Co-Investigators:
A. Hontela, Université du Québec à Montréal (UQAM).
Email: hontela.alice@uqam.ca
Tel. 514-987-6800, ext. 6602

J. Rasmussen, McGill University.
Email: jrasmu@bio1.lan.mcgill.ca
Tel. 514-398-6467

This project is designed to test the prediction that relations between metal body burdens in indigenous fish and metal-induced effects at the organism, population and community levels will be improved if the metal body burdens are expressed not as total metal, but rather in terms of the metal=s partitioning within particular target tissues. The key hypothesis to be tested is that there exists a mechanistic link between the intracellular speciation of the metals and the manifestation of deleterious effects at the organism and population levels. The overall objectives are thus (i) to determine whether metal <spillover> (Cd, Cu, Zn) consistently occurs in feral fish under conditions of chronic exposure to high ambient metal concentrations, and (ii) to demonstrate the following linkages: chronic metal exposure 6 metallothionein induction 6 intracellular metal spillover 6 endocrine / physiological impairment 6 population-level effects.

The main study area is centred around Rouyn-Noranda, a region for which we have already collected data relating to the degree of metal exposure in more than 20 lakes. The project involves the sampling of two fish species of differing tropic position, Perca flavescens (yellow perch) and Catostomus commersoni (white sucker), along a metal contamination gradient. The methodology entails the selection of lakes of contrasting degrees of metal contamination (e.g., in the vicinity of the Rouyn-Noranda mining and smelting complex), all of which must possess resident fish populations. Each of these lakes will be characterized (i) from a limnological perspective, to evaluate the habitat quality for fish, (ii) at the geochemical level, to determine the lake=s degree of metal contamination and (iii) in a biochemical context, to detect the incidence of metal <spillover> in the indigenous fish tissue cytosol. At these sites, we intend to characterize the response of the indigenous fish to the contamination gradient, both at the organism level (physiology, growth, endocrine status, reproductive status) and the population level (abundance, population dynamics).

In the startup year (1998-99), to refine our estimates of metal exposure in the potential study lakes, we collected water samples by in situ dialysis from 16 candidate lakes in July and September. The lakes were chosen to represent sites located up- and down-wind from the Horne smelter, along an anticipated metal concentration gradient. The samples were analyzed for total dissolved metal and for the free-metal ion (Cd²⁺, Cu²⁺, Zn²⁺). In addition to the water sampling, yellow perch were collected from a smaller number of lakes (6): two reference lakes (Opasatica, Dasserat), located upwind from the smelter, and four lakes downwind (Osisko, Dufault, Vaudray and Bousquet). Tissue metals and metallothionein levels are currently being measured in homogenates of the liver and interrenal tissues. In addition, method development work is being carried out on the chromatographic determination of subcellular metal partitioning in tissue cytosols. Chloride, glucose as well as cortisol levels were measured in fish from all six lakes, and fish efficiency in converting consumed food into body mass is being evaluated with a method based on ¹³⁷Cs mass balances. Our preliminary findings from these various analyses will be presented and discussed. The number of lakes and fish sampled was relatively small this year but the results suggest that the metal spillover hypothesis can indeed be tested in the Abitibi system.