O Brasil é um país megadiverso, entretanto a fauna e a flora encontram-se severamente ameaçadas por inúmeros fatores. Dentre eles, a introdução de espécies exóticas invasoras que, especialmente nos ambientes límnicos, é uma das grandes ameaças à conservação da biodiversidade, principalmente devido à predação, competição e introdução de novas doenças. Dentre os animais com grande potencial de invasão, casos envolvendo crustáceos são bastante documentados na literatura, como por exemplo, o lagostim Norte-Americano Procambarus clarkii, que é utilizado para fins de aquarismo e aquacultura em diversas partes do mundo. As informações sobre a ocorrência desta espécie no Brasil são escassas, havendo apenas cinco registros no estado de São Paulo. Inúmeros impactos já foram associados à presença desta espécie em várias partes do mundo, desde danos ao ecossistema até impactos sobre a biota nativa. Dessa forma, a dispersão de P. clarkii em território brasileiro pode gerar efeitos desastrosos aos ambientes límnicos. Sendo assim, o presente trabalho efetuou uma ampla revisão bibliográfica referente às características desta espécie e sua problemática de invasão no mundo, assim como investigou de forma integrada o presente, passado e futuro de seu processo de invasão no Brasil. Observou-se que o principal fator de introdução deste crustáceo no Brasil é o comércio ilegal para aquacultura e onze novas populações foram encontradas no estado de São Paulo. Adicionalmente, realizou-se uma análise de risco de invasão da espécie e constatou-se que a mesma apresenta alto poder de estabelecimento em território nacional e grande capacidade de geração de impacto. Os resultados deste trabalho alertam para a necessidade de investigações mais aprofundadas sobre o processo de invasão na América do Sul. Torna-se também imprescindível o investimento em fiscalização e em educação pública, a fim de evitar que os animais continuem sendo vendidos ilegalmente e introduzidos na natureza.

O Brasil é um país megadiverso, entretanto a fauna e a flora encontram-se severamente ameaçadas por inúmeros fatores. Dentre eles, a introdução de espécies exóticas invasoras que, especialmente nos ambientes límnicos, é uma das grandes ameaças à conservação da biodiversidade, principalmente devido à predação, competição e introdução de novas doenças. Dentre os animais com grande potencial de invasão, casos envolvendo crustáceos são bastante documentados na literatura, como por exemplo, o lagostim Norte-Americano Procambarus clarkii, que é utilizado para fins de aquarismo e aquacultura em diversas partes do mundo. As informações sobre a ocorrência desta espécie no Brasil são escassas, havendo apenas cinco registros no estado de São Paulo. Inúmeros impactos já foram associados à presença desta espécie em várias partes do mundo, desde danos ao ecossistema até impactos sobre a biota nativa. Dessa forma, a dispersão de P. clarkii em território brasileiro pode gerar efeitos desastrosos aos ambientes límnicos. Sendo assim, o presente trabalho efetuou uma ampla revisão bibliográfica referente às características desta espécie e sua problemática de invasão no mundo, assim como investigou de forma integrada o presente, passado e futuro de seu processo de invasão no Brasil. Observou-se que o principal fator de introdução deste crustáceo no Brasil é o comércio ilegal para aquacultura e onze novas populações foram encontradas no estado de São Paulo. Adicionalmente, realizou-se uma análise de risco de invasão da espécie e constatou-se que a mesma apresenta alto poder de estabelecimento em território nacional e grande capacidade de geração de impacto. Os resultados deste trabalho alertam para a necessidade de investigações mais aprofundadas sobre o processo de invasão na América do Sul. Torna-se também imprescindível o investimento em fiscalização e em educação pública, a fim de evitar que os animais continuem sendo vendidos ilegalmente e introduzidos na natureza.

