
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Puffin Chick photo
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Arctic
Subarctic
When did the Arctic become subarctic?
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Arctic
Subarctic
May
June
July
August
Sept.
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Arctic
Subarctic
When does the Arctic become subarctic?
May
June
July
August
Sept.
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June Arctic
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Late July
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August
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Predicted summer ice edge in 2050
Cooper Island
J.C. Comiso, NASA/GSFC and Rob Gersten, SSAI
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• Arctic Tern
• High population (gt50 pairs) and productivity in
  1970s when utilizing prey associated with
  multi-year pack ice
• Low numbers (lt10) and no productivity in 21st
  century
• Black Guillemot
• Rapid colony growth and high productivity before
  1990
• Decreased population and productivity after 1990
• Productivity in 21st century not sufficient to
  maintain population
• Possibility for a selection event
• Horned Puffin
• Not present at start of study
• First breeding in 1986
• Increasing numbers and breeding activity in 21st
  century

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Beaufort Sea nearshore now suboptimal for both
arctic and subarctic species

• Early summer nearshore waters have too much ice
  for Horned Puffins
• Arrival and egg laying delayed
• Hatching success low (25)
• Late summer nearshore waters have too much open
  water for Black Guillemots
• Adults unable to find prey for nestlings
• Fledglings must travel large distances (gt50 km)
  to reach ice edge

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Physical data is the most impressive
Summer Northern Sea Ice Extent
Days Ground Snow-free in Barrow
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Acknowledgements

• North Slope Borough
• Dept. of Wildlife Mgmt.
• Search and Rescue
• Mayors Office
• Collaborators
• Bob Stone, CMDL NOAA
• Jim Maslanik
• Sheldon Drobot
• Hajo Eicken

• BASC (Barrow Arctic
• Science Consortium)
• Residents of Barrow
• Friends of Cooper Island
• cooperisland.org

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Herschel Island
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Pack ice conditions in the Alaskan Beaufort Sea
on 15 and 16 August 2002
Legend
15 August 2002
16 August 2002