A number of social and behavioural traits inherent to the individual are known to influence the outcome of social interactions in salmonid fish. In addition, recent work has raised the possibility that the prior physiological condition of a fish may predetermine its social status. Therefore, the hypothesis that elevated plasma cortisol levels influence social rank was tested, with the prediction that rainbow trout (Oncorhynchus mykiss) treated with cortisol would be relegated to subordinate social status in pairwise contests with an untreated conspecific. Experimental elevation of plasma cortisol significantly increased the probability that the treated fish within each pair became subordinate, an effect later identified as cortisol specific, as it was abolished by simultaneous treatment with the glucocorticoid receptor antagonist, RU486. One possible mechanism through which cortisol could exert this effect was subsequently investigated, namely that cortisol influenced social status through behavioural modifications mediated by changes in brain monoaminergic activity. (Abstract shortened by UMI.)

Methylmercury (MeHg) enters most aquatic food webs primarily at the phytoplankton level. However, in the complex aquatic ecosystem, it is difficult to fully examine specific pathways. Consequently, in this study, the uptake of environmentally realistic levels of added MeHg concentrations (0.21 to 20 ng Hg L-1 ) by the freshwater green alga Pseudokirchniriella subcapitata grown in batch and semi-continuous cultures at biomass levels of (0.03, 0.15, 0.3 and 3 mg (dw) L-1) was investigated. In algal culture media without dissolved organic carbon (DOC) and in river water samples with DOC concentration of (2.8 mg L-1) uptake, uptake rate constant, algal concentration of MeHg and the bioconcentration factor (BCF) after 48 h was measured. MeHg uptake was biphasic, with rapid uptake of at least 50% of the total uptake taking place over the first 2 h of incubation followed by a more gradual uptake for the remaining 46 h. Desorption of MeHg from algal cells by re-suspension in acidic medium (pH 3) was < 10% of the total uptake at 48 h. Uptake rate constants of MeHg (ku) increased with aqueous MeHg concentration (r2 = 0.99). At 48 h, algal concentration of MeHg (MeHg (ng) divided by dry weight of algal biomass (g)) increased with aqueous MeHg concentration (r2 = 0.98) but decreased with increasing biomass (r2 = 0.75). This was shown to be a biomass dilution effect as the total uptake of MeHg did increase with biomass. Log MeHg BCF decreased with increasing algal biomass (r 2 = 0.99) with values of 6.9, 6.2 and 5.2 at 0.03, 0.3 and 3 mg (dw) L-1 respectively at all concentrations of MeHg added (0.5, 1.0 and 20 ng L-1).

