|Abstract Title:||Exploring Seasonal Variation of Mercury Burdens in Lake trout (Salvenlinus namaycush)|
|Presenter Name:||Sofia Pereira|
|Session:||Mercury in Freshwater Ecosystems|
Abstract Information :
Mercury (Hg) is a dietary-derived contaminant that can reach high concentrations in predatory fishes, posing a significant human health concern. Many studies have characterized the ecological and physiological factors that influence Hg burdens in fishes, with diet and growth rates appearing particularly important. However, little is known about how seasonal changes in fish behaviour and physiology may drive shifts in fish Hg burdens across the course of a year. Furthermore, the roles of sex and reproductive status in influencing Hg contamination in fishes are also poorly characterized. Here, we explored whether ecological or physiological factors better explain seasonal Hg variation in lake trout (Salvenlinus namaycush), a popular sport fish with distinct seasonal behaviours. Lake trout were sampled during all 4 seasons across two years in two different lakes in Algonquin Park, Ontario, Canada. Total mercury concentrations were measured in the liver tissue of each fish along with a suite of ecological and physiological traits. We found that liver Hg concentrations in lake trout varied between the sexes and were more strongly related to seasonal variation in physiological factors associated with reproduction (gonad mass, liver mass) than to dietary factors (ë15N-based trophic position, ë13C-based habitat use). Our findings stress the importance of both sex and the seasonal timing of life history events for dictating Hg burdens in temperate freshwater fishes. Consequently, this may become important when establishing consumption advisories, which are traditionally based solely on summer sampling.