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STUDY TITLE: Monitoring the "Boulder Patch" as part of the Arctic Nearshore Impact Monitoring in the

Development Area (ANIMIDA) Program (Phase II)

REPORT TITLE: Linking Water Turbidity and Total Suspended Solids Loading to Kelp Productivity within

the Stefansson Sound Boulder Patch, ANIMIDA Task 6 (Boulder Patch)

CONTRACT NUMBER: 1435-01-99-CT-30998; TASK ORDER (TO): 10906

SPONSORING OCS REGION: Alaska

APPLICABLE PLANNING AREA: Beaufort Sea

FISCAL YEARS OF PROJECT FUNDING: FY 2000-FY2003

COMPLETION DATE OF REPORT: November, 2003

COSTS BY FY: FY 2000: $100,000; FY 2001: $126,000; FY 2002: $129,380; FY 2003: $11,729

CUMULATIVE PROJECT COST: $367,109

PROJECT MANAGER: Ken Dunton

AFFILIATION: The University of Texas

ADDRESS: The University of Texas Marine Science Institute, 750 Channel View Drive, Port Aransas, TX

78373

PRINCIPAL INVESTIGATORS*: Ken Dunton, Adrian Burd, Dale Funk, and Robert Maffione

KEY WORDS: ANIMIDA, nearshore Beaufort Sea, Boulder Patch, kelp productivity, total suspended

sediments, light, Stefansson Sound, Arctic, Alaska

BACKGROUND:

The Arctic Nearshore Impact Monitoring in Development Area (ANIMIDA), a five-year study started in

1999, has provided baseline data and monitoring results for chemical contamination, turbidity, and

subsistence whaling in the vicinity of Northstar and Liberty development sites. Northstar is in State

waters, but includes production of some OCS oil through directional drilling. Liberty, if approved, would

be the first offshore OCS development project in the Beaufort Sea or elsewhere in the Alaska OCS. This

Task Order links water turbidity and total suspended solids (TSS) loading to kelp productivity within the

Stefansson Sound Boulder Patch in the ANIMIDA study area.

OBJECTIVES:

Our goals were to: 1) determine the physical characteristics of suspended sediments in the vicinity of the

Boulder Patch and how they affect the inherent optical properties of Stefansson Sound waters, 2)

ascertain the quantitative relationship between TSS concentrations, photosynthetic active radiation

(PAR), and water column inherent optical properties (lOPs), and how the relationship parameters vary

over spatial and temporal scales, and 3) develop a model providing reasonable productivity estimates

based on in situ measurements of surface irradiance and suspended sediment concentrations.

DESCRIPTION:

During the 2001-2002 summer periods, the lOPs, including absorption, attenuation, and backscatter of

Stefansson Sound waters were measured in conjunction with suspended sediment concentrations.

Measured values were input to a radiative transfer equation (RTE) and a TSS concentration specific

attenuation coefficient [Kd(A,I-] was calculated. The attenuation coefficient was used in conjunction with

a productivity model to estimate daily kelp production throughout the Boulder Patch. Preliminary model
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output agreed well with previously published measurements of annual kelp production based on the

number of hours of saturating irradiance available to the kelp under average water transparency

conditions.

SIGNIFICANT CONCLUSIONS:

The highest TSS levels (23.0 - 24.2 mg L1) occurred in nearshore areas during summer 2001 and were

coincident with increased light attenuation (11 .4 - 14.0 m1). In both years, lower TSS concentrations and

lower light attenuations were measured in areas furthest from the coast within the Boulder Patch kelp

community. Although light attenuation through the water column decreased in summer 2002, attenuation

and TSS were significantly correlated (p <0.01).

Our results clearly demonstrate that suspended sediment concentrations have varying but substantial

affects on light availability, and subsequent kelp production, during the summer open-water period.

Increasing average TSS concentrations from ito 10 mg L1, within ranges measured in situ, decreased

annual production by an order of magnitude. Even under an array of surface irradiance budgets,

production estimates and rates changed substantially under different TSS concentrations. Production,

modeled under a variety of summer surface light regimes, was always higher at lower TSS concentrations

and estimated kelp production was higher in offshore locations, despite deeper depths, because they are

characterized by lower TSS.

