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The environmental temperature increased during summer and decreased during winter to the limits that might negatively affect animal and human reproduction. The responses of Egyptian rams to either hot or cold climatic conditions were studied in six mature rams subjected to weekly testicular Doppler ultrasonographic examination, blood sampling, seminal plasma collection and semen evaluation. The maximum environmental temperature and the relative humidity were used to classify the climatic condition according to the heat stress equation of sheep into hot months where temperature–humidity index (THI) was >26 (31.67 ± 0.54), and cold months where THI was <22 (18.39 ± 0.41). Testosterone, estradiol, superoxide dismutase (SOD), glutathione peroxidase (GPX) and lipid peroxide product (malondialdehyde, MDA) were measured in both blood and seminal plasma, while catalase (CAT) and reduced glutathione (GSH) were measured in blood and seminal plasma, respectively. Results revealed that, during the hot months, rams displayed significantly decreased testicular blood flow, increased seminal plasma MDA, decreased seminal plasma (SOD, GPx and GSH) and blood CAT antioxidant enzymes. The present study evidenced two novel findings: (a) the marked decrease in testicular blood flow volume, that is remarkable increase in both resistive index (RI) and pulsatility index (PI) values, during hot months could be negatively affected both seminal plasma enzymatic activities and seminal attributes, and (b) the SOD and GPx activities in seminal plasma of such animals were suitable predictive markers for seminal attribute evaluation.

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Changing climates will likely result in more frequent midwinter ice jams along many Canadian rivers, thereby increasing the likelihood of flood damage and environmental changes. Therefore, the possibility of more frequent ice jams has to be considered during the planning of flood damage reduction measures, the design of waterway structures, and the enactment of measures to protect the environment. As a case study of midwinter jamming, four winter breakup and jamming events that occurred along an upper stretch of the Saint John River during the 1990s are described and the implications of similar midwinter jamming are discussed.Résumé : Vraisemblablement, les changements climatiques produiront plus fréquemment des embâcles de glace en cours d'hiver sur plusieurs rivières canadiennes, et de ce fait vont accroître la possibilité de dommages dus aux crues et de changements environnementaux. En conséquence, la possibilité d'embâcles de glace plus fréquentes doit être considérée lors de la planification des mesures de réduction des dommages dus aux crues, dans la conception de canalisations, et dans la mise en vigueur de mesures pour la protection de l'environnement. En tant qu'études de cas sur les embâcles en cours d'hiver, quatre événements de débâcles et d'embâcles qui se sont produites dans la partie supérieure de la rivière Saint-Jean au Nouveau Brunswick lors des années 90 sont décrits, et les implications d'embâcles similaires en cours d'hiver sont discutées.Mots clés : débâcle, glace en rivière, changement climatique, embâcle de glace, épaisseur de glace, hiver, dégel hivernal.[Traduit par la Rédaction] Beltaos et al. 88

During April 1991, major and damaging ice jams formed on the Saint John River at Dickey, Maine, and at Sainte-Anne-de-Madawaska, New Brunswick. Field investigations included the measurement of five water surface profiles along the ice jam at Sainte-Anne-de-Madawaska and of shear wall heights at both Dickey and Sainte-Anne-de-Madawaska after the jams had released. These measurements were supplemented by considerable information from local observers and data collection agencies. Following a description of freeze-up and winter conditions, and a chronology of 1991 breakup events, the available data were analyzed according to current ice jam theory. Using a simplified equilibrium analysis and taking into account discharge and channel characteristics, the 1991 Dickey ice jam thickness and water level were calculated and were in general agreement with observed values. In the case of the Sainte-Anne-de-Madawaska jam, sufficient data were obtained for application and calibration of the numerical model RIVJAM which determines the configuration of a jam in nonequilibrium reaches. This resulted in successful reproduction of a measured water profile along the jam and approximate prediction of jam thickness. Implications of the calibrated model coefficients are discussed.

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