O Brasil é um país megadiverso, entretanto a fauna e a flora encontram-se severamente ameaçadas por inúmeros fatores. Dentre eles, a introdução de espécies exóticas invasoras que, especialmente nos ambientes límnicos, é uma das grandes ameaças à conservação da biodiversidade, principalmente devido à predação, competição e introdução de novas doenças. Dentre os animais com grande potencial de invasão, casos envolvendo crustáceos são bastante documentados na literatura, como por exemplo, o lagostim Norte-Americano Procambarus clarkii, que é utilizado para fins de aquarismo e aquacultura em diversas partes do mundo. As informações sobre a ocorrência desta espécie no Brasil são escassas, havendo apenas cinco registros no estado de São Paulo. Inúmeros impactos já foram associados à presença desta espécie em várias partes do mundo, desde danos ao ecossistema até impactos sobre a biota nativa. Dessa forma, a dispersão de P. clarkii em território brasileiro pode gerar efeitos desastrosos aos ambientes límnicos. Sendo assim, o presente trabalho efetuou uma ampla revisão bibliográfica referente às características desta espécie e sua problemática de invasão no mundo, assim como investigou de forma integrada o presente, passado e futuro de seu processo de invasão no Brasil. Observou-se que o principal fator de introdução deste crustáceo no Brasil é o comércio ilegal para aquacultura e onze novas populações foram encontradas no estado de São Paulo. Adicionalmente, realizou-se uma análise de risco de invasão da espécie e constatou-se que a mesma apresenta alto poder de estabelecimento em território nacional e grande capacidade de geração de impacto. Os resultados deste trabalho alertam para a necessidade de investigações mais aprofundadas sobre o processo de invasão na América do Sul. Torna-se também imprescindível o investimento em fiscalização e em educação pública, a fim de evitar que os animais continuem sendo vendidos ilegalmente e introduzidos na natureza.

A knowledge of the basic biology of any fish is a primary requirement for the practical management of that stock of fish. This investigation was directed at a pure culture population of Yellowstone cutthroat trout, to describe the basic biology and provide a basis for management and further research. Kiakho Lake has a surface area of 67.42 acres, a maximum depth of 32 feet and a mean depth of 16.5 feet. Due to the rocky substrate, lack of littoral development and low total dissolved solids, the production of plankton and bottom fauna was small and characteristic of oligotrophic conditions. The food of cutthroat trout in Kiakho Lake in May was comprised of 83.9 percent by volume and 81.3 percent by occurrence of chironomid pupae. In June the food was 46.7 percent by volume and 45.8 and 35.5 percent by occurrence of chironomid larvae and Gammarus respectively. In July the Gammarus were 57.8 percent by volume and 60.3 percent by occurrence. In Lumberton Reservoir and Monroe Lake the Gammarus comprised 51.0 and 55.6 percent by volume and 34.4 and 78.2 percent by occurrence respectively of the food. In Garcia Lake, Chaoborus was 32.9 percent by volume and 36.0 percent by occurrence and the redside shiner, Richardsonius balteatus, was 27.8 percent by volume and 31.8 percent by occurrence. The fish appeared to be second in preference to Chaoborus. The body-scale relationship is described by a straight line having a slope of 1. A graph of instantaneous growth rate plotted against length, revealed that faster growing fish have a faster decrease in growth rate. Due to the absence of certain characteristics e.g. a concavity in the upper limit of the graph, the growth of Kiakho Lake cutthroat appeared to support the view that faster growing fish are selected by the fishery, and that it can be demonstrated in this type of graph. The data, fitted to a Parker and Larkin (1959) growth equation gave a z value of 0.71. The absence of "Lee's Phenomenon" gave support to the premise that the phenomenon can result from selection by a fishery, and invalidated the other ideas concerning the causes as far as this population was concerned. The spawning run in Kiakho Lake was estimated at 3,000 fish. A tagging program revealed that the fish spent on the average of 13 days to spawn, and that there was approximately a 54 percent mortality. The male fish appeared on the spawning grounds first. The female fish showed a decrease in size, later in the run, which was not shown by the males. The eggs hatched sometime in mid June and the young fish apparently spend one year in the outlet stream. The female fish mature between the ages of 2—4 and the males between 1—3. The mean number of eggs per female, plus or minus two standard deviations was 944± 393.29. A multiple regression analysis revealed that body length affected the number of eggs produced, 2.5 times as much as egg diameter. Recommendations were made, due to the probable effects of competition, that cutthroat trout be kept in pure culture populations. It was further suggested that cutthroat trout numbers be maintained in view of the severe reduction and almost extinction of the species in other areas. / Science, Faculty of / Zoology, Department of / Graduate

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 109-116). Also available on the World Wide Web.

