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

Data from the chemical analyses, toxicity tests, and benthic community analyses, together,
indicated that of the 100 stations sampled, 36 had sediments with significant toxicity and
elevated chemical contamination. Of these, 18 appeared to have benthic communities that
were possibly affected by chemical contaminants in the sediments. They included stations in
Sinclair Inlet, Dyes Inlet, Elliott Bay and the Duwamish River. These stations typically had
moderate to very high total abundance, including high numbers of Aphelochaeta species N1
and other pollution-tolerant species, moderate to high taxa richness, low evenness, and low
Swartz's Dominance Index values. Often, pollution-sensitive species such as arthropods and
echinoderms were low in abundance or absent from these stations. These 18 stations
represented an area of 8.1 km2, or about 1.1 % of the total survey area, while the remaining
other 18 stations represented an area of 9 1.6 km2, or about 12.5% of the total survey area.
Twenty-five stations located in Port Townsend, Admiralty Inlet, Possession Sound, the
central basin, Port Madison, Liberty Bay, the Bainbridge Basin, Rich Passage, Dyes Inlet, and
outer Elliott Bay, were identified with no indications of significant sediment toxicity or
chemical contamination, and with abundant and diverse populations of benthic infauna.
These stations represented an area of 359.3 1 km2, equivalent to 49% of the total survey area.
The remaining thirty-nine stations, located in Port Townsend, Possession Sound, the central
basin, Eagle Harbor, Liberty Bay, the Bainbridge Basin, and Elliott Bay and the Duwamish
River, displayed either signs of significant chemical contamination but no toxicity, or
significant toxicity, but no chemical contamination, and for the majority, the benthic
populations were abundant and diverse. Together, these stations represented an area of 272.6
km" equivalent to 37% of the total central Puget Sound study area.
A comparison of the "triad" results from both the northern and central Puget Sound study
areas showed some similarities and some differences. Although the spatial extent of toxicity
in the urchin fertilization tests and microbial bioluminescence tests was greater in the
northern area, the cytochrome P450 HRGS tests indicated degraded conditions were more
widespread in the central area. In both surveys, the percent of the total study areas displaying
toxicity, chemical contamination and altered benthos was similar (1.3 and 1.1% area,
respectively). Of the area surveyed in 1997 (773.9 km", ten stations representing 10.34 km"
(1.3% of the area) could be considered as having pollution-induced degradation. The
estimate of 1.3% area was similar to the estimate of 1.1 % for the 18 "degraded" stations
identified in the central Puget Sound study area. In addition, 10.6% of the 1997 northern area
had both high chemical contamination and high toxicity, but, was accompanied by high
benthic abundance and diversity. For central Puget Sound, this estimate was similar (12.5%).
In contrast, the samples with no contamination and no toxicity represented 19.6% of the
northern area and 49% of the central area. Conversely, the balance of samples in which
results were mixed (i.e., either chemistry or toxicity was significant, benthos was abundant
and diverse) was almost twice as high in the northern study area (68.5%) than in the central
study area (37%).
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