Myxobolus cerebralis, a myxozoan parasite of salmonids, is the causative agent of whirling disease. The parasite is considered widespread throughout northeastern Oregon in the Grande Ronde and Imnaha River basins where threatened and endangered salmonid populations exist. The work presented in this thesis comprises several studies that assess the effects of M. cerebralis on resident and anadromous salmonids in Oregon. Laboratory challenges to determine the susceptibility of indigenous Deschutes River, Oregon, salmonids to M. cerebralis were conducted as part of a study to assess the risk of reintroducing anadromous salmon above a migration barrier on that river. This study was the first to assess the susceptibility of kokanee salmon Oncorhynchus nerka to M. cerebralis, and results contribute to the understanding of salmonid susceptibility as it relates to species and age. Further, this study demonstrates that the indigenous salmonids present in the river are susceptible to infection, but resident rainbow trout Oncorhynchus mykiss would be most at risk should introduction of M. cerebralis occur in this system. The susceptibility of chinook salmon Oncorhynchus tshawytscha to M. cerebralis was assessed following laboratory challenges at different ages to different parasite levels. Results from this study indicate that chinook salmon are more resistant to M. cerebralis infection than susceptible rainbow trout; resistance to disease developed in chinook salmon exposed after 3 weeks of age. Sustained exposures to a low parasite dose were performed to model the conditions chinook salmon would encounter in a natural exposure. Following continuous exposure to low parasite densities, chinook salmon were very resistant to infection and disease. Managed populations of chinook salmon and steelhead Oncorhynchus mykiss juveniles are held in acclimation facilities on their natal streams before release to commence their seaward migration. Rainbow trout fry were held at each of the acclimation facilities to detect the presence of M. cerebralis and to assess the prevalence of exposure during the acclimation period. Results from these exposures indicate that the Wallowa acclimation facility is a high-risk site for parasite exposure of steelhead juveniles. Further, detection was confirmed in several rivers and streams where the presence of M. cerebralis has been suggested. Finally, a preliminary study on the effect of M. cerebralis on survival of steelhead juveniles upon transfer to saltwater was conducted. Results from this study indicate that M. cerebralis exposure and infection may increase mortality among juvenile steelhead during saltwater adaptation. / Graduation date: 2003

The species composition, temporal and spatial distribution of siphonophores in relation to hydrographic variables in the waters off eastern Taiwan were examined during the period from May 2000 to July 2001. In total, 54 siphonophoran species belonging to 21 genera and 6 families were identified, with the mean abundance of 284 ¡Ó 18 inds. /1000m3. The numerical abundance of siphonophores showed an apparent seasonal change, higher in autumn and lower in winter and summer. The six most dominant species were Chelophyes contorta, Abylopsis tetragona, Bassia bassensis, A. eschscholtz, Eudoxoides mitra and Diphyes chamissonisi, and together they contributed to 75.1 % of the numerical total of siphonophores. The mean abundance, but not for species number, of siphonophores was significantly higher in Kuroshio waters than in coastal waters. Most siphonophores found in this study were belonged to the widespread oceanic species, and the dominant species composition was similar to those in the northern South China Sea. The dominant siphonophoran species exhibited apparent seasonal succession. Different dominant species, as well as their ratio of sexual and asexual generations, showed different seasonal distribution patterns. The total abundance of siphonophores was not significantly correlated to water temperature and salinity. The abundance of the six most dominant species showed different correlations with water temperature and salinity. The abundance of C. contorta showed significant positive correlation with water temperature, but negative correlation with water salinity. The abundance of B. bassensis showed significant negative correlation with water temperature, but positive correlation with water salinity. The abundance of E. mitra showed significant negative correlation with water salinity. The others were not significantly correlated to water temperature and salinity.

Thesis (Ph. D.)--Columbia University. / Vita. Published also as Studies in history, economics and public law, v. 14, no. 3. Includes bibliographical references.

Inaug.-diss.--Breslau. / At head of title: Mittlere und neuere Geschichte. Lebenslauf. "Literaturverzeichnis": p. 6-10.

Inaug.-diss.-Berlin. / Lebenslauf. "Nur ein Teil der gesamten Dissertation, nämlich das VI. Kapitel aus dem II. Hauptteil." -verso of t.p. "Quellen-und literaturverzeichnis zum vorliegenden Teildruck": p. 68-70.

Thèse-Université de Toulouse.

Thesis (Ph. D.)--Columbia University, 1931. / Vita. Published also as Studies in history, economics and public law, edited by the Faculty of political science of Columbia university, no. 349. Includes bibliographical references (p. 559-565).

Thesis--Münster, 1975. / At head of title: Geschichte. Vita. Includes bibliographical references (p. 197-253).

These--Ankara. / Bibliyografya: p. [145]-148.

Thesis--Göttingen. / Lebenslauf. Bibliography: p. xiii-xix.