Physical Sciences and Mathematics Commons^™

How Beavers (Castor Canadensis) Affect Habitat Availability For Two Native Oregon Turtles: Actinemys Marmorata And Chrysemys Picta Bellii, Rodé Krige

University Honors Theses

Oregon is home to two native freshwater turtle species: the northwestern pond turtle and the western painted turtle. Both turtles are Oregon conservation strategy species with a status rating of sensitive, indicating declining populations. Oregon’s decline in these turtle’s populations is thought to be predominantly due to loss and degradation of habitat that results from development and urbanization. Beavers’ ability to dam streams and create ponds may be creating habitat usable by turtles, but the relationship is under-studied. This study assessed water temperature, basking habitat, and overall turtle habitat suitability at beaver-dammed and control ponds in Portland, Oregon. Average basking …

Using Biometrics, Behavioral Observations, And Multiple Molecular Techniques To Assess The Impacts Of Changes In Temperature And Salinity On The Common Bay Mussel (Mytilus Trossulus), Casey Martin

Dissertations and Theses

The intertidal zone is a place of rapid and frequent change that is home to a variety of creatures who are essential to the integrity of the habitat. Mussels are robust sessile bivalves that anchor to the rocks of the intertidal. The prominent species on the Oregon Coast, the Common Bay Mussel (Mytilus trossulus), plays an essential role as a coastal food source, water column filter, and barrier to prevent erosion due to wave action. Mytilus trossulus withstands daily shifts in temperature, salinity, and tide, as well as seasonal changes. Global climate change due to excess carbon emissions …

The Influence Of Polystyrene Microplastics On Juvenile Steelhead Trout (Oncorhynchus Mykiss), Kaitlyn Marie Baker

Dissertations and Theses

Mass production of plastic within the past decade has led to over 100 billion tons of plastics being added to the world’s oceans through rivers and effluent disposal and decomposition. For marine environments, the sudden and constant growth of microplastics (plastics 1 µm to 5 mm in diameter), is of particular concern to top-predatory fish such as steelhead trout (Oncorhynchus mykiss), who passively or actively uptake microplastics while consuming prey. Previous research has demonstrated clear detrimental impacts of microplastic accumulation in bivalves, seabirds, and zebrafish, including decreased diet, reproduction rates, and metabolism, as well as increased rates of …

Drivers And Dynamics Of Phytoplankton Communities And Harmful Algal Blooms In Mountain Lakes, Lara Stephanie Jansen

Dissertations and Theses

Harmful cyanobacterial blooms (cyanoHABs) are a complex and widespread disturbance in freshwater water bodies, impacting water quality for wildlife and human populations. While cyanobacteria often bloom in warm lakes impacted by human development like agriculture, blooms are increasingly reported in cooler waters with limited development in the surrounding watershed. As much of cyanoHAB research has focused on lakes in highly developed watersheds, the understanding of factors leading to cyanobacteria dominance and blooms in the absence of major development remains limited. Mountain lakes can serve as ideal systems to study bloom-forming cyanobacteria in watersheds with minimal development. In addition, mountain lakes …

Orthotrichum Lyellii As An Active Moss Biomonitor: Examining The Interplay Between Ambient Pm10, Bulk Deposition And Heavy Metals In An Urban Environment, Scott Bradley Kiel

Dissertations and Theses

The importance of monitoring and preventing pollution in the environment is a globally recognized issue. Of the criteria pollutants outlined by the United States Environmental Protection Agency, particulate matter is among these least understood in relation to toxicity and most wide-spread. Many governments have employed continuous air quality monitoring networks to track ambient levels of particulate matter, but are often too widespread to capture the heterogeneity of the urban environment, especially for heavy metal deposition. In Portland, OR, the epiphytic moss Orthotrichum lyellii was successfully used as a low-cost passive biomonitor to increase the spatial resolution of pollution around the …

Selenium Probes For The Detection Of Thioredoxin Reductase Activity, Tendai Joseph Mafireyi

Dissertations and Theses

The identification and quantification of proteins and enzymatic activity in living tissues frequently requires the use of invasive procedures such as biopsy. These techniques can inhibit measurements of protein levels in real-time, and the disruption of tissue can lead to the loss of important information concerning the spatial distribution and differential activities in various cell types. The use of small organic fluorescent probes that rely on activation or accumulation within a tissue embody robust methods of detection that address these issues. This dissertation describes the design, synthesis and evaluation of fluorescent probes that can detect the enzyme thioredoxin reductase (TrxR). …

Investigating Dose-Dependent, Multi-Generational, And Strain-Specific Effects Of 17Α-Ethynylestradiol Exposure In Zebrafish (Danio Rerio), Decatur Mitochondria Foster

