Peruvian Pinniped Canines as Indicators of Trace Element Bioaccumulation in the Humboldt Current Upwelling Marine Ecosystem

Author

• Ally E. Sheehan, Nova Southeastern UniversityFollow

Defense Date

4-28-2026

Document Type

Thesis

Degree Type

Master of Science

Degree Name

Marine Science

First Advisor

Dr. Amy C. Hirons

Second Advisor

Dr. Dimitrios G. Giarikos

Third Advisor

Dr. Susana Cárdenas-Alayza

Fourth Advisor

Dr. Michael Adkesson

Keywords

Trace elements, Dentin biochronology, El Niño–Southern Oscillation, South American sea lion (Otaria byronia; SASL), Peruvian fur seal (Arctocephalus australis; PFS)

Abstract

The South American sea lion (Otaria byronia; SASL) and Peruvian fur seal (Arctocephalus australis; PFS) are apex predators within the Humboldt Current ecosystem, where population dynamics respond to both natural variability and anthropogenic pressures, including El Niño–Southern Oscillation (ENSO) events and coastal mining. This study quantified 18 trace elements (TEs) in canine dentin from both species collected at Punta San Juan, Peru using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) to evaluate long-term environmental exposure. Because dentin is deposited incrementally, it preserves a chronological chemical archive reflecting ontogenetic shifts in diet and habitat use. Overall, TE concentrations were broadly similar between species; however, SASL exhibited elevated barium (Ba), strontium (Sr), and zinc (Zn), consistent with differences in foraging ecology and trophic position. Age-related variation was evident for several elements, including cobalt (Co), copper (Cu), iron (Fe), lithium (Li), molybdenum (Mo), and Zn, likely reflecting maternal transfer, developmental dietary transitions, and changing physiological demands. The strong 2015/2016 El Niño event corresponded with increased arsenic (As) and decreased aluminum (Al) and Cu concentrations, indicating that oceanographic conditions and associated changes in productivity and coastal runoff influence TE bioavailability and incorporation. Comparisons with other pinniped populations further revealed regional differences in exposure linked to local environmental conditions and prey composition. These findings demonstrate that dentin provides a robust matrix for reconstructing temporal patterns of TE accumulation. Species-specific, age-related, and environment-driven trends offer valuable insights into ecosystem health and contribute to conservation and management strategies for SASL and PFS populations along the Peruvian coast.

NSUWorks Citation

Ally E. Sheehan. 2026. Peruvian Pinniped Canines as Indicators of Trace Element Bioaccumulation in the Humboldt Current Upwelling Marine Ecosystem. Master's thesis. Nova Southeastern University. Retrieved from NSUWorks, . (235)
https://nsuworks.nova.edu/hcas_etd_all/235.