Graduation Year


Document Type




Degree Name

Doctor of Philosophy (Ph.D.)

Degree Granting Department

Marine Science

Major Professor

Ernst B. Peebles, Ph.D.

Co-Major Professor

Steven A. Murawski, Ph.D.

Committee Member

William F. Patterson, III, Ph.D.

Committee Member

Cameron H. Ainsworth, Ph.D.

Committee Member

David J. Hollander, Ph.D.


diet switch, eye lens, meta-analysis, otolith microchemistry, stable isotopes, trace elements


The focus of this work was on the use of otolith microchemistry and fish eye lens chemical profiles to measure fish movement and provided indirect support for the use of otolith microchemistry to examine exposure to crude oil. Chapter 1 provides an introduction to the applications of otolith microchemistry and eye lens isotopic profiles. In the second chapter, which examined associations between metal exposure and lesion formation in fishes collected after the Deepwater Horizon (DWH) oil spill, I did not observe any change in oil-associated metal concentrations in otoliths coinciding with the timing of the DWH oil spill. This suggests that either the technique used is not sensitive enough to detect any transient changes that may have occurred because of exposure to the oil spill or that the fish examined were not exposed to the oil spill. However, I did find that lesioned fish may have been exposed to a persistent source of trace-metals in the GoM prior to, during, and after the oil spill, and metal-induced immunomodulation may have occurred in these fish. These interactions between the physiological and environmental modulation of otolith element incorporation were explored further in Chapter 3 in which multiple tests demonstrated that physiology explained more of the variation in otolith chemical tags than ambient water chemistry. These findings suggest that the use of otolith microchemistry alone to track fish movement and potential exposure to harmful metals may be complicated by physiological control of otolith microchemistry. Thus, in Chapter 4, I pursued a novel method to evaluate the movement of fish across isoscapes of varying δ15N. I validated the use of fish eye lenses as potential lifetime recorders of isotopic histories and in Chapter 5 compared the use of fish eye lens δ15N profiles to otolith microchemistry profiles to examine fish movement. Both techniques suggested similar patterns of movement in Red Snapper from the northern GoM to the West Florida Shelf. This is the first study to use these complimentary techniques to track fish movement.