Browsing by Author "Hassell, K"

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    Effect of short-term dietary exposure on metal assimilation and metallothionein induction in the estuarine fish Pseudogobius sp.
    (Elsevier, 2021-06-10) McDonald, S; Hassell, K; Cresswell, T
    Metals introduced into the urban aquatic environment through anthropogenic activities have the potential to accumulate in organisms via multiple uptake routes. Understanding the impact different routes have on metal accumulation is important for the continued management of these ecosystems, where current water quality guidelines (WQGs) tend to be derived from aqueous metal exposure tests. In this study, the estuarine fish Pseudogobius sp. was exposed to a mixture of cadmium (Cd) and zinc (Zn) radiotracers dissolved in water or present in experimental food. Metal-spiked food was presented to fish as a single ‘pulse-chase’ feed or as three consecutive feeds, where the cumulative metal dose provided by both treatments was equal. Fish did not accumulate either metal from water, even after the length of exposure was increased from 12 h to 36 h. Fish did accumulate metals from diet and the assimilation efficiency (AE) was low following a single feed (12% for both Cd and Zn). Following multiple feeds fish displayed a significantly higher AE for zinc only, suggesting that fish are susceptible to retention of dietary Zn over an extended time period albeit at lower daily loadings. The final body burden and efflux rate did not differ between feeding regimes. Tissue accumulation of Cd and Zn indicated metal specific distribution. The gastro-intestinal (GI) tract contained >90% of total Cd body burden, whilst the carcass accounted for the majority (70–88%) of Zn body burden. There was significant induction of the biomarker metallothionein (MT) in the GI tract. These results demonstrate the differences in Cd and Zn metal uptake characteristics in this estuarine fish species, and how feeding frequency and metal loading of food may influence assimilation. This study highlights the importance of considering the inclusion of dietary exposures in WQG frameworks. ©2021 Elsevier B.V
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    Experimental design and statistical analysis in aquatic live animal radiotracing studies: a systematic review
    (Taylor & Francis, 2021-03-18) McDonald, S; Cresswell, T; Hassell, K; Keough, MJ
    Live animal gamma radioisotope tracing enables the monitoring of real-time contaminant uptake and retention in individual animals. It has been employed by ecotoxicologists to understand how animals respond to a variety of aquatic stressors. The use of the technique increases the complexity of the experimental design, resulting in the production of highly detailed and robust longitudinal data of individual animals. The greater complexity of the statistical models that underpin this data create risks from data being treated incorrectly. A systematic review of the literature was undertaken to comprehensively evaluate the experimental design and statistical approaches employed by current aquatic live animal radiotracing studies. The experimental design of current studies was categorized into one of five design “families”. Each experimental design could be described by at least one statistical model, which in turn informs a specific statistical approach. Collectively, 7% of studies provided insufficient information to determine the experimental design used, and 24% of studies undertook no formal statistical analysis of results. When the statistical approaches used in current studies were examined, in most cases the correct approach was undertaken, with only 18% of studies using a statistical approach that did not match the chosen experimental design. This review provides clear guidance on the analysis and interpretation of data collected from each experimental design and explains the advantages and disadvantages of each. Additionally, this paper identifies four key suggestions for future researchers, and provides commentary on the ethical, logistical and cost considerations associated with undertaking experiments that use live animal radiotracing. © 2021 Taylor & Francis Group.