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Aquatic ecosystems are subject to multiple interacting stressors that obscure regulatory mechanisms and reduce the effectiveness of management strategies. Here we estimate the unique and interactive effects of continental climate systems, regional meteorology, river hydrology, and internal lake characteristics on patterns of landscape-scale water quality in six productive lakes within a 52 000 [km.sup.2] catchment. We quantify variation in mean summer and monthly algal abundance, surface bloom intensity, water clarity, and density of potentially toxic cyanobacteria during 16 years on the Canadian Prairies. Internal lake characteristics best predicted overall water quality change, while climate systems, regional weather, and river hydrology characterized indirect pathways that influenced physicochemical environments. Scenario analysis of future environmental change predicted that atmospheric warming (3-5 [degrees]C) will have the strongest effect on water quality in these productive lakes, but unexpectedly predicted that even severe industrial water extraction (1% of inflow) will have negligible effects on transparency or algal abundance. Instead, nutrient management represents the only practical means to sustain water quality, although atmospheric and lake warming may override re-oligotrophication of eutrophied sites in future decades. Les ecosystemes aquatiques sont assujettis a de multiples facteurs de stress interagissant les uns avec les autres qui occultent les mecanismes de reglementation et reduisent l'efficacite des strategies de gestion. Nous estimons les effets individuels et interactifs des systemes climatiques continentaux, de la meteorologie regionale, de l'hydrologie des rivieres et des caracteristiques internes des lacs sur les motifs de qualite de l'eau a l'echelle du paysage dans six lacs producteurs dans un bassin versant de 52 000 [km.sup.2]. Nous quantifions les variations des abondances estivale et mensuelle moyenne des algues, l'intensite des efflorescences en surface, la carte de l'eau et la densite de cyanobacteries potentiellement toxiques sur une periode de 16 ans dans les Prairies canadiennes. Les caracteristiques internes des lacs predisent le mieux les changements generaux de la qualite de l'eau, alors que les systemes climatiques, la meteo regionale et l'hydrologie des rivieres caracterisent des voies indirectes qui influencent les environnements physicochimiques. L'analyse de scenarios de changements environnementaux futurs predit que le rechauffement atmospherique (3-5 [degrees]C) exercera l'effet le plus important sur la qualite de l'eau dans ces lacs producteurs, mais, contrairement aux attentes, predit egalement que meme une extraction industrielle d'eau intense (1 % de l'apport d'eau) aurait des effets negligeables sur la transparence ou l'abondance d'algues. La gestion des nutriments represente plutot le seul moyen pratique pour maintenir la qualite de l'eau, bien que le rechauffement atmospherique et des lacs pourrait contrer les effets de la reoligotrophisation de sites eutrophises dans les decennies a venir. [Traduit par la Redaction], Introduction Accurate prediction of the unique and interactive effects of climate and humans on aquatic ecosystems will require an improved mechanistic understanding of how ecosystems interact with and respond to [...]

Antibiotic activity is known to affect interactions among soil microbes but very little information is available on the ecology of antibiotic microbial population in soil. To understand this activity better the abilities of streptomycete isolates from prairie soil were studied.

We analyze the spatial variation in diurnal daytime-nighttime precipitation amounts and event frequency, using 24 years (1965-88) of hourly growing season precipitation records for 24 stations on the Canadian Prairies. Harmonic analysis indicates that both maximum amount of precipitation and maximum frequency of precipitation events occur during late night to early morning throughout the agricultural areas. Comparison of drier and wetter season precipitation patterns indicates further that the nocturnal maximum is weak in the drier and strong in the wetter growing seasons. Identification of these patterns might be helpful for more reliable forecasting of not only precipitation probabilities for various times of day during the growing season in general, but also those for drier vs. wetter seasons in particular.

Ninety male and 272 female mallards during two breeding seasons in the Prairie-Parkland region of Canada were captured, radiomarked and monitored. The findings suggested that breeding-season survival of males had little impact on mallard population growth and that management effort to increase female survival rates offered greater potential to enhance mallard production.

Research demonstrates that female mallard duck survival is contingent on the prevention of wetland loss. Findings also showed that female survival is lowest during nesting. Implications for habitat improvement are discussed.

One of Canada's most prominent water experts, Dr. David Schindler, is forecasting that the Prairies will experience droughts worse that the 1930 dust bowl years. He foresees the problem to [...]

Sandstorms in Asia and Africa are increasingly contributing to Canadian health problems. According to the "Ecosystems and Human Well-Being," a report released as part of the United Nations' Millennium Ecosystem […]