L’objectif de ce travail était d’évaluer le potentiel du chabot (Cottus sp.) comme espèce sentinelle utilisable pour la surveillance des milieux aquatiques à l’aide d’un ensemble de biomarqueurs. Pour y parvenir, la caractérisation des niveaux de réponses mesurés chez le chabot était réalisée en conditions contrôlées et en contexte terrain à l’aide de biomarqueurs reflétant la métabolisation des xénobiotiques (7-ethoxyrésorufine-O-dééthylase, EROD ; cytochrome P4503A, CYP3A ; glutathion-S-transférase, GST), le stress oxydant (glutathion peroxydase, GPx ; lipoperoxydation, TBARS) et la neurotoxicité (acétylcholinestérase, AChE). Les études de laboratoire ont permis de caractériser les réponses des biomarqueurs sélectionnés à l’aide de substances de références telles que la β-naphtoflavone (βNF), le cuivre et le fénitrothion. Les investigations in situ ont servi à évaluer le pouvoir discriminant des biomarqueurs et à caractériser les profils de réponses dans un contexte de contaminations multiples. Les résultats ont mis en évidence que le chabot pourrait être utilisé dans un contexte de biosurveillance pour mesurer une batterie de biomarqueurs sélectionnés. En effet, les profils de réponses observés permettent une bonne discrimination entre les sites de référence et les sites contaminés. Cependant, les réponses de l’AChE musculaire et des TBARS hépatiques sont difficiles à expliquer.Afin de mieux caractériser l’état de santé des poissons, il est apparu important de compléter cette batterie de biomarqueurs en y incorporant des marqueurs immunitaires à savoir l’activité du lysozyme et l’activité de la flambée oxydative phagocytaire. D’une manière générale, les premiers résultats obtenus au laboratoire et in situ ont montré que les marqueurs immunitaires chez cette espèce sont des paramètres sensibles et inductibles qui contribuent à une meilleure caractérisation de la contamination des milieux et de ses effets. L’étude des immunomarqueurs pourrait in fine permettre de prédire des modifications au niveau populationnel, du fait de la corrélation existante entre activité immunitaire et sensibilité aux pathogènes. Dans un contexte d’approche multi-marqueurs sur le terrain, l’étude du potentiel global des organismes en lien avec l’interaction polluants/pathogènes serait donc une perspective intéressante à développer. / The aim of this work was to evaluate the usefulness of bullhead (Cottus sp.) as a sentinel fish species to assess aquatic environment contamination using a set of biomarkers. In order to reach this objective, the characterization of response levels measured in bullhead was realized in laboratory and field context using biomarkers of xenobiotic metabolisation (7-ethoxyresorufin-O-deethylase, EROD; cytochrome P4503A, CYP3A; glutathione-S-transferase), oxidative stress (glutathione peroxidase, GPx; lipoperoxidation, TBARS) and neurotoxicity (acetylcholinesterase, AChE). Laboratory investigations were performed to characterize variations of biomarker responses with reference substances such as β-naphtoflavone (BNF), copper and fenitrothion. Field investigations aimed to evaluate discriminant power of selected biomarkers and to characterize response profiles in a multi-contamination context. The results showed that the European bullhead could be used in environmental monitoring context to measure a set of selected biomarkers. Indeed, observed response profiles allow a good discrimination between unpolluted streams and contaminated area. However, muscular AChE and hepatic TBARS responses are difficult to explain.To better characterize the health status of fish, it became important to complete this set of biomarker adding immune markers namely lysozyme and oxidative burst activities. Globally, the first results, obtained in laboratory and in situ, have shown that immune markers are sensitive and inductible parameters that contribute to a better characterization of environmental contaminations and their effects. These markers allow a better site discrimination and bring complementary informations to those provided by other biomarkers and more particularly to biotransformation enzymes. In fact, immunomarker analysis could allow, in fine, populational prediction due to link between immune activities and susceptibility to pathogens. In a context of field multiparametric approach, study of global health potential in organism, link with pollutants/pathogens interaction, was an attractive prospect for the future.

