The study of biological invasions is important to management and conservation. I assessed the occurrence of invasive mammals and native mesocarnivores in northern Patagonia. Invasive species had varying responses to anthropogenic disturbance, and were differentially influenced by environmental and anthropogenic factors. Invasive species were also a substantial part of native mesocarnivores diets and appeared to influence their temporal activity, but not occupancy. Overall, I observed high spatial and temporal overlap between native carnivores and coexistence seemed facilitated by diet. Humans had both a positive and negative influence in this community, being responsible for the introduction of invasive species and possibly further facilitating their expansion, while also limiting other invasive species and potentially benefiting native species directly and indirectly. Undoubtedly, biological invasions, anthropogenic disturbance, and native communities can present complex interactions which will require further study to provide effective tools for protected areas.

This thesis investigates the optimal ex-ante mix of self-protection and self-insurance technologies employed to reduce the risk of biological invaders in the presence of exogenous variables within the probability and damage functions. This is accomplished by using a theoretical endogenous risk model that extends previously developed frameworks. This thesis contributes to the previous work in two ways. (1) Employing a general framework with simultaneous decision making over self-protection and self-insurance, this thesis analyzes how each parameter including income, the costs of each activity, an exogenous factor that affects only the probability of an invasion, and a separate exogenous factor that affects only the damages influence the level of self-protection and self-insurance. (2) The comparative static results are derived in the benchmark case of risk neutral preferences and qualitatively compared to an extended case of risk averse preferences. The results of the analysis indicate that under risk neutral preferences the signs of the comparative statics are unambiguous while under risk aversion the results are not clearly defined. Thus, the ambiguity of signs in the latter case can be attributed to the unobservable utility terms present under risk averse preferences. Therefore, it can be concluded that the model is not capable of yielding a decision criteria that will hold universally because the results are dependent on the nature of the risk averse curve

Knowledge about the spatial dynamics of invasive species is essential to predict, restrict, and prevent their spread to new areas. Invasive Silver Carp (Hypophthalmichthys molitrix) populations are expanding on all fronts and are threatening to establish in the Laurentian Great Lakes. Understanding their movement patterns is vital to prevent their populations from spreading further and to improve management efficiency. This study looked at multiple factors to understand which have an influence on the movement of invasive Silver Carp in two different river systems. Chapter 1 examined the relationship between individual and environmental factors—including length, body condition, temperature, and discharge—and movement in invasive Silver Carp in the Illinois River. Several different movement metrics were examined—including range, upstream and downstream distance per detection, upstream and downstream movement rate, and total movement—to see if they were affected by any of these factors. Chapter 2 examined multiple morphological metrics—including geometric morphometrics, total length, caudal peduncle depth, and caudal fin aspect ratio—related to the movement of Silver Carp in the Wabash River to see if Silver Carp with similar movement have similar morphology. For both chapters, acoustic telemetry was used to track the movement of Silver Carp. For analysis, multiple generalized linear models were used. For Chapter 1, temperature and discharge were the most commonly included predictors across movement metrics. For Chapter 2, no morphological metrics were identified as predictors of movement. Quantifying the effects of individual and environmental factors can aid in the control and containment of this invasive species and may help to manage populations in at-risk environments. This study demonstrated that factors, like temperature and discharge, can be used to determine when individuals are more likely to expand the invasion front of Silver Carp in the Illinois and Wabash rivers. Which specific individuals are the largest threat to the invasion front can be predicted by individual factors like length, but not body shape.

This study examined relationships between simulated logging disturbances and growth and spread rates of roadside cogongrass patches into adjacent forest stands. Effects of varying levels of imazapyr and surfactant were evaluated to assess cogongrass control. Determination of the optimal cogongrass treatment regime along with the monetary impacts of cogongrass on Land Expectation Values (LEV) are analyzed and discussed. Growth and spread rates of roadside cogongrass plots one growing season after simulated logging disturbance were significantly higher than undisturbed control plots. Rhizome biomass and level of disturbance were primary causal factors. Arsenal AC at 3.5 oz, Accord Concentrate at 14.7 oz, and 11.8 oz of surfactant applied in a volume of 35 gallons per acre provided higher levels of cogongrass control (76%) two years after treatment. The monetary cost of cogongrass was $69 per acre in after tax LEV with assumption of no decreases in seedling mortality or growth and yield.

