MP9 Metals and Bioaccumulation
Monday, 14 November 2005: 8:00 AM - 5:30 PM in Exhibit Hall

(YAN-1117-805640) Food web impacts on bioaccumulation in walleye.

Yanch, L.E.¹, Hodson, P.V.¹, Campbell, L.M.¹, ¹ Queen's University, Kingston, Ontario, Canada

ABSTRACT- After decades of exposure to industrial pollutants, sediments along depositional zones at the St. Lawrence River waterfront at Cornwall, Ontario are highly contaminated with mercury (Hg). Specifically, the popular sport-fish species, walleye Sander vitreus and yellow perch Perca flavescens, are significantly more contaminated relative to other top consumer fish from other sites. Hg concentrations in walleye, standardized to 45 cm, in Lake St. Francis (downstream from Cornwall) between 1998 and 2000 were 0.59 g/g w.w; exceeding the Ministry of Environment guideline of 0.45 g/g w.w. Preliminary evidence using stable nitrogen and carbon isotope analysis indicates that differences in trophic chain lengt leading to yellow perch, among zones do not exist, so food chain length variation cannot explain the differential in Hg concentrations in yellow perch from different zones within the St. Lawrence River. Stomach content analyses indicate that yellow perch are highly selective and proportions of dietary items found in stomach samples do not reflect actual proportions of the same items in the field. In other words, prey selection, but not food chain length, may be an important factor in explaining variation in Hg burdens in yellow perch. Since walleye have been found to be more contaminated than yellow perch, it is important to determine the influence of trophic food chain length and dietary selection on Hg bioaccumulation. Presently, we are investigating the bioaccumulation of methyl-Hg transferred through the aquatic food chain to walleye. Fish stomach content identification and analysis, as well as trophic level assignment through the use of stable nitrogen and carbon isotope analysis will be used.

Key words: Hg, bioaccumulation, walleye