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  • Exxon Valdez Oil Spill Restoration Project Final Report

    Assessment of Bivalve Recovery on Treated Mixed-Soft Beaches In Prince William Sound

    Restoration Project 040574 Final Report

    Dennis C. Lees Littoral Ecological & Environmental Services

    1075 Urania Ave. Leucadia, CA 92024

    William B. Driskell 6536 20th Avenue NE Seattle, WA 98115

    For

    National Oceanic & Atmospheric Administration National Marine Fisheries Service

    Office of Oil Spill Damage & Restoration 11305 Glacier Highway

    Juneau, Alaska 99801-8626

    August 2007

  • The Exxon Valdez Oil Spill Trustee Council administers all programs and activities free from discrimination based on race, color, national origin, age, sex, religion, marital status, pregnancy, parenthood, or disability. The Council administers all programs and activities in compliance with Title VI of the Civil Rights Act of 1964, Section 504 of the Rehabilitation Act of 1973, Title II of the Americans with Disabilities Act of 1990, the Age Discrimination Act of 1975, and Title IX of the Education Amendments of 1972. If you believe you have been discriminated against in any program, activity, or facility, or if you desire further information, please write to: EVOS Trustee Council, 441 West 5th Avenue, Suite 500, Anchorage, Alaska 99501-2340; or O.E.O. U.S. Department of the Interior, Washington D.C. 20240.

  • Exxon Valdez Oil Spill Restoration Project Final Report

    Assessment of Bivalve Recovery on Treated Mixed-Soft Beaches In Prince William Sound

    Restoration Project 040574 Final Report

    Dennis C. Lees Littoral Ecological & Environmental Services

    1075 Urania Ave. Leucadia, CA 92024

    William B. Driskell 6536 20th Avenue NE Seattle, WA 98115

    For

    National Oceanic & Atmospheric Administration National Marine Fisheries Service

    Office of Oil Spill Damage & Restoration 11305 Glacier Highway

    Juneau, Alaska 99801-8626

    August 2007

  • i

    Assessment of Bivalve Recovery on Treated Mixed-Soft Beaches in Prince William Sound

    Restoration Project 040574

    Final Report Study History: This project began in 2002 as the field portion of the Assessment of Bivalve Recovery on Treated Mixed-Soft Beaches in Prince William Sound (initial project number 02574-BAA). The project number changed to 030574 when funding for the second year of the project (data analysis and report preparation) was approved, and again to 040574 when supplemental funds were approved for further sample analysis. The field study was conducted in July and August 2002. Sample and data analysis were carried out in 2003 and 2004. Report preparation was carried out in 2004 and 2005 and the first draft of the report was submitted in June 2005. After peer review, the report underwent major revisions and several additional analyses were added. A final draft was submitted in April 2007. Abstract: National Oceanic and Atmospheric Administration treatment effects studies from 1989 through 1997 suggested that bivalve assemblages on beaches in Prince William Sound treated with high-pressure washing were severely injured in terms of abundance, species composition, and function. Restoration Project 040574 assessed the generality and persistence of this apparent injury to this assemblage. We found that the initial conclusions were accurate, indicating that a considerable proportion of mixed-soft beaches in treated areas of the sound remained extremely disturbed and that these beaches are functionally impaired in terms of their ability to support foraging by humans and damaged nearshore vertebrate predators such as sea otters 13 years after the spill. Large, long-lived hard-shell clams remained 66% less abundant at Treated sites than at Reference sites. We also found that standard sediment properties did not appear implicated in lagging recovery. But, based on several lines of evidence, we deduced that a major cause for the delay was the disruption of surface armoring (a stratified organization of mixed-soft shoreline sediments common in southcentral Alaska), an effect of beach washing. Based on the apparent recovery trajectory, we predict that recovery to pre-spill status will take several more decades. We also found that sedimentary components and the biota in the armored mixed-soft sediments in Prince William Sound do not respond according to traditionally described paradigms for homogeneous sediments. Key Words: armoring, beach washing, bivalves, clams, Exxon Valdez oil spill, hard-shell clams, Hiatella arctica, high-pressure hot-water wash, injury, Prince William Sound, Protothaca staminea, recovery, recruitment, Saxidomus gigantea, sediment condition, shoreline treatment. Project Data: Description of data Extensive field notes were collected to document site conditions in Prince William Sound, Alaska. Sediment and infaunal samples were collected from intertidal field survey at 40 locations in August 2002. Sediment samples were composited from three locations along a transect at each site. The infauna was sampled with core samples to examine its smaller components and with larger excavations to examine its larger components. Elevation of the sampling site was measured relative to water level at each site and corrected to provide an elevation relative to Mean Lower Low Water. Water temperature and salinity data were collected. Considerable data showing site conditions are archived as digital images taken at

  • ii

    each site. Format Field notes are located in field notebooks. All infaunal, elevation, and water quality data exist as computer spreadsheet files. Digital photographs are in JPEG image formats. Samples of bivalves and other infaunal organisms from cores and excavation samples are archived in 70% isopropyl alcohol. Custodian Field notes, computer databases, and photo archives are in the custody of Dennis Lees and William Driskell. Bivalve samples from the core and excavation samples are in the custody of Dennis Lees, Littoral Ecological & Environmental Services, 1075 Urania Ave., Leucadia, CA 92924. Phone (760) 635-7998. Fax: (760) 635-7999, dennislees@earthlink.net. William B. Driskell, 6536 20th Avenue NE, Seattle, WA 98115. Phone: (206) 522-5930, bdriskell@comcast.net. Citation: Lees, D. C., and W. B. Driskell. 2007. Assessment of bivalve recovery on treated mixed-soft beaches in Prince William Sound, Alaska. Exxon Valdez Oil Spill Restoration Project Final Report (Restoration Project 040574). National Oceanic & Atmospheric Administration National Marine Fisheries Service, Office of Oil Spill Damage & Restoration, Auke Bay, Alaska.

  • iii

    TABLE OF CONTENTS EXECUTIVE SUMMARY................................................................................................................................................ 1 INTRODUCTION .............................................................................................................................................................. 7

    OBJECTIVES .................................................................................................................................................................... 10 HYPOTHESES................................................................................................................................................................... 10 STUDY AREA .................................................................................................................................................................. 11

    LITERATURE REVIEWED.......................................................................................................................................... 14 INTERACTIONS BETWEEN SEDIMENT CONDITIONS AND BIVALVE ASSEMBLAGES ..................................................... 14 SEDIMENTS AND RECRUITMENT: ................................................................................................................................... 14 INFLUENCE OF ADULTS ON RECRUITMENT ................................................................................................................... 15 EFFECTS OF DISTURBANCE ON BIVALVE ASSEMBLAGES ............................................................................................. 16 RATES OF RECOVERY FOLLOWING DISTURBANCE ....................................................................................................... 16

    METHODS ........................................................................................................................................................................ 18 SITE SELECTION.............................................................................................................................................................. 18 PHYSICO-CHEMICAL SEDIMENT ANALYSIS ................................................................................................................... 19 SHORELINE EXPOSURE ................................................................................................................................................... 19 BIOLOGICAL SAMPLING ................................................................................................................................................. 20 STATISTICAL ANALYSIS ................................................................................................................................................. 21

    Summary Statistics.................................................................................................................................................... 21 Outlier Analysis ..................................................................................................................

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