Reconstructing the Life History of Fishes Using the Stable Isotope Composition of Eye Lens Laminae
Date
2022-05
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Publisher
University of Delaware
Abstract
In order to improve our understanding of fish ecology, behavior, and habitat
utilization across ontogeny, researchers need approaches for understanding how these dynamics change throughout the lives of individual fishes. Stable isotope analysis (SIA), the comparison of isotope ratios in animal tissues to spatial variation in isotope values of prey and primary producer species throughout an environment, is one such tool that can be used to study animal migration and trophic ecology. However, researchers often use SIA of metabolically active tissues (e.g., muscle, liver) with faster turnover rates, which provides insight into the recent history of the animal. Analysis of eye lenses (laminae), a protein rich archival tissue that forms layers that do not change after deposition, is a newer method that is being developed. In this thesis, we used Cynoscion regalis, commonly known as Weakfish, in Delaware Bay as a model species to further explore the feasibility of stable isotope analysis on the laminae of individual fish in order to reconstruct their life histories. We analyzed the lamina from both eyes of 17 young of the year weakfish, measuring the carbon (δ13C), nitrogen (δ15N), and sulfur (δ34S). We then compared the isotopic composition of Weakfish eye lenses to published SIA data from weakfish muscle samples collected in Delaware Bay during prior research. I found that δ13C, δ15N and δ34S in lens lamina where similar to those of muscle samples, suggesting this approach produces reasonable data for this species and location. There were distinct changes in δ13C, δ15N and δ34S values between lamina layers that were indicative of changes in habitat and dietary shifts through ontogeny.
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Keywords
Fish, Stable isotope analysis, Weakfish, Eye lenses