T270 Insights from Microfossils and Their Modern Analogs: From Traditional to Emerging Approaches (Posters)

Wednesday, 25 September 2019
9:00 AM - 6:30 PM
Hall AB, North Building

FORAMINIFERAL ASSEMBLAGE IN THE TIDAL FLATS OF BUDD INLET, PUGET SOUND, WASHINGTON STATE, USA

Paper number: T270-9
Program: Technical Sessions
Time: 9:00 AM – 6:30 PM

Authors

Abstract

Puget Sound is the southern portion of the Salish Sea, a complex fjord system located in Washington State, USA, and British Columbia, Canada. Budd Inlet is located South Sound Basin and is nearly the southernmost inlet of Puget Sound. Olympia Washington is located at the head of Budd Inlet and the LOTT waste water treatment plant effluent is discharges 13 mgd near the head of the inlet. Additional fresh water input is contributed by the Deschutes River at the western head of the inlet. The combination of LOTT effluent and Deschutes River results in a significant fresh water outflow along the eastern side of the inlet. This outflow is balanced by a subsurface inflow from the open sound along the western margin of the inlet.

The Foraminiferal assemblage of the sub-tidal parts of Budd Inlet have been previously described (Derher et al., 2015). However, the foraminifera of the inter-tidal environment have not been studied in most of Puget Sound. This paper is the first report of the inter tidal foraminifera in the southern Puget Sound. The Budd Inlet inter tidal foraminiferal assemblage characterized by low diversity and low abundance. The assemblage is dominated by a single species Ammonia beccarii, in some samples a monospecific assemblage. The occurrence of this species is in contrast to the sub-tidal samples where it has not been previously recorded. Temperature limits on the distribution of Ammonia beccarii is the likely explanation for its exclusion from the subtidal realm. However, it’s nearly complete dominance of the inter-tidal region is not as easily explained. The high anthropogenic impact from the LOTT effluent combined with contaminant runoff may explain this dominance in part.

Other trends are increasing diversity and abundance from the head of the inlet to the mouth. Samples from the head of the inlet are barren of foraminifera while those from near the mouth have at least a low diversity assemblage. This pattern was expected due to both the fresh water inflow and high waste water effluent at the head of the inlet. These effects are diminished along the length of the inlet due to dilution by Puget Sound waters.

Reference:

Dreher, B. E., Frederick, D. L., Martin, R. A., and Nesbitt, E. A. 2015, Abundance and distribution of modern Foraminifera species in the southern Puget Sound, Washington State. Geological Society of America, Abstr., v. 47, p. 26.

Geological Society of America Abstracts with Programs. Vol. 51, No. 5

doi: 10.1130/abs/2019AM-338931

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