Dissertations and Theses

Endocrine disrupting chemicals (EDCs) pose a threat to biodiversity at the individual, population, and ecosystem level, as they can interfere with processes that are responsible for regulating metabolism, development, behavior, and reproduction in living organisms. 17α-ethynylestradiol (EE2) is a synthetic estrogen and EDC utilized in pharmaceutical and livestock industries, and contaminates waterways worldwide. This research explores the effects of dose-dependent and multi-generational exposure of EE2 in three strains of zebrafish. High dose (10-25 ng/L EE2) exposure led to complete reproductive failure, as well as significantly decreased survival and growth. A period in clean water (depuration) after exposure allowed for some …

Thinking Aloud In The Science Classroom: Can A Literacy Strategy Increase Student Learning In Science?, Lindsey Joan Mockel

Dissertations and Theses

This research study investigated the effect of using the think aloud protocol while reading informational text on students' ability to learn from text in a secondary science classroom. The participants in this study were high school students (n=47) in three classes of a mixed-grade Integrated Biology, Chemistry, and Physics course. The study tracked student achievement during a four-week curriculum unit on the theory of evolution and evidence for biological evolution. All students received instruction on using the think aloud protocol, and all students practiced the think aloud protocol when reading short articles related to scientific evidence for evolution. The researcher …

Interspecific Variation In Leaf-Level Biogenic Emissions Of The Bambuseae, Andrea Natalie Melnychenko

Dissertations and Theses

Plants emit a diverse range of biogenic volatile organic compounds (BVOCs) into the atmosphere, of which isoprene is the most abundantly emitted. Isoprene significantly affects biological and atmospheric processes, but the range of isoprene and BVOCs present in bamboos has not been well characterized. In this thesis I explore the range of isoprene emission found in bamboos and relate it to plant morphological and physiological characteristics. In addition, I measure and relate the entire suite of BVOCs present in the bamboos to their fundamental isoprene emission rate.

Interspecific variation in isoprene emission documented in a comprehensive survey of bamboos. Two …

A Determination Of Parentage, Mating System, And Genetic Diversity In A Captive Population Of The Straw-Colored Fruit Bat (Eidolon Helvum), Jan Zinck

Dissertations and Theses

Small populations tend to lose genetic variability. The magnitude of this loss is influenced by the number of founding individuals, the genetic diversity of the founders, and the species mating system. Genetic variability is the basis of adaptive evolution, and the loss of genetic variability may have harmful effects on development, growth, and survival. Therefore, a primary management goal for small, captive populations is the retention of genetic variability. Of considerable importance to conservation biology is the determination of parentage, from which mating, genetic, and demographic information can be derived. Microsatellites provide a robust molecular evolutionary tool for the study …

Photoadaptation Rate Of Synechococcus Wh7803 Cultures At Two Iron Concentrations, Jon Daniel Moulton

Dissertations and Theses

The marine cyanobacterium Synechococcus WH7803 adapts to changes in light intensity by changing its photosynthetic physiology. This work is a study o f the rate o f photoadaptation of Synechococcus WH7803 in laboratory cultures. Cultures were shifted from constant 8 µEm^-2s^-1 light to constant 80 µEm^-2s^-1 light, from constant 80 µEm^-2s^-1 light to 8 µEm^-2s^-1 light and from different light regimes to a single fluctuating light regime. The response of high iron cultures grown in modified aquil culture medium at 5*10^-6M Fe was compared with the …

Captive Environmental Influences On Behavior In Zoo Drills And Mandrills (Mandrillus), A Threatened Genus Of Primate, Erik Terdal

Dissertations and Theses

Drills (Mandrillus leucophaeus) are an endangered species of African monkey (Cercopithecidae), and their sole congener the mandrill (Mandrillus sphinx) is vulnerable to extinction. Both species are threatened in the wild by deforestation and hunting.

Drills have a poor record of captive reproduction. Many individuals appear to have behavioral deficiencies which interfere with reproduction. Thus, the zoo population of drills does not serve as a “hedge” against the species’ total extinction: drills are endangered in captivity as well as in the wild. Mandrills, by contrast, reproduce well in captivity. Information on the behavior of mandrills in captivity may help zoo managers …

The Combined Effect Of Cu And Zn On Selenastrum Capricornutum, Helmer Colonia-Roque

Dissertations and Theses

It has been demonstrated that the toxicity of heavy metals depends on their chemical speciation and can be related to their free ion activities, rather than the total metal concentrations. The objective of this study was to determine the effect of combined free ions of zinc and copper on the toxicity to the green alga Selenastrum capricornutum. This alga was grown in a defined medium, under controlled laboratory conditions, with a varying range of zinc and copper concentrations. The growth rate of the alga was inhibited at pZn = 5.93 or at pCu = 7.24. The results suggest that …