Through winter, Pacific sand lance (Ammodytes personatus) experience dormancy and declining body condition. Natural mortality from starvation can occur if their condition falls below a physiological “threshold of survival”. To quantify that minimum threshold, we gathered fish at two life stages – juveniles from beaches and adults from offshore subtidal sites in the San Juan Islands of the Salish Sea. Fish were held in separate tanks by life stage. To verify that these environments resembled natural habitats, we compared data from in-situ sampling conducted in 2018 and 2019 to tank observations from the same years. Juveniles declined in condition at the same rate in tanks and in-situ; adults did not. To characterize the threshold, we took condition measurements on fish that died naturally. Mortalities occurred when fish reached a consistent minimum condition, regardless of when the death occurred in the overwintering season. Condition at mortality differed significantly between life stages. Adults died in better condition, though this may indicate that condition metrics do not appropriately account for expected shifts in condition across life stage. We generated probability of mortality curves for juveniles and adults to calculate the likelihood that an individual would reach mortality, given a particular condition factor (K). The threshold of survival was defined as the condition at which fish have a 50% probability of mortality. Juveniles had a threshold condition factor of 16.8; for adults, it was 20. This threshold likely exists for other fishes and may be an important consideration for fisheries management. Juvenile fish are disproportionately affected by winter mortality. Variable mortality could have large effects on abundance and year class strength. Since mortality rates differ by life stage and based on environmental conditions, consideration of similar mortality curves and oceanographic conditions might inform estimates of overwinter mortality and annual projections of stock status and dynamics.

Nitrogen is a vital nutrient for plants, but excess nitrogen fertilizer has negative environmental impacts. Understanding the dynamics of how nitrogen moves through plant systems is thus scientifically and environmentally relevant. One aspect of nitrogen cycles is nitrogen fixing bacteria, or diazotrophs. Diazotrophic endophytes are such bacteria that live inside plant tissues. As part of the EndoPop project, our group is studying the effect of diazotrophic endophytes in poplar plants under nitrogen limited conditions. In these experiments, fertilizer with high or low nitrogen concentration is supplied to plants with and without endophytes, however, the dynamics of nitrogen in the pot-plant system are not well characterized. To gain a deeper understanding of the endophyte effect, it is vital to understand the nitrogen dynamics within the pot-plant system to see how endophytes alter these dynamics. A mechanistic mathematical model can provide insight into the underlying mechanisms of the system. To address this, I developed and implemented a compartmental model for nitrogen dynamics in a potted plant system, incorporating water balance, growth, and fertigation regimen as factors in the model. Additionally, endophytes are added to the model to address the change that endophytes would induce on nitrogen dynamics. The model is validated with growth and nitrogen content data from greenhouse experiments on the effect of endophytes on poplar plants under high and low nitrogen conditions. Potential insights from the model include characterizing nitrogen dynamics in the pot-plant system, which will be informative in setting up future experiments, and separating how the effect of endophytes on nitrogen dynamics contribute to the overall endophyte effect in poplar.

The field of plant microbiology has recently seen large developments in the understanding and appreciation of the internal plant microbiome. The microbes living within plants, termed endophytes, have been shown to play a vital role in many aspects of plant growth and development. These roles include nitrogen fixation, nutrient acquisition, tolerance to external stressors (such as heat or water deficit), auxin production, detoxification of harmful chemicals, and plant defense. Many of these plant growth promoting bacteria (PGPB) can be cultured and then used to inoculate new plants in order to boost these plants' health and success. However, in the course of inoculating plants with a consortium of these PGPBs, it has been found that there are inadequate and unequal levels of microbe colonization, leading to lower than expected plant health benefits. Our research has aimed to identify the causes of this poor colonization and rectify them. Strains were first grown individually and in mixed pools to identify any inhibitory relations between microbe strains, especially of key strains. My partner and I then inoculated sterile poplar (Populus sp.), with single strain inoculations, 4 two strain teams, and 2 consortiums. After poplar were allowed to grow, we tested for strain presence by plating shoot and root tissue extracts onto media and comparing to previous examples of strain growth. We then re-isolated strains in the consortiums to determine individual strain presence. Through our research, we discovered a key strain was inhibited in the old consortium and may be epiphytic rather than endophytic. We expect to see more specific interactions between strains through our two strain and consortium inoculations. Additionally, we have seen correlations between plant morphology and colonization, and expect to see more. Once complete, our results will be used to design a new consortium.

