Defense Date

8-9-2023

Document Type

Thesis

Degree Type

Master of Science

Degree Name

Marine Science

First Advisor

Amy C. Hirons, Ph.D.

Second Advisor

Dimitrios Giarikos, Ph.D.

Third Advisor

Milton Levin, Ph.D.

Fourth Advisor

Michael Adkesson, DVM

Keywords

Cytokines, Peruvian fur seal, South American sea lion, trace elements

Abstract

Large colonies of two vulnerable, sympatric pinniped species, Peruvian fur seals (Arctocephalus australis Peruvian subpopulation; PFS) and South American sea lions (Otaria byronia; SASL), reside and reproduce in Punta San Juan, Peru (PSJ) where they are exposed to stressors such as environmental contaminants and El Niño-Southern Oscillation (ENSO) events. Cytokine concentrations can be indicative of an animal’s health and immune function by allowing for immunoresponse characterization as Th1 or Th2 dominant. Utilizing an archived pinniped plasma collection of samples from 2009-2019 (n=148), 13 cytokines were analyzed in PFS and SASL: GM-CSF, IFN-γ, KC-like, MCP-1, TNF-α, IL-2, IL-6, IL-7, IL8, IL-10, IL-15, IL-18, and IP-10. Significant differences were found between sex in SASL for IFN-γ, IL-6, and KC-like; no significant differences were found between sexes in PFS. Analysis of PFS dam/pup pairs revealed an upregulated Th2 response in pups compared to dams. While no statistically significant relationships between cytokines and extreme ENSO events (sea surface temperature anomaly > ±1º C) were found, comparisons of Th1/Th2 ratios displayed trends toward upregulated Th2 responses during El Niño conditions and upregulated Th1 responses during La Niña conditions. Fifteen trace element concentrations in serum from these same pinnipeds revealed significant relationships between various cytokines and Al, As, Cr, Co, Cu, Hg, Ni, Se, and V. These results indicate a potential immunotoxic response by the immune system of PFS and SASL to these element concentrations.

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