Dr. Roxanne Razavi joined the Finger Lakes Institute as a postdoctoral researcher in May 2015, bringing her research experience on mercury (Hg) dynamics in freshwaters to the Finger Lakes Hg Project.
What is your role in the Finger Lakes Hg Project?
I work closely with the Finger Lakes Institute Director, Lisa Cleckner, and our collaborators, to ensure that all aspects of what we set out to do in our research proposal get done. I’m working in the field collecting samples on the lakes and tributaries, processing and analyzing samples in the lab, and then working on data analyses and writing up our results. I’m also involved in communicating our findings with students and the public.
Some of your previous research was in the St. Lawrence River (Canada), and in eastern China. How do the Hg dynamics in those locations compare to the Finger Lakes?
The work I did in the St. Lawrence River was in a Great Lakes Area of Concern. One of the reasons this site was listed was due to high Hg contamination found in the sediments from industries that disposed of tons of Hg waste directly into the river. The question we are investigating in the Finger Lakes isn’t about how contaminated sediments are releasing Hg into the food web, but rather, how Hg that is entering the lakes from the atmosphere is entering the food web. So the main source of Hg pollution is different between these two studies.
The source of Hg in China, however, was from the atmosphere. And there was a lot of it. However, the food webs in the Finger Lakes and reservoirs of eastern China are very different. In China, reservoirs are stocked with planktivores (fish that eat algae and zooplankton). Because these fish are low in the food chain, grow quickly, and are caught at a young age, they do not accumulate a lot of Hg. In the Finger Lakes, people are most interested in catching fish like Lake Trout and Walleye that are top predators, and so accumulate higher amounts of Hg in their tissues. So these two situations result in very different exposures of Hg to people that eat fish.
What are you most interested in finding out through this project?
I’m really curious to see how lake trophic status influences Hg accumulation in the Finger Lakes. There are so many factors that can affect how much Hg actually ends up in top predators. Often how productive the lake is, which we can assess by measuring the amount of chlorophyll-a, is really well correlated with Hg concentrations in zooplankton and fish. One reason for this is that chlorophyll-a is an indicator of how much algal biomass there is. When there is a lot, it can act to dilute the available Hg so that less ends up moving through the food chain, resulting in lower Hg concentrations in fish. But other factors are also important, like how big a watershed is relative to lake size, aspects of fish biology, and the species present in a food web. I’m really excited to find out which of these factors is most important in determining fish Hg concentrations in the Finger Lakes!