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

known to be pollution tolerant, including Paraprionospio pimi~ata, Scoletoma liiti, and
Prio?~o.s'pio steenstrupi, but the overall numbers of these organisms were low. Examination of
the triad of data for station 106 does not strongly suggest pollution impact at this station.
In the six large strata (strata 4-6, 8,11,12) located in southern Admiralty Inlet through the central
basin to the southern-most end of the study area, three of the 19 stations displayed both
significant toxicity results and elevated chemical contamination (stations 123, 113, 140), while 7
stations had no significant results (stations 1 12, 1 16, 1 17, 1 19-12 1, 141) (Tables 33-34, Figures
38-40). Samples collected from stations 112, 116, and 117 (stratum 4) in south Admiralty Inlet
(Figure 38), displayed no significant toxicity results or elevated chemical concentrations. The
infaunal communities from these samples varied in composition, with the community sampled
from station 1 12 (Oak Bay) differing from the communities sampled from stations 1 16 and 1 17
(Useless Bay), which were very similar to one another. Community differences are probably
associated with differing natural conditions including station depths (station 112-2511-1; station
1 16, 1 17-64 and 45m, respectively), grain size (station 1 12-28 % fines; station 1 16,117- 5% and
4% fines, respectively), and station proximity to one another. Most of the infaunal indices are
similar for stations 1 16 and 1 17, and they share six of their 10 dominant species, while the
indices are quite different at station 112, and no dominant species are shared with stations 116
and 117.
Similar to stratum 4, two of the samples (stations 11 9 and 120) collected from stratum 5,
Possession Sound (Figure 38), which were in close proximity to one another, displayed no
significant toxicity results or elevated chemical concentrations, and had similar infaunal index
values. The sediments at both stations were sandy (6% and 5% fines, respectively), had similar
highly diverse benthic indices, and shared 6 of 10 dominant species. The infaunal community
from station 11 8 in stratum 5, geographically distant from stations 119 and 120, displayed a
differing range of infaunal indices and shared no dominant species with the other two stations.
Sediments from this station did have levels of 4-methylphenol exceeding both state criteria, but
the difference in infaunal assemblage structure could be attributed to the differing sediment type
at station 11 8 (92% fines), rather than chemical contamination. All three stations were at similar
depth ranges (1 90-2 1 1m).
In general, examination of the infaunal community structure in sediments collected from Port
Townsend through Admiralty Inlet and Possession Sound revealed no clear patterns related to
chemistry and or toxicity data. Instead, similarities of infaunal indices and species composition
between stations appeared to be related to similarity in station depth, grain size, and geographic
proximity of stations.
The next four strata results presented (6, 8, 1 1, and 12), include 13 stations that were located in
Puget Sound's central basin (Figures 39 and 40). While the majority of these stations were
located in deep water (1 90-250m) and were composed of primarily silt-clay sediment particles
(81-98% fines), a few were shallower and/or had more mixed sediments. Three stations (123,
113, and 140) in these central basin strata had sediments with some degree of both chemical
contamination and toxicity.
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