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Ecology and Morphology of Copepods is organized under the following general topics: Behavior, Feeding, Genetics, Horizontal Variations, Morphology, Phylogeny, Reproduction, Seasonal Changes, Vertical Distribution, plus two special sessions on copepods of the genus Acartia and cyclopid/mosquito interactions. The Maxilliped Lecture, given by Dr. Arthur G. Humes of Boston University, clearly established the importance of copepods to the earth's organic diversity. The book consists of selected research articles from the different sections. The articles published here reflect the diverse research interests of copepodologists today, and are distinguished by their high quality. Their impact will ensure that this volume is consulted by a wide range of research biologists.

Ostracoda (Crustacea) are potentially excellent model organisms for evolutionary studies, because they combine an extensive fossil record with a wide recent distribution and therefore allow studies on both patterns and processes leading to extant diversity. The main scientific domains contributing theories, concepts, and data to evolutionary biology are morphology (including ontogeny), palaeontology, genetics, and ecology, and to all of these aspects ostracods can contribute. This is clearly illustrated by the fifteen papers presented under Theme 3 of the 13th International Symposium on Ostracoda (Chatham, UK) in 1997 which are grouped in the present proceedings, one of three volumes resulting from this meeting. The contributions deal with the evolution of both extant and fossil forms (including most of the Phanaerozoic), ecology of both marine and freshwater taxa, and (developmental) morphology of both soft parts and valves. Although the canvas is wide, each paper clearly shows how studies on Ostracoda can be relevant to general theory on evolutionary biology and ecology.

This volume contains papers presented either in oral or poster form at the international symposium `Limnology of Mountain Lakes', held at Stara Lesna (Slovakia) between 1 and 7 July 1991. Several papers covered contributions from the fields of physical and chemical limnology, palaeolimnology, zooplankton, phytoplankton and phytobenthos, and bacteria. Acidification, a process affecting water chemistry and biota of many mountain lakes in Europe was dealt with also. A series of papers on the lakes in Sumava has highlighted different aspects of these lakes, which are in the last stage of acidification. Other geographical areas covered extensively were the Tatras and the Alps.

The nutrient dynamics and biological structure of shallow non-stratified lakes differ markedly from that of deep and stratified lakes: for example, the return of nutrients lost through sedimentation is faster and the potential importance of fish and submerged macrophytes as food-web regulators is greater. In addition shallow lakes are more easily influenced by fluctuations in the physical environment caused by wind disturbance, temperature change, etc. Although shallow lakes are often the most common lake type in lowland countries, less attention has been paid to them than to deep stratified lakes and few comparisons have been made between shallow freshwater and brackish lakes. The volume is divided into five main themes, each introduced by an invited speaker: Nutrient dynamics with special emphasis on sediment water interactions and changes in loading (Professor Lambertus Lyklema); Biological structure and trophic interaction (Professor Stephen T. Threlkeld); Submerged macrophytes: dynamics and role in the lake ecosystems (Ass. Professor Kaj Sand Jensen); Comparison of freshwater and brackish lake ecosystems (Professor Brian Moss); Modelling the impact of nutrients, the biological structure and the recovery process (Dr Marten Scheffer).

What sight is more beautiful than a high-energy beach facing lines of rolling white breakers? What battleground is more ferocious than where waves and sand meet? What environment could be more exciting to study than this sandy interface between sea and land? And yet how much do we know about sandy beaches? Open sandy beaches are amongst the most neglected fields of scientific study in the coastal environment. This situation exists despite their great extent along most temperate and tropical coastlines and their value as recreational areas and buffer zones against the sea. The traditional oceanographer does not venture into the surf zone while the terrestrial ecologist stops short at the high water mark. Only a few coastal engineers have grappled with the problem of sand and sediment movement as it influences their construction of harbours and pipelines. The marine biologist on the other hand has regarded estuaries, coral reefs and rocky shores, obviously teeming with life, as more fruitful areas for study than the apparently poor animal life on sandy beaches. Sandy beaches have therefore tended to become a scientific no man's land. Over the last decade this situation has begun to improve. Recent work on high-energy beaches has revealed that they may in fact be rich and productive and fertile areas for study. It has even been suggested that beaches and their adjacent surf zones may constitute viable marine ecosystems.

