Développement d'un outil générique de simulation distribuée de marchés électroniques basés sur les enchères

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Biological Impacts and Uses of Black Bass Competitive Fishing Tournaments on Large Lake Systems

Recreational fisheries in North America are valued between $47.3 billion and $56.8 billion. Fisheries managers must make strategic decisions based on sound science and knowledge of population ecology, to effectively conserve populations. Competitive fishing, in the form of tournaments, has become an important part of recreational fisheries, and is common on large waterbodies including the Great Lakes. Black Bass, Micropterus spp., are top predators and among the most sought after species in competitive catch-and-release tournaments. This study investigated catch-and-release tournaments as an assessment tool through mark-recapture for Largemouth Bass (>305mm) populations in the Tri Lakes, and Bay of Quinte, part of the eastern basin of Lake Ontario. The population in the Tri Lakes (1999-2002) was estimated to be stable between 21,928-29,780, and the population in the Bay of Quinte (2012-2015) was estimated to be between 31,825-54,029 fish. Survival in the Tri Lakes varied throughout the study period, from 31%-54%; while survival in the Bay of Quinte remained stable at 63%. Differences in survival may be due to differences in fishing pressure, as 34-46% of the Largemouth Bass population on the Tri Lakes is harvested annually and only 19% of catch was attributed to tournament angling. Many biological issues still surround catch-and-release tournaments, particularly concerning displacement from initial capture sites. In the past, the majority of studies have focused on small inland lakes and coastal areas, displacing bass relatively short distances. My study displaced Largemouth and Smallmouth Bass up to 100km, and found very low rates of return; only 1 of 18 Largemouth Bass returned 15 km and 1 of 18 Smallmouth Bass returned 135 km. Both species remained near the release sites for an average of approximately 2 weeks prior to dispersing. Tournament organizers should consider the use of satellite release locations to facilitate dispersal and prevent stockpiling at the release site. Catch-and-release tournaments proved to be a valuable tool in assessing population variables and the effects of long distance displacement through the use of mark recapture and acoustic telemetry on large lake systems.

Changes in the Ecology and Abundance of Smallmouth Bass in Lake Ontario: 1958-2014

Understanding the reasons for long-term population change in a species requires an evaluation of ecological variables that may account for the observed dynamics. In this study, long-term changes in indices of Smallmouth Bass condition and population levels were examined for eastern Lake Ontario and the Bay of Quinte. Smallmouth Bass are an extremely important recreational fish species native to Lake Ontario. They have experienced numerous changes in their environment through direct human impacts, climate change, predation, and habitat sharing with non-native species. Smallmouth Bass have experienced an increase in body length and weight likely due to a diet shift from crayfish to predominantly Round Gobies which has allowed them to increase their growth rate. According to existing assessment data however, this increase in body size has not been associated with an increase in abundance. Long-term data from gill net sampling shows that Smallmouth Bass populations have been declining since the late 1980s with no indication of recovery. This could be due to a variety of factors, but it is most likely due to a change in the selectivity of gill nets because of the change in body size as well as a habitat shift away from gill net sampling sites. Adjusting for gill net selectivity has revealed that sub-adult bass abundance is currently greater than it was historically, and that very large bass are likely not being retained within the gill nets that are currently used. The use of a long-term data set in this study has led to a much better understanding of Smallmouth Bass abundance and ecology.

Conception de scénarios cartographiques pour la ceinture verte de Sherbrooke basés sur des fonctions prioritaires

