Current evidence suggests that thyroid hormones (THs) may impact development of the immune system. However, studies that explore the role of THs in immune development are limited, and the mechanisms leading to alterations in immune function are poorly understood. It is important to elucidate the role of THs in immune development given that many environmental contaminants have been shown to disrupt TH homeostasis and may also have negative impacts on the immune system. As such, the main goal of this study was to determine the long-term consequences of early life stage (ELS) hypothyroidism on immune function. To achieve this goal, it was first necessary to further characterize basic immune function in the selected model species, the fathead minnow (FHM, Pimephales promelas). Preliminary studies were conducted to describe the transcriptomic response to Yersinia ruckeri and adapt assays for the assessment of respiratory burst and phagocytic cell activity. To determine the long-term effects of ELS hypothyroidism, FHMs were exposed to the model thyroid suppressant propylthiouracil (PTU) from <1 to 30 days post hatch and reared under normal conditions. Upon reaching adulthood, ex vivo immune cell function and the in vivo immune response to Y. ruckeri were assessed. Fish exposed to PTU experienced …

Improving growth, lowering mortality rates, and having a faster turnaround to harvest is essential for the future of commercial aquaculture. The primary goal of this study was to determine if introducing a single strain probiotic Lactobacillus rhamnosus IMC 501 into the feed regimen of a commercially important aquaculture freshwater fish, Mozambique tilapia (Oreochromis mossambicus), would decrease mortality; change metabolic rates; and increase tissue wet mass (MW), standard length, growth rate and feed conversion rate (FCRs). IMC501 was added to the fishmeal in four increasing concentrations and compared to a control without probiotics. Results from two-way ANOVAs showed that both treatment levels and elapsed time had a significant effect on both mean standard length and wet mass; in the latter case, time points and treatments interacted with one another, showing that tilapia grew best with a moderate level of probiotics present. The growth benefits of probiotics continued for months after the initial treatments. Oxygen consumption (metabolic rate) was measured using closed respirometry and resulted in recording the first values for juvenile tilapia treated with probiotics. For oxygen consumption, there were significant treatment and time effects with significant interactions, indicating that metabolism increased with probiotics once the dosage exceeded three times the …

The Magellanic woodpecker (Campephilus magellanicus), the largest woodpecker in Central and South America, is declining throughout its range. Notably, limited research has been conducted on the Campephilus genus, especially for island populations. Mostly during austral summers 2015-2017, I explored the ecological importance and population structure of Magellanic woodpeckers on Navarino Island, Chile (55°04′S, 67°40′W). First, I assessed how coleopteran larval density and distribution within trees may influence Magellanic woodpecker foraging behavior. Second, I designed an experiment to determine which of three detection methods would best elicit a woodpecker detection. Third, I conducted a population genetics study to elucidate trends within and among Magellanic woodpecker populations to better inform management decisions. I identified two coleopteran species: one lucanid (Erichius femoralis) and one cerambycid (Microplophorus magellanicus) within two lenga (Nothofagus pumilio) trees foraged on by Magellanic woodpeckers. Maximum woodpecker excavation depths were 71-90 mm; most larval gallery depths were 51-70 mm. The drumming device most effectively influenced the likelihood of a woodpecker detection. The odds of a woodpecker responding were 2.14 times more likely than responding to either a playback or control. On Navarino Island, I observed a pattern of isolation by distance among sampled woodpeckers, slight female sex-biased dispersal, and family …

The City of Denton, located in a semi-arid region of Texas, has over 200 manmade ponds within its city limits. Many of these ponds, located in densely populated areas, are engineered to control storm water runoff. There is a general lack of recognition of the value these waters contribute to regional biodiversity and as greenspaces. This study, conducted in Denton, is monitoring habitat variables and macroinvertebrate diversity in a series of ponds selected to represent a gradient of urban influences. The objective of this study is to identify the variables associated with the highest diversity. Using drone imagery and a meter square box sampler, the quantitative approach allowed for delineation of three habitat types and area. The macroinvertebrates where identified to the genus level which allowed for higher resolution and resulted in stronger comparisons of the communities and conditions of the ponds. Taxa richness was positively correlated to pond size and trees along shoreline and negatively associated with average depth. Overall, submerged vegetation supported highest diversity and abundance, especially genera of Chironomidae (Diptera). Conductivity was associated with urban influences and the most urban influenced pond had the lowest taxa richness, but also reduced habitat area. Results of this study conclude …