Masters Theses

Date of Award

12-2016

Degree Type

Thesis

Degree Name

Master of Science

Major

Geology

Major Professor

Michael L. McKinney

Committee Members

Henri D. Grissino-Mayer, Colin D. Sumrall, Gerald R. Dinkins

Abstract

The goal of this research was to compare modern shell material to relic material of the main branch of the Holston River to examine freshwater mussel growth and mortality to discover possible inferences from changes in water quality. Relic shell material collected from two sample sites were dated using low precision C14 dating (a relatively new method) and racemization (used to give an idea of the time between death and discovery). Relic shell material was then compared to modern shell material for the species Actinonaias ligamentina to illustrate changes in growth and rates of mortality using growth annuli analysis.Relic specimens of the four species collected, Actinonaias ligamentina, Elliptio crassidens, Amblema plicata and Pleurobema rubrum, from the two sample sites along the Main Branch of the Holston River were geologically dated back to the Woodland and Early Mississippian Period in archaeological time using low precision C14 dating.Racemization indicated that most amino acids (apart from alanine) were at a low ratio of conversion, meaning that these shells were in the early stages of decay. While the acidity of the water and colder temperatures could have blurred the results of this test, it is also possible that other aspects affecting preservation of the shell may have caused the low ratio conversion of amino acids.Growth in the relic shells followed the pattern of more growth occurring in the warmer, summer months with a constant cessation of growth as shown by the halting of growth during the winter. For the modern shells (five recently dead Actinonaias ligamentina), individuals grew faster compared to some relic specimens of the same species and comparable age, with thicker growth annuli being observed in particular specimens. This was possibly due to an increase in nutrient content, as found through historical water quality data recorded by the Tennessee Department of Environment and Conservation (TDEC) and the Tennessee Valley Authority (TVA). A reduction of growth during the primary growth season for the modern specimens of Actinonaias ligamentina was evident, perhaps caused by temperature-induced growth disruption resulting from the release of the Cherokee Dam.

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