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Birds are potentially vulnerable to the toxicity of certain environmental pollutants due to limited detoxification capabilities of their liver microsomal cytochrome P450 (CYP) enzymes. In wild birds, ethoxyresorufin O-deethylation (EROD) activity, a marker of CYP1A activity in mammals and domestic chickens, has been used as a biomarker of exposure to polychlorinated biphenyls (PCBs), dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs). The aim of the present study was to investigate hepatic CYP activity as an indication of detoxification capacity in New Zealand birds. In addition to the use of conventional in vitro CYP activity assays, the applicability of a noninvasive CYP activity assay was tested using caffeine as the in vivo substrate. The ontogeny of liver microsomal 3-hydroxylation of quinine, a marker of human CYP3A activity, was investigated in Adelie penguins (Pygoscelis adeliae) from Ross Island, Antarctica. The results indicate that chicks (2-4 weeks old) possess a CYP3A-like isoform(s) as active as but not identical to the CYP3A-like isoform(s) in adults. Total CYP content was low at 2 weeks of age and increased rapidly and linearly approaching adult levels by 4 weeks of age implying a rapid development of CYPs other than the CYP3A-like isoform(s). The main study was conducted on adult (and some post-fledging immature) birds of two native species, the herbivorous paradise shelduck (Tadorna variegata) and the omnivorous southern black-backed gull (Larus dominicanus). Birds were shot for liver collection at three sites in the South Island of New Zealand; West Coast, Lake Waipori and Dunedin landfill, in 2001-2002. The results indicate that shelducks posssess multiple CYP isoforms that independently catalyse EROD, p-nitrophenol hydroxylation (p-NP) and erythromycin demethylation (EMD), markers of mammalian CYP1A, CYP2E and CYP3A activity, respectively. In contrast, gulls appear to possess a single isoform catalysing both EROD and p-NP but possess no isoform capable of catalysing EMD. EROD activity was high in shelducks and gulls from the landfill site, although it was not significantly associated with liver concentrations of PCBs (0.079-6.2 and 8.2-310 ng/g in shelducks and gulls, respectively), PCDD/PCDFs, toxic equivalents (TEQs) and dichlorodiphenyldichloroethylene (DDE) (0.85-317 and 44-4800 ng/g in shelducks and gulls, respectively) in either species. In shelduck livers from the landfill site, EROD was positively associated with Pb concentration but negatively associated with Hg concentration. Assessment of PCB congener patterns based on concentration ratios of individual congeners to the reference congener, 2,2�,4,4�,5,5�-hexachlorobiphenyl (IUPAC #153), indicate that the metabolism of 2,4,4�-trichlorobiphenyl (PCB#28) and 2,4,4�,5-tetrachlorobiphenyl (PCB#74) is inducible in shelducks but not in gulls. Hepatic reduced glutathione (GSH) content was higher in gulls than in shelducks suggesting greater resistance to oxidative stress in gulls. The in vivo caffeine metabolism test as a noninvasive method to determine CYP1A activity in shelducks and gulls gave a positive outcome. The test was performed by administration of a single intraperitoneal dose of caffeine (1 mg/kg body weight) followed by blood collection at 2 and 4 h after caffeine administration for determination of the serum concentration ratio of the metabolite, paraxanthine, to caffeine (PX/CA) by HPLC. In both species, the PX/CA ratio was markedly increased by pretreatment with the model CYP1A inducer, β-naphthoflavone (BNF). BNF treatment also increased EROD activity determined after death (80-fold and 20-fold compared to controls in shelducks and gulls, respectively). However, sensitivity of the PX/CA ratio approach was lower in gulls than in shelducks due presumably to the formation of unidentified caffeine metabolites in gulls. Immunoblot analysis failed to reveal increased CYP protein levels caused by BNF treatment in shelducks and gulls due to poor cross-reactivity of avian proteins with polyclonal antibodies raised against mammalian CYPs. EROD activity was also determined in livers of the piscivorous yellow-eyed penguin (Megadyptes antipodes) (1 chick, 3 post-fledging immature, 1 adult) from Otago, South Island of New Zealand, and found to be below the limit of quantitation. The adult liver contained 18.5 ng/g of total PCBs suggesting that EROD in this species is insensitive to induction. Comparison of the PCB congener pattern based on [PCBx]/[PCB#153] between the penguin and its putative source of PCB exposure, New Zealand marine fish, indicates that CYPs in yellow-eyed penguins metabolise 2,2�,5,5�-tetrachlorobiphenyl (PCB#52) and 2,2�,4,5,5�-pentachlorobiphenyl (PCB#101) as in many other avian species. The findings of this study highlight substantial species differences in CYP activity in wild birds. Whether CYP expression in New Zealand birds is genetically distinct from birds in other parts of the world may warrant further investigation.

Bibliography: leaves 217-229 / xvi, 229 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Salinity and eutrophication are regarded as significant threats to freshwater habitats - Addresses issues related to these problems. / Thesis (Ph.D.)--University of Adelaide, Dept. of Botany, 1998?

