Defense Date

8-7-2023

Document Type

Thesis

Degree Type

Master of Science

Degree Name

Marine Science

First Advisor

Amy C. Hirons

Second Advisor

Dimitri Giarikos

Third Advisor

David W. Kerstetter

Keywords

Heavy metals, Hawaiian monk seal, Neomonachus schauinslandi, Hawaiian Island Archipelago, bone, SECLER

Abstract

The Hawaiian monk seal (HMS) is an endangered, endemic seal native to the Northwestern Hawaiian Islands (NWHI). During the 21st century, members of the HMS population have established residency within the Main Hawaiian Islands (MHI). This habitat shift may increase exposure of the animals to greater anthropogenic (urban industrialization, agricultural practices, and military activity) and natural (volcanic activity) heavy metal contaminants. Induced coupled plasma mass spectroscopy (ICPMS) analysis compared 16 heavy metal concentrations in HMS bone segregated by region, age, and sex. In additions, metal concentrations from potential prey items from the southern extent of the Northwestern Hawaiian Islands were analyzed relative to temporospatial distribution and species’ biometrics. The MHI and NWHI seals and potential prey contain all 16 heavy metals studied. The HMS bone was found to have the highest concentrations of Zn and Fe, both elements used structurally by bone. The MHI had significantly lower concentration. Anthropogenic sources of heavy metals might be sinking near their sources instead of dispersing out into the marine environment. Concentration differences of Cu and Fe found among ages and between sexes showed evidence of potential maternal offloading while concentration differences of Cd found among ages showed potential evidence bioaccumulation and/or biomagnification. The HMS had significantly higher concentrations of Sn, Zn, and Fe than the potential prey items. Tin may be biomagnifying within the food web while Zn and Fe are related sample tissue differences (bone vs whole organism) as heavy metals do not equally bind to all tissues.

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