In May, adult Yellowstone cutthroat trout (Salmo clarkii lewisii) moved from Kiakho Lake into its outlet to spawn. Upon emergence from the gravel, most young fry descended at night from the fast flowing, gravel bottom areas into slow flowing, mud and sand bottom regions where they spent the summer. The majority of fry over-wintered in the creek before ascending to the lake. The research was conducted in the summers of 1959 and 1960. It had two objectives: (1) to describe fry distribution and (2) to examine some characteristic fry "behavior" including movement. Traps and an experimental trough were operated. Behavior was observed, movements of marked fish were studied, and fry distribution was determined. Temperature, barometric pressure, water level, and light were recorded. Darkness apparently influenced the downstream movement of recently emerged fry for 90% of it occurred at night. A slow current apparently greatly slowed the rate of descent. The gradual descent of these fry in the "sluggish" Beaver Meadow during July evidently produced the late July uniform Beaver Meadow fry density. Long distance upstream and downstream movement of "healthy" fry in August was quite limited though short temporary movements of fry from their "home", may have been common. At least 60% of the fry held the same "home" for two weeks. Fry defended territories. The August 1960 Beaver Meadow fry population decrease was due to natural mortality. Month-old Beaver Meadow descending fry were characterized by small size and "physical weakness". In a week, the number of day versus night descenders was about equal, but within a 24 hour period, there was no correlation between the two. Bright moonlight appeared to depress night downstream movement, a fluctuating water level may have increased it, and a week long drop in creek temperature apparently depressed all downstream movement. Fry moving upstream were generally larger than average size fry. There was a moderate association between rising daily maximum water temperature over a period of several days and increased upstream movement. Fry in a trough ascended more at 20°C. than at 9°C. A week long drop in water temperature likely depressed movement. Because more than 80% of the movement occurred in the day, a certain minimum light intensity may be required before fry ascend much. The Kiakho outlet observations were compared to the findings of other researchers. Generally, stream dwelling Salmoninae appear to exhibit territorialism, homing, and limited movement,, Several other generalizations about stream dwelling trout, were suggested,, / Science, Faculty of / Zoology, Department of / Graduate

Thesis (M.S.)--Western Washington University, 2007. / Includes bibliographical references (leaves 73-84).

La question de la coexistence entre espèces est cruciale dans le contexte des changements globaux, où certaines espèces colonisent de nouveaux écosystèmes, tel le cas des espèces invasives. Dans les habitats discontinus, la coexistence entre espèces invasives et natives gagne à être considérée à la lumière de la théorie des métacommunautés, et en particulier en examinant séparément les processus de dispersion et les interactions locales afin de déterminer leurs effets relatifs. Les approches observationnelles en milieux naturels permettent par ailleurs la prise en compte de la complexité des relations possibles. C’est le travail abordé dans cette thèse à travers l’exemple de l’effet de l’invasion de l’écrevisse de Louisiane sur les amphibiens natifs dans des réseaux de mares. La densité des larves et la distribution des amphibiens ont montré la conccurrence avec l’écrevisse dans les mares. Grâce à la génétique du paysage, la dispersion de l’écrevisse s’est révélée fortement contrainte par le caractère discontinu des habitats, contrairement à celle des amphibiens, bien qu’elle ait été variable parmi les trois espèces étudiées. Les analyses d’isotopes stables ont montré que malgré sa position centrale dans les réseaux trophiques, l’écrevisse n’avait pas de fortes interactions trophiques avec les amphibiens, tout au plus un effet indirect par la modification de l’habitat. Sur la base des mécanismes considérés ici, la coexistence entre les amphibiens natifs et l’écrevisse invasive semble ainsi envisageable. Des suites de ce travail sont envisageables à l’échelle des communautés grâce à l’ADN environnemental. / The question of species coexistence is crucial in the context of global changes, where some species colonize new ecosystems, such as the case of invasive species. In patchy habitats, the coexistence between invasive and native species gains at being considered in the light of the metacommunity theory, and particularly by examining separately the processes of dispersal and local interactions to determine their relative effects. Besides, observational approaches in natural habitats allow to account for the complexity of the possible relationships. It is the work tackled in this thesis through the example of the effect of the red swamp crayfish on native amphibians in pond networks. The density of larvae and the distribution of native amphibians showed the co-occurrence with the crayfish in ponds. Owing to landscape genetics, the dispersal of crayfish was shown to be highly constrained by the patchy nature of habitats, contrary to that of amphibians, although it was variable among the three species considered. The stable isotope analyses showed that, despite its central position in the food webs, the crayfish did not have strong trophic interactions with amphibians, all the more an indirect effect through habitat modification. On the basis of the mechanisms considered here, the coexistence between native amphibians and the invasive crayfish seem possible. Perspectives from this work are envisaged at the community scale using environmental DNA.

