Spatial Extent Of Degraded Sediment Quality In Puget Sound (Washington State, U.S.A.) Based Upon Measures Of The Sediment Quality Triad

Abstract

A survey was designed and conducted to determine the severity, spatial patterns, and spatial extent of degraded sediment quality in Puget Sound (Washington State, USA). A weight of evidence compiled from results of chemical analyses, toxicity tests, and benthic infaunal analyses was used to classify the quality of sediments. Sediment samples were collected from 300 locations within a 2363 km(2) area extending from the US/Canada border to the inlets of southern Puget Sound and Hood Canal. Degraded conditions, as indicated with a combination of high chemical concentrations, significant toxicity, and adversely altered benthos, occurred in samples that represented about 1% of the total area. These conditions invariably occurred in samples collected within urbanized bays and industrial waterways, especially near the urban centers of Everett, Seattle, Tacoma, and Bremerton. Sediments with high quality (as indicated by no toxicity, no contamination, and the presence of a relatively abundant and diverse infauna) occurred in samples that represented a majority (68%) of the total study area. Sediments in which results of the three kinds of analyses were not in agreement were classified as intermediate in quality and represented about 31% of the total area. Relative to many other estuaries and marine bays of the USA, Puget Sound sediments ranked among those with minimal evidence of toxicant-induced degradation.

Evaluating consistency of best professional judgment in the application of a multiple lines of evidence sediment quality triad

“…Habitat measures are often combined into a multiple lines of evidence (MLOEs) triad that integrates exposure and effect to assess chemical concentration levels in terms of biological concern (Long and Chapman 1985). Presently, no single, universally accepted method for interpreting triad data and classification of sediments on the basis of an MLOE approach exists (Chapman et al 2002; Long and Sloane 2005; Wenning et al 2005). Each regulatory or monitoring program uses an approach developed through their unique experience.…”

“…Multiple approaches for integrating triad data have been developed, including simple logic systems based on presence/absence, statistical summarization, and best professional judgment (Burton et al 2002; Chapman et al 2002; Wenning et al 2005). Regardless of the specific integration approach, most MLOE assessment approaches use some form of best professional judgment (BPJ) to address uncertainties or conflicts in the data (Forbes and Calow 2004; Chapman and Anderson 2005; Long et al 2005). Expert systems based on fuzzy logic methods have also been used to integrate complex data sets and interpret uncertain results in a consistent fashion (Hollert et al 2002), yet even these approaches must rely on BPJ for the development of classification rules.…”

Anatomy of a decision II: Potential effects of changes to Tier I chemical approaches in Canadian Disposal at Sea program sediment assessment protocols

“…Because the EC ( ) photoluminescent bacteria method is a solid‐phase test, whereas the database results were from a Microtox™ solvent‐extract test, Canada's pass/fail criterion could not be readily applied. As a result, the present paper used pass/fail criteria for the database Microtox™ measures that were based upon values developed by Long et al ( ).…”

“…Long et al ( ) generated 2 new Microtox™ critical values, both based upon statistical analyses of data from a subset of the original data from which the NOAA surveys ( n = 1013) that the present study draws upon were compiled. The first value (0.06 mg/mL) represents the 90% lower prediction limit (LPL) of the entire data set.…”

“…The second Long et al ( ) value (0.51 mg/mL) represents the 80% LPL with the lowest (most toxic) 10% of the data values removed from the database to eliminate their influence on the distribution of the data. Samples with EC50 values <0.51 mg/mL or >0.06 mg/mL would be considered as moderately toxic in this test.…”