Mercury concentration in fish as a function of change in reservoir size

Therriault, Thomas Wayne (1996) Mercury concentration in fish as a function of change in reservoir size. Masters thesis, Memorial University of Newfoundland.

[English] PDF (Migrated (PDF/A Conversion) from original format: (application/pdf)) - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (24MB) [English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. (Original Version)

Abstract

Increased fish mercury concentrations are often observed following impoundment of a reservoir. Following impoundment, there is a flux of organic matter and nutrients from the flooded soil, providing food to bacterial communities which methylate inorganic mercury. Based on the hypothesis that mercury enters a reservoir via the flooded soil, I investigated whether the change in fish mercury concentrations could be predicted from the change in reservoir size. Mercury monitoring data for three fish species, northern pike (Esox lucius), walleye (Stizostedion vitreum), and lake whitefish (Coregonus clupeaformis) from reservoirs in northen Manitoba and northern Quebec were used to derive parameter estimates for four models. Models were evaluated on their ability to predict cases not used in the model development. Models were applied for predictive purposes to assess the impact of creating a reservoir and to assess the impact of altering the size of an existing reservoir. Skill (closeness of predicted and observed values) and explained variance were also used to assess the models. The preferred models consisted of a single enrichment term (a measure of change in flooded area) that successfully predicted the mercury ratio. This study also demonstrated that parameter estimates for one species could be applied successfully to predict the mercury ratio for species with comparable food habits.

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