This thesis looks toward the construction of a contextual understanding of redemption in light of women's experiences in the Newfoundland and Labrador 1 (NL) fishery. Specifically, I consider how we might speak about redemption in a way that is meaningful to their experiences in the midst of the 1990s fishery closure in the province. With the closure of the fishery there has been much loss in the way of personal and cultural identity, belief and way of life. There have been many economic, social, ecological and cultural impacts on women and men and the whole ecological system of the fishery. Women's experiences in the wake of the impact of the closure of the NL fishery make a significant contribution to a contextual understanding of redemptive hope. The Christian language of redemption is appropriate for an understanding of how we speak, theologically, about social and ecological hope. Redemption is embodied in an earthly hope, given by God and embodied in action toward the building of communities of solidarity and an ethical approach rooted in the here and now of people's everyday lives. Redemption also involves an eschatological horizon where the Mystery of God's creative and redemptive love is beyond our imagining. This promise is made known to us historically through our lived experience. Both dimensions of redemption are relevant to a construction of redemption in light of women's experiences. In the NL fishery context, the language of redemptive hope is especially pertinent in light of women's experiences of personal and community loss and devastation. This devastation is also ecological because of foreign, and, to a lesser extent, domestic overfishing that has led to the closure of the fishery and the almost non-renewability of a species---northern cod. Fundamentally, how we speak about our salvation as human beings is inextricably linked with the whole ecological well-being of our local and global communities. Theological discourse, especially around salvation and our human participation in it, fails to have meaning if it is not directly connected with our earthly, historical realities, especially in relation to experiences in times of crisis. I have chosen to focus solely on insights from women's experiences in the fishery because women's experiences as fish plantworkers and fishers are rarely highlighted. From the methodologies of feminist and liberation theologies, an experience of redemption or liberation begins with the action of God in the history of those most excluded in our societies, whose voices have not been heard. Ecofeminist theologians explore theological constructions from ecological perspectives, citing the earth itself as our place of salvation. There are many theologians who have written about redemption from liberation and ecofeminist perspectives. I will draw from three theologians---Edward Schillebeeckx, Ivone Gebara and Rosemary Radford Ruether---to consider how they speak about a socially-engaged redemption. In dialogue with these theologians' insights on redemption, I use NL women's narratives, from the fields of sociology and health, to consider women's voices during the years immediately following the closure of the fishery. Then, I consider these narratives and what they are saying theologically, individually and collectively. Specifically, I choose to articulate an understanding of redemption out of the particular context of women's lives in a fishery closure. It is my finding that these women's narratives, in dialogue with theologians' insights, contribute to a new way of speaking about redemption for today. I hope this thesis will contribute to new ways of speaking about NL women's experiences in the fishery and the fishery itself and consider new avenues for discourse on contextual, lived experiences of redemptive hope. It is a contextual understanding of this particular context and as such is one avenue of bringing the complex notion of redemption into view. It does not intend to offer a comprehensive treatment of redemption. In the context of the NL fishery I speak about the possibility of community building and ecological sustainability. These are two major components of a vision of redemptive living in the NL fishery. By taking these women's experiences into account and the reality of the ecological community of the whole fishery, I consider our redemptive hope from the perspective of interdependence of human with other life. With this development of a contextual theology around redemption in the NL fishery, I also reconstruct an understanding of the person of Jesus Christ and God born out of dialogue with theologians and women's experiences in the fishery. This new theological understanding of redemption involves the cultivation of resistance and resilience as modes of redemptive living. This is the major finding of the thesis and shapes a contextual, earth-centred, creation-focussed theology of redemption. 1In this thesis, I will refer to Newfoundland and Labrador in its abbreviated form as NL except when citing another source.

Human pharmaceuticals have been reported in the aquatic environment but information pertaining to their effect(s) in aquatic non-target species was scarce when this project was initiated. The two main objectives of this research were to determine if these new emerging contaminants are available to aquatic species and to assess if exposure can lead to unfavourable effects in two fish species, the goldfish (Carassius auratus) and the rainbow trout (Oncorhynchus mykiss). Most studies were done with the fibrate drug gemfibrozil (GEM), although the other fibrates bezafibrate (BEZA), clofibrate (CLO) and fenofibrate (FENO) were used for specific experiments. Waterborne GEM exposure resulted in bioconcentration factors up to 500 in goldfish using LC-MS/MS estimates. Results provided strong evidence that environmental concentrations of GEM are not indicative of plasme concentration in fish. Tissue distribution for the three peroxisome proliferator-activated receptors (PPARs) subtypes were established in goldfish and rainbow trout by estimating mRNA levels using reverse-transcriptase PCR (RT-PCR). The monitoring of PPARalpha mRNA was found not to be a good indicator of GEM exposure as mRNA levels were not modified. Interestingly PPARbeta mRNA appears to be modulated in comparable ways in the two species and PPARgamma was affected but only in rainbow trout. Identified potentially harmful effects resulting from exposure to fibrate drugs include (1) a challenged hepatic antioxidant defense system in goldfish exposed to an environmentally relevant concentration of GEM determined using spectrophotometric assays and (2) an impaired cortisol response in rainbow trout exposed to high concentrations of CLO and FENO determined through in-vitro head kidney cell stimulation. A mechanistic approach to understand the effects of fibrate drugs allowed identifying potential target steps of corticosteroidogenesis, hence contributing to the understanding of basic endocrinology. This thesis is an important contribution to the emerging field of the effects of pharmaceuticals in the aquatic environment as it provides evidence that environmental concentrations significantly underestimate in-vivo drug levels and that exposure to human drugs may challenge or impair essential physiological functions in fish. Future research should focus on assessing effects over longer periods of time and at lower concentrations.

