Worldwide, estuaries are under increasing pressure from numerous contaminants. There is a need to develop reliable bioassay methodologies to assess the effects of these stressors on estuary health. This thesis aimed to develop and validate toxicity tests in a New Zealand marine harpacticoid copepod species for use in monitoring and evaluating the effects of estuarine pollution. A survey and toxicological assessment of a range of native copepod species resulted in the selection of Quinquelaophonte sp. as the ideal bioassay species. This selection was based on a broad regional distribution, ease of culture and high reproductive rate in the laboratory, sexual dimorphism, and sensitivity to contaminants. To validate the bioassay, spiked sediments were used to expose Quinquelaophonte sp. to three reference compounds representing important categories of estuarine chemical stressors: zinc (a metal), atrazine (a pesticide), and phenanthrene (a polyaromatic hydrocarbon). A method for spiking sediments that Quinquelaophonte sp. inhabit was developed to ensure even contaminant distribution in sediments. Two sediment bioassays using lethal and sublethal endpoints were validated, one acute (96 h) and one chronic (14 d). These assays incorporated both lethal and sublethal endpoints, which included reproductive output and mobility. Acute-to-chronic ratios were calculated for use in environmental risk assessment and to provide insight into the mode of action of the reference contaminants. The chronic sediment bioassay was used to assess sediment quality in three estuaries across New Zealand: Napier, Christchurch and Invercargill. This validated the bioassay for use with naturally-contaminated field sediments with varying mixtures of pollutants and sediment types (coarse sandy to fine silty organic rich sediments). Quinquelaophonte sp. was also tested to assess whether it can be used to characterise multi–generation impacts. After four generations of exposure to zinc, there were changes in acute sensitivity, indicating this species possesses mechanisms for acclimating or adapting to toxic stressors. Sediment bioassays in Quinquelaophonte sp. were successfully developed and validated, offering significant promise as a tool for monitoring effects of pollution in New Zealand estuaries.

This research examined the toxicity of complex industrial effluents as measured by chemical analyses, whole effluent toxicity (WET) tests and surveys of the receiving water biota. Toxicity of final effluents from 45 diverse facilities was examined to determine whether inferred toxicity based on presence and concentration of priority substances could predict WET, calculated from a battery of bioassays on bacteria, cladocerans and algae. Following corrections of inferred toxicity for particle-bound contaminants and adjustment for free ion activity, correlation between inferred and whole effluent toxicity was highly significant. Effluents with elevated metal concentrations exhibited lower WET than predicted, likely due to negative interactions among trace metals; kraft mill effluents exhibited higher WET than predicted which is consistent with findings in the literature. / The ability of laboratory WET tests to predict thresholds of invertebrate community response to a complex industrial effluent was examined. Patterns in invertebrate community structure were detrended for environmental factors and compared to measured instream effluent concentrations. Laboratory effect thresholds, reported as Maximum Allowable Toxicant Concentrations (MATC), were calculated from a battery of toxicity tests on bacteria, algae, cladocerans and fish. Declines in taxonomic richness corresponded to calculated lab thresholds, while changes in abundance of total taxa and sensitive taxa, (Ephemeroptera, Plecoptera, Trichoptera) occurred at lower concentrations than predicted from MATCs. The tendency for invertebrate abundance to decline at lower instream effluent concentrations than richness supports findings in the literature. Lack of correspondence between lab and field thresholds may be ameliorated by the addition of behavior endpoints, (e.g. avoidance) to toxicity tests.

Along with an increasing understanding of the harmful effects on the environment of a wide range of pollutants has come the need for more sensitive, faster and less expensive detection methods of identification and quantitation. Many environmental pollutants occur in low levels and often in complex matrices thus analysis can be difficult, time consuming and costly. Because of the availability and easy cultivation of the microorganisms with potentially high specificity, there is considerable interest in the use of living microorganisms as the analytical component (the biocomponent) of sensors for pollutants. While a number of biosensors using bacteria have been developed, yeast has been comparatively rarely used as the biocomponent. Yeast are attractive because they are easy to culture and they are eukaryotes which means their biochemistry is in many respects closer to that of higher organisms. This thesis describes the development of whole cell bioassays that use yeast cells as a sensing element and redox mediators to probe the intracellular redox reactions to monitor the catabolic activity of the yeast resulting from the external substrate, steady-state voltammetry is utilised as the electrochemical detection technique. The isogenic differential enzyme analysis (IDEA) concept of Lincoln Ventures Limited, lead NERF funded research consortium uses bacteria that have been cultured using specific organic pollutants as the carbon source which are the biocomponent in sensors. The use of wild type yeast Arxula adeninivorans that has the ability to use a very wide variety of substrates as sources of carbon and nitrogen was used as an alternative to bacteria to validate the “IDEA” concept. Naphthalene and di-butyl phthalate were chosen as model target contaminant molecules. The performance, detection limits and the usefulness of yeast based biosensor applications for environmental analysis are discussed. This thesis also describes the development and optimisation of a simple, cost effective in vivo estrogens bioassay for the detection of estrogens using either genetically modified or a wild type yeast Saccharomyces cerevisiae. In this study, catabolic repression by glucose was exploited to achieve specificity to estrogens in complex environmental samples that eliminates the requirement for conventional sample preparation. This is the first time that the use of wild type yeast to quantify estrogens has been reported. The attractive features of the bioassay are its use of a non-GMO organism, its speed, its high specificity and sensitivity with a detection limit of 10-15 M. The similarity of binding affinities for major estrogens to those of human estrogens receptors makes this in vivo estrogen bioassay very useful for analytical/screening procedures. The electrochemical detection method also makes it easy to interface with a variety of electronic devices.

Zugl.: Berlin, Freie Univ., Diss., 2005 / Dateiformat: zip, Dateien im PDF-Format. - Erscheinungsjahr an der Haupttitelstelle: 2005

Thesis (M. Ag. Sc.)--University of Adelaide Department of Plant Physiology, 1968. / Includes bibliographical references.

Thesis (M.S.)--Ohio University, March, 2004. / Includes bibliographical references (p. 62-67).

Stuttgart, Univ., Diss., 2003.

Thesis (doctoral)--Universität Konstanz, 2005.

Thesis (M.S.)--Ohio University, March, 2004. / Title from PDF t.p. Includes bibliographical references (p. 62-67)

Thesis (M. Sc.)--University of Hong Kong, 2006.