ACCESS NUMBER: TO-85242

STUDY TITLE: Susceptibility of sea ice biota to disturbances in the shallow Beaufort

Sea: Phase 1: Biological coupling of sea ice with the pelagic and benthic realms

REPORT TITLE: Susceptibility of sea ice biota to disturbances in the shallow Beaufort

Sea: Phase 1: Biological coupling of sea ice with the pelagic and benthic realms

CONTRACT NUMBER(S): 1435-01-98-CA-30909

TASK ORDER (TO): 85242

SPONSORING OCS REGION: Alaska

APPLICABLE PLANNING AREA(S): Chukchi Sea, Beaufort Sea

FISCAL YEAR(S) OF PROJECT FUNDING: 2002-2004

COMPLETION DATE OF REPORT: November 2005

COST(S): $95,461

CUMULATIVE PROJECT COST: $95,461

PROJECT MANAGER(S): Rolf Gradinger

AFFILIATION (of project manager): University of Alaska Fairbanks

ADDRESS: PRINCIPAL INVESTIGATOR(S)*: Institute of Marine Science, School of

Fisheries and Ocean Sciences, UAF, Fairbanks, AK 99775-7220

KEY WORDS: landfast ice zone, nearshore Beaufort Sea, nearshore Chukchi Sea, sea ice

biota, sea ice sediment

BACKGROUND: Sea ice is a key component in structuring polar environments. It

serves as a habitat for a unique highly specialized community of bacteria, algae, protozoa

and metazoa, which contribute to the biogeochemical cycles of the Arctic seas. Light

availability is a key factor for the development of the ice community. Our study aimed at

understanding the impact of sea ice sediments on the sea ice biota through alterations of

the light climate. Our results contribute to the understanding of the impact of increased

sediment loads in coastal Arctic regions due to climate change and exploration activities

on the marine biology of these regions.

OBJECTIVES: Our objectives were: 1) to determine the diversity, abundance and

biomass of ice related fauna in comparison to planktonic and benthic communities in

relation to ice sediment load, 2) to determine algal biomass in the sea ice, water column

and benthos to assess the absolute and relative amount of available food in sea ice in

relation to sediment load, and 3) to identify the relevance of sea ice-produced organic

material for the nearshore food web based on stable isotope analysis.

DESCRIPTION: Sampling was conducted April 24-28, 2002 and February 12-17,

April 1-5 and May 27-30, 2003. The fast ice was sampled in level, un-ridged areas in

two regions that differed mainly in the amount of incorporated sediment. Samples were
collected from the ice (ice corer), water (plankton nets, baited traps, water sampler) and

sea floor (benthic corer). At each location, we measured snow and ice thickness, water

depth, ice and water temperatures and salinities as well as algal biomass (chlorophyll,

particulate organic carbon) in the ice, water and sea floor. In addition, the abundance and

diversity of ice and pelagic algae and metazoans were determined using optical

techniques. Stable isotope ratios (d'3C and d15N) were used to assess food web

interactions between ice and pelagic biota.

SIGNIFICANT CONCLUSIONS: A strong ice algal bloom developed in the sedimentfree fast ice, reaching a maximum pigment concentration of 330 tg Chl a F' in the

bottom 10cm of the ice in May while it remained below 1g Chl a F' in the water

column. With increasing ice algal biomass, the ratio of sea ice POM increased from

an initial average value of -25% in February to -16% in May, while no enrichment was

observed in pelagic POM. The abundance of ice metazoans increased with progressing

season to a maximum of 276,000 animals m2, dominated by nematodes and

merosympagic polychaete juveniles. Abundances of meroplanktic stages of benthic

polychaetes in the water column were consistently at least one order of magnitude below

abundances in the ice, suggesting sea ice as an important feeding habitat for young life

stages, an example for cryo-benthic coupling. The sediment loaded sea ice had a total

particle load of 106 g m2. Light was thereby reduced by more than 99% compared to the

clean ice site, which had a particle load of only 6 g m2. In the dirty ice we observed no

substantial increase over time for any of the studied biological parameters. Stable isotope

analyses of ice meiofauna and gut/stomach content analyses on amphipods supported the

concept of sea ice algae being important food in Arctic coastal food webs in early spring.

STUDY RESULTS: Our observations demonstrate that sea ice sediments have a

profound impact on sea ice biology, suppressing biological spring bloom formation by

orders of magnitude compared to clean ice. We did not observe a notable increase in the

abundance of primary producers in dirty ice during the spring season. The reduced light

intensities caused a domino effect along the ice-associated food chain, starting with

reducing the build-up of ice algal biomass, followed by diminished development of ice

meiofauna densities. The input of organic matter from the sea ice to the realms below was

reduced and the sediment laden ice provided less food for the merosympagic and

meroplanktic larvae and juveniles. Future studies should focus on providing regional

estimates of light availability at the bottom of the ice (e.g. by ROy, AUV or divers)

together with field sampling identifying the role of ice, snow, ice algae and ice sediment

in the attenuation of light. Such a study would provide the basis for a reasonably accurate

estimate of the impact of sea ice sediment load on the primary production in the Chukchi

and Beaufort Seas.

