Elevated invertebrate methylmercury concentrations across functional feeding groups in a eutrophic bog post-flooding

Mercury is a toxic environmental contaminant that is known to undergo long range transport, resulting in deposition in remote and pristine ecosystems. Increases in methylmercury concentration at low trophic levels may result in greater risk to top predators in food webs. As a result, low trophic level invertebrates are important sentinels for ecosystem contamination and overall ecosystem health. Big Meadow Bog, located on Brier Island, Nova Scotia, is a disturbed wetland habitat that was subject to colonization by herring gulls (Larus argentatus), resulting in significant phosphate nutrient input from guano and is also affected by a recent water table restoration. Aquatic and terrestrial invertebrate families were sampled from Big Meadow Bog in addition to surface waters to examine the impacts of nutrients and flooding on mercury speciation and accumulation. Methylmercury (MeHg) and total mercury (THg) were analyzed in all samples and water to calculate invertebrate bioconcentration factors. Methylmercury concentrations were significantly different across invertebrate families, and functional feeding groups (FFG). Concentrations of MeHg in Big Meadow Bog were on average 1.61 times higher than MeHg concentrations observed at similar undisturbed sites.