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Traditional herbicide formulations such as Roundup® contain the active ingredient glyphosate paired with the non-ionic surfactant polyethoxylated tallow amine (POEA). The impacts of POEA in aquatic environments are uncertain. In this study the environmental fate and effects of POEA was evaluated. A mesocosm field study confirmed that POEA dissipated rapidly from the water, but was persisted in the sediment; biological effects were negligible. In the laboratory, histological analysis of gills did not indicate negative effects on gill function in Pimephales promelas exposed to POEA. Proliferation of mucous cells in gills was significantly greater following 7 days of exposure. Liver histology appeared normal following exposures. Mean thiobarbituric reactive substances (TBARS) doubled in minnow livers exposed to 10 µg.L-1 POEA for 7 days; however was not statistically significant. The present study indicates that POEA may persist in sediment and may influence benthic communities over the long term. / May 2016

Fathead minnows (Pimephales promelas) were exposed to mercury (1.69, 6.79, and 13. 57 µg/l HgCl2; 10 d exposure) and afterwards tested using various metrics of foraging ability while feeding in a vegetated habitat. Among the foraging metrics were foraging efficiency, capture speed, and the ability to learn and retain information regarding habitat characteristics. Comparisons with control fish and fish from the two highest exposure groups revealed consistent performance deficits in foraging efficiency and capture speed. However, no treatment effects on learning were detected. In determining the underlying proximate cause of the foraging deficits, it is believed that the greater pause time exhibited by treatment fish while foraging was the main cause of treatment differences. In the future, behavioral studies will continue to allow toxicity testing of environmentally relevant variables such as those used by behavioral ecologists. Such tests, when combined with tests of field collected specimens, could prove powerful in linking laboratory toxicity to toxicity in wild populations. / Master of Science

The presence of many human pharmaceuticals in the aquatic environment is now a worldwide concern and yet little is known of the chronic effects that these bioactive substances may be having on aquatic organisms. This study used mammalian pharmacodynamics to predict the mode of action of the 13-blocker, propranolol, on fish, in order to identify chronic effects in fathead minnows. β-blockers target β1- and β2-adrenergic receptors in humans and hence these receptors were characterised in the fathead minnow. It was found that fish possess β1- and β2-ARs that are structurally very similar to their mammalian counterparts. Further, the distributions of these two β-ARs in various organs of the fathead minnow were similar to those in mammals. Pair-breeding assays were conducted, in which fathead minnows were exposed to various concentrations of propranolol. To discover whether β-ARs had been up or down regulated by propranolol, molecular analysis was conducted on different tissues of the exposed fish using real-time polymerase-chain reactions (RT-PCR). Exposure of fathead minnows to propranolol caused acute toxicity at 10 mg/L. Propranolol caused a statistically significant decrease in reproduction at 1.0 mg/L, dose-related decreases in male weight, condition index and fatpad weight, and a dose-related increase in female GSI. Molecular analysis of βl- and β2-AR expression levels revealed a dose-related decrease in β2-AR expression in fathead liver and heart. LOEC and NOEC values were 0.1 mg/L and 0.01 mg/L, respectively. Propranolol plasma concentrations in fish exposed to water concentrations of 0.1 and 1.0 mg/L were greater than the human therapeutic concentration and hence these data very strongly support the fish plasma model proposed by Huggett et al. (2001).

Parasites exert substantial costs on their hosts. Thus, natural selection should favour behavioural defenses that reduce hosts’ exposure to parasites. This prediction has rarely been tested for aquatic hosts exposed to parasites. I designed experiments to test if fathead minnows could detect cercariae of the trematode, Ornithodiplostomum sp. and engage in antiparasite behaviours to avoid them. Minnows exposed to cercariae formed 20.1% tighter shoals compared to water controls. Further, minnows greatly reduced their overall activity, but only when they were exposed for a second time. The latter result is important because it provides the first indication that hosts can learn to avoid parasites. Lastly, I tested if epidermal club cells play a defensive role against cercariae. Club cells did not, but other components of the epidermis, probably mucus cells, decreased cercarial infectivity by 61-68%. My results show that fish can detect, learn, and ultimately avoid aquatic larval stages of parasites. / 105 leaves : ill. ; 29 cm.

