The International Symposium on Trophic Relationships in Inland Waters, held from 1st-4th September 1987, at the Balaton Limnological Research Institute of the Hungarian Academy of Sciences, Tihany (Hungary), was intended to give an insight into current research on limnology of inland waters. The meeting was organized on the occasion of the 60th anniversary of the Institute in order to promote the exchange of ideas and discussion of new results. Papers presented during the Symposium dealt with four main topics: (1) Interactions of inorganic nutrients, primary producers and bacteria, (2) Interactions between primary and secondary producers, (3) Trophic relationships between plankton and fish, (4) Studies on complex trophic systems. Participants from 18 countries presented 40 oral lectures and 15 posters, that reviewed the structure and functioning of inland water ecosystems from different aspects. Since in such functioning nutrients are main forcing factors, the pathways of nutrients., as well as trophic connections, are widely studied nowadays. The IX papers of these proceedings thus present a series of different approaches to the main results of current limnological research in this very important field. The structure of these proceedings was somewhat altered when papers were ranked into three main groups: (1) Long-term changes, (2) Annual and seasonal cycles and (3) Short-term changes and pilot scale operations. The sequence of papers within these groups follows the four main subjects discussed during the Symposium.

Long-term changes.- Trophic status and the pelagic system in Lago Maggiore.- The spring development of phytoplankton in Lake Erken: species composition, biomass, primary production and nutrient conditions - a review.- Some characteristics of the community of autotrophs of Lake Sevan in connection with its eutrophication.- Aspects of the ecology of a filamentous alga in a eutrophicated lake.- The relation of biotic and abiotic interactions to eutrophication in Tjeukemeer, The Netherlands.- Zooplankton community changes in Lake Kinneret (Israel) during 1969-1985.- The contribution of silver carp (Hypophthalmichthys molitrix) to the biological control of Netofa reservoirs.- Changes in the fish and zooplankton communities of Ringsjön, a Swedish lake undergoing manmade eutrophication.- The dynamics of a population of roach (Rutilus rutilus (L.)) in a shallow lake: is there a 2-year cycle in recruitment?.- Annual and seasonal cycles.- Phosphorus eutrophication research in the lake district of south western Friesland, The Netherlands. Preliminary results of abiotic studies.- Phosphorus dynamics following restoration measures in the Loosdrecht Lakes (The Netherlands).- Seasonal variability of N : P ratios in eutrophic lakes.- Trophic response to phosphorus in acidic and non-acidic lakes in Nova Scotia, Canada.- Trophic interactions among heterotrophic microplankton, nanoplankton, and bacteria in Lake Constance.- Influence on phytoplankton biomass in lakes of different trophy by phosphorus in lake water and its regeneration by zooplankton.- Algal growth and loss rates in Lake Loosdrecht: first evaluation of the roles of light and wind on a basis of steady state kinetics.- Interactions between sediment and water in a shallow and hypertrophic lake: a study on phytoplanktoncollapses in Lake Søbygård, Denmark.- Interactions between phytoplankton, zooplankton and fish in a shallow, hypertrophic lake: a study on phytoplankton collapses in Lake Søbygård, Denmark.- Phytoplankton and zooplankton (Cladocera, Copepoda) relationship in the eutrophicated River Danube (Danubialia Hungarica, CXI).- Zooplankton structure in the Loosdrecht lakes in relation to trophic status and recent restoration measures.- Ecological background and importance of the change of chironomid fauna (Diptera: Chironomidae) in shallow Lake Balaton.- Trophic relationships in the pelagic zone of Mondsee, Austria.- Trophic relationships between primary producers and fish yields in Lake Balaton.- Predation pressure from above: observations on the activities of piscivorous birds at a shallow eutrophic lake.- The distribution of waterfowl in relation to mollusc populations in the man-made Lake Zegrzy?skie.- Short-term changes and pilot-scale operations.- Light-limited algal growth in Lake Loosdrecht: steady state studies in laboratory scale enclosures.- Stir-up effect of wind on a more-or-less stratified shallow lake phytoplankton community, Lake Balaton, Hungary.- Heterotrophic flagellates and ciliates in the hypertrophic Lake Søbygaard, Denmark - seasonal trends and methodological difficulties.- An assessment of the importance of emergent and floating-leaved macrophytes to trophic status in the Loosdrecht lakes (The Netherlands).- The effect of Daphnia on filament length of blue-green algae.- Qualitative and quantitative relationships of Amphipoda (Crustacea) living on macrophytes in Lake Balaton (Hungary).- Impact of cyprinids on zooplankton and algae in ten drainable ponds.- Restoration by biomanipulation in a small hypertrophie lake: first-year results.- Operation ofthe Kis-Balaton reservoir: evaluation of nutrient removal rates.- Enclosures study of trophic level interactions in the mesotrophic part of Lake Balaton.- Summary of the workshop on perspectives of biomanipulation in inland waters.- Concluding remarks.- General Index.