http://hdl.handle.net/1957/17891 Wed, 22 May 2013 02:35:11 GMT 2013-05-22T02:35:11Z http://hdl.handle.net/1957/37548 Response to Hypoxia in the staghorn sculpin, (Leptocottus armatus) Wagner, Sara Anne Long-term subae lal survival has been anecdotally noted in the staghorn sculpin, Leptocottus armatus. In this study, I quantified this phenomenon physiologically by examining the following parameters: standard metabolic rate and indications of reduced standard metabolic rate during subaerial exposure; capacity for and mechanism(s) of oxygen consumption in air; capacity for anaerobic production of lactate and/or ethanol; and blood pH. The staghorn sculpin appears well-suited for the subaerial exposure it experiences in nature. Mean subaerial survival time was 6 hours which would enable fish to survive intertidal stranding. Staghorns breathe air through well-supported gills and supplement depressed rates of subaerial aerobiosis by anaerobic production of lactic acid. Most remarkably, the staghorn sculpin may also substantially reduce minimal energy expenditure requirements during periods of hypoxia by reducing resting metabolic rate. Graduation date: 1991 Fri, 02 Nov 1990 00:00:00 GMT http://hdl.handle.net/1957/37548 1990-11-02T00:00:00Z http://hdl.handle.net/1957/37344 The role of gonadotropin-releasing hormone in the regulation of courtship behavior in the male red-sided garter snake, Thamnophis sirtalis parietalis Smith, Mitchell Todd Graduation date: 1994 Thu, 14 Apr 1994 00:00:00 GMT http://hdl.handle.net/1957/37344 1994-04-14T00:00:00Z http://hdl.handle.net/1957/37322 The symbiotic relationships and morphology of Paravortex sp. nov. (Turbellaria, Rhabdocoelida) a parasite of Macoma nasuta Conrad, 1837 Hanson, Alfred Warren Rhabdocoels of the genus Paravortex are parasites of marine molluscs. The bent-nosed clams, Macoma nasuta(Conrad, 1837) of Yaquina Bay, Lincoln County, Oregon are commonly infected with a new species of Paravortex. The morphology of the adult worm has been described and it has been compared to the other three species of this genus. The percent infection increased as the size of the clams increased. Analysis of the size frequency distribution of the clam population suggests at least two age classes. Incidence of infection was substantially lower in the younger of these two classes. Clams less than 14 mm in length were not infected. Possible reasons for this distribution of the parasite population were discussed. A peak in the percent of infection, in the incidence of multiple infection, and in the abundance of immature worms was found during April, May, and June, 1968. These data suggest a seasonal periodicity in the reproduction of Paravortex sp. nov. A correlation between the sex of the bent-nosed clams and the incidence and degree of infection could not be established. Paravortex sp. nov. was found only in the pericardial cavity of Macoma nasuta. It is postulated that the rhabdocoel enters this cavity from the suprabranchial space by passing through the kidney. Possible methods by which this endoparasitic rhabdocoel obtains food were discussed. Physical damage to the host clam could not be shown to be the result of parasitic infections. Multiple infections of as many as 28 worms did not appear to physically impair the clam. Observations of the morphology and behavior of living worms were made and conclusions were reached concerning the nature of the symbiotic relationship between Paravortex sp. nov. and its host. Examination of collections of Macoma nasuta made in Coos Bay, Oregon, and Puget Sound, Washington,produced no rhabdocoels. Graduation date: 1970 Thu, 11 Dec 1969 00:00:00 GMT http://hdl.handle.net/1957/37322 1969-12-11T00:00:00Z http://hdl.handle.net/1957/37316 An ecological study of Diatomovora amoena, an interstitial acoel flatworm, in an estuarine mudflat on the central coast of Oregon Thum, Alan Bradley The distribution and abundance of the interstitial acoel turbellarian, Diatomovora amoena Kozloff, 1965 was studied in an estuarine intertidal sand flat in Yaquina Bay, Oregon, from May 1970 through May 1971. Monthly measurements of biological (organics, sulfides, chlorophyll, and carotenoids), pore water (salinity, pH,oxygen, and temperature), and sediment (fine sediment percentage, grain size, sorting, skewness, and kurtosis) factors were made along a transect at four intertidal stations with elevations of -2.0, 0.0, 1. 