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Master of Science (MS) in Biology
Metal pollution in aquatic systems is complicated and expensive to manage; establishing a sentinel species for contaminated habitats, rather than measuring abiotic parameters, can provide a more complete perspective of the impacts of pollutants. I conducted a dual field/laboratory study to determine whether an amphipod (Hyalella azteca) can serve as a sentinel in a mining-impacted area in Northern Idaho, the Coeur d’Alene (CDA) River Basin. My objectives in the field study were to (1) determine seasonal abundance and metal burden of amphipods in nine chain lakes and a reference lake (Benewah L.) and (2) compare aqueous trace metal levels and limnologic parameters from lake water to patterns in amphipod abundance, size, and metal burden. I predicted that aqueous metal concentrations correlate with amphipod abundance and body burden. I found that amphipod abundance differed across the lakes and over time, but patterns in amphipod abundance and size could not be explained by the factors that I measured. The results confirm that the metals are bioavailable and that uptake is influenced by limnological factors. In the laboratory study, I compared the Zn and Pb tolerances of amphipods from three chain lakes to that of amphipods from the reference site (Benewah L.) and from a commercial source. I hypothesized that chain lake amphipods would have higher metal tolerance, indicated by higher survival and swimming activity following a 96-hour exposure. Chain lake amphipods exhibited higher Zn tolerance than did the commercial amphipods but were not consistently more tolerant than were reference lake amphipods. The Zn tolerance of all amphipod populations varied seasonally. Differences in Pb tolerance were difficult to detect, likely reflecting issues with Pb solubility. The activity assay was not sensitive enough to detect among-population differences as swimming was strongly affected by all Zn and Pb doses. Taken together, these results confirm that chain lake amphipods are more tolerant of metals than are the commercially-obtained amphipods that are routinely used for toxicity testing. Hyalella azteca could become a sentinel for this basin, but only if amphipods from a reference lake serve as the (negative) control population and if the amphipods are monitored year-round.
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Higbee, Chantilly S., "CAN AMPHIPODS BE USED TO MONITOR MINING-IMPACTED LAKES?" (2017). EWU Masters Thesis Collection. 461.