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Made available in DSpace on 2015-06-17T19:34:28Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-01-21. Added 1 bitstream(s) on 2015-06-18T12:48:47Z : No. of bitstreams: 1 000829802.pdf: 1465255 bytes, checksum: 2d7e1dd40db91bb9503377e7965f6c9d (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação do Instituto de Biociências (FUNDIBIO) / Inserido na realidade de contaminação dos rios amazônicos pelo mercúrio, este trabalho busca, por meio do estudo metaloproteômico, a identificação e a caracterização de proteínas do tecido muscular de três espécies diferentes de peixes do rio Madeira que possam atuar como possíveis biomarcadores da toxicidade deste elemento na região de influência do Aproveitamento Hidrelétrico de Jirau (AHE JIRAU). As estratégias para este estudo foram separadas em três componentes distintos: de seletividade, de sensibilidade e estrutural. Ao longo desta pesquisa, diferentes metodologias foram empregadas nessas etapas para o estudo metaloproteômico: componente de seletividade - 2D PAGE no fracionamento bidimensional das proteínas; componentes de sensibilidade - SR XRF e GFAAS para identificação e quantificação do mercúrio nos spots proteicos, respectivamente; componente estrutural - ESI MS MS na caracterização das proteínas identificadas com mercúrio em sua estrutura. As espécies de peixes estudadas foram: dourada (Brachyplatystoma rousseauxii), pacu (Mylossoma sp., Myleus sp.) e jaraqui (Semaprochilodus sp.). Entre os resultados obtidos, a 2D PAGE se mostrou eficiente no fracionamento proteico do tecido muscular de peixes. Utilizando análises qualitativas por SR XRF foi possível identificar a presença de mercúrio no spot 68 da dourada (massa molar 20,8 kDa e pI 5,6) e no spot 72 do pacu (massa molar 19,8 kDa e pI 7,5). Determinações por GFAAS permitiram a quantificação do mercúrio no tecido muscular e em 28 spots, que apresentaram concentrações de 11,3 a 41,2 mg g-1 de mercúrio em sua composição; esses resultados possibilitaram o cálculo da estimativa do número de átomos de mercúrio por molécula de proteína entre os spots estudados. Após análise por ESI MS MS, foi possível caracterizar oito proteínas com diferentes isoformas em 21 spots que apresentaram pI de 3,5 a 9,8 e massa molar ... / Inserted in the context of mercury contamination of Amazonian rivers, this work pursues through metaloproteomic study the identification and characterization of proteins from muscle tissue of three different species of fish from Madeira River that may act as potential biomarkers of toxicity of this element in the region of influence of Jirau Power Plant. The strategies for this study were separated into three distinct components: selectivity, sensitivity and structural. Throughout this research, different methodologies were used in these steps for metaloproteomic study: component of selectivity - 2D PAGE in two-dimensional proteins fractionation; components of sensitivity - SR XRF and GFAAS for mercury identification and quantification in protein spots, respectively; structural component - ESI MS MS in the characterization of proteins identified with mercury in its structure. The species studied were: dourada (Brachyplatystoma rousseauxii), pacu (Mylossoma sp., Myleus sp.) and jaraqui (Semaprochilodus sp.). Among the results, the 2D PAGE proved efficient in protein fractionation of fish muscle tissue. Using qualitative analysis by SR XRF was possible to identify the presence of mercury in the spot 68 of dourada (molar mass of 20.8 kDa and pI 5.6) and spot 72 of pacu (molar mass of 19.8 kDa and pI 7.5). Determinations by GFAAS allowed the mercury quantification in muscle tissue and in 28 spots that showed concentrations from 11.3 to 41.2 mg g-1 of mercury in its composition; these results enabled an estimative calculation of the number of mercury atoms per protein molecule between the spots studied. After analysis by ESI MS MS it was possible to characterize eight proteins with different isoforms in 21 spots that showed pI 3.5 to 9.8 and molar mass between 9.9 and 18.1 kDa, indicating that these proteins may be potential candidates for mercury biomarkers in ...

