Protist diversity and community dynamics in High Arctic Canadian lakes


Wednesday June 13, 2012
Redfield Auditorium - 12:00 Noon
Ms. Sophie Charvet
PhD Candidate
Laval University, Quebec City, Canada

The Arctic is warming more rapidly than other regions and the effects on protist communities living in arctic lakes are unknown. We investigated protists by way of microscopy, clone libraries, high throughput tag sequencing and experimental manipulations in three Canadian High Arctic lakes, Char Lake, Ward Hunt Lake and Lake A. Chrysophytes dominated all of the lakes in August 2008. In contrast, the protist communities of early spring in Lake A were dominated by ciliate and dinoflagellate sequences. The exceptional extreme high temperatures recorded in the region during the summer of 2008 caused many High Arctic lakes to lose their perennial ice covers, possibly influencing the communities. We experimentally investigated potential effects of loss of perennial ice cover using microcosms to simulate increased meltwater and irradiance. Our results suggest that mixotrophic chrysophytes use prey as a source of nutrients when limited by inorganic nutrient supply, as is the case in oligotrophic arctic lakes during mid and late summer.