STUDY PRODUCT(S):

R. Gradinger and B.A. Bluhm 2002. Susceptibility of sea ice biota to disturbances in the

shallow Beaufort Sea. Phase 1: Biological coupling of sea ice with the pelagic and

benthic realms. CMI Annual Review, Fairbanks.
R. Gradinger, M. Nielson, and B. Bluhm 2002. Cryo-benthic coupling in coastal sea ice

off Barrow, Alaskaconcept and preliminary results. AAAS meeting, Fairbanks.

R. Gradinger and B.A. Bluhm 2002. Cryo-benthic coupling in coastal sea ice off Barrow,

Alaskaconcept and preliminary. IARC, Fairbanks.

R. Gradinger and B.A. Bluhm 2003. From the shoreline across the Arctic shelves:

Biological properties of sea ice ecosystems. SEARCH open science meeting, Seattle.

R. Gradinger and WA. Bluhm 2003. Susceptibility of sea ice biota to disturbances in the

shallow Beaufort Sea. Phase 1: Biological coupling of sea ice with the pelagic and

benthic realms. CMI Annual Review, Fairbanks.

B.A. Bluhm and R. Gradinger 2003. Evidence for cryo-benthic cou5pling in coastal

Alaskan waters, based on community and stable isotope ('3C, 1 N) analysis

preliminary results. Gordon Research Conference, "Polar Science", Ventura.

R. Gradinger and B. Bluhm (M. Nielson, presenter) 2004. Susceptibility of sea ice biota

to disturbances in the shallow Beaufort Sea. Phase 1: Biological coupling of sea ice

with the pelagic and benthic realms. CMI Annual Review, Fairbanks.

C.P. McRoy, R. Gradinger, A. Springer, B. Bluhm, S. Iverson, S. Budge 2004. Stable

carbon isotopes reveal food web shifts due to Arctic sea ice decline. AGU Montreal.

R. Gradinger and B. Bluhm (presenter) 2005. Susceptibility of sea ice biota to

disturbances in the shallow Beaufort Sea. Phase 1: Biological coupling of sea ice

with the pelagic and benthic realms. CMI Annual Review, Fairbanks.

B.A. Bluhm, R. Gradinger, M.R. Nielson 2005. Biological coupling of sea ice with the

pelagic and benthic realms: the effect of sediment in sea ice. ASLO Conference, Salt

Lake City. Feb 20-25, 2005.

R. Gradinger and B.A. Bluhm (presenter) 2005. Susceptibility of sea ice biota to

disturbance in the shallow Beaufort Sea. Phase 1: Biological coupling of sea ice with

pelagic and benthic realms. Minerals Management Service Information Transfer

Meeting, Anchorage. Mar 14-16, 2005.

B.A. Bluhm, R.R. Gradinger, and M.R. Nielson 2005. The role of sea ice sediments in the

seasonal development of near-shore Arctic fast ice biota of Barrow, Alaska. Gordon

Research Conference, Polar Science, Ventura. Mar 13-18.

Public outreach

Gradinger, R. and B. Bluhm, Project related webpage:

http://www.sfos. uaf.edu/research/seaicebiotalcmi/barrow2002/index.html

R. Gradinger and B. Bluhm 2003. Hidden Life in the Arctic Sea Ice: From Barrow's

Shore-Fast Ice to the Central Arctic Ocean. Public lecture, Barrow, Alaska. Feb 15,

2003.

Bluhm B. and R. Gradinger 2003. Explorations under the Pack-Ice of the Arctic Ocean.

Public lecture, Barrow Alaska. May 31, 2003.

Arctic Sounder 2003. "Ice life" plays major role in ecosystem by Earl Finkler. Featuring

the CMI project.
Barrow public radio station 2003. "Ice life" plays major role in ecosystem by Earl

Finkler. Featuring the CMI project.

Student training

Mette Nielson, Graduate student at SFOSparticipated in project activities since 2002

Reports and publications

R. Gradinger and B.A. Bluhm 2002. First field trip of new CMI project completed. SFOS

Newsletter 6.

R. Gradinger and B.A. Bluhm 2003. susceptibility of sea ice biota to disturbances in the

shallow Beaufort Sea. Phase 1: Biological coupling of sea ice with the pelagic and

benthic realms. CMI Annual Report 9: 8 1-88

R. Gradinger and B.A. Bluhm 2004. Susceptibility of sea ice biota to disturbances in the

shallow Beaufort Sea. Phase 1: Biological coupling of sea ice with the pelagic and

benthic realms. CMI Annual Report No. 10: 70-78.

R Gradinger and B.A. Bluhm 2005 . Susceptibility of sea ice biota to disturbances in the

shallow Beaufort Sea. Phase 1: Biological coupling of sea ice with the pelagic and

benthic realms. CMI Annual Report No. 11: 50-59.

R. Gradinger, B.A. Bluhm, and M.R. Nielson (in revision). The pivotal role of sea ice

sediments for the seasonal development of near-shore Arctic fast ice biota off

Barrow, Alaska. Mar. Ecol. Prog. Ser.
CHUKCHI SEA

ARCTIC SUBREGION

ALASEA

BEAUFORT SEA

Focus area for nearshore fast ice biota study

I CANADA

Chukchi Se

/

E3au fort Sa

Location of the fast ice sampling sites close to Barrow,

Alaska