ENVIRONMENTAL IMPLICATIONS OF CHANGES IN BENTHIC FORAMINIFERAL ASSEMBLAGES IN SOUTHERN PUGET SOUND, WASHINGTON STATE, USA
Since 1997, the Washington State Department of Ecology has been conducting a long term sampling program in the Puget Sound. As a part of this program, 10 Long Term stations located down the length of Puget Sound have been sampled annually in mid-April. These Long Term stations provide nearly 20 years’ record of changing conditions. This paper discusses the Foraminiferal record in two of these sampling locations. Station 44 is east of Anderson Island (Lat. 47.1612o N.; Long. 122.6736o W.) and Station 49 is in central Budd Inlet (Lat. 47.0799o N.; Long. 122.9135o W.), the two most southern Long Term stations in the WDOE program. In addition, samples recovered in the vicinity of both stations in a separate study in the 1980s provide further historical data. Station 44 lies in a relatively open channel with sediment dominated by sand, while Station 49 is a in a restricted inlet with sediment dominated by clay and silt, and a record of low dissolved oxygen. Foraminiferal assemblages at these two stations reflect the differing settings, with Station 44 containing relatively high estuarine diversity (up to 21 species), while station 49 has a very low diversity (<8 species) and is often barren of foraminifera. Unlike other parts of Puget Sound, diversity and abundance at station 44 has increased over time. In contrast, Station 49 diversity remains very low and includes samples barren of foraminifera. Presumably the increased diversity and abundance at Station 44 reflects improving ecologic conditions with diversity returning to close to that recorded in the area in 1980’s. This is particularly true for the number of calcareous species. In contrast, Station 49 exhibits a continued degradation in conditions as the foraminiferal assemblages declined and/or disappeared.