Hood Canal Marine Sediments Data Summaries, Findings, Publications

Hood Canal

The following table contains links to data summaries. (Click on X to open files. Zip files will need to be extracted into another folder. Shaded boxes indicate summaries not yet available.)

Year Sampled Station Locations Physical Chemical Toxicity Benthic Invertebrates Sediment Quality Triad Indicators
1999 * * * * * *
2004 X X X X X X
2015            

* Available upon request.

 

The Hood Canal Sediment Quality Triad Index (PDF) offers a one-page summary of these findings.

Puget Sound Marine Sediment Indicators is a webpage that describes the Sediment Quality Triad Index, a method to rate the health of marine sediments.

 

Findings 1999, 2004

All our studies assess sediment quality by evaluating chemistry, toxicity, and benthic (sediment-dwelling) invertebrate community structure. Results are compared with those from similar surveys, conducted with the same methods, to determine changes in sediment quality.

  • Naphthalene was measured above Washington State Sediment Quality Standards (SQS) at one site of 21 (in Port Ludlow) in 1999. None of the 2004 samples was classified as chemically contaminated (i.e., no chemical concentrations exceeded SQS).
  • Toxic responses in sea urchin fertilization tests increased from 3 sites in 1999 to 5 sites in 2004.
  • In 1999, 14 of the 21 sites sampled (67%) had adversely affected benthic invertebrate communities. Sites with adversely affected benthic invertebrate communities increased in 2004 to 23 of the 30 sites (77%).
  • The high percentage of stations with only impaired benthos and no chemical contamination or toxicity may be a result of low near-bottom dissolved oxygen (DO) levels. Further studies are needed to determine the magnitude and nature of hypoxia effects on the benthos in Hood Canal.

Results are rolled up into the Sediment Quality Triad Index, which categorizes sediment quality on a 5-level scale from unimpacted to clearly impacted.  The triad index combines information on measures of exposure (sediment contamination), response (toxicity), and biological effects (benthic invertebrates).

  • The majority (82%) of  Hood Canal sediments in 2004 were of unimpacted or likely unimpacted quality.
  • No sediments sampled in Hood Canal in 2004 were of clearly impacted quality.
  • The proportion of area categorized as having likely impacted sediment quality increased from none (0%) in 1999 to 14.5% in 2004, due primarily to adversely affected benthic invertebrates and toxic responses in laboratory tests.

Hood Canal Focus Study:  Relationships between Sediment Quality, Dissolved Oxygen, and Benthic Invertebrates in Hood Canal.

Analysis of available Hood Canal sediment quality, DO, and benthic invertebrates data suggests the following:

  • Generally, chemical contamination and toxicity levels were low and confined to Port Ludlow, Port Gamble, and Dabob Bay. These factors appeared to have a very limited influence on benthic community structure in Hood Canal as a whole.
  • Water quality data showed a steady decline over time in DO content and an increase in the area affected by low DO, especially in southern Hood Canal.
  • In all but a few northern locations, benthic invertebrate communities in Hood Canal generally were less abundant and diverse than communities found in other parts of Puget Sound.
  • Nine unique benthic communities were distinguished throughout Hood Canal, adapted to the particular sediment and DO characteristics found in each area.
  • The total number and variety of benthic invertebrates declined, and several stress-tolerant invertebrate species became dominant, from north to south along the canal’s main axis.
  • Benthic communities changed as:
    • Sediment texture became finer-grained (that is, as silt clay content increased).
    • DO levels near the bottom decreased.
    • Nutrient content (measured as percent total organic carbon) in the sediments increased.
    • Depth increased.
  • Noticeable changes in community structure occurred as DO levels decreased from >10 mg/L to >3-6 mg/L and then to <1 mg/L. Various benthic invertebrates responded differently, with either increased or decreased abundance, to changes in the range of near-bottom DO levels.
  • Further analysis indicated that there was little change in northern Hood Canal benthic invertebrate communities that could be attributed to declining oxygen levels. However, between 1991 and 1999, changes in benthic invertebrate community structure at a location near the Great Bend were consistent with declining DO concentrations.  

Results suggest that benthic invertebrates were likely to be sensitive to natural and human-caused changes to sediment grain size and organic content, as well as to levels of DO in bottom waters of Hood Canal.   The full report describes initial steps to develop critical DO thresholds which can be used to determine when benthic invertebrates are at risk. Additional information and research needed to develop better thresholds are also identified.