Orientador: Pedro de Magalhães Padilha / Banca: Clelia Akiko Hiruma Lima / Banca: Marília Afonso Rabelo Buzalaf / Banca: Paulo dos Santos Roldan / Banca: Lincolin Carlos Silva de Oliveira / Resumo: Inserido na realidade de contaminação dos rios amazônicos pelo mercúrio, este trabalho busca, por meio do estudo metaloproteômico, a identificação e a caracterização de proteínas do tecido muscular de três espécies diferentes de peixes do rio Madeira que possam atuar como possíveis biomarcadores da toxicidade deste elemento na região de influência do Aproveitamento Hidrelétrico de Jirau (AHE JIRAU). As estratégias para este estudo foram separadas em três componentes distintos: de seletividade, de sensibilidade e estrutural. Ao longo desta pesquisa, diferentes metodologias foram empregadas nessas etapas para o estudo metaloproteômico: componente de seletividade - 2D PAGE no fracionamento bidimensional das proteínas; componentes de sensibilidade - SR XRF e GFAAS para identificação e quantificação do mercúrio nos spots proteicos, respectivamente; componente estrutural - ESI MS MS na caracterização das proteínas identificadas com mercúrio em sua estrutura. As espécies de peixes estudadas foram: dourada (Brachyplatystoma rousseauxii), pacu (Mylossoma sp., Myleus sp.) e jaraqui (Semaprochilodus sp.). Entre os resultados obtidos, a 2D PAGE se mostrou eficiente no fracionamento proteico do tecido muscular de peixes. Utilizando análises qualitativas por SR XRF foi possível identificar a presença de mercúrio no spot 68 da dourada (massa molar 20,8 kDa e pI 5,6) e no spot 72 do pacu (massa molar 19,8 kDa e pI 7,5). Determinações por GFAAS permitiram a quantificação do mercúrio no tecido muscular e em 28 spots, que apresentaram concentrações de 11,3 a 41,2 mg g-1 de mercúrio em sua composição; esses resultados possibilitaram o cálculo da estimativa do número de átomos de mercúrio por molécula de proteína entre os spots estudados. Após análise por ESI MS MS, foi possível caracterizar oito proteínas com diferentes isoformas em 21 spots que apresentaram pI de 3,5 a 9,8 e massa molar ... / Abstract: Inserted in the context of mercury contamination of Amazonian rivers, this work pursues through metaloproteomic study the identification and characterization of proteins from muscle tissue of three different species of fish from Madeira River that may act as potential biomarkers of toxicity of this element in the region of influence of "Jirau Power Plant". The strategies for this study were separated into three distinct components: selectivity, sensitivity and structural. Throughout this research, different methodologies were used in these steps for metaloproteomic study: component of selectivity - 2D PAGE in two-dimensional proteins fractionation; components of sensitivity - SR XRF and GFAAS for mercury identification and quantification in protein spots, respectively; structural component - ESI MS MS in the characterization of proteins identified with mercury in its structure. The species studied were: "dourada" (Brachyplatystoma rousseauxii), "pacu" (Mylossoma sp., Myleus sp.) and "jaraqui" (Semaprochilodus sp.). Among the results, the 2D PAGE proved efficient in protein fractionation of fish muscle tissue. Using qualitative analysis by SR XRF was possible to identify the presence of mercury in the spot 68 of "dourada" (molar mass of 20.8 kDa and pI 5.6) and spot 72 of "pacu" (molar mass of 19.8 kDa and pI 7.5). Determinations by GFAAS allowed the mercury quantification in muscle tissue and in 28 spots that showed concentrations from 11.3 to 41.2 mg g-1 of mercury in its composition; these results enabled an estimative calculation of the number of mercury atoms per protein molecule between the spots studied. After analysis by ESI MS MS it was possible to characterize eight proteins with different isoforms in 21 spots that showed pI 3.5 to 9.8 and molar mass between 9.9 and 18.1 kDa, indicating that these proteins may be potential candidates for mercury biomarkers in ... / Doutor

Subterranean ecosystems are regarded as the most extensive biome on earth, comprising terrestrial and aquatic systems - the latter constituting freshwater, anchialine and marine systems. This system plays a key role in the distribution and storage of freshwater, once it contains 97% of the world’s total liquid freshwater (Chapter 1), which has been progressively explored in quality and amount. Initial observation of the subterranean environment began with speleological studies by the recognition of a typical fauna adapted to live inside caves. The first studies to provide information about aquatic subterranean fauna commenced in Slovenia, with the description of the Proteus aguinus by Laurenti in 1768. After an initial faunal classification by the Danish zoologist Schiödte (1849), the Austrian naturalist Schiner (1854) established the most commonly used classification for cave fauna and a great portion of modern research dealing with ecobilogy of aquatic subterranean fauna has mostly evolved from the European biospeleology (Chapters 1 and 3). Studies in biospeleology have made a significant contribution to the progressive knowledge in aquatic subterranean ecology, especially in those circumstances where the access of the underground through smaller voids (e.g. crevicular spaces) is not possible. Accessibility to the underground environment is in fact a negative factor that has led a large number of studies consider about subterranean