La ville de Sherbrooke a présenté dans son schéma d'aménagement et de développement révisé 2012-2027 son projet d'implanter une ceinture verte sur son territoire. Elle n'a cependant pas défini d'orientations claires quant aux objectifs et à la délimitation de celle-ci. Le but de cet essai est d'alimenter la réflexion des décideurs de la ville de Sherbrooke à ce sujet en présentant des scénarios cartographiques de ceintures vertes. Pour réaliser ces scénarios, une revue de littérature a été effectuée afin de définir le concept de ceinture verte et d’identifier les fonctions remplies par ces ceintures vertes. Parmi ces fonctions, cinq sont priorisées par la Ville de Sherbrooke, soit : contrôler l'étalement urbain, préserver la biodiversité, favoriser l'accès des citoyens à un espace vert, protéger contre les inondations et connecter la ceinture verte avec les corridors écologiques régionaux. Les scénarios cartographiques produits sont basés sur des indicateurs et indices spatiaux aptes à représenter ces fonctions sur le territoire de la municipalité. Ces traitements géomatiques ont permis de créer des cartes représentant les zones de sensibilité du territoire de Sherbrooke pour l'implantation d'une ceinture verte selon ces cinq fonctions prioritaires. Ces traitements ont permis de déterminer que les zones les plus prioritaires pour l’implantation d’une ceinture verte représentent un peu plus de la moitié du territoire de la ville de Sherbrooke. Elles encerclent la trame urbaine tout en incluant quelques îlots en périphérie et le secteur sud-ouest du territoire municipal. L'approche de conception de scénarios de ceinture verte présentée ici est comparée à d’autres approches utilisées au Québec et dans d’autres études sur le sujet. Cette approche multi-fonction est novatrice et constitue un outil précieux pour les responsables municipaux qui souhaitent se doter d'une ceinture verte. Cette démarche est adaptative et le scénario de ceinture verte produit pour la Ville de Sherbrooke pourra être mis à jour selon l’évolution de leur réflexion sur les fonctions prioritaires. Cette démarche est également facilement généralisable à d’autres contextes municipaux.

Barry Lieberman & Friends present Catalin Rotaru, double bass March 15, 2015

Concert Program

Edward W. Taylor / Patricia Cranton, and Associates (Hrsg.): The Handbook of Transformative Learning, Theory, Research, and Practice. San Francisco, CA: Jossey-Bass 2012 [...] [Sammelrezension]

Sammelrezension von: 1. Edward W. Taylor / Patricia Cranton, and Associates (Hrsg.): The Handbook of Transformative Learning, Theory, Research, and Practice, San Francisco, CA: Jossey-Bass 2012 (598 S.; ISBN 978-1-111-21891-4) 2. Jack Mezirow / Edward W. Taylor, and Associates (Hrsg.): Transformative Learning in Practice, Insights from Community, Workplace, and Higher Education, San Francisco, CA: Jossey-Bass 2009 (303 S.; ISBN 978-0-470-25790-6)

The impacts of environmental and anthropogenic stressors on largemouth bass: an integration of field and laboratory studies

Several environmental stressors can impact the physiology and survival of fishes. Fish experience natural fluctuations in temperature and dissolved oxygen, but variations in these parameters due to anthropogenic sources are typically greater in magnitude and duration. Changes in temperature and oxygen of anthropogenic origins may therefore have larger negative impacts on fish than those occurring during natural events. Physiological parameters are sensitive indicators of the impacts of stressors by providing insight into the manner in which fish are disturbed by the stressor. Fish may display cumulative physiological responses to successive stressors, but the concept of synergy among multiple thermal stressors is poorly understood. Further, some fish species can be subjected to competitive angling events, which expose fish to an array of additional stressors that can increase mortality. The impacts of these events may change over seasons as fish display seasonal changes in behavior and physiology. Latitudinal origin may also affect the physiological response and mortality of fish exposed to common environmental stressors as individual populations are adapted to local environmental conditions. This thesis focuses on addressing these potential impacts on physiological parameters and mortality of largemouth bass (Micropterus salmoides) and provides implications for management and conservation. Largemouth bass were relatively robust to abrupt changes in temperature and oxygen, but were perturbed from physiological homeostasis during large (12°C) temperature shocks and low (< 4 mg O2/L) levels of dissolved oxygen. Cumulative physiological impacts of multiple cold shocks were only slightly greater than the disturbances sustained during a single cold shock, suggesting largemouth bass are able to tolerate successive thermal stressors. Largemouth bass exhibited seasonal changes in physiological parameters but the responses of fish to angling tournaments were relatively similar across seasons when compared with seasonal controls. Mortality was low during angling tournaments held during four seasons and no apparent seasonal trends were observed. Lastly, largemouth bass from two latitudinally separated populations exhibited differences in their physiological responses to acute cold stressors and overwinter mortality, characterized by greater mortality and physiological disturbances of southern fish than northern fish. Knowledge gained from this study can be used to make management and conservation decisions regarding a host of environmental factors and provides insight into the mechanisms by which fish species can persist over large latitudinal ranges.