In the summer, five creeks on the Fort Apache Indian Reservation were examined. Apache trout generally selected the deepest pools with the greatest amounts of instream cover and bankcuts. Though fish in three creeks may be Apache trout x rainbow trout hybrids, they were found to occupy the same type of pools. Regression models on environmental conditions in two creeks accounted for 83% and 76% of the variability in biomass of Apache trout. There was adequate nursery habitat (and successful reproduction) on two creeks, but such habitat was lacking in the other three creeks, and no evidence of successful reproduction was found. There was little evidence of survival of smaller Apache trout in areas of co-occurrence with non-native trouts but there was evidence of their survival upstream where fewer numbers of non-natives occur. The exclusion of smaller Apache trout may be from elimination or emigration. Greater populations of Apache trout may be supported through eradication of non-native trouts, the addition of instream cover, and structures designed to create longer lasting pools and bankcuts.

The Sonora chub (Gila ditaenia) is a small minnow that is federally-listed as threatened. My research objectives were to quantify characteristics and persistence of macrohabitats used by this species through critical summer periods, and to quantify microhabitat selection in Sycamore Creek, Arizona. By the end of the summer drought, macrohabitats containing adults were deeper, larger and decreased less rapidly than areas with only immature fish or unoccupied areas. Loss of surface area was highest in inundated unoccupied areas and areas with only immature fish. Loss of Sonora chub from drying pools was highest in pools with immature fish. Ephemeral and unoccupied areas had higher percentages of floating algae and coarser substrates than persistent, occupied areas. General microhabitat characteristics selected by Sonora chub were areas with bedrock or fine substrates near cover and zero velocity. Microhabitat use usually differed among life stages, and availability and selection varied among pools.

Bluehead sucker (Catostomus discobolus) and speckled dace (Rhinichthys osculus) were the only native species in Shinumo Creek above a waterfall located about 120 m upstream from the confluence of Shinumo Creek and the Colorado River. Rainbow trout (Oncorhynchus mykiss) was the only introduced species found upstream of the waterfall. I attribute the coexistence of the native and introduced species is attributed to differential use in resources and the similarly small size of bluehead sucker and rainbow trout. Mean total length of bluehead suckers was 160 mm and the largest fish captured was 230 mm (n = 77). Mean length of rainbow trout was 149 mm (maximum = 300 mm; n = 46). Bluehead suckers in Shinumo Creek were smaller than individuals observed in the mainstem Colorado River. Small size may be a response to the decreased size of the habitat available. The permanence of the waterfall barrier near the mouth of Shinumo Creek is a result of regulation of the Colorado River that prevents inundation of the waterfall.

A freshwater clam, Nephronaias tempisquensis, was studied in its seasonal tropical environment. This particular research was conducted because many studies of unionids from temperate waters have been conducted, but little is known of unionids from tropical waters. In mussels from temperate regions, initiation of reproductive activity, the age of sexual maturity, and seasonal activities vary among species. Nephronaias tempisquensis is an endemic clam of the tropical Tempisque River drainage basin. Its reproductive activities, population fluctuations and some of the possible environmental factors affecting its distribution are analyzed Sample collection was conducted over a period of 26 months, in three phases. The first phase of the study was begun in 1976 with monthly collections of mussels in different parts of the Rio Tempisque; individual size and distribution of the population were studied The second phase of the sampling was conducted during a period of 18 months (1979-1981); clams were collected at random from Rio Tempisque, Rio Canas, and occasionally from Rio Tempisquito and Rio Salto. Analysis in vivo of the clams and host-glochidia relationships were recorded The third phase of the study was conducted in the hope of finding the clams' natural feeding habits. Clams from Rio Tempisque, Rio Tempisquito and Rio Canas were collected and examined In all phases, external factors that probably strongly influenced the clams under study were also considered: pH, nature of the substratum, water and air temperatures, light periods and predators Among the environmental parameters that were considered for this study, rainfall is the most important factor that affects the populations of Nephronaias tempisquensis Reproductive activity is related to the most favorable environmental conditions, the beginning of the summer, and during the 'little summer'. However, reproductive activity in Nephronaias tempisquensis is continuous, but increases twice a year; from November through December and January, and from June through August Sexual dimorphism of the shells of N. tempisquensis is present, though very difficult to determine without histological studies. . . . (Author's abstract exceeds stipulated maximum length. Discontinued here with permission of author.) UMI / acase@tulane.edu

