Defense Date

8-7-2023

Document Type

Thesis

Degree Type

Master of Science

Degree Name

Marine Science

First Advisor

Amy C. Hirons, Ph.D.

Second Advisor

Dimitrios G. Giarikos, Ph.D.

Third Advisor

Verena Gill, M.S.

Keywords

Alaska, Enhydra lutris kenyoni, northern sea otter, SECLER, trace elements, vibrissae

Abstract

The northern sea otter population which resides along the Alaska coast has undergone significant declines since the 1970s and continues to fluctuate. The population consists of three distinct stocks: southwest (SW), southcentral (SC), and southeast (SE). While the SC and SE stocks are slowly increasing, the SW stock continues to decline for indeterminant reasons. One potential contributor may be anthropogenic contaminants. Trace elements are naturally and anthropogenically sourced, potentially arising anywhere from volcanic activity to mining remnants, both prevalent in Alaska. These trace elements are known to have potential toxic effects in mammals, but toxic concentrations are unknown in sea otters. This study utilized inductively coupled plasma mass spectrometry (ICP-MS) to evaluate concentrations of 16 essential and nonessential elements including aluminum (Al), arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), mercury (Hg), manganese (Mn), molybdenum (Mo), nickel (Ni), lead (Pb), selenium (Se), tin (Sn), vanadium (V), and zinc (Zn) in vibrissae (whisker) samples of sea otters. Vibrissae (n=141) were collected during 2004-2014 from the SW (n=49), SC (n=64), and SE (n=28) stocks. The ability to obtain tissues non-invasively for contaminant research is a distinct advantage, particularly when studying a threatened species. All 16 elements were detected in vibrissae. Southcentral (SC) was the only stock to exhibit significant differences among eight trace element concentrations while SW and SE did not. No notable temporal fluctuations were in evidence. Southcentral male sea otters significantly differed in 10 elements, while only two elements differed for female otters. As much as the threatened SW sea otter stock is of heightened concern, results from this study unexpectedly indicated variability in trace element concentrations within SC otters. With this knowledge, further contaminant studies should be pursued to assess their potential influence on the precarious sea otter stocks.

Comments

Samples were collected under MMPA permit No. MA041309-5 issued to Gill in the U.S. Fish and Wildlife’s Marine Mammals Management office. Funding for this research was provided by the U.S. Fish and Wildlife Service Section 6 funds awarded via Alaska Department of Fish and Game, through Cooperative Agreement #20-076.

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