Indigenous partnered research on contaminants in subsistence fish from the Sudbury Basin

Abstract

Wahnapitae First Nation (WFN) is a small Anishinaabe Community in Ontario, Canada, whose members regularly harvest fish for subsistence. Thus, like many Indigenous Communities, the quality and health of these fish are of great concern. The goal of this project is to better understand contaminant levels in subsistence fish from the waters of WFN’s Traditional Territory, which has been heavily impacted by local mining and smelting activity. Through a collegial partnership between the Community and academic researchers and a robust data- sharing agreement, we incorporated Community input into our study design. We specifically focused on five species of freshwater fish (burbot, lake trout, lake whitefish, smallmouth bass, walleye) from two chemically and physically distinct lakes that are important to WFN’s food security and sovereignty. We sampled three tissues commonly eaten by Community members (i.e., muscle, liver, and pyloric ceca, which is known as the chum in WFN and referred to as such herein) and analyzed them for total arsenic and selenium, as well as total and methyl mercury, at an accredited lab. Results show a consistent pattern for Hg bioaccumulation among species, with the expected higher mercury concentrations ([Hg]) observed in the larger fish and in top predators such as walleye. Fish muscle [Hg] from Lake Wanapitei frequently exceeded the Province of Ontario “8 meals/month” benchmark for consumption, while samples from Kukagami Lake had significantly lower [Hg]. Instead, Kukagami Lake fish exceeded the Provincial “8 meals/month” benchmark due to elevated selenium concentration ([Se]). In both lakes, [As] were generally low except for all tissues in burbot. The stark differences in [Hg] and [Se] between lakes, which are in close proximity to each other, emphasize the need for lake and population-specific consumption guidelines. Our data also show differences in elemental concentrations between the three tissues, suggesting physiological and biokinetic differences between fish populations. Although, benchmark exceedances were generally less in liver and chum than in muscle, with the exception of [Se] in lake trout liver and arsenic in burbot. Lastly, despite the differences in [Se] between the two lakes, we found a positive relationship between [Hg] and [Se] across all tissues, suggesting a co-bioaccumulation of these elements. This appears contrary to the commonly assumed protective effects of Se on Hg accumulation and warrants further study. In addition to improving our understanding of contaminant distributions amongst tissues in fish, this project will provide WFN with the resources for more informed fish consumption and guide future monitoring efforts.