This volume presents recent advances in the research on meromictic lakes and a state-of-the art overview of this area. After an introduction to the terminology and geographic distribution of meromictic lakes, three concise chapters describe their physical, chemical and biological features. The following eight chapters present case studies of more than a dozen meromictic lakes, showing the variety of physical and biochemical processes that promote meromixis. The result is a broad picture of the ecology and biochemistry of meromictic lakes in tropical and cold regions, in man-made pit lakes and euxinic marine lakes, and in freshwater as well as hypersaline lakes. In the final chapter the editors provide a synthesis of the topic and conclude that the study of meromictic lakes also offers new insights into the limnology of inland lakes. The book appeals to researchers in the fields of ecology, limnology, environmental physics and biophysics.

The Netherlands, like the other industrialized countries in the northern hemisphere, is faced with increas ing environmental pro blems. Being a country rich in water - at least in terms of surface area - and low-lying, problems related to water are as old as the nation itself. The problems in regard to water quality are becoming more acute and complicated due to the progressive rise in air and ground pollution. Glaring examples are the acid rains and contamination of ground-water resources by toxic, and often illegal, waste dumps. Being a delta country, the Netherlands is also very vulnerable to pollution from the*water sources outside the country's national boundaries, i.e. the rivers Rhine, Meuse and ScheIdt. Not only the national but also the international authorities are active in developing measures to both prevent and combat water pollution, and to restore as far as possible the natural balance or a 'reasonable' water quality. The pollution abatement programmes are based on ecological theories; accepting waterbodies as aquatic ecosystems, the authorities concerned try to influence and lead the progresses in the systems to reach or maintain the desired ecosystem structure. Suter II (1981) mentioned a number of reasons why the attempts to use ecosystem theories to assess the impacts on the environment have been disappointing to date. It is clear that one of the reasons for the failure is lack of proper knowledge.

This work presents the state of the art of aquatic and semi-aquatic ecological restoration projects in The Netherlands. Starting from the conceptual basis of restoration ecology, the successes and failures of hundreds of restoration projects are described. Numerous successful projects are mentioned. In general ecological restoration endeavours greatly benefit from the progressive experience achieved in the course of the years. Failures mainly occur through insufficient application of physical, chemical or ecological principles. Spontaneous colonization by plants and animals, following habitat reconstruction, is preferred. However, sometimes the re-introduction of keystone species (for example, eelgrass, salmon, beaver) is necessary in case the potential habitats are isolated or fragmented, or if a seed bank is lacking, thus not allowing viable populations to develop. Re-introducing of traditional management techniques (for example, mowing without fertilization, low intensity grazing) is important to rehabilitate the semi-natural and cultural landscapes that are so characteristic of The Netherlands.

This volume presents recent advances in the research on meromictic lakes and a state-of-the art overview of this area. After an introduction to the terminology and geographic distribution of meromictic lakes, three concise chapters describe their physical, chemical and biological features. The following eight chapters present case studies of more than a dozen meromictic lakes, showing the variety of physical and biochemical processes that promote meromixis. The result is a broad picture of the ecology and biochemistry of meromictic lakes in tropical and cold regions, in man-made pit lakes and euxinic marine lakes, and in freshwater as well as hypersaline lakes. In the final chapter the editors provide a synthesis of the topic and conclude that the study of meromictic lakes also offers new insights into the limnology of inland lakes. The book appeals to researchers in the fields of ecology, limnology, environmental physics and biophysics.

The Netherlands, like the other industrialized countries in the northern hemisphere, is faced with increas ing environmental pro blems. Being a country rich in water - at least in terms of surface area - and low-lying, problems related to water are as old as the nation itself. The problems in regard to water quality are becoming more acute and complicated due to the progressive rise in air and ground pollution. Glaring examples are the acid rains and contamination of ground-water resources by toxic, and often illegal, waste dumps. Being a delta country, the Netherlands is also very vulnerable to pollution from the.water sources outside the country's national boundaries, i.e. the rivers Rhine, Meuse and ScheIdt. Not only the national but also the international authorities are active in developing measures to both prevent and combat water pollution, and to restore as far as possible the natural balance or a 'reasonable' water quality. The pollution abatement programmes are based on ecological theories; accepting waterbodies as aquatic ecosystems, the authorities concerned try to influence and lead the progresses in the systems to reach or maintain the desired ecosystem structure. Suter II (1981) mentioned a number of reasons why the attempts to use ecosystem theories to assess the impacts on the environment have been disappointing to date. It is clear that one of the reasons for the failure is lack of proper knowledge."

This work presents the state of the art of aquatic and semi-aquatic ecological restoration projects in The Netherlands. Starting from the conceptual basis of restoration ecology, the successes and failures of hundreds of restoration projects are described. Numerous successful projects are mentioned. In general ecological restoration endeavours greatly benefit from the progressive experience achieved in the course of the years. Failures mainly occur through insufficient application of physical, chemical or ecological principles. Spontaneous colonization by plants and animals, following habitat reconstruction, is preferred. However, sometimes the re-introduction of keystone species (e.g. eelgrass, salmon, beaver) is necessary in case the potential habitats are isolated or fragmented, or if a seed bank is lacking, thus not allowing viable populations to develop. Re-introducing traditional management techniques (e.g. mowing without fertilization, low intensity grazing) is important to rehabilitate the semi-natural and cultural landscapes that are so characteristic for The Netherlands.

This volume is a record of the proceedings of the IXth International Rotifer Symposium, which was held in Khon Kaen, Thailand, on January 16-23, 2000. It contains reviews and research papers dealing with diverse aspects of scientific research related to Rotifera and their ecology. Some of the topics addressed are: taxonomy and zoogeography, ecology, phylogeny and evolution, physiology, biochemistry and population genetics, aquaculture, and ecotoxicology. This book contains a compilation of contemporary rotifer-related research, and is the eighth of a series of rotifer symposium proceedings published in "Developments of Hydrobiology". This update of Rotifera studies should be of great interest to invertebrate zoologists, hydrobiologists, ecologists, and aquaculturists, particularly those interested in freshwater habitats.