Document Type

Thesis

Abstract

Determining the ontogenetic trophic ecology of sympatric, morphologically similar fishes is critical for increasing our understanding of life history. We combined bulk and amino acid compound-specific stable isotope analysis of eye lenses with stomach-content analysis to examine ontogenetic trophic dynamics of four amphidromous whitefishes (Arctic Cisco Coregonus autumnalis, Least Cisco C. sardinella, Broad Whitefish C. nasus, Humpback Whitefish C. pidschian) from the central Beaufort Sea, Alaska. Compound-specific stable nitrogen isotope results showed slight increases in trophic position across ontogeny for each species and indicated the feasibility of this method for comparing the trophic ontogenetic development of closely related, mobile predator species. Bulk δ15N and δ13C ontogenetic timelines were reflective of an amphidromous geographic life-history strategy, where foraging occurs primarily in freshwater habitats early in life and nearshore marine habitats at larger sizes. Stomach-content analysis revealed that diet was dominated by a single prey item (amphipods) in all four species, but that short-term diets differed for five of six pairwise species interactions (only Arctic and Least Cisco had diet compositions that overlapped). This was the first study to compare trophic ontogenies of multiple fish species through eye lens compound-specific stable nitrogen isotope analysis. Trophic dynamics were similar among whitefishes from the central Beaufort Sea, highlighting the vulnerability of this ecologically and culturally important clade.

Publication Date

12-17-2024

Handle

http://hdl.handle.net/11122/15668

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