fauna initially being limited to caves. Spatial constraint was (and still is) a limiting factor in accessing a diverse range of subsurface habitats, although during the last decade, modern research has been using advance technology as a tool to overcome the physical barriers to subterranean research. For a long time the classification of subterranean aquatic organisms was an unclear subject, with the classification subterranean fauna mostly related to terrestrial cave fauna (troglofauna). The classification system dealing with aquatic subterranean groups (stygofauna) is more recent. A few nomenclature schemes have been proposed to describe these relationships, based on morphological, behavioural, and ecological adaptations of animals to the underground life and their level of relationship with groundwater (Chapter 4). The prefix “stygo” is suggested as the most descriptive to refer ecologically to a group of animals related to groundwater habitats. Groundwater related fauna (stygofauna) is comprised by groups of animals encompassing aquatic surface, intermediate and subterranean habitats. They represent diverse group of animals that have different interactive relationships with the groundwater habitat. Some may transact between surface water and groundwater systems, while others spend the whole life cycle in the subterranean voids (Gibert et al., 1994). This transition zone between surface streams and groundwater is recognized as a critically important boundary or ecotone, constituted by a habitat that contains a reservoir of invertebrate fauna biodiversity. It is therefore from the study of karst systems that most information on groundwater ecobiology is resourced, once the open structure of most karsts terrains promotes a number of caves, streams, crevices, sinkholes, and springs to allow human access. Karst systems are well fractured because of the relation between the rock mass and the action of meteoric water, as well as the dissolution rate of calcium carbonate rocks that high. The latter increases with time, producing a terrain with a great drainage potential (Chapter 2). Once porosity is high and the flow of percolating water is fast, it allows good vagility for subterranean fauna and nutrients, as well as penetration of contaminants. In subterranean karsts, much water saturates some areas inside rock spaces. The saturation in the rock in turn promotes large water pockets, known as aquifers. When these groundwater aquifers are found to be interconnecting with the adjacent ecosystems, they became active eco-hydrological components, due to their key participation in the surface-groundwater continuum. Groundwater has different degrees of importance, depending on the available sources of surface water. In many countries it supplies a significant proportion of urban and rural drinking water, industrial, and agricultural. Yet, groundwater systems are “hidden”, difficult in access and to study (Chapter 4, 5 and 7), consequently the recognition of the groundwater aquifer as a natural resource that needs to be protected is largely ignored. Moreover, studies in the ecobiology and distribution of stygobitic invertebrates (Chapter 5), and the need to identify a frame of methods for quality assessment and the suitability of groundwater invertebrates as bioindicative elements, has not been developed (Chapter 6). Finally, strong management and public education programs are required to emphasize the need for a better understanding of the nature of groundwater resources, their participation and complexity (Chapter 8), with the conceptualization of the groundwater aquifer integrity as an ecosystem still receiving little attention in South Africa. / Dr. J.F. Durand Prof. G.J. Steyn

M.Sc. (Aquatic Health) / Aquatic ecosystems in rural South Africa have been impacted over many years by commercial and subsistence anthropogenic activities (DWAF, 2001). These impacts include commercial and subsistence farming, domestic use (e.g. washing of clothes, cars and bathing) and recreational use (e.g. fishing). In the northern parts of the Limpopo Province of South Africa (Vhembe District) the land use is primarily dominated by various agricultural activities and human settlements. Rivers in this region flow through mixed agricultural use, including commercial agriculture (tea and timber plantations) as well as subsistence farming and housing. Perennial rivers in this region include the Mutale, Mutshindudi and Tshinane rivers. These rivers are located in the Water Management Area 2 (WMA 2 Luvuvhu-Letaba) (Kleynhans, et al., 2007a). They are highland river systems, originating in the nearby Soutpansberg Mountain, and these rivers all form part of the larger drainage system of the Luvuvhu River, a tributary of the Limpopo River. The wetlands in the catchment of these rivers are also heavily utilised by the local communities (Working on Wetlands, 2013) used for grazing, sand mining and subsistence cultivation, thus providing a livelihood for the surrounding communities (SANBI, 2012). The aim of the study was to assess aspects of the biological integrity of the Mutale, Mutshindudi and Tshinane rivers. This study formed part of a larger study that included assessments of both abiotic and biotic aspects of these river systems. For this study, the focus was on assessing the fish community structure through the application of Fish Response Assessment Index (FRAI), riparian vegetation through the application