Used tires have the potential for becoming popular in pollution control media used in stormwater applications including pervious pavement sub bases, green roof growth media, and upflow filters. Using tire crumb to decrease nutrients can minimize impacts on ecology while reducing the human footprint left by used tires. However, if tire crumb is not examined for toxicity, the ecological balance could unknowingly be disrupted. This research tested the acute toxicity of tire crumb in aquatic systems by finding the Lethal Concentration for 50% kill (LC50). Using an extreme tire crumb load, P. promelas (fathead minnow) were exposed to leachates created with tire crumb and several different types of water including distilled water, tap water, and detention pond water. For distilled and tap water, the addition of tire crumb increased the survival of P. promelas. For detention pond water, the addition of tire crumb decreased the survival of P. promelas, though only enough to find an LC50 for detention pond water influenced immediately by stormwater runoff. An LC50 was found when 100 percent tire crumb filtrate is prepared with 25 grams of tire crumb per liter of detention pond water collected directly after a storm. The LC50 found is resultant of a tire crumb load significantly higher than what can be expected in the environment. Based on this research, tire crumb is considered non-threatening to aquatic fish and safe to use with detention pond water.

Postpartum depression (PPD) is a major health problem that affects many women worldwide. In Egypt, PPD is neglected despite the expected high prevalence rate among women during the transition period after the Egyptian revolution. This research investigated the prevalence, risk factors, and interventions of postpartum depression in southern rural Egypt. Interviews were conducted with 57 participants recruited from public and private hospitals. Questionnaires and the Arabic version of the Edinburgh Postnatal Depression Scale were administered. The prevalence of PPD is 73.7%. PPD is associated with low income and age at childbirth. Most participants regarded screening mothers after childbirth for PPD as effective; in comparison to, antidepressants that were regarded by most participants as ineffective. Women in southern rural Egypt prefer high number of pregnancies, so investigating the influence of sertraline, an antidepressant medication, on female hormones becomes important. In this research, fathead minnows were exposed to 3 and 10 ppb sertraline for 7 days. Real-time Polymerase Chain Reaction was used to detect the change in gene expression of the Follicle-stimulating hormone (FSH) and luteinizing hormone (LH). Results showed that a down regulation at the 10 ppb was evident on the LH and to a lesser extent on FSH. Our results increased levels of sertraline inhibited GnRH which influenced expression of LH and FSH.

Fishes in the superorder Ostariophysi, including fathead minnows (Pimephales promelas), possess specialized epidermal club cells that contain an alarm substance. Damage to these cells, as would occur during a predator attack, causes the release of the alarm substance and can indicate the presence of actively foraging predators to nearby conspecifics. For nearly 70 years, research involving epidermal club cells has focused on the alarm substance and the role it plays in predator/prey interactions. However, recent studies have indicated that there may be a connection between epidermal club cells and the fish immune system. Fish increase investment in epidermal club cells upon exposure to skin penetrating pathogens and parasites. In this study I tested for differences in epidermal club cell investment by fathead minnows exposed to the immunosuppressive effects of the glucocorticoid hormone cortisol. In experiment 1, fathead minnows were exposed to either a single intraperitoneal injection of corn oil or no injection at all. The purpose of this experiment was to determine whether corn oil, the vehicle for cortisol injections in later experiments, had an effect on epidermal club cell density. The treatments had no effect on epidermal club cell size, cell area, or epidermal thickness. In experiment 2, skin extract was prepared from the skin of corn oil injected and non injected fathead minnows as in experiment 1 to determine whether corn oil had an effect on the epidermal club cell alarm substance concentration. The treatments showed no significant differences in observed anti-predator behaviour, including change in shelter use, dashing and freezing. In experiment 3, fathead minnows were exposed to either a single intraperitoneal injection of cortisol or corn oil. The purpose of this experiment was to determine whether cortisol, a known immunosuppressant, had an effect on epidermal club cell investment. Fathead minnows exposed to a single cortisol injection had significantly reduced respiratory burst activity of kidney phagocytes indicating that there was suppression of the innate immune system. Furthermore, cortisol treated fathead minnows showed significantly lower numbers of epidermal club cells. The treatments had no effect on individual epidermal club cell area, epidermal thickness and serum cortisol levels after 12 days. The results from this experiment suggest that pharmacological cortisol injections in fathead minnows have a suppressive effect on the fish innate immune system. Furthermore, the findings that cortisol induced immunosuppression also influences epidermal club cell investment provides support for the hypothesis that epidermal club cells may function as part of the fish immune system.

