Thesis (Ph. D.)--University of Washington, 1996. / Vita. Includes bibliographical references (leaves [294]-305).

Thesis (Ph.D.)--Brigham Young University. Dept. of Biology, 2007. / Includes bibliographical references (p. 31-41).

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Includes bibliographical references (leaves 152-169).

The traditional approach for predicting the risk of hydrophobic organic contaminants in sediment is to relate organic carbon normalized sediment concentrations to body residues or toxic effects in organisms. This method is limited, however due to the plethora of variables that can influence bioavailability. Therefore, a matrix independent method of predicting bioavailability needs to be developed in order to be universally applicable. Solid phase microextraction (SPME) and Tenax are two commonly used bioavailability-based methods. While both SPME fiber and Tenax extractable concentrations can be correlated to tissue residues of aquatic species, the majority of this research (with a few exceptions) focuses on compounds that are not acutely toxic or biotransformed. Less is known about the potential applicability of these methods to predict bioaccumulation, and ultimately toxicity, for highly toxic, rapidly biotransformed compounds, such as pyrethroid insecticides. This class of compounds is of particular concern due to frequent environmental detection in sediments at concentrations lethal to benthic species. This research has four specific goals: Determining exposure conditions that may change the concentration on the SPME fibers at equilibrium (Chapter 2); Comparing the ability of SPME fibers and Tenax to predict the bioavailability of two pyrethroids (permethrin and bifenthrin) (Chapter 3); Developing bioavailability-based toxicity endpoints for bifenthrin using two aquatic species (Chapter 4); and, Validating these techniques using sediments from known contaminated field sites (Chapter 5). Overall this research was focused on comparing and contrasting the ability and applicability of SPME fibers and Tenax to adequately predict the exposure of pyrethroids under varying conditions. While comparing these two methods, they were optimized to better provide accurate predictions of bioavailability and toxicity for pyrethroids from sediments. Regardless of the fiber or animal density examined, the SPME fibers exposure did not significantly affect fiber concentrations for permethrin or DDE. Additionally, bioaccumulation of parent permethrin and bifenthrin was predicted using both SPME fibers and Tenax using 6 or 24 h extraction times. Further, a single regression model predicted bioaccumulation across compounds and species using Tenax extractable concentrations. Once demonstrated that these techniques could predict bioaccumulation, median lethal and effect levels were examined for bifenthrin and as expected the bioavailability-based endpoints were more uniform across sediments than use of whole sediment concentrations. Additionally, the relationships among the two methods were compared across multiple sediments. Despite the SPME fiber's ability to determine toxicity in laboratory sediments, the field validation study determined that lethal levels were often too low to detect on the SPME fibers using current methodologies, but Tenax extractable concentrations correlated to toxicity. Overall, while both methods could predict bioavailability, the limitations of SPME fibers including lower sensitivity, inability to function across compounds, and long equilibration time, made Tenax extraction a preferable method.

Aquatic pollution from urban and industrial effluents represents a growing area of concern. The number and volume of xenobiotic chemicals in aquatic ecosystems is alarmingly high, due in part to increasing globalization and the associated demands. Invertebrates, in particular molluscs, represent species of great commercial importance and can therefore fail to be considered in terms of their significance in the transmission of human disease. Schistosoma mansoni is a trematode parasite transmitted to humans by aquatic snails of the genus Biomphalaria. S.mansoni infects up to 200 million people globally and transmission primarily occurs in developing countries with poor infrastructure, factors which also happen to be associated with high levels of aquatic pollution. Despite the medical importance of S.mansoni and its occurrence in potentially polluted environments, very few attempts have been made to study this parasite-host relationship in the context of ecotoxicology. In this thesis I have applied both adapted and novel approaches in order to combine the fields of parasitology and ecotoxicology toward a better understanding of the effects of globally-prevalent xenobiotic chemicals on the S.mansoni-B.glabrata relationship. In vitro assays, with various end-points, were performed based on exposure of hemocytes, the primary immune effector cells of molluscs, while whole snails were developmentally exposed to an effluent extract and subsequently infected as part of an in vivo study. Taken together, my results suggest that the immunocompetance of B.glabrata hemocytes is broadly reduced in the presence of DDE, BPA, E2 and an effluent extract; chemicals that occur at high levels in transmission countries. Reduction in the key hemocyte functions of motility, phagocytosis and encapsulation, caused by exposure to these chemicals, appears to be exacerbated by subsequent S.mansoni infection which results in an opportunity for increased parasite shedding. My hope is that this broad work will serve as a reference and facilitate more focused studies, particularly of a molecular and epidemiological nature, into what is an understudied and potentially very important topic with the potential for human health implications.

