Seminar 2
Hediyeh Shakeri
Dr. McMillan
BIOL 156
14 March 2014
Seminar Summary #2
Ecotoxicology in Ontario, Canada
According to Dr. Kathleen Harding, it takes 20 years for mercury levels to return back to their prior, basic levels when a dam is built. Dr. Harding illustrated her work during her master’s thesis in Ontario lakes, where she told that fish had higher mercury levels than other places. The ministry of Ontario wanted to monitor mercury levels, so Dr. Harding studied the streams and rivers around the Great Lakes area. She illustrated the differences associated with inflows and outflows of lakes and the various water chemistry between the two. She measured inflows and outflows of lakes by determining mercury levels present in insects within the same demographic locale, in comparison to that of the larvae, with Black flies. She talks about the background of this species and how they are plentiful and are easily found subjects to test and measure. For each specimen, the head, abdomen ,and thorax were separated and measured for mercury levels that she later compared to that of Black Fly larvae. This species is a food source for trout and other fish, since the Black Flies exist in dense populations due to the fact they are filter feeders, feeding on small amounts of bacteria and algae. Black flies also are a major consumer of dissolved organic matter, in which mercury is bound to. Her results illustrated that there is a larger proportion of mercury present than anticipated in the Great Lakes region, starting from 0.2-0.7 micrograms of dry weight. She took samples of adults from 3 different sites (due to the lack of variability) as well as larvae. The pHs of the inflow sites was quite acidic in comparison to that of outflows. She believes that pH may be a better indicator of mercury concentration than that of dissolved organic matter. Her results also demonstrated how Black Fly larvae concentrations correlate with dissolved organic matter concentration in
Dr. McMillan
BIOL 156
14 March 2014
Seminar Summary #2
Ecotoxicology in Ontario, Canada
According to Dr. Kathleen Harding, it takes 20 years for mercury levels to return back to their prior, basic levels when a dam is built. Dr. Harding illustrated her work during her master’s thesis in Ontario lakes, where she told that fish had higher mercury levels than other places. The ministry of Ontario wanted to monitor mercury levels, so Dr. Harding studied the streams and rivers around the Great Lakes area. She illustrated the differences associated with inflows and outflows of lakes and the various water chemistry between the two. She measured inflows and outflows of lakes by determining mercury levels present in insects within the same demographic locale, in comparison to that of the larvae, with Black flies. She talks about the background of this species and how they are plentiful and are easily found subjects to test and measure. For each specimen, the head, abdomen ,and thorax were separated and measured for mercury levels that she later compared to that of Black Fly larvae. This species is a food source for trout and other fish, since the Black Flies exist in dense populations due to the fact they are filter feeders, feeding on small amounts of bacteria and algae. Black flies also are a major consumer of dissolved organic matter, in which mercury is bound to. Her results illustrated that there is a larger proportion of mercury present than anticipated in the Great Lakes region, starting from 0.2-0.7 micrograms of dry weight. She took samples of adults from 3 different sites (due to the lack of variability) as well as larvae. The pHs of the inflow sites was quite acidic in comparison to that of outflows. She believes that pH may be a better indicator of mercury concentration than that of dissolved organic matter. Her results also demonstrated how Black Fly larvae concentrations correlate with dissolved organic matter concentration in