Chukchi Sea Epibenthic Community and Food Web Structure

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Chukchi Sea Epibenthic Community and Food Web
Structure
Katrin Iken Bodil Bluhm University of Alaska
Fairbanks Ken Dunton Texas AM at Austin Boris
Sirenko Sergej Gagaev Zoological Institute RAS
St. Petersburg
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Background

• Part of RUSALCA program 2004
• (Russian-American Long-term Census of the
  Arctic )
• CIFAR / NOAA funded
• Ecosystem-oriented study of Bering Strait
  Chukchi Sea in climate change context
• BS Gateway to Arctic, CS region affected by sea
  ice changes, HC connection to Arctic basins
• Interdisciplinary synoptic status quo / change

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Objectives

• baseline of epibenthic megafauna community
  structure and diversity
• delineate benthic food web structure as in
  different water masses

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Epibenthic megafauna (w/o fish)

• Megafauna trawl-fauna
• Account for 25 or more of benthic community
  remineralization on Arctic shelves (e.g.,
  Piepenburg et al. 1996, 1997, Ambrose et al.
  2001)
• Fauna of potential commercial / subsistence
  interest
• Long-lived long-term indicators of oceanographic
  conditions

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Station locations
17 stations 2 Bering Strait 9 southern Chukchi 6
Herald Canyon 34 m to 101 m
?
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Community distribution
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Epifaunal vs infaunal biomass
Dunton et al. 2005
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Environmental control
Transform Log(X1)
3D Stress 0.11
Resemblance S17 Bray Curtis similarity
MDS by relative biomass
Substrate
h
s
13
23
11
15
106
25
27
58
18
20
107
85
62
73
17
6
10
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Food web structure

• Food web structure describes
• how material is passed through the system
• how pelagic and benthic systems are linked
  (bottom-up)

• Stable isotopes
• food web indicators food sources (C) and trophic
  level (N)
• 1 for d13C, 3.5 for d15N
• food web marker with reduced noise

Are isotopic patterns of food webs characteristic
of the water mass in which the community occurs?
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N3 per station
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Carbon flux in benthic food web d13C
Station 6 (ACC)
Leptasterias polaris
Station 10 (AW)
Chionoecetes opilio
Strongylocentrotus sp.
Hyas sp.
Polynoidea
Gorgonocephalus sp.
Actinaria
Evasterias echinosoma
Gersemia rubiformis
Bryozoa
Alcyonidium gelatinosum
POM
N3 per species
-25
-24
-23
-22
-21
-20
-19
-18
-17
-16
d13C
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Trophic levels in benthic food web d15N
Station 6 (ACC)
Station 10 (AW)
Hyas sp.
Chionoecetes opilio
Actinaria
Gorgonocephalus sp.
Polynoidea
Leptasterias polaris
Evasterias echinosoma
Gersemia rubiformis
Strongylocentrotus sp.
Bryozoa
Alcyonidium gelatinosum
POM
N3 per species
4
6
8
10
12
14
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d15N
13
Trophic position of species by station/water mass
18
16
14
12
d15N
10
8
6
4
10
23
18
6
11
25
20
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Station ( AW ? ACC)
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Discontinuous food web in ACC conditions -
possible explanations -

• Stronger additional trophic levels in ACC

• Other carbon source than POM, e.g. ice algae,
  terrestrial material

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Implications

• Epifauna community composition Substrate
  indicator, probably not water mass indicator
• Isotopic signature water mass indicator
• Food web structure useful indicator for changes
  in oceanographic conditions

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Acknowledgements

• Crew and scientists on the Khromov
• Trawling Brenda Holladay
• Isotope processing Melanie and Götz
• Taxonomists Ken Coyle, Igor Smirnov,
• Daphne Fautin, Chris Mah
• Funding CIFAR/NOAA ARO, BASIS, SFOS, CoML

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