Date of Award

2026

Document Type

Open Access Master's Thesis

Degree Name

Master of Science in Biological Sciences (MS)

Administrative Home Department

Department of Biological Sciences

Advisor 1

Gordon Paterson

Committee Member 1

Christopher Adams

Committee Member 2

Evan Kane

Abstract

Sea lamprey (Petromyzon marinus) continue to be a concern in the upper Great Lakes decades after their introduction, but their life history and feeding ecology make them useful subjects to study the bioaccumulation of contaminants in aquatic food webs. This research characterized mercury (Hg) bioaccumulation among sea lamprey collected from across the southern coast of Lake Superior and utilized carbon (δ13C) and nitrogen (δ15N) stable isotopes to infer dietary characteristics and trophic ecology of these parasitic fish. The goals of this research were to i) compare Hg bioaccumulation to examine for regional differences and ii) compare δ13C and δ15N values relative to those for potential hosts from across the southern coast of Lake Superior. Mercury concentrations averaged from 2.4 – 4.5 μg/g wet weight and males were 13 % more contaminated than females on average and all fish exceeded national and international guidelines for Hg concentrations in contaminated fish and seafood. Sea lamprey returning to tributaries in the central region of the southern shoreline had lower Hg concentrations relative to fish collected from the eastern- and western-most tributaries. Carbon isotopes indicated variation in sea lamprey diets across the lake with nitrogen isotopes representative of their consistent trophic status. These results supported predictions that there are regional variations in sea lamprey Hg bioaccumulation, and that sea lamprey parasitize a variety of host species such as the high fat content siscowet lake trout (Savelinus namaycush) and burbot (Lota lota) in addition to lean lake trout in Lake Superior. This research also suggests that the levels of Hg bioaccumulation by lamprey in combination with spawning run estimates represents a non-trivial source of Hg cycling in tributary streams and likely increases risks for secondary Hg exposure among terrestrial and aquatic organisms that inhabit these tributaries.

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Available for download on Friday, June 18, 2027

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