A standard methodology was developed for performing avoidance-preference tests, using Rainbow Trout (Salmo gairdneri) as the test organism. Experiments were conducted in a hydraulic channel, 9.15 m long by 0.30 m wide, partly divided along its length, and at a flow depth of 0.30 m. The design combined steep and shallow gradient characteristics. The toxicants investigated included Cu(II), Cr(III) and Cr(VI). The lowest avoidance threshold values were established at 2.1 $ mu$g/l for Cu(II) and 0.0026 mg/l and 0.026 mg/l for Cr(III) and Cr(VI) respectively while avoidance reactions increased with levels of toxicant in the channel. Similar experiments were performed with rainbow trout which were pre-exposed at sublethal levels to the toxicant, in order to assess the influence of toxic pre-exposure to the subsequent fish avoidance response. The length of pre-exposure varied between 7-20 weeks. Avoidance threshold values were correlated with safe levels of toxicant exposure. / Pre-exposed fish exhibited decreasing avoidance reactions compared to non-exposed populations. Increased tolerance to the toxicant, was suggested by the increase in avoidance threshold values with pre-exposure levels. Fish exposed to test concentrations matching their pre-exposure levels, clearly preferred this same concentration over the adjacent lower or higher test concentration. / A two mechanism avoidance model was proposed independent of toxicant used or level of pre-exposure. The toxicant concentration where the second mechanism begins to dominate was referred to as avoidance breakpoint, and was correlated to a MATC level for the toxicant in question. Olfactory responses were proposed to be associated with fish avoidance responses below the avoidance breakpoint, while hypoxic stress along with osmo- and iono regulatory stress appeared to be responsible for driving fish avoidance reactions beyond the avoidance breakpoint. / A clearance period of 7 days was sufficient to allow fish to recover normal avoidance behaviour following pre-exposure to Cr(VI) below the avoidance breakpoint.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.75767 |
| Date | January 1988 |
| Creators | Anestis, Ioannis D. |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Civil Engineering and Applied Mechanics.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 000665126, proquestno: AAINL46147, Theses scanned by UMI/ProQuest. |
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