TA7 Bioaccumulation and Kinetics of POPs
201 Oregon Ballroom
8:00 AM - 12:00 PM, Tuesday
() PCB bioaccumulation in Lake Superior and other lake trout lakes: phytoplankton composition may explain lake to lake variation.
Muir, D.1, Whittle, D.2, Kidd, K.3, Drouillard, K.4, Haffner, D. 4, Kling, H.5, Guildford, S.6, DeVault, D.7, Bronte, C.8, Swackhamer, D.9, 1 National Water Research Institute, Burlington, ON, Canada2 Fisheries and Oceans, Burlington, ON, Canada3 Fisheries and Oceans, Winnipeg, MB, Canada4 University of Windsor, Windsor, ON, Canada5 Freshwater Institute, Winnipeg, MB, Canada6 University of Waterloo, Waterloo, ON, Canada7 US Fish and Wildlife Service, Fort Snelling, MN, USA8 U. S. Geological Survey, Ashland, WI, USA9 University of Minnesota, Minneapolis, MN, USA
ABSTRACT- Variability among lakes in the concentrations of persistent organic pollutants (POPs) in lake trout (Salvelinus namaycush) has been attributed to food chain composition and lake trophic status as well as to age and lipid content of the fish. To examine this issue in more detail we sampled lake trout as well as pelagic food web organisms in western Lake Superior and Siskiwit Lake (Isle Royale) in 1998, and 4 lakes in northwestern and 2 in central Ontario in 1999-2000. Samples were analysed for PCB congeners as well as stable isotope ratios of C and N. Atmospheric inputs are known to be the dominant sources of PCBs to these lakes and these are similar throughout the study area. Thus if physical and biological characteristics of the lakes were not important we might expect similar concentrations of OCs in lake trout from Lake Superior and in nearby inland lakes. However, total PCB concentrations in lake trout from Lake Superior (N=95) were 4 to 7 times higher than in Lakes Eva, Opeongo, Paguchi, Sandy Beach, Simcoe, and Thunder, and 1.5-fold higher than in Siskiwit Lake (Isle Royale). Lake trout growth rates were lower in Superior and Siskiwit compared to the other lakes, however, this did not entirely explain the elevated PCB concentrations in Superior. Trophic magnification factors for PCB 153 did not differ significantly among lakes indicating similar rates of accumulation of recalcitrant PCB congeners in pelagic food webs. The proportion of the algae Peridineae was 3-6x higher in Superior than in the other lakes. These heterotrophic algae consume bacteria by phagotrophy and, where present, may thus introduce an extra trophic level in the pelagic food web. The results suggest that phytoplankton composition may be a significant factor for explaining differences in levels of OCs between Superior and other nearby lakes.
Key words: bioaccumulation , PCB, lake trout, phytoplankton