Physical Sciences and Mathematics Commons^™

Effects Of Zostera Marina Roots And Leaf Detritus On The Concentration And Distribution Of Pore-Water Sulfide In Marine Sediments, Alexandra G. (Alexandra Garcia) Simpson

WWU Graduate School Collection

Sulfide toxicity is implicated in seagrass declines worldwide. Studies examining the relationship between seagrass presence and sulfide concentrations have yielded conflicting results. Interpretation of the seagrass-sulfide relationship is complicated due to the opposing effects of the root system which can increase sulfide oxidation and the burial of organic matter from the plant itself which can increase sulfide production. To quantify the impact of eelgrass leaf detritus and the Zostera marina rhizosphere on pore-water sulfide concentrations, field samples of pore-water sulfide were collected in areas with and without eelgrass. To decouple the effects of live versus dead eelgrass tissue, laboratory studies …

Microzooplankton Grazing, Growth And Gross Growth Efficiency Are Affected By Pco2 Induced Changes In Phytoplankton Biology, Kelly Still

WWU Graduate School Collection

Accumulating evidence shows that ocean acidification (OA) alters surface ocean chemistry and, in turn, affects aspects of phytoplankton biology. However, very little research has been done to determine if OA-induced changes to phytoplankton morphology, physiology and biochemistry may indirectly affect microzooplankton, the primary consumers of phytoplankton. This is one of the first studies to explore how OA may indirectly affect microzooplankton ingestion, population growth and gross growth efficiency (GGE). I hypothesized 1) that the physiology, biochemistry and morphology of the phytoplankton Rhodomonas sp. would be directly affected by elevated pCO₂ and 2) that pCO₂-induced changes in Rhodomonas …

Fine-Scale Topoclimate Modeling And Climatic Treeline Prediction Of Great Basin Bristlecone Pine (Pinus Longaeva) In The American Southwest, Jamis M. Bruening

WWU Graduate School Collection

Great Basin bristlecone pine (Pinus longaeva) and foxtail pine (Pinus balfouriana) are valuable paleoclimate resources due to the climatic sensitivity of their annually-resolved rings. Recent treeline research has shown that growing season temperatures limit tree growth at and just below the upper treeline. In the Great Basin, the presence of precisely dated remnant wood above modern treeline shows that this ecotone shifts at centennial timescales tracking long-term changes in climate; in some areas during the Holocene climatic optimum treeline was 100 meters higher than at present. Such phenomena has motivated this analysis; regional treeline position models built exclusively from climate …

Cluster Analysis As A Means Of Examining Topographically-Mediated Bristlecone Pine (Pinus Longaeva) Growth In The American Southwest, Tyler J. Tran

WWU Graduate School Collection

Tree-ring analysis can provide information about the surrounding environment of trees, as ring widths often reflect the variability of the factors that limit their growth. Great Basin bristlecone pine (Pinus longaeva D. K. Bailey) provides crucial tree-ring data to understand paleoclimate, but the growth signals can be difficult to interpret. The bristle- cone record could present a potentially confounding narrative because of its mixed growth signals; in many cases, not all trees at one site are limited by the same environmental variable. Trees that are sensitive to patterns in temperature tend to grow in the alpine upper treeline ecotone, and …

Predicting Risk To Estuary Water Quality And Patterns Of Benthic Environmental Dna In Queensland, Australia Using Bayesian Networks, Scarlett E. Graham

WWU Graduate School Collection

Predictive modeling can inform natural resource management by demonstrating stressor-response pathways and quantifying the effects on selected endpoints. This study develops a risk assessment model using the Bayesian network-relative risk model (BN-RRM) approach, and, for the first time, incorporates eukaryote environmental DNA data as a measure of benthic community structure into an ecological risk assessment context. Environmental DNA sampling is a relatively new technique for biodiversity measurements that involves extracting DNA from environmental samples, sequencing a region of the 18s rDNA gene, and matching the sequences to organisms. Using a network of probability distributions, the BN-RRM model predicts risk to …

The Effect Of High-Intensity Visible Light On The Bloom Niches Of The Phototrophic Dinoflagellates Alexandrium Fundyense And Heterocapsa Rotundata, Elizabeth C. (Elizabeth Colleen) Cooney

WWU Graduate School Collection

Photosynthetic bloom-forming dinoflagellates heavily influence coastal ecosystems worldwide. Many of these protist algae bloom in surface waters during summer when light intensities are highest. Despite its likely role as a top-down regulator of bloom formation, the consequences of high-intensity sunlight exposure on cells are not well understood. This study sought to reveal the effect of high light exposure on cells, keeping in mind the potential consequences for bloom-formation. The suite of conditions under which a species is best adapted to bloom is referred to here as its “bloom niche”. To investigate, I measured physiological changes deemed relevant to bloom health …

Spatial Variability Of Snow Chemistry Of High Altitude Glaciers In The Peruvian Andes, Lindsay K. Wallis

WWU Graduate School Collection

Atmospheric contaminants become incorporated in glaciers through both wet and dry deposition. Some of this particulate matter can act as a source of contamination to glacial streams, leading to a concern for the chemical contamination to cause downstream toxicity to aquatic organisms and toxicity to people ingesting that water. Other portions of this particulate matter, including black carbon, can decrease the amount of light reflected off the snow, thereby contributing to increased rates of glacial melting. These issues are especially of concern to tropical glaciers, which are receding rapidly and are relied on heavily to provide drinking water in the …

Teaching Environmental/Stem College Access Curriculum In Two Western Washington Title I Elementary Schools, Wendelin Dunlap

WWU Graduate School Collection

This study attempts to answer the question: What are the best methods for designing Environmental/STEM College Access Curriculum for Title I Classrooms? Participants were 98 5^th-grade classes at two Title I schools. The treatment was 15 hours of College Access Curriculum: 7 hours occurred at the North Cascades Institute’s Mountain School, eight hours in the students’ regular classrooms. The curriculum was taught by Western Washington University students trained as coaches. Data were gathered from elementary students (pre- and post-program surveys, retrospective questionnaire and open-ended question), coaches (essays and teacher evaluations) and teachers (feedback form).

Data gathered from elementary …