Nest sites of reticulate sculpin (Cottus perplexus) were located in two stream reaches, one from a basalt basin and one from a sandstone basin. Stream reaches were similar in gradient, basin area, elevation, climate, and riparian vegetation but differed in biologic community structure and substrate characteristics. An electivity index was used to determine if selection for nest sites occurred and also to compare patterns of selection between habitat types and stream reaches. Eggs from nests were collected so comparisons in reproductive effort could be made between streams and habitat types. Cobble sized substrate was positively elected in all habitat units examined and moderate embeddedness (6-25%) was positively elected in all units but one. No nests were found on bedrock, wood, or fine sediment substrate. A small number of nests were found on both larger gravel and boulder size particles. Only two out of 471 nests located were associated with rocks which were embedded 51% or more. Reproductive effort on a per nest basis was greater in the basalt stream. Nest weights in the basalt stream exceeded nest weights in the sandstone stream by 90% (95% confidence interval 52-152%) on average and the number of eggs per nest was 39% (95% confidence interval 8-79%)greater in the basalt stream. Differences in reproductive effort per nest within an individual stream were not detected in comparisons among scour pools, riffles, high cobble density and low cobble density habitat units. Reproductive effort per nest varied through the sampling period with intermediate effort early, low effort in the mid portion and the highest effort late. This pattern was apparent in both streams but statistically significant in the sandstone stream only. Nest densities were similar at 0.16 nest/m�� and 0.17 nest/m�� for the basalt and sandstone streams respectively. Differences in nest densities within streams were not detected between scour pools and riffles in either stream or between high and low cobble density units in the basalt stream. A difference was detected between high and low cobble density units in the sandstone stream (p=0.02). Nest densities were greater on average in the tailout portions of pools as opposed to the head and body portions in both streams but statistically significant in the sandstone stream only (p=0.04). We speculate that because patterns of electivity were similar between streams and between different habitat types within a stream, all with different levels of habitat availability, that male fitness is tightly linked with habitat selection for nest sites. Our results would suggest that reticulate sculpin nest site selection and reproductive effort are not strongly influenced by habitat on a geomorphic channel unit scale. It may be more appropriate to delineate sculpin habitat by substrate patches within geomorphic habitat units. / Graduation date: 1998

L’objectif de ce travail était d’évaluer le potentiel du chabot (Cottus sp.) comme espèce modèle pour l’étude des effets des perturbateurs endocriniens (PE) in situ. Pour y parvenir, ce travail a débuté par l’étude de la reproduction des populations sauvages de chabots. En effet, le chabot présentant un mode de reproduction complexe, cette étape nous a semblé être un pré-requis indispensable avant d’envisager l’utilisation de cette espèce en tant qu’indicateur de la contamination par des perturbateurs endocriniens. Cette première étape a permis de confirmer l’existence de deux stratégies reproductives chez les chabots (annuelle ou saisonnière) dans notre zone d’étude inhérente au programme INTERREG et a mis en évidence les facteurs environnementaux qui en sont responsables. Par ailleurs, cette étude a permis la confirmation d’une hypertrophie dans le rein des chabots mâles en période de reproduction et la mise au point d’une méthode histologique permettant de la quantifier : la mesure de l’épaisseur de l’épithélium rénal (KEH). Ce travail a ensuite consisté à caractériser les niveaux de réponses mesurés chez le chabot en conditions contrôlées et en contexte terrain. Les études de laboratoire ont permis de statuer sur l’inductibilité ainsi que la sensibilité et la spécificité de l’hypertrophie rénale à l’aide de substances de références androgéniques ou non androgéniques. Les investigations in situ ont servi à évaluer le pouvoir discriminant de cet indicateur en contexte de pollution environnementale mais également de statuer sur le potentiel du chabot comme espèce modèle pour évaluer les effets des PE à l’aide d’autres marqueurs reflétant la perturbation endocrinnienne. Les résultats ont mis en évidence que l’utilisation de la méthode KEH chez le chabot comme un indicateur d’exposition aux androgènes n’était pas pertinente aussi bien au laboratoire que sur le terrain. En effet, il est apparu être faiblement inductible et moins sensible que ceux déjà disponible chez d’autres espèces. De plus, les profils de réponses observés sur le terrain n’ont pas permis une discrimination des sites de références et des sites contaminés tout comme les réponses des autres marqueurs utilisés. En résumé ce travail démontre le faible potentiel du chabot pour renseigner sur la perturbation endocrinnienne. Les efforts doivent néanmoins se poursuivre pour identifier et caractériser les protéines inductibles par les androgènes responsables des modifications histologiques afin de développer et valider une méthode de dosage quantitative spécifique et sensible utilisable comme biomarqueur d’androgénicité qui permettrait d’envisager l’utilisation du chabot comme espèce sentinelle utilisable pour la surveillance des milieux aquatiques. / The aim of this study was to assess the potential of the European bullhead (Cottus sp.) as a model species for studying the in situ effects of endocrine disruptors compounds (EDCs). To achieve this goal, this work began by studying the reproduction of wild populations of bullheads. In fact, bullheads present a complex mode of reproduction and this step seemed to be an essential prerequisite before considering the use of this species as an indicator of the contamination by endocrine disruptors. This first step confirmed the existence of two reproductive strategies in bullhead (annual or seasonal) in our study area inherent in the program INTERREG and highlighted the environmental factors that are responsible for this phenomenon. Furthermore, this study allows to confirm the hypertrophy in the kidney of male bullhead during the breeding period and to develop a histological method to quantify it : the measurement of the kidney epithelium height (KEH). This work then consisted in characterizing the response levels measured in bullhead in controlled conditions and in the field. Laboratory studies, using androgenic or no androgenic reference substances, have allowed to determine the inducibility, the sensitivity and the specificity of the renal hypertrophy. In situ investigations were used to assess the discriminating power of this indicator but also to decide on the potential of bullhead as a model species to evaluate the effects of EDCs with other markers reflecting endocrine disruption.The results showed that using the KEH method in bullheads as an indicator of exposure to androgens was not relevant for both laboratory and field studies. Indeed, it appeared to be weakly inducible and less sensitive than those already available in other species. Moreover, response profiles observed in the field did not allow to discriminate references and contaminated sites as the responses of others biomarkers used. In summary, this work shows the weak potential of bullhead to provide information on endocrine disruption. Nevertheless, efforts need to continue in order to identify and caracterize the molecular signals responsible for histological changes in order to develop and validate a specific and sensitive quantitative assay which could be used as a biomarker of androgenicity. In this way, bullhead could be considering as a sentinel species for monitoring aquatic.