Ulm, Univ., Diss., 2001.

L’étude des effets des radionucléides et des métaux sur les organismes vivants est nécessaire pour évaluer leur toxicité et leur risque écologique. Notre approche a visé dans un premier temps à étudier les impacts du cadmium (Cd) et de l’Uranium (U) sur différents niveaux biologiques de l’écrevisse Procambarus clarkii après exposition aigue et chronique. Nous avons évalué leurs impacts sur les mitochondries, les réponses face à un stress oxydant, les structures histologiques et la survie. Nous avons tenté de lier ces effets entre eux et à la bioaccumulation dans les branchies et l’hépatopancréas. Nous avons aussi essayé de différencier la chimio- et la radiotoxicité de l’U en exposant des écrevisses soit à l’U appauvri soit au 233U (présentant une activité spécifique plus élevée) au travers des mêmes critères d’effets. Nous avons démontré que le gène mt codant pour la métallothionéine était toujours surexprimé en présence du Cd. De ce fait, il semble être un bon biomarqueur de toxicité du Cd chez P. clarkii. Nous avons mis en évidence que les deux métaux affectent les mitochondries grâce au suivi des niveaux d’expressions des gènes mitochondriaux (12s, atp6 et cox1), et que leur mécanismes d’action ne semblent pas être toujours les mêmes. Nous avons aussi prouvé que l’U génère plus de stress oxydant que le Cd grâce à la comparaison des niveaux d’expressions de gènes qui codent pour des antioxidants (sod(Mn) et mt) et des réponses enzymatiques de la superoxyde dismutase, la catalase, la glutathion peroxydase et la glutathion S transférase. Toutefois, les symptômes des atteintes histo-pathologiques semblent être les mêmes pour les deux métaux. En comparant leurs effets sur la survie des écrevisses, nous avons conclu que le Cd était plus toxique que le radioélément. D’autre part, nous avons démontré que les effets toxiques de l’U aux concentrations rencontrées dans l’environnement, sont plus liés à la chimiotoxicité qu’à la radiotoxicité de cet élément. Nous avons démontré que, les réponses moléculaires varient en fonction de l’intensité et la durée du stress chimique imposé aux organismes. Nous avons proposé d’utiliser les expressions de l’ensemble des gènes étudiés en tant que biomarqueurs de toxicité de l’U plutôt que les activités enzymatiques à cause de leur sensibilité. Ce travail de thèse propose des mécanismes d’actions de l’U basé surtout sur les réponses moléculaires et confirme la nécessité d’approfondir l’étude du profil écotoxicologique de ce radioélément. / The study of the effects of radionuclides and metals on organisms is necessary for the evaluation of their toxicity and their ecological threats. We first aimed to study the impacts of cadmium (Cd) and Uranium (U) on different biological levels of the crayfish Procambarus clarkii after acute and chronic exposures. We evaluated their impacts on mitochondria, oxidative stress responses, on histological structures, and the survival rates. We tried to connect these effects between them and to the bioaccumulation in the gills and the hepatopancreas. We also tried to discriminate the chemo and the radiotoxicity of U by exposing crayfish to either depleted or enriched U (233U: presenting a higher specific activity) using the same criteria of effects. We demonstrated that the gene mt encoding for the metallothionein was always over-expressed in the presence of Cd. Therefore, it seems to be a good biomarker of Cd toxicity in P. clarkii. The follow up of mitochondrial genes expressions (12s, atp6 and cox1), showed that both metals affect mitochondria and that their mechanisms of action do not seem to be always the same. We also observed that U generates more oxidative stress than Cd when comparing the expression levels of genes encoding for antioxidants (sod (Mn) and mt) and the enzymatic activities of superoxide dismutase, the catalase, the glutathione peroxidase and the glutathione S transferase. However, the symptoms of histo-pathological damages after Cd and U contamination were similar in both conditions. After comparing the survival rates of the crayfish, we concluded that Cd was more toxic than the radioelement. Moreover, we demonstrated that the toxic effect of U on P. clarkii exposed to a low environmental concentration is mainly due to its chemotoxicity rather than to its radiotoxicity. We established that, the molecular answers vary according to the intensity and the duration of the chemical stress applied to the organisms. We suggested the use of the expressions of all the studied genes as biomarkers of toxicity of U rather than the enzymatic activities because of their sensitivity. This work proposes mechanisms of actions of U based especially on the molecular responses and confirms the necessity of studying the ecotoxicological profile of this radioelement.