Graduation Year

2016

Degree

M.S.

Degree Name

Master of Science (M.S.)

Degree Granting Department

Geology

Major Professor

Gregory S. Herbert, Ph.D.

Committee Member

Gregory S. Ellis, Ph.D.

Committee Member

Jonathan Wynn, Ph.D.

Keywords

methods optimization, molluscan shell organics, mollusk, shell organic matrix

Abstract

Mollusk shells contain proteins within and between the crystals of calcium carbonate. These organic molecules play an important role in biomineralization and shell function, and their stable isotope ratios of carbon and nitrogen are also thought to record important ecological information about the animal's diet and nutrient sources. These proteins can be preserved for millions of years, offering potential insight into pre-anthropogenic ecological conditions. However, shell organics in older shells are typically recovered in reduced abundances due to leaching and remaining organics are often converted from insoluble proteins to soluble, free amino acids, making them difficult to detect and recover. Therefore, demineralization and organics-capture methods must be optimized for yield to extract much-needed ecological information from older shells. This project compared insoluble and soluble organic yields of modern gastropod Strombus alatus shells demineralized with acids of varying concentrations and temperatures. Results suggested that demineralizing shell fragments with 0.1 M HCl at a ratio of 0.9 L HCl/g of shell was optimal. Average percent organic yields ~0.2% for modern and ~0.06% for fossil Strombus. Future applications of this work include using this refined method to reconstruct food webs across broad temporal scales.

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