GSA Annual Meeting in Seattle, Washington, USA - 2017

Paper No. 378-12
Presentation Time: 9:00 AM-6:30 PM


SORENSON, Adrienne, Burke Museum, University of Washington, Box 353010, Seattle, WA 98195-3010; Earth and Space Sciences, Univeristy of Washington, Box 353010, Seattle, WA 98195-3010, MARTIN, Ruth A., Earth and Space Sciences, University of Washington, Box 353010, Seattle, WA 98195-3010 and NESBITT, Elizabeth A., Burke Museum, University of Washington, Box 353010, Seattle, WA 89195-3010, adann83@u.washingtonedu

Studies using recent benthic foraminiferal assemblages to assess changes in environmental conditions have proven to be effective throughout the world. In Washington State, the Puget Sound Foram Research Project is using such studies to focus on anthropogenically impacted embayments. One such site is Hood Canal, a restricted arm of the Puget Sound estuary, well known for both its seasonal hypoxia and shellfish industry. This study seeks to define the recent foraminiferal assemblages and to assess changes in relation to point and non-point pollution sources and fluctuating oxygen levels.

Initial findings indicate that there is great heterogeneity in assemblages throughout Hood Canal, both geographically and temporally. Five geographical sub-regions were identified and samples were used that spanned the time period from 1985 to 2016. Even with high heterogeneity, there are noteworthy trends. There is a relatively high species diversity compared with the other Puget Sound embayments, and the same taxa are usually present. The calcareous species, Buliminella elegantissima is found throughout the canal, and is a large portion of populations in four of the sub-regions. Agglutinated taxa are most common in the southernmost part where the water is deep, has a high water residency time, and is influenced by influx from the Skokomish River. Dabob Bay, the location of much of Hood Canals’ industrialization, has the lowest density of foraminifera overall indicating unfavorable conditions. This area also has the highest percentage of Trochammina species in Hood Canal. At the terminus of Hood Canal, Lynch Cove is shallow, muddy, and highly susceptible to hypoxic conditions. It also has the lowest percentage of agglutinated species, the highest rate of dissolution of calcareous shells, and the highest species richness.