Résumé :
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The book presents the Lake Webmodel, a general model to quantify all important lake foodweb interactions, including biotic/abiotic feedbacks. The model has been critically tested against very comprehensive empirical data sets mainly from Eastern and Western Europe, including many new empirical models. Lake Web includes the key functional groups of organisms: phytoplankton, bacterioplankton, benthic algae, macrophytes, zoobenthos, herbivorous and predatory zooplankton, prey fish and predatory fish. The model is based on many new approaches of structuring lake foodweb interactions. It uses ordinary differential equations and gives weekly variations in production and biomass for its nine groups of organisms. The model also includes a new mass-balance model for phosphorus and new approaches to quantify suspended particulate matter and the depth of the photic zone. Fundamental concepts include consumption rates, metabolic efficiency ratios, distribution coefficients, migration of fish and predation pressure. An important feature of LakeWeb is that it can be run by just a few driving variables readily accessible from standard maps and monitoring programs. Several scenarios describe how the model can be applied to address important management issues, like consequences of biomanipulations (fish kill catastrophes), changes in land-use (eutrophication and humification), acidification and global temperature changes. LakeWeb is a powerful tool to simulate such measures and to get realistic expectations of positive and negative consequences of remedial measures. The present version of LakeWeb has been tested for lakes smaller than 300 km2, but many of the structural components should be valid also for larger systems, e.g., for coastal areas (like the Baltic or Norwegian fjords), or the large lakes of the world (like Great Lakes of America, the Caspian Sea or Lake Ladoga).
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