M.Sc. (Zoology) / The Vaal River system is constantly subjected to pollution from various industrial, mining and agricultural activities. Consequently, pressure is continually exerted on the health of its fish communities and it was suspected that this may be a contributing factor to the repeated fish kills that have occurred in various sections of the river over the past few years. The aim of this study was to assess the health status of three fish species that were affected by the most recent mass fish mortality in the Vaal River. This was done using a combination of techniques including a histology-based health assessment (HHA) that involved a standard fish necropsy, the evaluation of blood parameters as well as a microscopic assessment of the liver, kidney, gills, and gonads. The histological results were semi-quantitatively assessed. Selected chemical substances were also tested for in water, sediment and the skeletal muscle tissue of the fish. Clarias gariepinus, Labeo capensis and Labeo umbratus specimens were collected from the Vaal River, approximately 2480m below the Vaal Dam (Latitude 26°51'17.47"S; Longitude 28° 7'16.58"E) following the latest occurrence of a fish kill in November 2011. Fish were collected using gill nets. Water was sampled in triplicate at three locations, and in situ measurements were done for selected physico-chemical parameters. Sediment samples were also collected and subjected to a sequential extraction technique and quantification of the heavy metals was done using Inductively Coupled Plasma-Mass Spectroscopy (ICP-MS). Metals in skeletal muscle tissue and water were quantified using the same technique. An analysis of variance (ANOVA), followed by the appropriate post-hoc test was performed to determine differences between means of variables i.e. morphometric, histological, substance concentration and blood parameters...

published_or_final_version / Ecology and Biodiversity / Doctoral / Doctor of Philosophy

Gong Jun. / "March 2004." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (p. 254-294) / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

The purpose of this work was to determine if environmentally-relevant concentrations of chlorpyrifos and copper, two commonly detected chemicals in Western surface waters, can negatively impact the biological health of salmonids. Both compounds are highly neurotoxic to fish, but each with distinct biological target sites and mechanisms of action. We used common biochemical and physiological indicators of toxicity, and correlated these effects with potentially significant behavioral alterations. For chlorpyrifos, the mechanism of toxic action is the inhibition of acetylcholinesterase (AChE) throughout the peripheral and central nervous system. Here, we conducted biochemical assays of AChE activity in brain and muscle tissues after exposing steelhead trout (Oncorhynchus mykiss) and coho salmon (0. kisutch) to chlorpyrifos for 96 hours. We then correlated the AChE inhibition with behavioral impairment in swimming and feeding activities. In juvenile steelhead and coho exposed to 0.6-2.5 ��g/L chlorpyrifos, AChE activity was inhibited between ~10-65%. This biochemical indicator was significantly correlated with changes in behavioral patterns. Spontaneous swimming rates were reduced ~30-80% in the exposed fish, and strikes at food items (brine shrimp) were reduced ~10-70%. For copper and some other neurotoxicants, the olfactory nervous system is a sensitive target site in fish. The highly-developed olfactory system in salmonids is particularly susceptible to toxic insult by dissolved chemicals since receptor neurons are in direct contact with the aquatic environment. Here, we used electrophysiological techniques to record odor-evoked responses from the sensory epithelium and the olfactory bulb as direct measures of olfactory function in juvenile coho salmon. In fish exposed to copper, chlorpyrifos, or esfenvalerate for 7 days, field potentials recorded from the sensory epithelium and the olfactory bulb showed reduced or obscured olfactory responses to two classes of odorants, which activate non-overlapping populations of receptor neurons. To determine if this reduced sensory input can subsequently alter or diminish olfactory-mediated predator avoidance behaviors, paired physiological and behavioral tests were conducted on juvenile coho exposed to copper. In fish exposed to 2-20 ��g/L copper for 3 hours, olfactory sensitivity was reduced by ~50-9O%. When these fish were presented with a predatory alarm cue (conspecific skin extract), fish with reduced olfactory function increasingly failed to exhibit antipredator behavior. In the following experiments, we show that chlorpyrifos and copper can impair the biochemical and physiological biology of salmonids at environmentally-relevant concentrations, and that these sublethal effects can alter potentially important behavioral patterns. / Graduation date: 2004

Indo-Pacific humpback dolphin (Sousa chinensis) is one of the residential cetaceans in Hong Kong. It is threatened by different anthropogenic activities and one of the threats is the vessel disturbance. According to the past research studies and scientific data, the heavy marine traffic has caused negative impacts to the dolphins, by increasing the risk of boat collisions; creating a noisy environment within the dolphin habitats; causing short-term behavioural changes of dolphins and dolphins may have potential to displace from the Hong Kong waters in the long-term. The current conservation and mitigation measures are inadequate and ineffective towards this situation. An action plan is formulated based on the literature review of the practices from other countries and the results of the questionnaire survey. Mitigation measures such as speed restriction, re-routing or use of technology tools are common measures used by other countries such as the United States or Spain. From the results of the questionnaire survey, the high-speed ferry passengers were willing to spend 23.5 minutes more of their trips for a speed restriction or a longer ferry route in order to reduce the vessel impacts to the dolphins. At the same time, they were willing to pay for HKD 9.26 extra as a surcharge on the ferry fare to serve as a financial support to the dolphin or marine conservation in Hong Kong. It reflected the public had a high willingness to pay for the dolphin conservation in Hong Kong. The action plan summarized the practical mitigation measures according to these findings in order to suggest sound conservation and management measures to the related authorities to mitigate the impacts and to stop the declining trends of dolphin abundance in Hong Kong waters. / published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

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The research used dendro-chemical analysis of ash tree rings and current year leaf litter to track Cd, Pb, Zn, Cu, Mn, Cr, and Sn spread and cycling from a closed garbage dump-toxic waste site. This technique allowed for determination of areal extent, contaminant levels and time period of initial contaminant contact. Only Zn, Sn, and Cu were found in elevated quantities in the xylem wood and Pb in the leaf litter. Elemental concentrations of Pb, Sn and Cd in xylem wood and leaves of ash were positively correlated. Tin was the only element to demonstrate a clear initial contact period and elemental accumulation with age. Significant levels of Cu accumulated in the heartwood while Zn revealed significant but inconsistent accumulated patterns. Expected attenuation zones associated with municipal solid waste landfill leachate dispersion were not found; thus the pathway for contaminant dispersion was likely through groundwater flow. / An elemental index was developed to facilitate the use of dendro-chemical analysis in periods of suppressed tree growth resulting from environmental pollution.