Research on natural environments, over the last decade, is replete with microbial diversity studies that used culture-independent approaches. The cloning and sequencing of the 16S rRNA genes has been the driving force in the expansion of awareness about the great diversity of previously undiscovered microorganisms. Well-known uncultured groups of microorganisms...
Pre-spawning mortality (PSM) presents a major problem for population recovery of spring Chinook salmon (Oncorhynchus tshawytscha) in the Willamette River basin. In certain reaches and years, PSM has exceeded 90%. Histology has been used as the primary diagnostic method to investigate PSM in the Chinook Salmon, and a collection of...
Chlorpyrifos (CPF) is a widely used broad-spectrum organophosphate insecticide. Following exposures, CPF and its more toxic oxon metabolite (CPFO) elicit neurotoxic effects by inhibiting the activity of the acetylcholinesterase enzyme (AChE), resulting in altered fitness and death at high doses. Following exposure, organisms bioactivate CPF to CPFO through the Cytochrome...
The short-term duration of most ecological studies can make it difficult to capture the long-term dynamics of ecosystems and populations. Infrequent or high-impact events can be missed, or erroneously documented as baselines. Long-term ecological research enables a deeper understanding of complex processes, provides a foundation for future insights, and can...
Year-round habitat use of marine predators provides knowledge of important marine areas throughout different life stages. Large-scale, environmental variability, both in space and time, causes changes in the behavior and distribution of marine predators that are important to quantify for conservation. In the Northern California Current System (NCCS), common murres...
The mouth of the Columbia River (MCR) is an intersection of more than a river and ocean, but also multiple economically valuable activities including dredging to maintain a deep draft shipping channel and an active Dungeness crab (Metacarcinus magister) fishery. More than three million cubic meters of sediment are annually...
Studies indicate that many cancers occur more frequently in adult males than females. This male predominance must either be due to disparate environmental exposures or innate, biologic mechanisms, or a combination of the two. Using data and statistical software from the Surveillance, Epidemiology, and End Results (SEER) Program, male:female incidence...
This study examined the effects of stage of preoperational thought, sex and mode of exploration on preschoolers ability to represent a small-scale model configuration of objects. Forty-eight subjects between the ages of 2 years, 5 months and 5 years, 4 months were classed in spatial conceptualization as either Stage I...
The objectives of this thesis were to examine the links between soil microbial community composition and function using the nitrogen (N) cycle as a model for these interactions and to assess the impact of environmental factors such as microclimate, vegetation type, and nutrient availability on microbial diversity and N transformations...
The microbial loop plays a crucial role in remineralization of organic matter and fuels recycled production in the aquatic environment. The capability of microbes to utilize particular compounds can be examined through their ectoenzyme (found outside the cell) activities using fluorogenic substrate analogs. These catalysts hydrolyze polymers otherwise too large...