STP1219: Shoreline Ecology Program for Prince William Sound, Alaska, Following the Exxon Valdez Oil Spill: Part 1—study Design and Methods

    Page, DS
    Bowdoin College, Brunswick, ME

    Gilfillan, ES
    Bowdoin College, Brunswick, ME

    Boehm, PD
    Arthur D. Little, Inc., Cambridge, MA

    Harner, EJ
    West Virginia University, Morgantown, WV

    Pages: 33    Published: Jan 1995


    Abstract

    Part 1 of a three-part series, this paper describes the design and analysis of a large field and laboratory program to assess shoreline recovery in Prince William Sound following the Exxon Valdez oil spill. The study was designed so that results could be generalized area-wide (biology, chemistry) or habitat-wide (toxicology) and projected forward in time (chemistry). It made use of the “sediment quality triad” approach, combining biological, chemical, and toxicological measurements to assess shoreline recovery. Key aspects of the study include the following: • Coordinated field sampling for chemical, toxicological, and biological studies • Stratified random sampling (SRS) as a basis for spatial generalization • Periodic sampling to assess trends, including sites with worst-case conditions • Analysis of oil-spill effects on hundreds of species • Statistical methods based on normal and non-normal theory, consistent with the structure of the data, including generalized linear models and multivariate correspondence analysis

    Prince William Sound shorelines were stratified into four types of habitat (exposed bedrock/rubble, sheltered bedrock/rubble, boulder/cobble, and pebble/gravel) and four different levels of oiling (unoiled, light, moderate, and heavy). Sixty-four SRS sites were randomly selected with an average of four replicates in each combination of habitat type and oiling level. The SRS sites were sampled in 1990 to assess the state of recovery in the sound. Twelve additional non-random sites, including some of the most heavily oiled locations in the sound, were monitored annually to assess trends from 1989 to 1991.

    At sedimentary sites, sediment samples were taken for hydrocarbon analysis, sediment toxicology, and biological (infaunal) analysis. At bedrock/rubble sites, filter wipes and surface scrape samples were taken to assess chemistry and epibiota. Where present, mussel samples were taken to determine the bioavailability of any petroleum residues.

    Spill-affected shorelines are judged to have recovered when the biological communities are statistically indistinguishable from those at unoiled reference sites. Given the large natural variability observed among sites, this study provides a more accurate and comprehensive picture of shoreline recovery than approaches that focus on only a few species at subjectively chosen locations.

    Keywords:

    Exxon Valdez, oil spill, shoreline ecology, shoreline recovery, stratified random sampling, generalized linear models, correspondence analysis


    Paper ID: STP19867S

    Committee/Subcommittee: E47.04

    DOI: 10.1520/STP19867S


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