A review of characteristics influencing lake mercury dynamics, and drivers of variation in mercury concentration within stocked lake fish

Timmons, Patrice Marie (2022) A review of characteristics influencing lake mercury dynamics, and drivers of variation in mercury concentration within stocked lake fish. Masters thesis, Northern Arizona University.

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Abstract

Mercury (Hg) is a pollutant released naturally and anthropogenically, depositing in waterways, where it accumulates in organisms such as plants and animals. Above certain concentrations, Hg causes health, particularly neurological, effects. Within my thesis, I addressed knowledge gaps in Hg dynamics within lake food webs. In the first chapter, I conducted a literature review on how characteristics such as elevation or pH, climate stressors, and mitigation techniques influence Hg food web dynamics in lakes. I compiled information from scientific journal articles, and ran statistical analyses to assess whether lake characteristics were significant predictors of Hg biomagnification within food webs. I found that no single variable was strongly correlated with TMS or TMF within lakes. Additionally, I found that environmental stressors have complicated influences on Hg cycling, which can increase or decrease Hg biomagnification within lake food webs. Fortunately, mitigation techniques approach water systems from various angles such as lake water and sediment, fish stocking, and industrial activities. In the second chapter, I narrowed the focus of study to one lake. I investigated total Hg (THg) dynamics within the food web of Benka Lake, a stocked lake in subarctic Alaska, USA, and I studied drivers of variation within rainbow trout (Oncorhynchus mykiss) in Benka Lake. I used a dataset with information on fish THg concentrations and other variables. I ran univariate statistical analyses to assess whether variables such as length, age, stable isotope ratios, and collection date were significant predictors of THg concentration in individual rainbow trout. I found that standard length and length:age ratio were positively correlated with THg concentration in rainbow trout, while carbon isotope ratio was negatively correlated with THg concentration in rainbow trout.

Item Type:	Thesis (Masters)
Publisher’s Statement:	© Copyright is held by the author. Digital access to this material is made possible by the Cline Library, Northern Arizona University. Further transmission, reproduction or presentation of protected items is prohibited except with permission of the author.
Keywords:	fish; lake; mercury; Benka Lake, Alaska; Biomagnification; Food web;
Subjects:	Q Science > QH Natural history
NAU Depositing Author Academic Status:	Student
Department/Unit:	Graduate College > Theses and Dissertations College of the Environment, Forestry, and Natural Sciences > Biological Sciences
Date Deposited:	01 Jun 2023 16:44
Last Modified:	01 Jun 2023 16:44
URI:	https://openknowledge.nau.edu/id/eprint/5937

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