Sea ice algae, a major food source for herbivorous plankton and benthos in the eastern Bering Sea.

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Sea ice algae, a major food source for
herbivorous plankton and benthos in the eastern
Bering Sea.

• Rolf Gradinger, Bodil Bluhm. Katrin Iken (UAF)

Hypotheses (H1) Sea ice algal communities are
the main sources of algal biomass and primary
productivity in the BEST study area in spring
during periods of ice cover. (H2) The
accumulation of ice algal biomass is following
the seasonal and regional gradients in light and
nutrient availability. (H3) Release of
ice-derived particulate organic material (POM)
occurs mainly during periods of ice melt. (H4)
The carbon stable isotope ratio (?13C) of sea ice
POM differs from pelagic material. (H5) The ?13C
ratio can be used to trace the sea ice-derived
material through the Bering Sea food web.
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Objectives
(1) measure chemical (nutrients, salinity) and
physical parameters (ice thickness, snow depth,
ice temperature, light) of sea ice and the
under-ice water layer (2) describe and quantify
the temporal and spatial variability of ice algal
parameters (algal pigments, taxonomic
composition, size spectra, POC, PON, ?13C
ratio) (3) quantify the primary production of ice
algae (using labeled precursors) (4) quantify
the same parameters as in objectives (1) and (2)
for the phytoplankton immediately under the sea
ice and quantify algal pigments and ?13C stable
isotope ratio in benthic sediments (5) determine
characteristics of sedimenting particles
(species/particle type, algal pigments, PON, POC,
?13C and ?15N) by deploying drifting short term
(lt24hours) sediment traps under Bering Sea ice
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Approach

• 3 expeditions, four participants, 15 stations
  each
• 3 ice floes per station, one with sediment traps
  (gt12 hours)
• Zodiak and/or from ice breaker
• plankton nets, water column (CTD), van Veen
  grabs

BEST study area and prospective sampling
grid. For each process station (green boxes on
map), we will ideally sample several ice floes
(I), as well as water column (P) and benthos (B)
to obtain biological and physical data.
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Turnover rates
Experiments during expedition/in Fairbanks
(climate control rooms) one pelagic (copepod),
one benthic species (amphipod)
Outreach

• a project-specific web page up be end of 2007
• Bering Sea school district village of Golovin -
  Martin L. Olson School in Golovin- field class
  with students in 2009
• Nome in fall 2007?
• Fairbanks High School Science Seminar series in
  2008
• host a Teacher-at-sea in 2009?
• interest from German TV team to participate in
  expedition in 2008
• (two people, 2 weeks)
• - Sea ice class (March 2008) in Barrow, Alaska
  (anyone interested?)