AMINO ACID ISOTOPE DYNAMICS AND ASSOCIATED ECOLOGICAL METRICS ACROSS ACCRETIONARY TISSUES OF MARINE FISHES

Author

• Sofia Piccone, University of Rhode IslandFollow

Date of Award

2026

Degree Type

Thesis

Degree Name

Master of Science in Oceanography

Specialization

Biological Oceanography

Department

Oceanography

First Advisor

Kelton W. McMahon

Abstract

Compound-specific isotope analysis of amino acids (CSIA-AA) applied to the organic growth layers of accretionary fish tissues, including eye lenses, otoliths, and scales, has made it possible to reconstruct histories of fish physiology, ecology, and environmental conditions. Yet it remains uncertain whether amino acid isotope values, and the ecological information they contain, are conserved across these archival tissues or if differences in tissue composition, growth, protein structure, and metabolic routing produce tissue-specific offsets that alter inferred carbon sources, d¹⁵N_Baseline, and trophic position. We tested this question with individually paired CSIA-AA of eye lenses, otoliths, and scales compared to muscle for two ecologically and morphologically distinct fisheries species, black sea bass (Centropristis striata) and summer flounder (Paralichthys dentatus) (n = 7 individuals species^-1). Non-essential d¹³C and trophic d¹⁵N amino acids exhibited larger tissue and species-specific deviations from muscle compared to essential δ13C and source d¹⁵N values. Resulting essential d¹³C “fingerprints” and d¹⁵N_Baseline values were generally conserved across tissues, whereas trophic position offsets varied more by tissue and species. Eye lenses were most comparable to muscle for d¹⁵N_Baseline and generally produced the smallest trophic position offsets, whereas essential d¹³C source estimates were more tissue and species dependent. Scales showed potential for non-lethal carbon source reconstructions with species-specific validation, however they produced variable trophic position offsets. Otoliths were analytically challenging due to low protein content and showed species-specific variability in essential d¹³C fingerprints. These findings demonstrate that accretionary tissues preserve ecological isotopic signals differently and that tissue selection should be both matched to the target ecological metric and validated for species of interest.

Recommended Citation

Piccone, Sofia, "AMINO ACID ISOTOPE DYNAMICS AND ASSOCIATED ECOLOGICAL METRICS ACROSS ACCRETIONARY TISSUES OF MARINE FISHES" (2026). Open Access Master's Theses. Paper 2745.
https://digitalcommons.uri.edu/theses/2745