of Vegetation Response Assessment Index (VEGRAI) and fish health aspects with special reference to liver and gonadal histopathology. Water quality parameters were found to be within the target water quality range for aquatic ecosystems. The results did however vary between upstream and downstream sampling sites. Similarly, compared to upstream sites, the FRAI showed the Mutale River to improve in fish community structure whereas the Tshinane and Mutshindudi rivers showed a decrease in the FRAI score. The VEGRAI results showed a decrease in EcoCondition in the Mutale and Mutshindudi rivers whereas the Tshinane indicated an increase. This can be attributed to land use change up to the edge of the river systems. Visual observation at the various study sites showed a definite localised impact of human activities on the beds and banks of many parts of the rivers. No histological alterations were identified in any of the gonadal or liver tissue of the Chiloglanis pretoriae (Shortspine suckermouth) (Van der Horst, 1931) and the fish were found to be in a healthy condition according to the selected parameters (gonads and livers) assessed. The fish community structure of the three rivers were found to be in a moderately to largely modified condition according to the ecological state categories calculated. However, the fish health assessment showed no histological alterations in the sampled fish. It is proposed that future studies investigate the influence of the domestic use of the rivers as well as attempt to quantify the impact of agriculture on the system.

D.Phil. / By virtue of its position on the eastern border of South Africa, the Kruger National Park (KNP) receives the flow of six main riven, of which the greater part of the specific catchment areas are situated upstream from the park itself. The Olifants River has the largest catchment area both in size and in proportion of catchment area beyond the park boundary. Increased competing demand for water by the urban, industrial, mining and agricultural sectors within the catchment boundaries of the Olifants River has focused attention on the ecological water requirements of the river. Of particular concern was the high degree of mineralisation of the Olifants River due to mining activities on the western boundary of the KNP. When one considers the demand for water by the Kruger National Park it is evident that water is required for more than one use, i.e. for potable use, game watering and ecosystem (aquatic and riparian) maintenance. In order to facilitate proper water quality management it is necessary to develop a comprehensive water quality management plan for the river. The development of such a plan requires a thorough understanding of the fate and effects of pollutants in the environment. It is furthermore important to have reliable information on the trends and status of important water quality determinants in these systems. This study was therefore aimed at investigating the metal ecotoxicology of the lower Olifants River and the Selati River, a tributary of the Olifants River which flows through the Phalaborwa area. Water quality is a driving variable in aquatic ecosystems. Full assessment of water quality of the Olifants River included evaluation of the physical, chemical and biological attributes of the system. The difference between the physical/chemical and biological attributes is that the former provide an instantaneous and often specific assessment of the water quality, whereas the latter integrate changes in the system over time. Water and sediment samples were collected bi-monthly from February 1990 to February 1992 at six stations along the lower Olifants River, one in the Selati River and one in the Letaba River. At each of these sites physical and chemical water quality characteristics were measured. Two metal bioaccumulation indicator species, Labeo rosae and Oreochromis mossambicus, were also sampled during the same period at three stations in the Olifants River and at the Selati River sampling station. Two additional surveys were undertaken to reference sites in the KNP (i.e. Pioneer Dam, and Nhlanganini Dam) during February 1992 and April 1992 respectively. Tissue samples (muscle, gill, liver, gonads, fat and blood) were collected and analysed for Cr, Cu, Fe, Mn, Ni, Pb and Zn using atomic absorption spectrophotometry. The routine monitoring of chemical and physical water quality attributes produces large quantities of complex data which are often difficult to interpret. To reduce the complexity, data may be standardised and summarised into an index. The Aquatic Toxicity Index (ATI) that was developed Metal Ecotoxicology in the Olifants River it Summary during this study presented the water quality of all the sampling stations, during each survey as a single value. This value reflected the water quality's suitability-for-use by fish at the different sampling stations. The ATI showed definite temporal and spatial trends in water quality in the Olifants River. The Selati River was the main contributing factor to the poor water quality measured in the Olifants River within the KNP. This was due to high TDS, metal and fluoride concentrations. Deterioration of the water quality was experienced during flood conditions when the turbidities and total metal concentrations increased. The water quality generally increased between summer and winter surveys (February to June). Bioindicators are species used to quantify