Biological Implications of Arctic Change

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Biological Implications of Arctic Change
Jacqueline M. Grebmeier Chesapeake Biological
Laboratory University of Maryland Center for
Environmental Sciences, Solomons, Maryland, USA
11 November 2008 GEOS 489/689 IPY Course
Texas A M
University
College Station, Texas
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Introduction

• highly productive ecosystem under Pacific water
  influence in west
• sea ice important for system
• timing annual production critical for water
  column production, carbon cycling, and
  pelagic-benthic coupling
• short food chains lower trophic level impacts
  cascade efficiently to higher trophic organisms
• potential impacts of change have broad-reaching
  implications for long-term ecosystem structure

courtesy Tom Weingartner
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2007 minimum Arctic sea ice
NSIDC, 2007 see http//www.nsidc.org

• Decline in September ice extent from 1979 to 2007

• September rate of sea ice decline 1979-2007
• 2007 is the maximum ice retreat on record, with
  2008 the 2nd lowest

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Albedo effects
movie

• polar ice reflects light from sun (high albedo)
• as ice melts, less reflection and more
  absorption by ocean and land, raising
  temperature of both
• ice-albedo feedback is a positive loop,
  resulting in loss sea ice and continued seawater
  warming

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Record Sea Ice Retreat 2007
movie
NSIDC, 2007 see http//www.nsidc.org

• September is the usually minimum month for sea
  ice retreat and over time, ice is retreating more
• 2007 is the minimum ice retreat on record

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Bering Strait region
NSIDC, 2008 see http//www.nsidc.org
- Continued high sea ice retreat compared to
average, near 2007 record minimum
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Ice algae important in spring vs water column
production in summer
courtesy Rolf Gradinger
Wassman et al. 2004
Ice algae slower rates of decay compared to
temperate diatoms allows more labile
material to fuel benthic production in shelf
regions timing/location critical
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Settling of spring bloom to the benthos over two
week time period in May 2007
Integrated water chlorophyll a (chl a)
Surface sediment chlorophyll a (mg/m2)
Settling of water column chl a to middle depths
(left) and to the sediments after few weeks
(right)
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Arctic Marine Food Web
courtesy Rolf Gradinger
Rolf Grandinger 2004
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Local Alaskan Communities are concerned by
unpredictability of ice conditions and its impact
on subsistence hunting, lifestyle and the
associated ecosystem
photos courtesy Gay Sheffield, ADFG
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BENTHIC PROCESSES

• Influenced by
• extent and duration of sea ice
• water temperature and salinity
• water column production and grazing
• net carbon flux to the sediments
• sediment grain size
• predator-prey relationships
• Benthic fauna are excellent indicators of
  climate change since they reflect large scale
  changes in biological response
• Pelagic-benthic coupling can be studied via
  underlying sediment processes on various time
  scales
• Sediment metabolism days-to-weeks
• Sediment tracers (e.g. chl a) weeks-to-years
• Benthic faunal populations months-to-years
  (integrators)

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HAPS Coring system 133 cm2 core designed for
shipboard measurement of gas exchange,
particularly oxygen respiration, over bottom
sediments
0.1 m2 van Veen grabs for benthic macrofaunal
collections
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Pelagic-benthic coupling
Grebmeier et al. , 2006, Prog. Oceanogr., 71

• Integrated chlorophyll (mg m-2 1975-2004)
• regular patterns of high plant production
  resulting from inflow high nutrient Pacific water

• Sediment community oxygen consumption (mmol O2
  m-2 d-1) from 1984-2004
• an indicator of carbon supply to the benthos

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Pelagic-benthic coupling
Grebmeier et al. in prep.
Grebmeier et al. , 2006, Prog. Oceanogr., 71

• Macrofaunal biomass (g C m-2) from 1977-2004
• foot prints of carbon deposition and benthic
  biomass on the shallow continental

• Dominant benthic taxa by biomass (g C m-2) from
  1977-2004
• variations by food supply, sediment grain size
  and predator-prey interactions

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Northern Bering Sea-Time-series Study
Cascading potential high
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Case Study-St. Lawrence Island Polynya region
photos by J. Lovvorn
Spectacled Eider and benthic food supply
(dominated by bivalves Nuculana radiata, Nucula
belloti, Macoma calcarea)
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Seasonal sediment oxygen uptake (mmol O2 m-2 d-1)
Cooper et al., MEPS 2002

• Highest organic carbon deposition to benthos in
  May-June after spring bloom

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Sediment chlorophyll (mg m-2)
Cooper et al. MEPS, 2002

• Highest water column chlorophyll deposition to
  benthos in May-June after spring bloom

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Benthic infaunal data from 1973-2004

