T256 Oceans and Climates through Earth History: From Proxy Reconstructions to Model Assessments (Posters)

Wednesday, 7 November 2018
9:00 AM - 6:30 PM
Halls J-K

THE OCCURRENCE OF AMMONIA BECCARII IN SOUTHERN PUGET SOUND: A POTENTIAL CLIMATE CHANGE INDICATOR

Paper number: T256-19
Program: Technical Sessions
Time: 9:00 AM – 6:30 PM

Authors

Abstract

The complex fjord system of Puget Sound is highly susceptible to climate change, particularly as increasing temperatures can have significant impacts on the ecosystem. Determining the amount and rate of temperature increase is a problem in areas where there is little historic data particularly for bottom waters. This study documents the occurrence of Ammonia beccarii a temperature limited species of benthic foraminifera in South Puget Sound and its potential as a proxy for bottom water temperatures.

Ammonia beccarii is a common benthic foraminiferal species in many nearshore marine environments. A major factor determining the distribution of this species is water temperature. Experimental data indicates Ammonia beccarii has a lower reproductive temperature limit of 18-20oC and lower growth limit of 10oC (Bradshaw, 1961). As a result of these limits Ammonia beccarii has not been previously recorded in sub-tidal samples of Puget Sound. One previous study documented this species in the inter-tidal area of the northern Puget Sound (Jones and Parker, 1979). This study documents the occurrence of Ammonia beccarii in the litoral environment of Southern Puget Sound and the first known sub-tidal occurrence. Ammonia beccarii is a dominate part of the assemblage in inter-tidal areas of Budd Inlet and is present in three shallow sub-tidal samples from Oakland Bay, Peale Passage, and Budd Inlet collected in 2011. These occurrences coincide with the highest bottom water temperatures recorded in the 2011 sample set. It appears this species while present in the inter-tidal area subject to higher temperatures is, at least seasonally, spreading into the sub-tidal environment as bottom water temperatures increase. Thus, the presence/absence of this species can be used as a temperature proxy in areas where historical data is not available.

Bradshaw, John S. 1961. "Laboratory Experiments on the Ecology of Foraminifera." Contributions from the Cushman Foundation for Foraminiferal Research. 12 (3): 87-106.

Ross, G. D., and C. A. Jones. 1979. "Seasonal Distribution of Foraminifera in Samish Bay, Washington." Journal of Paleontology, 53 (2): 245-257.

Geological Society of America Abstracts with Programs. Vol. 50, No. 6

doi: 10.1130/abs/2018AM-319663

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