Accurately examining animal endocrine profiles pose unique challenges due to possible human interaction influencing basal values. Standard methods of gathering information about an animal’s endocrine status are often dependent upon restraint and use of invasive methodologies. However to accurately monitor the influence management practices, blood sampling sometimes requires that hormone measurements be observed from animals in a relaxed state. To this end, methods for non-invasive monitoring (NIM) are greatly needed to obtain basal endocrine measurements. Such methods include fecal collections followed by hormone extraction, and remote sampling technologies for obtaining blood samples without handling. The overall objective of this study was to use NIM techniques to effectively collect and monitor hormone profiles from domestic and non-domestic species in an effort to more completely understand stress responses and reproductive cyclicity in animals in which handling may not be possible or desired.

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<p> Photodynamic therapy (PDn is an effective treatment option for various types of invasive tumors, the efficacy of which depends strongly on selective cell uptake and selective excitation of the tumor, which relies on proper dosage. The characterization of the fluorescence lifetimes of photosensitizers localized inside living cells may provide the basis for further investigation of in vitro PDT dosage measurements using time-domain spectroscopy and imaging. In this thesis, the fluorescence lifetimes of localized Photofrin ® and delta-aminolevulinic acid (ALA) induced protoporphyrin IX (PpiX) were investigated in living MAT-LyLu (MLL) rat prostate adenocarcinoma cells. Cells were incubated with the photosensitizers, and then treated with light under well-oxygenated conditions using a two-photon fluorescence lifetime imaging microscope (FLIM). Fluorescence lifetime images of these cells were recorded with average lifetimes of 5.5 ± 1.2 ns for Photofrin and 6.3 ± 1.2 ns for ALA-induced PpiX over 600 to 750 nm. Two channel FLIM revealed lifetimes of7.8 ± 0.5 ns for Photofrin® and 10.8 ± 1.7 ns for PpiX over 620 to 645 nm, while photoproducts observed on the second channel yielded lifetimes of 5.1 ± 0.4 ns over 650 to 670 nm for Photofrin® and 6.3 ± 1.0 ns over 670 to 690 nm for PpiX. Fluorescence lifetimes of both photosensitizers were found to be significantly shorter when localized in cells than when measured in solutions, suggesting that photosensitizers' lifetimes go through significant changes when bonded to intracellular components. These changes in lifetime also provide opportunities to quantitatively measure and monitor the binding states of the photosensitizers and their microenvironment, which may be used in real-time PDT dosimetry, as well as for diagnostic purposes. </p> / Thesis / Master of Applied Science (MASc)

The Ohio River Basin, including the Ohio, Cumberland, and Tennessee rivers, and the contiguous Tennessee - Tombigbee Waterway are under threat due to the ongoing invasion of bigheaded carps. In the Tennessee River, bigheaded carps were first documented in Kentucky Lake in 2004. I tested whether there were differences in abundance of Gizzard Shad, a competitor, before and after the bigheaded carps invasion, but no effects were detected. I also surveyed bigheaded carps colonization of Bay Springs Lake in the Tennessee - Tombigbee Waterway. Catch rates with gillnets were low and conformed with those documented elsewhere in the Ohio Basin considering distance from the Mississippi River.

Invasive Silver Carp (Hypophthalmichthys molitrix) have spread throughout the Mississippi River basin and threaten native species. The Lower Mississippi Alluvial Valley has numerous water-control structures. These structures could potentially be operated to limit expansions of invasive fishes. My goal was to examine the effects of two water-control structures on movements of Silver Carp within a floodplain network of waterbodies, including an oxbow lake (Eagle Lake; LA, MS). I monitored Silver Carp movements with an acoustic array and bi-monthly active tracking. No movements occurred through the structure managed to deter carp while nine carp passed through the structure that is not managed to limit carp movements. The passages happened when i) the structure was opened, ii) hydraulic head was near zero, and iii) when Silver Carp are reportedly staging and spawning. Ultimately, my findings could help managers tailor operations of similar water infrastructure to slow the spread of invasive species.