To be successful, individuals that are susceptible to predation have to optimize the trade-offs between predator avoidance and other fitness related activities such as foraging or reproduction. One challenge for prey is to identify which species pose a threat and should be avoided, and which species should be ignored. The goal of this study was to investigate whether minnows can generalize recognition of predators and non-predators using visual cues. I conducted experiments in both clear and turbid conditions to test whether the level of turbidity affects the quality of visual information available to the prey and hence the ability of prey to generalize. Latent inhibition and learned irrelevance are mechanisms of learning that can be used by prey to recognize stimuli as non-risky. Repeated exposure to an unknown stimulus in the absence of risk leads to the stimulus being categorized as non-risky. Fathead minnows were pre-exposed to the sight of brook trout or control water to provide minnows the opportunity to learn to recognize the trout as a non-predator. Following this the fish were conditioned with alarm cues (AC) to the sight of each predator paired and then their responses to the sight of brook trout, rainbow trout, and yellow perch were tested either in clear or turbid water. In clear water, minnows conditioned to recognize one of the trout species generalized their response to the other species. However, when the minnows were pre-exposed to the sight of a brook trout, they were inhibited from subsequently recognizing the sight of brook trout as threat and generalized this non-predator recognition to the sight of rainbow trout but not to yellow perch. In turbid water, however, minnows that were pre-exposed to the sight of brook trout had impaired responses to all predators while those pre-exposed to water showed an intermediate intensity anti-predator response toward each predator. Overall, my results demonstrate that minnows were able to distinguish between predators and non-predators in the clear environment but turbidity influences the visual information used by minnows and hence impaired the minnow’s ability to recognize and generalize the sight of predators and non-predator species.

Fishes in the superorder Ostariophysi, including fathead minnows (Pimephales promelas), possess specialized epidermal club cells that contain an alarm substance. Damage to these cells, as would occur during a predator attack, causes the release of the alarm substance and can indicate the presence of actively foraging predators to nearby conspecifics. For nearly 70 years, research involving epidermal club cells has focused on the alarm substance and the role it plays in predator/prey interactions. However, recent studies have indicated that there may be a connection between epidermal club cells and the fish immune system. Fish increase investment in epidermal club cells upon exposure to skin penetrating pathogens and parasites. In this study I tested for differences in epidermal club cell investment by fathead minnows exposed to the immunosuppressive effects of the glucocorticoid hormone cortisol. In experiment 1, fathead minnows were exposed to either a single intraperitoneal injection of corn oil or no injection at all. The purpose of this experiment was to determine whether corn oil, the vehicle for cortisol injections in later experiments, had an effect on epidermal club cell density. The treatments had no effect on epidermal club cell size, cell area, or epidermal thickness. In experiment 2, skin extract was prepared from the skin of corn oil injected and non injected fathead minnows as in experiment 1 to determine whether corn oil had an effect on the epidermal club cell alarm substance concentration. The treatments showed no significant differences in observed anti-predator behaviour, including change in shelter use, dashing and freezing. In experiment 3, fathead minnows were exposed to either a single intraperitoneal injection of cortisol or corn oil. The purpose of this experiment was to determine whether cortisol, a known immunosuppressant, had an effect on epidermal club cell investment. Fathead minnows exposed to a single cortisol injection had significantly reduced respiratory burst activity of kidney phagocytes indicating that there was suppression of the innate immune system. Furthermore, cortisol treated fathead minnows showed significantly lower numbers of epidermal club cells. The treatments had no effect on individual epidermal club cell area, epidermal thickness and serum cortisol levels after 12 days. The results from this experiment suggest that pharmacological cortisol injections in fathead minnows have a suppressive effect on the fish innate immune system. Furthermore, the findings that cortisol induced immunosuppression also influences epidermal club cell investment provides support for the hypothesis that epidermal club cells may function as part of the fish immune system.