| dc.description.abstract | Exposure to mercury has been linked to health risks in both people and wildlife.
In Ontario, mercury pollution is to blame for 85% of the consumption restrictions on
fish from inland lakes. Heavy metals like mercury accumulate up the food chain.
Different rates of contaminant accumulation may be caused by variations in feeding and
food web biomagnification. To assess the role of food web biomagnification in an apex
predator, four distinct classes of lake trout (Salvelinus namaycush) prey with increasing
food chain lengths were compared to determine whether differences in food chain length
could account for the differences in muscle tissue mercury concentration. The analysis
for this study included fish, water chemistry, and mercury concentrations that were
collected from the IISD-Experimental Lakes Area (1973-2019) and the Ontario Ministry
of Natural Resources and Forestry’s Broad-scale Monitoring Program where the
Ministry of Environment and Climate Change analyzed the fish tissue. Accounting for
variation in fish body size, lake trout mercury concentration cannot be explained by food
chain length as predicted, although a significant interaction between body size and lake
class suggests there is a positive relationship with body size that varies based on food
web class. In attempt to contextualize this result, I examined the possibility that
environmental factors, such as lake chemistry (dissolved organic carbon, pH, total
dissolved phosphorus), and lake morphometry (i.e. maximum lake depth, surface area)
are also associated with variation mercury concentration. All environmental variables
examined show a positive correlation with mercury concentration; amongst the variables
assessed, dissolved organic carbon (DOC) had the strongest association with fish
mercury concentrations. Understanding the biotic and abiotic factors that influence
mercury accumulation can help make decisions on fish consumption guidelines and can
help further research opportunities. | en_US |