At a concentration of approximately 8 ppm, naphthalene inhibited circadian black pigment dispersion in the integumentary chromatophores of the fiddler crab no matter what the initial state of the black pigment. The inhibition was concentration dependent. Naphthalene was not toxic to fiddler crabs under these conditions at any concentration up to 16.69 ppm. Naphthalene has no effect on the black chromatophores themselves. The black chromatophores in naphthalene exposed crabs disperse to a point equal to controls when injected with an eyestalk extract. Naphthalene, then must act somewhere in the central nervous system. Eyestalk extracts made from naphthalene exposed crabs show that these crabs have functional black pigment dispersing hormone (BPDH), but more of it is stored in the eyestalk neurosecretory apparatus than in the control crabs. It appears that naphthalene acts to decrease black pigment dispersion during the dark phase of the Circadian rhythmn by inhibiting the release of BPDH. This hypothesis is strengthened by the finding that BPDH activity stored in the eystalks of naphthalene exposed crabs can be released by exogenous norepinephrine (NE) No chemically induced phase shift in the circadian rhythm of naphthalene exposed crabs occurs. In addition there is no difference in the mean black chromatophore index at midnight between control and naphthalene exposed crabs, indicating that the release of black pigment concentrating hormone (BPCH) is not being influenced by naphthalene. The only possibility remaining is that naphthalene must interfere with some aspect of the control of BPDH release by NE. Exposure to naphthalene does not inhibit black pigment dispersion when crabs are placed on a black background or kept on a black background throughout the experiment. This argues against naphthalene acting to inhibit the synthesis of NE, or to promote its metabolism, since NE is involved in adaptation to a black background. Naphthalene, therefore, must act to prevent the release of BPDH by interfering with some aspect of the presynaptic control of BPDH release by NE / acase@tulane.edu

Long-term population trends of colonial wading birds (Ciconiiformes) in Louisiana, Florida, Texas, and California were examined using data from Audubon Christmas Bird Counts (1949-1988) and Breeding Bird Surveys (1966-1989). Winter populations of most Louisiana wading birds increased over the 40-year period, with the sharpest increases occurring during the last 20 years. Increased acreage of crayfish (Procambarus) aquaculture in Louisiana appears to be the most significant factor explaining the observed population increases. First, populations of wading-bird species that use crayfish were correlated positively with the wild crayfish harvest, and more strongly with crayfish pond acreage. Second, the regularity of pond management provided a more predictable foraging habitat than did comparable natural areas. Third, the use of crayfish ponds by wading birds peaked during pond drawdowns, which may have increased reproductive success by concentrating prey available to wading birds during their nesting season. Fourth, wading bird species that specialized on crayfish showed the greatest population increases and the strongest correlation with crayfish pond acreage A field study comparing crayfish farms with natural habitats found significant differences in prey availability, and in the relative foraging success of Great Egrets, Snowy Egrets, and White Ibises. Wading birds on crayfish farms took significantly more prey for less effort, and selected more preferred prey. Wild sites had more fish $(P<0.001),$ more total prey $(P<0.001),$ and higher prey densities $(P<0.001)$ than flooded farm ponds. Farm ponds during drawdown, however, had higher densities of fish, more crayfish $(P<0.001),$ and higher prey densities than wild sites $(P<0.001).$ When foraging on crayfish farms, Great Egrets took more total prey $(P<0.05),$ Snowy Egrets took more fish $(P<0.05),$ and White Ibises took more crayfish $(P<0.01)$ than in the wild. Juvenile White Ibis foraged significantly more successfully on crayfish farms than did adult birds on farms or in the wild. Crayfish farms thus provide superior foraging habitats for wading birds during the nesting season. Recent increases in crayfish farm acreage in Louisiana appear to be a major factor causing the long-term population increases of Louisiana's colonial wading birds. These findings have important implications for the conservation and management of Louisiana's wading bird populations / acase@tulane.edu