Mobile genes are commonly found in bacteria, and they are capable of being transferred between unrelated bacterial cells via a process termed horizontal gene transfer (HGT). Mobile genes that undergo HGT can evolve in various “host” bacteria and thereby evolve in several different genomic backgrounds. In a recent publication, my lab constructed a mathematical model to assess the effects of HGT (i.e “host-switching”) on mobile gene evolution. I have built upon this work by probing additional factors that may influence mobile gene evolution. In phase one of my project, I compared the original evolutionary model used in the publication to a newly expanded, more ecologically realistic model in which growth rates of the bacteria depend on resource availability. To compare the models, I ran simulations with both models on a set of bacterial-host pairs and compared the resulting evolutionary outcomes from both models. I found that the categorical effect of HGT occurring (i.e. HGT confers a higher, lower, or neutral change in host fitness) was the same across both models, indicating that ecological factors are less predictive of mobile gene evolutionary outcomes. For the second phase of my experiment, I assessed the effect of variable HGT rate on mobile gene evolutionary outcomes. I ran simulations using a set of bacterial host-pairs while varying the HGT rate along a biologically relevant range, and found a positive correlation between HGT rate and the magnitude of positive fitness effects conferred by a mobile gene that has undergone HGT. This indicates that HGT rates play an important role in governing the evolutionary outcomes of mobile genes. Using evolutionary simulations has allowed us to gain insight into the predictive factors governing mobile gene evolution and thereby mobile gene-containing bacterial evolution. This is especially important, as many genes conferring antibiotic resistance are mobile.

The northeastern quadrant of Washington State is an area of vast public lands. It includes 2-3 National Forests, three State Forests, three Indian Reservations, five Wildlife Areas, and 28 Sno-Parks that contain a wide variety of recreational amenities, including kayaking, rafting, horseback riding, snowshoeing, skiing, camping, and backpacking, among others. This area is also part of the Okanogan Dry Forest and Canadian Rockies Mountains ecoregions, which are characterized by dense coniferous forests that are easily ignitable. As a result, the region is regularly impacted by devastating wildfires, which are accompanied by heavy smoke and pose significant threats to local air quality, small town economies, and natural resources. The purpose of this project is to understand how smoke and fire impact two important resources serving tourists in the area: outdoor recreational amenities, and the production of apples and wine. To investigate these impacts, I reviewed data on recent fires that caused damage to orchard and vineyard land, tribal land, recreational land, and private real estate, looking at the cost of this damage in terms of lives and property lost and the particular impacts of smoke hazards. This data was augmented with interviews of local real estate agents, business owners, and members of the Washington State Department of Natural Resources. The final results I'm expecting from this research is on how recreational amenties are impacted by mega-fires that causes devestating damage towards the forest, recreation amenties, local tribes, people lives,property, public health and the community. By doing this reserch it help me get better understanding how we should managed fire on recreational areas in the Okanogan Highlands area by following proper fire suppression tactics and resources. The results of this project help us better understand the growing effects of fire and smoke on this region in general, and on recreational and tourist activity in particular.

While Tropical Storm Harold struck off the coast of Corpus Cristi, the Texas State Legislature ratified a bill effectively making their state a fossil fuel sanctuary. Scientists agree that the Deep South is one of the most vulnerable regions in the United States to climate change and the rise in climate-caused disasters. Why is it that despite being the most vulnerable region, the Deep South continues to offer pushback against climate mitigation? This research project attempts to understand the psychological components that induce preferences to policy. In the past, researchers have primarily focused on the economic lobbying power of Big Oil and Coal industries within jurisdictions. Utilizing rational choice theory, this project evaluates this puzzle from the perspective of voter preferences in response to economic reliance on the fossil fuel industry. The fossil fuel industry proves vitally important to local communities, providing jobs and resources. Using multivariate regression, I examine the effect of employment in the fossil fuel industry and reliance on nonrenewable energy within 467 different counties across the Deep South and other states. I weigh these results against possible other factors including partisanship, age, race, and vulnerability to observe if economic reliance accurately characterizes the misalignment observed within the Deep South. Based on previous literature and rational choice theory, I hypothesize that in counties economically dependent on the fossil fuel industry there will be less support for climate change legislation. Policy implications of this research include securing resources for communities threatened by a transition to renewable energy sources.