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 53-61). Also available on the World Wide Web.

Freshwater sculpins (Cottus) are common throughout temperate regions of the Northern Hemisphere. Their broad distribution in the Western North America makes them a good model for understanding phylogeographic relationships among western fishes. Within much of the interior west three lineages, C. bairdii, C. confusus, and the C. beldingii complex, are most prevalent. The distribution of these three overlap in the Snake River Basin. All occur below Shoshone Falls on the Snake River. However, only two currently reside in the Upper Snake River above the falls. An exception are the Lost River streams of central Idaho. While these streams are technically part of the Upper Snake River Basin, they do not directly connect with the Snake River. Preliminary studies with a single mitochondrial DNA (mtDNA) gene suggested multiple pathways for Cottus introduction into the Lost River stream complex. Here, three mitochondrial and five nuclear genes were examined to investigate the phylogenetic relationships of these three lineages. Sequences were obtained from 71 different populations in the Lost River streams and surrounding basins. Maximum Likelihood (ML) phylogenies were constructed using these data. Our data indicate that relationships among populations within these species are complex and that no single invasion into the Lost River streams and surrounding regions can account for the phylogenetic signals detected. Instead, it appears that multiple invasions in an evolving landscape played a significant role in the modern distribution of species in this region.

In the Pacific Northwest ecoregion of North America, sculpins represent a major constituent of freshwater assemblages in coastal rivers. Based on their prevalence and abundance, sculpins are likely important ecologically, yet little is known of their interactions with co-occurring species, such as widely studied salmon and trout (salmonines). In this study, I evaluated inter- and intraspecific interactions involving cottids (Cottus sp.) and coastal cutthroat trout (Oncorhynchus clarkii clarkii). I used a response surface experimental design to independently evaluate effects of cutthroat trout and sculpin biomass on growth and behavior. There was evidence of both intra- and interspecific interactions between cutthroat trout and sculpins, but the interactions were asymmetrical with biomass of cutthroat trout driving both intra- and interspecific interactions, whereas sculpins had little influence overall. Cutthroat trout biomass was positively related to conspecific aggressive interactions and negatively related to growth. Sculpin exhibited increased use of cover during the day in response to greater biomass of cutthroat trout, but not sculpin biomass. Nocturnal use of cover by sculpins was unaffected by biomass of either species. This experiment provides insights into the species interactions and the mechanisms that may allow sculpins and salmonines to coexist in nature. As cutthroat trout appear to be superior competitors, coexistence between sculpins and cutthroat trout may depend on some form of refuge, either in the form of in-stream cover or crypsis coupled with diel resource segregation. Cutthroat trout are usually active during the day, indicating that nocturnal foraging by sculpins may in part represent a behavior that minimizes interspecific competition with cutthroat trout. / Graduation date: 2012

