The main objective of this study was to investigate small-bodied fish caging as an approach to evaluate selenium (Se) bioaccumulation and speciation in native fish species inhabiting lakes influenced by uranium (U) milling effluent in northern Saskatchewan, Canada. In contaminated environments freshwater fish show a high propensity to accumulate Se beyond levels needed for normal physiological function. Maternal transfer of elevated Se concentrations to offspring can cause deformities and reduced survival in fry, and in certain cases negatively impact the sustainability of native fish populations. This research included a caging validation study using wild, naïve (i.e., collected from a reference lake) lake chub (Couesius plumbeus) and spottail shiner (Notropis hudsonius), and three field based 21-day caging studies to investigate the dominance of the feeding pathway with respect to Se uptake and speciation in wild populations of northern small-bodied fish exposed to a gradient of Se. Three feeding regimes were used: an in situ benthic diet, a basal Se diet of Chironomus dilutus (1.5 µg Se/g dry weight) and a Se-spiked diet of C. dilutus (5.5 µg Se/g dry weight). Lake chub were identified as more suitable candidates for caging due to higher survival and condition factor at the completion of the in situ 21-day trial. The resulting Se bioaccumulation was compared among treatments as well as to wild small-bodied fish populations from the study area. Results from the caging experiments showed that caged lake chub exposed to natural and controlled diets with elevated Se had significantly greater whole-body Se concentrations after 21 days compared to fish caged in the reference lake. The results also showed that whole-body Se concentrations exceeded conservative Se thresholds, and approached the currently proposed USEPA regulatory threshold (7.91 µg/g dry weight) designed to protect fish species in only three weeks. The use of stable carbon (C), nitrogen (N), and sulphur (S) isotope ratios indicated that alternate benthic food sources native to the exposure lake were consumed in conjunction with the controlled diets. Stable isotope analysis of both wild and caged lake chub indicated that the N and S isotopic signatures decreased with increasing Se exposure, representing differences in isotopic signatures of the food sources. Speciation results from caged lake chub indicated that Se substituted for S in methionine (i.e. selenomethionine) was the dominant Se species found in caged lake chub exposed to dietary sources of elevated Se. Overall, this research demonstrates that using caged native lake chub represents a useful biomonitoring approach to investigate patterns of Se bioaccumulation and speciation in fish.
| Identifer | oai:union.ndltd.org:USASK/oai:usask.ca:etd-06282011-232436 |
| Date | 28 July 2011 |
| Creators | Phibbs, James Robert |
| Contributors | Janz, David, Pietrock, Michael, Liber, Karsten, Davies, John-Mark |
| Publisher | University of Saskatchewan |
| Source Sets | University of Saskatchewan Library |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://library.usask.ca/theses/available/etd-06282011-232436/ |
| Rights | restricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Saskatchewan or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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