 

Publications

Hood Canal Regional Monitoring - 2004

Long, E., S. Weakland, M. Dutch, K. Welch, and V. Partridge. 2010. Sediment Quality Assessment of Puget Sound's Hood Canal Region, 2004. Washington State Department of Ecology Publication 10-03-006.
Long, E., S. Weakland, M. Dutch, K. Welch, and V. Partridge. 2010. Sediment Quality Assessment of the Hood Canal Region of Puget Sound, 2004: Spatial/Temporal Sediment Monitoring Element of the Puget Sound Assessment and Monitoring Program. Washington State Department of Ecology Publication 10-03-005.

Relationships Between Water Quality, Sediment Quality, and Benthos in Hood Canal.

Dutch M., E. Long, S. Aasen, V. Partridge, K. Welch, and D. Shull. 2008. The Influence of Sediment Quality and Dissolved Oxygen on Benthic Invertebrate Communities in Hood Canal. Poster presentation - 2008 PERS Conference, Newport, OR; 2008 PNW SETAC Conference, Corvallis, OR; and 2008 South Sound Science Symposium, Lacey, WA. Poster
Dutch, M. 2007. Focus on Hood Canal: Relationships between Sediment Quality, Dissolved Oxygen, and Benthic Invertebrates in Hood Canal. Washington State Department of Ecology Publication 07-03-048, Olympia, WA, and Western Washington University, Bellingham, WA. 2 pp.
Dutch M., E. Long, S. Aasen, V. Partridge, K. Welch, and D. Shull. 2007. The Influence of Sediment Quality and Dissolved Oxygen on Benthic Invertebrate Communities in Hood Canal. Washington State Department of Ecology Publication 07-03-047, Olympia, WA, and Western Washington University, Bellingham, WA. 4 pp.
Long, E., S. Aasen, M. Dutch, K. Welch, and V. Partridge, and D. Shull. 2007.  Relationships between the Composition of the Benthos and Sediment and Water Quality Parameters in Hood Canal, WA: Task IV – Hood Canal Dissolved Oxygen Program. Washington State Department of Ecology Publication 07-03-040, Olympia, WA, and Western Washington University, Bellingham, WA. 197 pp + appendices.
Dutch, M., E. Long, S. Aasen, K. Welch, and V. Partridge. 2007. Relationships between Benthos, Sediment Quality, and Dissolved Oxygen Levels in Hood Canal, WA. Oral presentation - 2007 Georgia Basin/Puget Sound Research Conference, Vancouver, BC. Slides
Dutch, M., S. Aasen, E. Long, and K. Welch. 2007. Infaunal Invertebrate Assemblage Structure in Hood Canal, WA (1989 – 2005). Poster presentation - 2007 Georgia Basin/Puget Sound Research Conference, Vancouver, BC. Poster.
Dutch, M., S. Aasen, and E. Long. 2007. Chemical Contamination and Toxicity in Sediments from Hood Canal, WA (1952 – 2005). Poster presentation - 2007 Georgia Basin/Puget Sound Research Conference, Vancouver, BC. Poster.
Aasen, S., M. Dutch, K. Welch, and E. Long. 2005. Sediment Quality In Hood Canal. In: T.W. Droscher and D.A. Fraser (eds). Proceedings of the 2005 Puget Sound/Georgia Basin Research Conference. Poster.
Dutch, M., S. Aasen, K. Welch, E. Long, B. Grantham, and D. Shull. 2005. Relationships between benthic infaunal community structure and dissolved oxygen levels in bottom waters of Hood Canal. In: T.W. Droscher and D.A. Fraser (eds). Proceedings of the 2005 Puget Sound/Georgia Basin Research Conference. Slides
Dutch, M., E. Long, S. Aasen, and K. Welch. 2005. Benthic infaunal community structure in Hood Canal in relation to sediment and water quality variables. Poster.

Quality Assurance Project Plan

Dutch, M., V. Partridge, S. Weakland, K. Welch, and E. Long. 2009. Quality Assurance Project Plan: The Puget Sound Assessment and Monitoring Program Sediment Monitoring Component. Washington State Department of Ecology Publication 09-03-121. 98 pp.