• Dominant bivalve families Nuculanidae,
  Nuculidae, and Tellinidae

modified from Grebmeier and Barry 2007
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St. Lawrence Island
Annual July cruises on CCGS Sir Wilfrid Laurier
Seawater temperature extending from the Aleutian
Islands, Alaska (top left) to Barrow, Alaska (top
right) in July 2001 from the CCGS Sir Wilfrid
Laurier. Bottom panel above is time series of
bottom water temperatures (lt0C) in cold pool SW
of St. Lawrence Island.
Grebmeier et al., 2006, Science 311
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Potential restructuring of marine ecosytem
Northern Bering Sea Ice Concentration (April
2000-2004 A) and St. Lawrence Temperature
Changes (B)
Grebmeier et al., 2006, Science 311
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Change in sediment oxygen uptake (indicator of
carbon supply to benthos) and benthic
macrofaunal biomass SW of St. Lawrence
Island trend lines through station means
BSEO-S sites embedded in Group C, orange
Grebmeier et al., 2006, Science 311
Simpkins et al., 2003, Polar Biology 26
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GRP FAMILY A Nuculanidae 53
Nuculidae 26 B Nuculanidae 40
Nuculidae 12 C Nuculidae 20
Nuculanidae 16 D Nuculidae
26 Nuculanidae 24
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3
5
2
1
Time
Group Station Year A SLIP 1,2 1988-1998 SLIP
3 1988-1993 B SLIP 1,2 1999-2002 SLIP
3 1993-2002 C SLIP 1,2,3 2002-2006 SLIP
5 2007 D SLIP 4 1998-2007 SLIP 5 1998-2006
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(modified from Humphrey, M.S. thesis, 2008, in
review)
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Surface Seawater Temperature (5 m)
2000
2001
2002
2003
2004
Juvenile Sockeye Salmon Distribution and Seaward
Migration Pathway change in Bristol Bay sockeye
salmon distribution and seaward migration
pathways in relation to warming sea surface
temperatures
High Survival
Low Survival
courtesy Ed Farley/NOAA
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Pink salmon
Pollock
10 Million new Salmon in the N. Bering Sea in
2004 coincident with increased northward
movement of pollock courtesy Jack Helle/NOAA
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Chirikov Basin, Northern Bering Sea in the 1980s

• Basin is downstream end of Gulf of Anadyr-Bering
  Sea Greenbelt production zone
• Pelagic-benthic coupling supports high benthic
  biomass (Grebmeier et al. 1989, Mar. Ecol. Prog.
  Ser.)
• Dense assemblages of tube-building ampeliscid
  amphipods
• Gray whale surveys indicate feeding area in
  northern Bering Sea (Moore et al. 2003,
  Can.J.Zool.)

movie
Gray whale sightings
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Drop in Benthic Productivity in 1990s
BSEO Benthic Time Series

• Highsmith and Coyle report evidence of 30
  production downturn 1986-88 (MEPS, 1992)
• decline of ampeliscid amphipod biomass at 4
  stations (Moore et al., Can. J. Zool., 2003)
• LeBoeuf et al. 2002 suggest this amphipod
  decline in the Chirikov Basin as causal to gray
  whale mortalities
• Shift gray whales north of Bering Strait
  normally like ice-free areas

Gray whale
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Fish/prey photos Sherry Cui
Shorthorn sculpin
gt40 ampharetid worms
Live ampharetid worm
C3O July 2007-benthic camera
movie
PhotoArt Howard/ PolarPalooza
10 cm spacing between green laser dots
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The Western Arctic Shelf-Basin Interactions (SBI)
Project

• SBI Arctic / global change project 2002-2004 map
• intensive field studies during the record summer
  sea ice retreat
• investigating production, transformation and
  fate of carbon at the shelf-slope interface in
  the northern Chukchi and Beaufort Seas
• downstream of the productive shallow western
  Arctic shelves
• prelude to understanding the impacts of a
  potential warming of the Arctic

Grebmeier and Harvey 2005
http//sbi.utk.edu
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Shelf-Basin Interactions
courtesy Leif Anderson
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Benthic Carbon Cycling and Ecosystem Structure in
the Northern Bering and Chukchi Seas in RUSALCA

• Objectives
• evaluate carbon export to benthos via sediment
  oxygen uptake rates (HAPS corer)
• sediment tracers (TOC, chl a, Be-7, C-13, grain
  size)
• benthic infaunal population structure and
  biomass (van Veen grab)
• benthic camera for epifauna

Cooper et al. 2008 in press
-decadal shift from 1988 1995 to 2000s with
more enriched 13C to benthos in 2004 on Russian
side, likely due to nutrient-rich Anadyr water
being more restricted to western Chukchi Sea
(more freshwater through Strait?)
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• Important biological and geological processes on
  the outer shelf and slope of the Chukchi Sea

modified from Grebmeier et al. 2006 and unpubl.
data
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Within 2 days of each other 4-6 August 2002
(left) and 5-7 August 2004 (right)
SST August 12-16, 2004
Red squares abandoned walrus pups with rapid ice
retreat
photo by Ev Sherr
data from Cooper et al., 2006 Aquat. Mammals, 32
Jacqueline Grebmeier-Arctic
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RELATIONSHIP TO SEA ICEMoore and Huntington
Ecological Applications 2008
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Pacific walrus
Beluga whales
Polar bear
Threatened status with reduction sea ice-current
and pending?
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Marc Webber, USFWS
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Summary

• Pacific-influenced continental shelf region in
  the northern Bering Sea is experiencing earlier
  spring transition between ice-covered and
  ice-free conditions and increasing seawater
  temperatures
• changes in the timing of productivity and
  grazing over shelf will change carbon export to
  the benthos and trophic structure
• currently carbon deposition occurs over
  days-weeks in May-June in the northern Bering Sea
  as the spring bloom settles to the benthos
• time series station have declined in both carbon
  deposition and benthic biomass since the early
  1990s, with lower levels being maintained in the
  2000s change bivalve dominance observed early
  2000s
• time-series observation sites critical for
  identifying ecosystem status and trends with
  environmental change

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Thank you. Any questions?
movie
clip courtesy of Tony Fischbach, Alaska Science
Center, USGS
Support from U.S. National Science Foundation,
National Oceanic and Atmospheric Administration,
North Pacific Research Board, Office of Naval
Research
photo courtesy Karen Frey