ROLE OF FOOD-WEB STRUCTURE ON LIPID AND BIOACCUMULATION OF ORGANIC CONTAMINANTS BY LAKE TROUT (SALVELINUS-NAMAYCUSH)

The interacting roles of food web structure and lipid content on bioac cumulation of PCB and DDT in lake trout (Salvelinus namaycush) was eva luated in Ontario inland lakes and Great Lakes. It previously has been reported that longer food chains resulted in greater bioaccumulation of PCBs (Rasmussen et al. 1990. Can. J. Fish. Aquat. Sci. 47: 2030-203 8); however, longer food chains also resulted in increased lipid conte nt, and it is uncertain whether the measured bioaccumulation was attri butable to food chain length or Lipid content. ANCOVA demonstrated tha t both factors are significant. PCB and DDT concentrations were each p roportional to lipid content in all systems but the magnitude of the c oncentrations varied, due to either food chain length or differences i n contaminant loading. It is suggested that the presence of Mysis reli cta is especially important with respect to the observed food web effe cts and as a vector for contaminant transport from contaminated sedime nts. Significant differences between the Great Lakes and inland lakes were identified which largely result from differences in loadings of c ontaminants. The observed significant relationship between concentrati ons of PCBs and DDTs suggests that similar relationships could apply t o other contaminants with similar chemical and bioaccumulative propert ies.