Fertilization strategies for Sea Bass Dicentrarchus labrax (Linnaeus, 1758): effects of pre-incubation and duration of egg receptivity in seawater

Studying gamete biology can provide important information about a species fertilization strategy as well as their reproductive ecology. Currently, there is a lack of knowledge about how long sea bass Dicentrarchus labrax eggs can remain viable after being activated in seawater. The objectives of this study were to understand the effects of pre-incubation of fresh and overripe sea bass eggs in seawater and to determine the duration of egg receptivity. Pooled eggs (fresh and overripe) from four females were pre-incubated in seawater for 0 min (control), 0.5 min, 1 min, 3 min, 10 min and 30 min and then fertilized by pooled sperm from four males. The fresh eggs had a higher fertilization success than overripe eggs. Our results revealed a significant effect of pre-incubation time for both the fresh (P < 0.01) and overripe eggs (P < 0.01). Fertilization success of eggs significantly declined for both these treatments after 3 min of pre-incubation, which clearly indicates that sea bass eggs are able to be fertilized by sperm for up to 3 min after release into seawater. This study has particular importance for understanding fertilization strategies, reproductive potential, as well as reproductive ecology of sea bass.

Evaluation of the impact of polyethylene microbeads ingestion in European sea bass (Dicentrarchus labrax) larvae

Microplastics are present in marine habitats worldwide and may be ingested by low trophic organisms such as fish larvae, with uncertain physiological consequences. The present study aims at assessing the impact of polyethylene (PE 10-45µM) microbeads ingestion in European sea bass (Dicentrarchus labrax) larvae. Fish were fed an inert diet including 0, 104 and 105 fluorescent microbeads per gram from 7 until 43 days post-hatching (dph). Microbeads were detected in the gastrointestinal tract in all fish fed diet incorporating PE. Our data revealed an efficient elimination of PE beads from the gut since no fluorescent was observed in the larvae after 48h depuration. While the mortality rate increased significantly with the amount of microbeads scored per larvae at 14 and 20 dph, only ingestion of the highest concentration slightly impacted mortality rates. Larval growth and inflammatory response through Interleukine-1-beta (IL-1) gene expression were not found to be affected while cytochrome-P450-1A1 (cyp1a1) expression level was significantly positively correlated with the number of microbeads scored per larva at 20 dph. Overall, these results suggest that ingestion of PE microbeads had limited impact on sea bass larvae possibly due to their high potential of egestion

Calcium response of KCl-excited populations of ventricular myocytes from the European sea bass (Dicentrarchus labrax): a promising approach to integrate cell-to-cell heterogeneity in studying the cellular basis of fish cardiac performance

Climate change challenges the capacity of fishes to thrive in their habitat. However, through phenotypic diversity, they demonstrate remarkable resilience to deteriorating conditions. In fish populations, inter-individual variation in a number of fitness-determining physiological traits, including cardiac performance, is classically observed. Information about the cellular bases of inter-individual variability in cardiac performance is scarce including the possible contribution of excitation-contraction (EC) coupling. This study aimed at providing insight into EC coupling-related Ca2+ response and thermal plasticity in the European sea bass (Dicentrarchus labrax). A cell population approach was used to lay the methodological basis for identifying the cellular determinants of cardiac performance. Fish were acclimated at 12 and 22 A degrees C and changes in intracellular calcium concentration ([Ca2+](i)) following KCl stimulation were measured using Fura-2, at 12 or 22 A degrees C-test. The increase in [Ca2+](i) resulted primarily from extracellular Ca2+ entry but sarcoplasmic reticulum stores were also shown to be involved. As previously reported in sea bass, a modest effect of adrenaline was observed. Moreover, although the response appeared relatively insensitive to an acute temperature change, a difference in Ca2+ response was observed between 12- and 22 A degrees C-acclimated fish. In particular, a greater increase in [Ca2+](i) at a high level of adrenaline was observed in 22 A degrees C-acclimated fish that may be related to an improved efficiency of adrenaline under these conditions. In conclusion, this method allows a rapid screening of cellular characteristics. It represents a promising tool to identify the cellular determinants of inter-individual variability in fishes' capacity for environmental adaptation.

