The idea of convening an international workshop on hypertrophic ecosystems originated during the 20th S.I.L. Congress in Copenhagen. A group of about 30 delegates met there in an informal gathering to discuss the specific problems of lakes which have reached a noxious stage of eutrophication. This ad hoc group realized its own specific identity within the limnological community and suggested the organization of a specialized future meeting on hypertrophic ecosystems. After two years of preparatory work, the workshop was fmally held in Vaxjo, Sweden, between September 10 and 14, 1979, on the premises of the University campus. The Institute of Limnology, University of Lund (Professor Sven Bjork), undertook the task of host and organizer. The City ofVaxjo and the University of Lund co-sponsored the event, which was held under the auspices and patronage of the Societas Internationalis Limnologiae. The objective of the workshop was to seek better understanding of highly-eutrophic, disturbed and unstable aquatic ecosystems (lakes, reservoirs and ponds developing noxious algal and bacterial blooms, fluctuating in their water quality on a daily and seasonal scale, producing gases, off-flavor and toxic substances, experiencing periodic anoxia and massive fish kills, etc.), Le., systems requiring corrective measures and new concepts for their solution beyond those generally accepted for 'normal' eutrophic systems.

Ecosystem analysis and ecological modelling is a rapidly developing interdisciplinary branch of science used in theoretical developments in ecology and having practical applications in environmental protection. In this book, the authors introduce new holistic, particularly cybernetic, concepts into ecosystem theory and modelling, and provide a concise treatment of mathematical modelling of freshwater ecosystems which covers methods, subsystem models, applications and theoretical developments.Part I begins with a brief introduction to the principles of systems theory and their applications to ecosystems, and provides a summary of various methods of systems analysis. In Part II emphasis is laid on the pelagic processes in standing water, characterised by relatively uninvolved structures from which models can be readily developed. Part III describes applications of the technique of modelling to solutions of theoretical and practical problems, with different modelling methods and objectives being used in the various chapters. More recent developments in the methods and theory of ecosystem modelling are covered in Part IV which also includes a discussion of future trends. The book is addressed to practising ecologists and engineers in the fields of ecology, limnology, environmental protection, and water quality managements, as well as to graduate/post-graduate university students in science and engineering. Students and researchers involved in environmental applications of mathematics and cybernetics will also find the book of interest.

The international journal Ecohydrology & Hydrobiology (E&H) has been created to promote the concept of Ecohydrology, which is defined as the study of the functional interrelations between hydrology and biota at the catchment scale. Ecohydrology extends from the molecular level to catchment-scale processes and is based on three principles: • framework (hydrological principle) - quantification and integration of hydrological and ecological processes at a basin scale; • target (ecological principle) - necessity of enhancing ecosystem absorbing capacity and ecosystem services; and • management tool (ecological engineering) – the use of ecosystem properties for regulation the interplay between hydrology and biota. The journal encourages the submission of manuscripts which adopt an integrative approach to aquatic sciences, explaining ecological and hydrological processes at a river-basin scale or propose practical applications of this knowledge. It will also consider papers in other hydrobiological fields. Especially welcome are papers on regulatory mechanism within biocenosis and the resistance and resilience of freshwater and costal zones ecosystems. There is no page charge for published papers. All submitted papers, written exclusively in English, should be original works, unpublished and not under consideration for publication elsewhere. All papers are peer-reviewed. The following types of papers are considered for publication in E&H: • original research papers • invited or submitted review papers, • short communications

From microbial to plant ecosystems, this book examines how changes in UV radiation, caused by anthropogenic ozone depletion, as well as changes in radiation levels throughout the evolution of life on Earth, can alter species composition and interspecies competitiveness. It focuses on the evolutionary aspects of the effects of UV as well as the various synergistic interactions of UV radiation with other environmental factors. Because our knowledge of UV effects on whole ecosystems is still at a relatively early stage, an important part of each chapter is an overview of future research directions and indications of where new date and knowledge is needed.

In its statutory authority (National Science Foundation Act of 1950, as amended), the NSF is directed to both initiate and support basic scientific research. In its Ecology Program, one mode of initiating research is to en courage the development of new ideas through advisory workshops. The NSF is specifically directed to strengthen our nation's research potential. In addition, stimulating new approaches to research will continue to be prominent in the coming years as federal attention is given to increasing the innovativeness and competitiveness of the U. S. in science and engineering. A decision to initiate a workshop does not arise de novo in the Ecology Program. Rather, it emerges from panel discussions, conversations with in vestigators at meetings or on the phone, and from discussions between pro gram officers in the Division of Biotic Systems and Resources. This workshop was developed to provide advice to the NSF and the lim nological community. Some NSF perceptions on future funding for ecolog ical research on lake communities are presented here. Researchers often mentioned a paucity of innovative lake ecology at the community level. This perception was accompanied by a certain frustration since lakes probably have the best empirical data base of any natural environment and should continue to lead in the development of ecological concepts. Members of NSF advisory panels sometimes expressed similar concerns during consid eration of proposals for lake research.

This Workshop was organized to assess the status of knowledge on the behaviour of phosphorus in sediments and to define gaps and reassess research strategies, particularly with respect to prevalent methodology and future approach; and to define gaps and reassess research strategies for water management measures in aquatic ecosystems, especially in relation to the release of phosphorus from the sediments and its impact on the functioning of the whole system.