Multiple use of natural waters and watersheds poses many practical problems, some of which are clearly limnological, relating for example to carrying capacities oflakes, deterioration of water quality and fisheries management. It is thus important to consider limnological aspects when making decisions in the field of water management. To further this attitude the Finnish Limnological Society considered 'Lakes and Water Management' to be a suitable theme for the Society's Jubilee Symposium, held in Helsinki on 22-23 September, 1980 at the Viikki Campus of the University of Helsinki, to mark the Society's 30th Anniversary. The Finnish Limnological Society has arranged nationallimnological symposia everyone or two years. The papers presented at these symposia have been published in the series 'Limnologisymposion' (in Finnish or Swedish, with short summaries in an internationally spoken language). Due to financial difficulties, the series was terminated as of the symposium in 1979. When preparing the 30th Anniversary of the Finnish Limnological Society, the Governing Board of the Society decided to arrange an international symposium on a theme relevant to modern limnology both in Finland and elsewhere. The selected results of the successful meeting on lakes and water management, which was attended by 220 people from 7 countries, are presented in this volume.

Inhalt

The first half century of limnology in Finland.- One: Structure and Function of Lake Ecosystems.- 1.1 Unpolluted waters.- Dynamics of phytoplankton in Finnish lakes.- Dispersion patterns of phytoplankton in lakes.- On the annual variation of phytoplankton biomass in Finnish inland waters.- Dynamics of phytoplankton in the brackish-water inlet Pojoviken, southern coast of Finland.- Carbon, phosphorus and nitrogen budgets of the littoral Equisetum belt in an oligotrophic lake.- The diversity, biomass and production of zooplankton in Lake Inarijärvi.- The food and parasites of fish in some deep basins of northern L. Päijänne.- Size and structure of crayfish (Astacus astacus) populations on different habitats in Finland.- Seasonal and spatial distribution of humus fractions in a chain of polyhumic lakes in southern Finland.- 1.2 Eutrophic and polluted waters.- The role of nitrogen as a growth limiting factor in the eutrophic Lake Vesijärvi, southern Finland.- Seasonal succession of phytoplankton in an ice-free pond warmed a thermal power plant.- The annual flood regime as a regulatory mechanism for phytoplankton production in Kainji lake, Nigeria.- The effect of land use on the diatom communities in lakes.- Convection in bottom sediments and its role in material exchange between water and sediments.- Winter microbial activity in Lake Tuusulanjärvi.- The influence of sulphite mill effluents on heterotrophic activity as measured glucose assimilation.- Establishing the pattern of heterotrophic bacterial activity in three Central Amazonian lakes.- Two: Modelling.- Nutrient dependence of phytoplankton production in brown-water lakes with special reference to Lake Päijänne.- An oxygen models for Lake Haukivesi.- Three: Water Management.- 3.1. Water quality control.- Limnological research can improve and reduce the cost of monitoring and control of water quality.- The limnological basis for planning water quality management.- The phosphorus economy of a hypertrophic seepage lake in Scania, south Sweden - groundwater influence.- Changes in quality of Finnish inland waters revealed grouping analysis.- Muddy odour: a problem associated with extreme eutrophication.- Factors influencing odour production actinomycetes.- Faecal indicator bacteria at fish farms.- 3.2 Restoration of lakes.- Goals, methods and possibilities for directing development of limnic ecosystems.- Changes in the phytoplankton of Lake Trummen induced restoration.- The recovery of L. Vesijärvi following sewage diversion.- 3.3. Fisheries.- Experimental manipulations of the fish populations in Windermere.- The management of fisheries in Lake Vörtsjärv.- A plan for fisheries management in the lakes drained the Oulujoki river.- Fish stock assessments in Lake Konnevesi.