6, and 3.0 feet, stratified by selection from a curve for tidal exposure, and at two depths (0, 0 cm to 0. 5 cm and 0. 5 cm to 1. 0 cm) of the sediment. Estuarine factors that were monitored continuously included temperature, salinity, tide elevation, and insolation. The interrelationships among these environmental parameters, their roles in the interstitial sediment system, and the hydrology of the groundwater in the beach, were investigated in order to characterize the interstitial environment of the sand flat and to determine the environmental factors limiting the distribution and abundance of D. amoena. Seasonality was indicated in most of the factors measured. The sediment system was strongly reducing during summer and fall as organic production increased. Particle size analyses showed that transport and deposition of fine sediments contributed to the development of reducing conditions. The properties of the interstitial environment of D. amoena were found to be controlled by the level of groundwater, rate of percolation, and degree of mixing within the beach. Density of D. amoena was highest during the fall and early winter, and lowest throughout the winter. Summer production of plant material in the lower intertidal lead to reducing conditions at the sediment surface. Reduction in animal density at the lower two stations was attributed to these reducing conditions, and to the rafting of animals away from the intertidal with the algal mat. Decrease in animal density in the upper two stations was attributed to lethal low temperatures and salinities that occurred during heavy precipitation in the winter and coincided with low tidal exposure. Exclusion of animals from depths greater than 0. 5 cm in the sediment was attributed to lethal levels of sulfide. Tolerance of D. amoena to temperature, salinity, and sulfide was determined experimentally. The 25 combinations of temperature and salinity, and the 12 combinations of temperature and sulfide that were employed were selected on the basis of actual levels measured in the study area. The temperature and salinity survival results were fitted to a response surface which was used to evaluate these factors in limiting animal distribution. Survival of acoels was independent of temperature up to 6 hours of exposure, and strongly temperature-dependent after 24 hours of exposure. Initial mortality was attributed to osmotic stress. Upon exposure to sulfide at 50 μgm S/ml, these animals did not survive beyond 6 hours, demonstrating that sulfide in high concentrations is toxic to D. amoena. At lower concentrations of sulfide (10 μgm S/ml), the acoels were able to live for over 20 hours. Lowering the temperature at both concentrations helped to prolong the lives of the animals. Levels of sulfide similar to those used in the experiment Levels of sulfide similar to those used in the experiment (10 μgm S/0.5 cm³ = 50 μgm S/ml.) were found at the sediment surface in the lower two stations during September, at which time animal density was found to be decreasing. At the upper two stations in September, where the level of sulfide was 3 μgm S/0.5 cm³, the acoel population was found to be increasing, thus bearing out the assumption that population density is, indeed, affected by sulfide. The nature of the interstitial sediment system as a habitat for meiofaunal organisms was explored and the role of the groundwater hydrology, as a buffer against seasonal variation in the estuary, in maintaining this system was examined. A portion of the littoral shore considered in this investigation was conceptualized as a factor model, the principal parts of which were selected for study. The seasonal cycles of the major input factors were found to be relatively stable from year to year, while the timing of these cycles varied. The numerous positive and negative correlations that were found within and between the biological, pore water, and sediment groups of factors indicated the multiplicity of direct and indirect interactions and supported the contention that the tidal flat is a complex interrelated system. Change in one or more of the major factors, such as precipitation, river runoff, sedimentation, or tidal prism, can be expected to have diverse effects on the littoral sediment environment. Graduation date: 1972 Fri, 17 Dec 1971 00:00:00 GMT http://hdl.handle.net/1957/37316 1971-12-17T00:00:00Z