STUDY RESULTS:

Our results suggest that TSS can have variable influences on annual productivity in the Stefansson

Sound Boulder Patch. Low summer TSS concentrations will usually result in high annual kelp productivity

by increasing the number of hours Laminaria solidungula can sustain maximum carbon fixation or Pmax.

Any increase in TSS will result in decreased production. Under certain conditions, substantial TSS

concentrations and/or low surface irradiance may result in negative production rates, where the metabolic

costs of respiration exceed photosynthesis. Comparison of model output with in situ blade elongation

data indicates that the model does provide reasonable estimates of productivity, but is extremely sensitive

to accurate measurements of TSS. Future monitoring efforts should continue to focus on the critical

linkages between light attenuation (based on the lOP's of the water column), continuous surface

irradiance, TSS, and site specific kelp biomass and annual growth. Using these measurements, we can

provide nearly instantaneous estimates of kelp productivity using the model we have developed. Site

specific biomass would contribute to more accurate estimates of kelp production per unit area across

Stefansson Sound and allow more precise comparisons of kelp production in response to both natural

and anthropogenic events.

STUDY PRODUCTS:

Aumack, C. and K. Dunton. 2004. Linking water turbidity and total suspended solids loading to kelp

productivity in the Alaskan Beaufort Sea. Arctic [in prep].

Dunton, K and C. Aumack. 2004. Living on the edge: sensitivity of arctic kelp to environmental change.

XVIII International Seaweed Symposium, Bergen Norway, June 2004. Invited.

Dunton, K.; Burd, A.; Funk, D.; Maffione, R.; and C. Aumack. 2004. Linking Water Turbidity and TSS

Loading to Kelp Productivity within the Stefansson Sound Boulder Patch, ANIMIDA Task 6 (Boulder

Patch). OCS Study MMS 2004-i435-0i-99-CT-30998. Final Report 1435-Oi-99-CT-30998, TO

10906. Prepared by The University of Texas for Minerals Management Service Alaska OCS Region.

Anchorage, AK.

Aumack, C.; Dunton, K.; Burd, A.; Funk, D.; and Maffione, R. 2003. Linking Water Turbidity and TSS

Loading to Kelp Production within the Stefansson Sound Boulder Patch. Presented at SETAC 24th

Annual Meeting in North America, November 9-13, 2003. Austin, TX: SETAC.

Dunton, K.; Maffione, R.; and A. Burd. 2003. Linking Water Turbidity and TSS Loading to Kelp

Productivity within the Stefansson Sound Boulder Patch. In: Alaska OCS Region Ninth Information

Transfer Meeting And Barrow Information Update Meeting Final Proceedings, OCS Study MMS 2003-
42, PP. 25-26. Prepared by MBC Applied Environmental Sciences. Anchorage, AK.: United States,

DOl, MMS, Alaska OCS Region.

Aumack, C. F., K.H. Dunton, and R.A. Maffione. Linking water turbidity and TSS loading to kelp

production within the Stefansson Sound Boulder Patch. ASLO Aquatic Sciences Meeting, February

2003, Salt Lake City,

*pls affiliation may be different than that listed for Project Manager(s).

TO.

ST.

CHUKCHI SEA

ARCTIC 8UBREGION

SEAUFORT SEA

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Focus area for Arctic Nearshore Impact Monitoring in the Development Area (ANIMIDA) Program.

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-149° -148° 30' 1480 -147° 30' -147°

700 36'

700 24'

70° 12'

1490 -148° 30' -148° -147° 30' -147°

Location of Stefansson Sound, Alaska (adapted from Weingartner and Okkonen, 2001).
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Narwhal Narwhal Station Iand

Study sites of various measurements in summers 2001 and 2002. Grey shaded areas represent Boulder

Patch extent based on geologic surveys conducted in 1980 and 1999 (Hopkins, 1979; Dunton etal.,

1982). Dark grey represents areas of boulder cover> 25%. Light grey represents areas of boulder cover

between 10% - 25%.