biologically available level of metals in the aquatic ecosystem. These organisms take up metals from the ambient water and from food, and the concentrations in their tissues (or changes in concentrations) provide a time integrated measure of metal bioavailability. Temporal bioavailability of metals in the tissues of the bioindicators showed similar trends to the water quality. Highest metal concentrations were measured in fish tissue samples collected during flood conditions (December 1990) and during low-flow conditions (June to October). This was attributed to increased exposure due to metal adsorption to suspended sediments during the flood conditions and to increased ambient metal concentrations during lowflow conditions. The distribution of metals in tissues varied based on the uptake, depuration and metabolism strategies for each metal. In general the gill tissue bioaccumulated the highest metal concentrations, with only Cu and Fe occurring in higher concentrations in liver tissue. Significant positive correlation's were found between bioaccumulation in muscle tissue and the other tissues: Space-bulking and time-bulking of results were carried out to elucidate spatial bioaccumulation patterns. The highest bioaccumulation of Cu, Pb and Ni were recorded in samples from the Selati River, whereas Zn and Cr concentrations were the highest in the Olifants River. An equilibrium partitioning (EP) technique was used to integrate bioaccumulation data and metal concentrations in different phases of the water and sediment and produce specific Cu and Zn criteria for the Olifants and Selati rivers. Although there is a multitude of data available for Cu and Zn toxicity and BCF's, the quality criteria produced during this study, for the first time, made use of results obtained under local conditions. The results from bioaccumulation studies carried out in the field can not provide information regarding the potential effects or the risks the metals may pose to the exposed organisms. Therefore the susceptibility of the organisms to metal contamination can be determined using laboratory studies. Physiology is toxicology's closest relative and contributes markedly in assessing the toxicological risk of metals. Bioassays were conducted to determine the uptake kinetics, acid-base disturbances and haematological effects of a metal mixture containing Cu, Fe and Zn on Tilapia sparrmanii. The effects of the individual metals (Cu, Fe and Zn) and different Metal Ecotoxicology

This study investigated the vegetation and soil characteristics in relation to distance from water points under different land management systems in semi-arid rangelands of South Africa. Six study sites, two each from communal grazing, commercial farming and game reserves were selected. Two watering points were selected in each study site. Two 500 m transects were laid from the selected watering points. Each transect was divided into sub-transects at 25 m, 50m, 100m, 200m, 300m and 500m from water points. A 100 m2 plot was marked in each sub-transect to record grass biomas, species composition, structure and distribution of woody vegetation and physical and chemical soil properties. Data were collected for two seasons 2012/13 (winter and summer). Thirty and 41 grass and woody species respectively were identified in all study areas. The most common and dominating grass species include Cynodon dactylon, Digitaria eriantha, Eragrostis obtusa, Setaria sphacelata and Sporobolus fimbriatus. Cynodon dactylon and S. sphacelata occurred more abundantly (p < 0.05) in the game reserves than in the other land management catergories. All the grass species had similar (p > 0.05) abundance along distance gradient from water points. Grass dry matter (GDM) showed significant differences (p < 0.05) between and within land management systems. However, GDM was not significantly affected by season, location of water point within each farm or reserve and distance along water points. Acacia karoo, Coddia rudis and Ehretia rigida were the most dominant woody species. Tree equivalent (TE) density of all encroaching woody plants combined was significantly (p < 0.05) higher on the communal area (1732 TE ha-1) than the commercial ranches (1136 TE ha-1) and game reserves (857 TE ha-1), but with no marked variations along distance from water points under all the land management systems. The electric conductivity (EC) was significantly (P < 0.01) higher in game reserves than in communal grazing areas and ranches. Soil organic matter percentage showed greatest and lowest values in the game reserves and commercial respectively. Soil pH and bulk density did not vary but soil organic matter (SOM), EC, bulk density and soil compaction were significant different with no increasing or decreasing trends. Soil properties were affected by herbivore pressure and trampling around water points with inconsistence magnitude and direction. In conclusion, grass species composition and GDM did not respond to distance from water points because either grazing gradient was absent or the length of transects was not enough to explain the absence or presence of gradients. High proportion of A. karoo and high densities of seedlings and saplings would seem as very good indicators of the woody vegetation changes in the different land management systems and distance from water points. The soil quality indicators around the water-points showed that livestock and game affected soil parameters.