Symbiotic relationships display plasticity through time, depending on a variety of factors that include host properties, symbiont densities, and environmental conditions. Invasive species can affect symbiotic relationships by introducing invasive symbionts, reducing the population of native symbionts, or competing for native symbionts as a resource. There is an established symbiotic relationship between crayfish and annelid worms in the order Branchiobdellida. Branchiobdellidan worms can have a mutualistic cleaning symbiosis with crayfish, or at times become parasitic and feed on crayfish gill tissue if nutrients on the host are low. With the introduction of invasive crayfish in the Southern Appalachians in Virginia, branchiobdellidan worm populations have sharply declined due to invasive crayfish being less competent hosts for the symbionts. However, degree of competency as a host may differ among invasive species to, as invasive hosts have their own unique context-dependent symbiotic relationships. To investigate how symbiotic relationships differ between invasive hosts, I encouraged symbiotic relationships between invasive hosts Faxonius virilis and Faxonius cristavarius and native symbionts Cambarincola ingens. In two experiments spanning several months, I observed changes in growth rates of hosts and damage to gill tissues over varying levels of symbiont exposure. One species of invasive host, F. cristavarius, had increased growth rates when exposed to native symbionts at low symbiont densities, while for the other invasive host, F. virilis, growth rates and gill chamber damage was not impacted by the presence of symbionts. I also compared an invasive host F. cristavarius to a native host Cambarus appalachiensis to measure the response of growth rate, symbiont damage to gills, and behavior of worms across a gradient of symbiont exposure. The native host's growth rates increased over time, but not due to an effect of symbionts. However, the invasive host exhibited effects from parasitism when symbiont densities were high. My findings suggest that invasive hosts can have their own unique context-dependent relationship with native symbionts. Because there is no one-size-fits-all rule for invasive hosts, when invasive hosts enter a region, new symbiotic relationships can be formed that are beneficial for invasive hosts and native symbionts. Invasive hosts or native symbionts could also be rejected by the other which may lead to decreases in either of their populations. / Master of Science / Symbiotic relationships are relationships between two or more organisms lasting for long periods of time and are often associated with proximity or touch. In symbiotic relationships there can be a host and a symbiote. The difference between the host and symbiont can be found in their roles such as protection from predators or parasites or by providing nutrients or transportation and the difference in size with the host being larger. Symbiotic relationships are not static and can change over time due to a variety of reasons, such as host size, symbiont abundance, or nutrient availability. The introduction of harmful non-native species, otherwise known as invasive species, can disrupt symbiotic relationships across ecosystems. Invasive species can introduce non-native symbionts, and also can become potential hosts for native symbionts. The relationship between crayfish and Branchiobdellidan worms, an order of small, segmented worms, has been established over decades of research as a useful system for studying symbiosis. Branchiobdellidan worms can provide a beneficial cleaning service by removing harmful symbionts or bacteria from their crayfish host. Alternatively, they can become parasites and feed on crayfish gills if nutrients are not available on the host. Introduced invasive crayfish can decrease the population of brachiobdellidan worms within the Southern Appalachians in Virginia. However, an established relationship between native symbionts and invasive crayfish hosts has not been studied. To investigate the effects of a symbiotic relationship over the time span of several months between invasive hosts and native symbionts, I experimentally reduced the ability of invasive hosts to remove branchiobdellidan symbionts to allow native branchiobdellidan worms time to acclimate on to invasive crayfish and establish a symbiotic relationship. In two experiments over several months, I recorded changes in host growth rates and gill damage. Invasive hosts had an increased growth rate when there was a low abundance of worms. I also compared an invasive host to a native host to see how changes in growth rates, gill chamber damage, and locations of worms on their host may differ. The native host's growth rates increased, but the invasive host had a negative growth rate when worm densities were too high. My findings suggest invasive hosts can have their own unique symbiotic relationship with native symbionts. When invasive hosts are introduced to a region, native symbiont populations may either decrease or native symbionts may find compatible invasive hosts. By examining relationships between native symbionts and invasive hosts, we can understand how invasions may influence symbiotic relationships and how other organisms are affected in the ecosystem.