The Nova Scotia Mercury Project: Quantifying environmental factors influencing biomagnification trends in aquatic food webs.

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Mercury contamination via atmospheric deposition is a world-wide issue, and the lakes of Nova Scotia are not exempt. The presence of old mines, coal-fired power generating plants and distinctive geological and lake features has meant that Nova Scotia has some of the most Hg-contaminated aquatic ecosystems in North America. This is of major concern given that many lakes have key fish species, including brook trout, yellow perch and smallmouth bass, important to both humans and wildlife. On the other hand, Nova Scotia also has remote sites with low concentrations of mercury. This range of mercury concentrations in fish across Nova Scotia means that the lakes can be viewed as "test tubes" to assess hypotheses to why mercury is high in fish from some lakes, but not in other lakes. My NSERC research will bridge the gaps in our knowledge of mercury food web bioaccumulation trends across the province. First, we will look at how algal levels in lakes caused by excess nutrient runoff can impact on mercury biomagnification in fish food webs: does the fish food webs from the more productive ("green") lakes have slower rates of mercury biomagnification? Second, we will be assessing the role of acid rain on enhancing mercury bioavailability in lakes and whether sulfate concentrations in lake sediments have an important role in determining how much mercury is biomagnified in food webs. Third, we will be comparing the differences between coastal lakes exposed to a lot of saltwater from the sea and valley lakes with very little saltwater and see if mercury biomagnifies at the same rates in both types of lakes. As a result of those studies, we will have better data on how mercury behaves in a wide variety of Nova Scotia lakes.