Great Blue Herons (Ardea herodias) breeding near a pulp mill at Crofton B.C. failed to raise young in 1987 and 1988. Elevated levels of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo-furans were detected in their eggs. The highest 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) toxic equivalent level observed was 496 ng/kg (wet weight) in 1987 (Elliott et al. 1989). I compared the Crofton colony with a less contaminated colony on Sidney Island in 1988 and 1989. I examined three possible explanations for nesting failure: (i) abnormal nesting behaviour by parents because of contamination, (ii) disturbance by human activities, and (iii) predation by Bald Eagles (Haliaeetus leucocephalus), Northwestern Crows (Corvus caurinus) and Common Ravens (Corvus corax). The Crofton colony was successful in 1989 and 1990. Within the TCDD toxic equivalent range of 34 - 257 ng/kg (1989), I observed no abnormal heron nesting behaviour or reduction in numbers of chicks fledged. In 1988 the herons at Crofton were disturbed repeatedly by human activities. Bald Eagles were observed daily at both Crofton and Sidney Island. The heron colony on Sidney Island failed in 1989 and 1990. The failures on Sidney Island were thought to involve a disturbance by eagles followed by rapid removal of eggs and young chicks at unattended nests by crows and ravens. It is likely that disturbance and predation played a part in the failure at Crofton in 1988, but there remains the possibility that environmental contaminants may have increased the sensitivity of herons to disturbance and predation. / Land and Food Systems, Faculty of / Graduate

This study examines the effects of a low oxygen environment, in concert with fluctuating temperature and salinity conditions, on the nearshore depth distributions (0-1 m) and flood tide movements of juvenile chinook (Oncorhynchus tshawytscha) and chum (O. keta) salmon. Comparisons are made between an unpolluted and a sewage polluted estuarine intertidal flat in the Fraser River estuary, British Columbia, the polluted area being characterized by the regular occurrence of low dissolved oxygen levels. Results are based on 380 beach seine samples taken between April and June of 1984. In general, chum and chinook salmon of increasing length were captured in increasing depths, though this pattern was modified by seasonal changes in water temperature. Low dissolved oxygen conditions in deeper waters may have been responsible for the presence of larger, and often sluggishly swimming fish in higher oxygenated surface water layers or in shallow waters near the shore. In both areas, the risk of aerial predation was high. On a flood tide, the likelihood of capturing a chinook salmon was reduced as temperatures increased and oxygen levels decreased. A combination of avoidance behaviour and a regularity in the movement patterns of chinook onto the study area in the later stages of the flood tide may account for their rare occurrence in low oxygen concentrations (<6 mg/1) and high temperatures (>20 °C). Fish mortalities were most likely to occur on the ebb tide when fish were forced into waters of low oxygen content by the drainage patterns characteristic of the polluted study area. Though wide ranges in salinity were recorded on both tidal flats, this factor was not strongly correlated to Chinook distributions. However, significantly higher salinity levels in the unpolluted area may account for the greater numbers of chum salmon captured there. An understanding of the influence of estuarine water quality conditions on the distribution of juvenile salmonids may assist in the identification of significant sources of mortality in their early marine life. This knowledge is particularly important in the evaluation of water quality changes as caused by human activity. / Science, Faculty of / Zoology, Department of / Graduate

Sertraline is a selective serotonin reuptake inhibitor (SSRI) that is widely used for the treatment of depression and anxiety. Due to the abundant therapeutic use of sertraline, low levels have been detected in municipal wastewater effluents suggesting that aquatic organisms may be exposed. The purpose of this study was to evaluate the steroidogenic effects of sertraline on larval (FHM) and adult female fathead minnows (FFHM), Pimephales promelas. Larval FHM were exposed to 0.1, 1, and 10 µg/L sertraline for 28 days and analyzed via RT-qPCR for differential expression of 11β-Hydroxysteroid dehydrogenase (11β-HSD), 20β-Hydroxysteroid dehydrogenase (20β-HSD), aromatase (CYP19), and nuclear thyroid receptor alpha (TRα). FFHM were exposed to 3 or 10 µg/L sertraline for 7 days with the brain and ovary excised at exposure termination. Juvenile FHM exposed to 0.1 μg/L sertraline had a significant upregulation of both 20β-HSD and TRα. FFHM exposed to 10 µg/L sertraline had a significant upregulation of 11β-HSD expression in brain tissue, while no steroidogenic changes were observed in the FFHM ovary. Similarly, in FFHM brain tissue, CYP19 and 20β-HSD expression levels were significantly higher in fish exposed to 10µg/L sertraline compared to control. The significance of these findings with respect to survival, growth and reproduction are currently unknown, but represent future research needs.