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Norman Yan

[photopress:yan.jpg,thumb,alignright]Pure & Applied Science

Associate Professor
Department of Biology, Faculty of Pure & Applied Science
Lumbers Building, 212B
115 Ottawa Road
Tel: 416-736-2100 x22936 (voicemail)

Research Interests

Because so many of our ecosystems have been historically damaged, Professor Yan is attempting to identify the key factors that regulate the recovery of lakes from historical damage. He is using acid and metal damage in his model, with work conducted in and around Sudbury, Ontario. Given their similar acid rain history, several Scandinavian colleagues are collaborating with Professor Yan in this research. There are many challenging and interesting complexities in the ecological recovery process and a simple return to the pre-damaged state should not be anticipated.

Professor Yan is also attempting to determine the influence of exotic species – the second largest global source of biodiversity loss – on Ontario's lakes. Several Eurasian invertebrates have recently invaded the Great Lakes and are now spreading inland. He is quantifying the effects of one key invader, the Eurasian spiny water flea Bythotrephes, on aquatic ecosystem function in Ontario's inland lakes.

He is also exploring the influence of climatic change on the zooplankton of Shield lakes, working with provincial government colleagues who have generated some of the finest long-term zooplankton data sets in existence.

Finally, Professor Yan is exploring the interactive impacts of multiple environmental stresses on Ontario's inland lakes. For example, his team is assembling evidence that the joint effects of climate change and acidification cannot be predicted from an examination of the individual impacts of these two stressors. They are also beginning to recognize linkages between contaminant partitioning and the introduction of exotic species.

Much of his field work is executed in partnerships with Ontario government scientists at their laboratories near Dorset and Sudbury, and his students. These locations are ideal for imnological research because of the diversity of nearby lakes and the excellence of baseline data and ongoing data collections. He has been awarded a CFI grant to construct a laboratory designed for research on impacts of multiple ecological stressors on zooplankton. This facility should be completed at the Dorset site in 2003, and it will greatly enhance his team's research capabilities.

Selected Publications

Holt, C.A. and N.D. Yan  2003. "Recovery of zooplankton communities from acidification in Killarney Park, Ontario, 1972–2000: pH 6 as a recovery goal," Ambio in press.

Yan, N.D., B. Leung, W. Keller, S. E. Arnott, J. M. Gunn, and G.G. Raddum. 2003. "Developing a conceptual framework for the recovery of aquatic biota from acidification: a zooplankton example," Ambio in press.

Arnott, S.E., N.D. Yan, W. (Bill) Keller and K. Nicholls. 2001. "The influence of drought-induced acidification on the recovery of plankton in Swan Lake," Ecol. Applicat. 11: 747–763.

Yan, N.D., A. Perez-Fuentetaja, C.W. Ramcharan, D.J. McQueen, E. Demers and J.A. Rusak. 2001, "Changes in the crustacean zooplankton communities of Mouse and Ranger Lakes – Part 6 of the Dorset food web piscivore manipulation project," Archiv Hydrobiol, Spec. Issues Advanc. Limnol. 56: 127–150.

Yan, N.D. and T.W. Pawson. 1997. "Changes in the crustacean zooplankton community of Harp Lake, Canada, following invasion by Bythotrephes cederstroemi," Freshwater Biol. 37: 409–425.


Canadian ecosystems are currently challenged by many local, regional and global environmental stressors including the introduction of exotic species, climatic change and stratospheric ozone depletion. Professor Yan's long-term interest is quantifying the effects of these and other man-made stressors on the life in Canadian Shield lakes, particularly on their animal plankton, or zooplankton. Zooplankton are good target organisms for such work because of their diverse life styles, ecological responsiveness, and ease of sampling.

Over the years Professor Yan has have quantified the impacts of many different stressors on zooplankton, including acid rain, trace metals, UV radiation, excessive nutrient loading, protozoan parasites, exotic invaders, and vertebrate and invertebrate predators. Recently he has begun to explore the interactive impacts of these stressors, and to explore the factors that regulate recovery of damaged ecosystems once the stressors are removed. To do this he uses a variety of research approaches, including whole-lake manipulation experiments, laboratory bioassays, bioenergetic modeling, and large-scale and long-term ecological surveillance. This methodological mix reflects his enjoyment of collaborative research, and his emphasis on sound field work. Professor Yan's broad research focus also reflects his desire to provide information of significance to both ecologists and to lake managers.