| Summary: | This thesis is an investigation of linkages of climate change and mercury concentrations in landlocked Arctic char and underlying food webs in Canadian Arctic lakes. Although the neurotoxin mercury is globally present in all environments, temporal and spatial trends in aquatic biota are often inconsistent, or do not exist for remote environments. Knowledge gaps include the influence of abiotic factors, possibly climate, and food web parameters on mercury accumulation in top predators. Furthermore, anthropogenic and natural mercury present in the environment are not well differentiated. To address these research needs, we collected landlocked Arctic char from 27 systems and food web organism from 18 lakes, and recorded abiotic lake characteristics expected to influence mercury cycling. Total mercury (THg) and monomethylmercury (MeHg) concentrations, and stable isotopes of carbon ([delta]13C), nitrogen ([delta]15N), and mercury ([delta]xHg) were determined. Relationships among these measures and with environmental characteristics were investigated. A temporal trend of mercury in Arctic char (muscle tissue) from the largest lake in the Canadian High Arctic from an existing dataset and newly collected char was investigated. Two abundant char morphotypes from Lake Hazen differed in mercury concentrations, and the resulting variability was accounted for using a statistical adjustment. Mercury concentrations did not change over the 16-year period (1990-2006), which is consistent with nearby measurements of gaseous elemental mercury at Alert (Nunavut, Canada). Food chain lengths (FCL) of 18 lakes were characterized, biomagnification of mercury was investigated using [delta]15N, and results compared among regions. Food web biomagnification was confirmed using trophic magnification factors (TMFs) in 18 Arctic char bearing lakes (TMFs 3.5 - 64.3). Benthic coupling was apparent from char [delta]13C signatures that resembled [delta]13C in chironomid midges. TMFs and FCL partly explained THg in adult char, but no latitudinal ...
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