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Graduate STEM Fellow Profile

Jesse John

Project Title: City as Lab
Thesis: Trace Element Concentrations in Dentine and Enamel in Shark Teeth
College/University: City University of New York - Brooklyn College
Research Advisor: John Chamberlain
Degree Sought: M.S., Geology
Department: Earth and Environmental Science
Research Focus: Use of trace metal analysis of shark teeth as a potential proxy for habitat, diet, and geochronology
Teaching Partner(s): Marcus Watson, Calvin Byers

Description of Research

Trace element concentration in shark teeth may be useful in distinguishing an individual shark’s diets, habitats, and life history. This information can be very useful to conservation and management of individual shark species especially in the wake of the rapidly expanding exploitation of shark populations world wide due to commercial fishing for shark fins and delicacies over the past two decades. We have developed and tested a method for analyzing trace element concentrations in dentine and enamel of shark teeth. This method entails using diamond scribe precision sampling and ICP-MS (Inductively Coupled Plasma Mass Spectrometry) analysis. We have the capacity to utilize loose teeth shed by live sharks and also to extract teeth from dead/preserved animals. Live specimens do not need to be sampled directly. This study aims to develop a framework to eventually compare sharks from pelagic, inshore, and coastal environments to determine the effects of behavior and habitat on trace element concentration in tooth dentine and enamel. In addition to the work proposed above, we intend to develop a chemical means of detecting, and perhaps circumventing, changes in trace metal concentration of fossil shark teeth that occur during rock formation long after an animal’s death. Success in this endeavor is of great relevance to geologists because it will provide a basis for generating reliable geologic ages for fossil shark teeth, the most abundant vertebrate skeletal material present in the rock record.

Example of how my research is integrated into my GK-12 experience

To incorporate my research into the classroom, students were given an exercise using radioactive dating to calculate the age of numerous fossils. The students were given several bags each containing marbles of various colors. They were informed that the bag itself represents the entire fossil and the marbles inside represent some of the millions of atoms that make it up. I then told them what radioactive dating system we were using and which color marble represented the parent and daughter atoms. As geochronologists, their job was to count the number of parent and daughter isotope atoms in each bag, and from this data, determine how many half-lives the isotope had gone through and therefore the age of the fossil. This exercise helped students understand some of the basic principles behind using fossils as a tool for radioactive dating.

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