Sediment Quality in Puget Sound Year 2 - Center for Coastal ...

Correlations were determined for all the substances that were quantified, including trace metals
(both total and partial digestion), metalloids, un-ionized ammonia (UAN), percent fines, total
organic carbon (TOC), chlorinated organic hydrocarbons (COHs), and polynuclear aromatic
hydrocarbons (PAHs). Concentrations were normalized to TOC where required for SQS and
CSL values.
Those substances that showed significant correlations were indicated with asterisks (*= p0.05,
** = po.~l, ***= pO.001, and ****= pg.0001) depending upon the level of probability. A
Bonferroni's adjustment was performed to account for the large number of independent variables
(157 chemical compounds). This adjustment is required to eliminate the possibility of some
correlations appearing to be significant by random chance alone.
Benthic Community Analyses
All benthic infaunal data were reviewed and standardized for any taxonomic nomenclatural
inconsistencies by Ecology personnel using an internally developed standardization pro'cess.
With assistance from the taxonomists, the final species list was also reexamined for identification
and removal of taxa that were non-countable infauna. This included (1) organisms recorded with
presencelabsence data, such as colonial species, (2) meiofaunal organisms, and (3) incidental
taxa that were caught by the grab, but are not a part of the infauna (e.g., planktonic forms).
A series of benthic infaunal indices were then calculated to summarize the raw data and
characterize the infaunal invertebrate assemblages identified from each station. Indices were
based upon all countable taxa, excluding colonial forms. Five indices were calculated, including
total abundance, major taxa abundance, taxa richness, Pielou's evenness (J'), and Swartz's
Dominance Index (SDI). These indices are defined in Table 5.
Benthic Community/Chemistry and Benthic Community/Toxicity Analyses
Nonparametric Spearman-rank correlation analyses were conducted among all benthic indices,
chemistry, and toxicity data. The correlation coefficients (rho values) and their statistical
significance (p values) were recorded and examined to identify which benthic indices co-varied
with toxicity results and chemistry concentrations. Comparisons were made to determine
similarities between these correlation results and those generated for the chemistry/toxicity
correlation analyses.
Sediment Quality Triad Analyses
Following the suggestions of Chapman (1 996), summarized data from the chemical analyses,
toxicity tests, and benthic analyses were compiled to identify the sampling locations with the
highest and lowest overall sediment quality and samples with mixed or intermediate results. The
percent spatial extent of sediment quality was computed for stations with four combinations of
chemicalltoxicitylbenthic results. Highest quality sediments were those in which no chemical
concentrations exceeded numerical guidelines, toxicity was not apparent in any of the tests, and
the benthos included relatively large numbers of organisms and species, and pollution-sensitive
species were present. Lowest quality sediments were those with chemical concentrations greater
than the guidelines, toxicity in at least one of the tests, and a relatively depauperate benthos.
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