| Project Title |  |
| Project
C2: Assessing biological effects of chronic metal exposures in fish.
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| Research Team | |
| C. Wood, McMaster
Univ. Email: woodcm@mcmaster.ca Tel: 905-525-9140 Co-Investigators:
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| Project Summary | |
| Contribution to
Ecological Risk Assessment. This project employs laboratory-based studies to
understand and model the chronic impacts of Cu, Cd, and Zn on the health of fish
in the field exposed to these metals either in the water and/or in the diet. Particular
emphasis is placed on the modifying effects of water chemistry (hardness, pH, alkalinity,
DOC, Na+, and Cl-) and of diet (quantity, quality). Our near term goal is the development
of a suite of environmentally relevant biomarkers for the effects of chronic metal
exposures on fish species endemic to metal contaminated environments. Our ultimate goal is
the development of a Biotic Ligand Model (BLM) for chronic toxicity comparable to
the acute BLM which is currently being used to develop a new generation of site-specific,
acute Ambient Water Quality Criteria for metals. In this context, we will conduct a
detailed examination of the chronic sublethal effects of waterborne Cu, Cd, and Zn on the
yellow perch (Perca flavescens), a species endemic to metal impacted lakes of the
Rouyn-Noranda area and elsewhere. The goal here is to bring our level of knowledge on the
perch up to that on the rainbow trout (Oncorhynchus mykiss), a less
environmentally relevant "model" species on which most pathophysiological and
BLM development work has been performed to date. A parallel chronic study on the
trout is currently underway in our laboratory, supported by other funding sources. In the
perch work, particular emphasis will be placed on the relationship(s) between water
chemistry, tissue-specific metal distribution, gill metal binding properties, and
objective measures of fish health. The second major focus is an experimental analysis of
the complex interactions between dietary quantity and quality (specifically NaCl, calcium,
and energy content) and responses of both trout and perch to chronic metal
exposures, in both the water and the diet. This issue is of great relevance in
understanding trophic and bioenergetic responses in the field, but has not been considered
in previous studies. The results will be of practical importance to those in the public
and private sectors who are interested in the biological monitoring of the effects of
toxic metals in the aquatic environment, and to regulators charged with establishing
rational water quality criteria for metals. Links to other projects. This project will link most closely with the field studies of Campbell, Hontela and Rasmussen (Project C.3). Specifically, our co-ordination efforts will consist of the following: At the outset of the project, and periodically thereafter, we will exchange æblindÆ water and tissue samples for QA/QC on metal analyses. As the project evolves, we will also harmonize methods for the measurement of tissue metallothionein levels, subcellular distribution of metals in cytosolic ligand pools, and biochemical and physiological condition. The purpose is to facilitate lab-field comparisons, in particular to tease out specific effects of individual metals from metal-metal interactions and indirect (i.e. trophic level) metal effects. We intend to incorporate field experience (e.g. exposure levels, feeding rates etc) wherever possible in the design of our experiments. We may also be able to offer advice to field workers in the development of new biomarkers, and in refining current biomarkers for exposure (e.g. tissue metal content ratios for assessing waterborne vs. dietary routes of exposure; methodologies for field assessment of swim performance). We also anticipate interaction with the respective field (Hare & Tessier, B.2) and laboratory projects (Borgmann & Dixon, C.1) on the bioaccumulation of metals by aquatic invertebrates. Specifically their work will provide guidance for us on realistic levels of Cd, Cu, and Zn occurring in invertebrate-based diets. Furthermore, there is valuable parallelism between their laboratory experiments (on invertebrates) and our approach (on fish) in looking at waterborne vs. dietary routes of uptake and toxicity. |
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