La température de l'eau joue un rôle majeur dans le cycle de vie des poissons. Dans un contexte de changement climatique global, le réchauffement peut avoir un impact fort sur la croissance, la fécondité et la survie. L'enjeu de cette thèse est la modélisation mathématique de l'influence de la température sur les traits d'histoire de vie d'une population de chabot (Cottus gobio) afin de faire de la prédiction à la fois au niveau individuel et populationnel. Les données expérimentales qui permettront de calibrer les modèles sont issues du bassin de la Drôme (France) et plus particulièrement du sous-bassin du Bez. Dans une première étape, il s'agit de développer un modèle de rétrocalcul qui peut être utilisé pour calculer les longueurs individuelles des chabots aux âges précédents à partir des données mesurées à la capture. Il s'agit, dans un deuxième temps, de développer un modèle de croissance dépendant de la température de l'eau qui sert à prédire la longueur moyenne des chabots à un âge donné. Enfin, il s'agit de passer de l'échelle de l'individu à celle de la population en prenant en compte tous les traits d'histoire de vie et leurs dépendances vis-à-vis de la température. Plus précisément, un modèle matriciel de type Leslie, à la fois dépendant du temps et de la température, structuré en classe d'âges est développé et utilisé pour prédire la dynamique de population sous différents scénario du réchauffement climatique / Water temperature plays a key role in the life cycle of fish. Therefore, increasing temperatures due to the expected climate change may have a strong impact on growth, fecundity and survival. The goal of this thesis is to model the impact of temperature on the life-history traits of a bullhead population (Cottus gobio) in order to make predictions both at individual and at population level. The models developed here are calibrated on experimental field data from a population living in the Bez River network (Drôme, France). First, a new back-calculation model is derived that can be used to compute individual fish body lengths at earlier ages from capture data. Next, a growth model is proposed that incorporates the water temperature and can be used to predict the mean length at a given age and temperature. Finally, the population is modelled as a whole by linking all life-history traits to temperature. For this purpose, a spatialised time- and temperature-dependent Leslie matrix model structured in age classes was used to predict the population dynamics under different temperature scenarios

The study of the Utah sculpin in Logan River was based on 801 specimens collected during 1949 to March 1951. Numbers of fish examined for various catagories of the study wares length-frequency, 495; aging by vertebrae, 407; length-weight relationship, 601; and food habits, 275. Fish were collected by use of an electric shocking machine generating 600 watts and 220 volts. Numbers of fish occurred as high as 150 per tenth mile of stream. Preferred habitats occurred in areas of coarse gravel and small rocks. Vertebrae dissected from the fish were used in age determination. Length-frequency proved to be a general correlation to the aging technique. Fish were difficult to sex by external observation except during the breeding season. Relationship between standard length and weight is described by the following formula: W = 4.236 X 10-4 L2•900 The coefficient of condition (K) increased with length up to 60 millimeters in standard length and decreased in length in fish ranging from 60 to 125 millimeters in standard length. The greatest variation in K occurred in fish below 50 millimeters in length. The factor for converting total length to standard length as determined from 601 specimens between 24 and 112 millimeters. standard length was 0.812. The factor for converting standard length to total length for the same fish was 1.232. The bulk of the diet consisted almost entirely of aquatic insects. Most of the aquatic insects were diptera. Ephemeroptera, plecoptera, and trichoptera were consumed in almost equal numbers. Food availability and preference were determined from bottom samples of the river. Competition for food is minimized somewhat by the fact that the sculpin is a bottom feeder and the trout is primarily a surface feeder. Predation of trout eggs by the sculpin was almost non-existent.

A curvilinear regression model was used to determine an expected stomach capacity for any size Bear Lake sculpin with a standard length between 4-9.5 centimeters. Stomach contents were then expressed as a percent fullness and the change in percent fullness with time intervals was used to compute an instantaneous digestion rate. The instantaneous consumption rate was computed by the formula C=log P1-log P0 +d, where C=instantaneous consumption rate. The amount of food consumed during a time interval was computed from the formula It=CtSt, where It=amount of food ingested during a time interval expressed in percent fullness of stomach. The 24 hour consumption rate was computed by summing the consumption rates for 4 consecutive time intervals of 6 hours each. Studies in September, December, and May give instantaneous digestion rates of -.424, -.214, and -.235 and total food consumption rates of 22.2, 10.2, and 6.1 percent of stomach capacity for each individual fish in the population.

Bear Lake sculpin (Cottus extensus) exhibited an ontogenetic habitat shift during their first year of life. Soon after hatching in the littoral zone, the fry swam to the surface where they dispersed throughout the lake. Most juveniles that initially settled in the profundal zone returned to the littoral zone during their first summer. Patterns in the daily growth increments of otoliths confirmed the history of habitat residence and the individual size at the habitat switch. We used this habitat shift to test a μ/g model incorporating a growth rate-mortality risk trade-off. A trade-off occurred in the littoral zone because both growth rate and mortality risk were greater in this habitat. Given initial profundal residence, the directed movement of juveniles to the more profitable littoral zone was consistent with model predictions. Contrary to model predictions, juvenile sculpin initially occupied both habitats and switched habitats at a wide range of sizes. lack of a discrete switch size may have resulted, in part, from the lack of a strong trade-off or from an inability of fish to respond facultatively to environmental variables at the large spatial scale of this system.