Hotel Victory on South Bass Island

The Hotel Victory opened on South Bass Island in 1892. It was an enormous structure that accommodated 625 guests and had a capacity for 800 dinner guests. The owners believed the hotel, located on a bluff on the west side of the island, could compete with the prestigious summer retreats on the East Coast. Promotional materials boasted that the Hotel Victory was the largest seasonal hotel in the country. The hotel burned to the ground in a massive fire in 1919. Today the grounds are part of the South Bass Island State Park.

South Bass Island Toboggan Water Slide

This aerial view shows the toboggan water slide on South Bass Island. Many such water slides existed on bathing beaches on Lake Erie's islands during the 1920s. .

President William Howard Taft and First Lady Nellie Taft at South Bass Island

This picture shows President William Howard Taft and First Lady Helen Herron Taft readying to lay the cornerstone of Perry's Victory and International Peace Memorial on South Bass Island in August 1912. The monument was built between 1912 and 1915 to commemorate Commodore Oliver Hazard Perry's victory on Lake Erie over the British fleet in September 1813. It also represented the lasting peace between the U.S., Canada, and England.

Conception, synthèse et activité anticancéreuse d’analogues basés sur la molécule FTY720 (Gilenya)

FTY720 (aussi connu sous le nom de Fingolimod ou Gilenya) agit sur les récepteurs sphingosine-1-phosphate (S1P) et induit la suppression du système immunitaire (immunosuppression). Cette molécule est reconnue pour avoir une activité contre plusieurs cellules cancéreuses. Cette activité est indépendante de l’action sur les récepteurs S1P et on attribue plutôt la mort (apoptose) des cellules cancéreuse à la capacité que possède la molécule à réduire le transport des nutriments dans la cellule. Toutefois, malgré ses nombreux avantages, FTY720 ne peut pas être utilisé afin de traiter des humains puisque l’activation secondaire des récepteurs S1P1 et S1P3 mènent à une diminution du rythme cardiaque (bradycardie) chez les patients. Notre groupe s’est donc concentré sur la synthèse d’analogues qui potentiellement n’activeraient pas le récepteur S1P tout en gardant une activité biologique contre plusieurs cellules cancéreuses. Malgré le fait que nos analogues agissent également sur la diminution du transport des nutriments dans les cellules, nous ne connaissons pas le mécanisme d’action par lequel ceux-ci agissent. Au passage, le projet de recherche ci-présenté nous aura par ailleurs permis de développer une grande variété de sondes photo-actives dans l’espoir d’isoler une ou plusieurs protéines qui seraient impliquées dans le mécanisme d’action.

Intraspecific individual variation of temperature tolerance associated with oxygen demand in the European sea bass (Dicentrarchus labrax)

The European sea bass (Dicentrarchus labrax) is an economically important fish native to the Mediterranean and Northern Atlantic. Its complex life cycle involves many migrations through temperature gradients that affect the energetic demands of swimming. Previous studies have shown large intraspecific variation in swimming performance and temperature tolerance, which could include deleterious and advantageous traits under the evolutionary pressure of climate change. However, little is known of the underlying determinants of this individual variation. We investigated individual variation in temperature tolerance in 30 sea bass by exposing them to a warm temperature challenge test. The eight most temperature-tolerant and eight most temperature-sensitive fish were then studied further to determine maximal swimming speed (U-CAT), aerobic scope and post-exercise oxygen consumption. Finally, ventricular contractility in each group was determined using isometric muscle preparations. The temperature-tolerant fish showed lower resting oxygen consumption rates, possessed larger hearts and initially recovered from exhaustive exercise faster than the temperature-sensitive fish. Thus, whole-animal temperature tolerance was associated with important performance traits. However, the temperature-tolerant fish also demonstrated poorer maximal swimming capacity (i.e. lower UCAT) than their temperature-sensitive counterparts, which may indicate a trade-off between temperature tolerance and swimming performance. Interestingly, the larger relative ventricular mass of the temperature-tolerant fish did not equate to greater ventricular contractility, suggesting that larger stroke volumes, rather than greater contractile strength, may be associated with thermal tolerance in this species.