Mercury concentrations in invertebrates from a contaminated wetland, Montague Gold Mines, Dartmouth, Nova Scotia

Abstract

Mercury pollution has become a significant concern to environmentalists over the past several decades. With natural releases of mercury and increasing anthropogenic activities releasing larger quantities of mercury into the environment over the last several decades, harm to organisms and ecosystems is also on the rise. One anthropogenic activity that will be considered in this report is gold mining and its products’ bioavailability, via mercury contaminated‐tailing material, in aquatic invertebrates at a wetland located in the Montague Gold Mining District in Dartmouth, Nova Scotia. Sediment from the study wetland at Montague Mining District showed significantly elevated total mercury concentrations with all samples far above the Canadian Council of Ministers of the Environment freshwater sediment values. Focal invertebrates (Anisoptera, Zygoptera and Dolomedes) were collected from the study wetland as well and analyzed for total mercury content displaying significantly higher total mercury concentrations than invertebrates of the same sub‐order and genus collected from a non‐contaminated reference site. Additionally, Anisoptera total mercury levels far exceeded levels found at a similar study conducted at Kejimkujik National Park, indicating this site in particular is of high concern for mercury contamination, bioavailability and potential biomagnification through terrestrial and aquatic food chains. With respect to parental Hg transfer to young, our results suggest that Hg transfer from Dolomedes to their young within their egg sacs is likely. Due to the nature of the odonate and dolomedes lifecycles and their potential to spread contamination not only to terrestrial landscapes, but also to other aquatic habitats, it is clear that the impacts go beyond the boundaries of the Old Stamp Mill wetland.