The rewarding properties of drugs in the mammalian system depend on their ability to activate appetitive motivational states. The associated underlying mechanism is strongly conserved in evolution and invertebrates have recently emerged as a powerful new model in addiction research. The natural reward system in crayfish has surprisingly proven sensitive to human drugs of abuse, providing a new model for research into the basic biological mechanisms of drug addiction. In this study, we examined the presence of natural reward systems in crayfish, and then characterized its sensitivity to 2.5 μg/g, 5.0 μg/g and 10.0 μg/g doses of methamphetamine (METH). Using the conditioned place preference (CPP) paradigm, we demonstrated that irrespective of the number of doses of METH injected into the pericardial system, crayfish seek out a particular tactile environment that had previously been paired with the METH. This study demonstrates that crayfish offer a comparative and complementary approach in addiction research. It contributes an evolutionary context to our understanding of a key component in learning and of natural reward as an important life-sustaining process.

Sea urchins are an ecologically important species that can drastically alter marine communities due to their consumption and destruction of macroalgal beds (e.g. kelp forests). These beds form highly productive ecosystems that provide shelter and nursery habitat for many benthic and pelagic species. When their populations explode, due to a lack of predators and/or various environmental conditions, sea urchins can overgraze and decimate macroalgal beds. This creates areas called sea urchin barrens, which is a problem seen around the world. Sea urchin aquaculture is a method to remove these over-populated sea urchins from the environment, feed them either a prepared or macroalgal diet for approximately 12-weeks to produce a marketable roe product in a process termed roe or gonad enhancement. Two feeding trials were conducted on two species of sea urchins that are native to the waters off Vancouver Island, British Columbia, Canada: the green (Strongylocentrotus droebachiensis) and red (Mesocentrotus franciscanus) sea urchin. There were nine treatments per feeding trial, where three diets (two prepared diets; V10.1.9 and V10.1.10, and one natural bull kelp (Nereocystis luetkeana) diet and three different temperatures (8, 12, and 16oC; which are temperatures commonly found in the waters around Vancouver Island) were examined to assess the feasibility of a sea urchin gonad enhancement operation with these species and diets. Overall, green sea urchins fed V10.1.9 at 8 and 12°C produced the highest gonad yields (mean ± SE: 29.4 ± 1.1% and 29.4 ± 1.5%, respectively) while V10.1.9 at 12°C also had the highest gonad yield increase per week (mean ± SE: 2.2 ± 0.2%) and the lowest FCR-G (mean ± SE: 1.0E-2 ± 9.0E-4 feed g gonad increase g-1). Green sea urchins fed V10.1.10 at 12°C, however, produced the most preferred gonad taste, gonad yields still above market minimum (mean ± SE: 25.6 ± 1.5%), and the third lowest FCR (mean ± SE: 1.5E-2 ± 1.9E-3 feed g gonad increase g-1), while urchins fed V10.1.10 at 16°C had the best colour (mean degree of colour difference ± SE: 6.0 ± 0.9). Therefore, it can be suggested that optimal conditions moving forward for green sea urchins would be feeding V10.1.10 at 12°C. For red sea urchins, those fed V10.1.10 produced the highest gonad yields at 12°C (mean ± SE: 12.7 ± 1.5%) and the best colour at 16°C (mean degree of colour difference ± SE: 30.3 ± 3.1), while red sea urchins fed V10.1.9 at 16°C produced the second highest gonad yields (mean ± SE: 11.0 ± 0.4%), the lowest FCR-G (1.9E-3 ± 2.8E-4 feed g gonad increase g-1), the most preferred gonad taste, and a low degree of colour difference (mean ± SE: 32.3 ± 2.1). Therefore, it can be suggested that optimal conditions moving forward for red sea urchins would be feeding V10.1.9 at 16°C. / Graduate

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学位プログラム名: 京都大学大学院思修館 / 京都大学 / 0048 / 新制・課程博士 / 博士(総合学術) / 甲第22610号 / 総総博第10号 / 新制||総総||2(附属図書館) / 京都大学大学院総合生存学館総合生存学専攻 / (主査)教授 山敷 庸亮, 准教授 趙 亮, 准教授 竹門 康弘 / 学位規則第4条第1項該当 / Doctor of Philosophy / Kyoto University / DFAM