This volume is a collection of papers concerning the biology of large branchiopod crustaceans: Anostraca, Conchostraca, and Notostraca. Many of the individual papers were first presented at the Third International Large Branchiopod Symposium (ILBS-3) held at the University of San Diego, CA, USA, July 15-18, 1996. Contributions on additional topics from participants at the symposium, and from colleagues not able to join us in San Diego, are also included. In addition, there is a supplement to the 1995 `Checklist of the Anostraca'. The theme of the ILBS-3 was `understanding and conserving large branchiopod diversity'. Researchers from around the world presented papers on a variety of topics related to conservation of large branchiopods, with contributions ranging from alpha-taxonomy and zoogeography to community structure and studies of ecology and evolution. One important issue developed in many of the papers in this volume is the need to advance our understanding of basic aspects of branchiopod biology throughout the world in order to enhance our efforts to conserve them. Although we have made important strides in understanding the biology of large branchiopods, we have, with few notable exceptions, made little progress in assuring the conservation of their diversity. We hope this volume will supply the reader with new ideas, and generate enthusiasm for research and public education efforts on behalf of branchiopod conservation.

Our knowledge of the limnology of the waters situated, roughly, between the tropics of cancer and of capricorn, has depended for a long time on the expedition-approach, and therefore developed in a rather irregular, haphazard way, with the personal incentive of a small number of individuals as the main driving force. Things slowly started to change in the 1950s, and at an accelerating rate in the 1960s and 1970s. The IBP, and later the SCOPE and MAB programs, whatever their shortcomings are or may have been, promoted in-depth research of a small number of tropical lakes. For one thing, they showed the need for the creation of in situ limnological research institutes. When, in the 1970s, limnological research facilities or their nuclei began to appear in the tropical zones of all continents, an interesting phenomenon occurred: while most of the young native limnologists had received their training in advanced centres or courses held in the temperate (and developed) climatic zones, quite a few of their former supervisors or their associates became interested in warm lakes and rivers as well, using the new or newly expanded local institutes. We are, today, still in this phase and it is, apparently, expanding even further. Although not all experiments of this kind lead to happy marriages, a few were quite successful, and several papers contained in the present volume are hoped to reflect this.

Turbellarian platyhelminths (or, as they are known now among cladistic systematists, free-living Platyhelminthes) comprise a widely distributed assemblage of lower worms found in marine, freshwater, and even occasionally in terrestrial habitats. The phylum Platyhelminthes may be more widely known for its parasitic members since the major parasitic groups of the tapeworms, flukes, and their relatives are more speciose and have greater impact on everyday human life; but the turbellarians are more diverse and, as inhabitants of virtually any aquatic habitat, are more widespread as well. Many of the lower turbellarians are rather simple in morphology and have served as models for ancestors of the Bilateria, i.e., the bulk of the animal phyla. Others are quite complex organisms, especially in the morphology of their reproductive systems which are highly specialized. The majority are free-living in aquatic habitats but a number of interesting parasitic and commensal species are found scattered among the higher turbellarian taxa. But turbellarians are more than just taxonomic curiosities. They have served as illustrative models in research on a variety of basic life processes. For example, their high capacity for regeneration has made them the subject of a large literature in developmental biology, the occurrence of mixoploidy and other karyological oddities among turbellarians has been important in understanding evolution of the genome, and the fine structure and biochemistry of the nervous system in turbellarians is revealing important principles of the organization of so-called primitive neural systems.

At the end of the first international Symposium on Rotifers diately accepted to do this, and kindly made an entire in Lunz, Austria, September 1976, entousiastic pleas were special volume of its Journal 'Hydrobiologia' available made for a second gathering of possibly the same format for this purpose. Also, arrangements were made to have and spirit that had made the first one such a great success. the proceedings out as quickly as possible. The proceedings include all papers that were presented One of us (HJD), 'supported' herein by his friends Charles E. King and Jens Petter Nilssen in particular, tentatively in Gent, and two communications by collegues who could suggested that Gent University might host a meeting of not attend in person. They thus amount to 23 original con­ this kind, having in mind that since the Xlth congress of tributions, including the summaries of the workshops. All SIL in 1950, no other SIL activity had take places in have been reviewed by the editors, and many, in addition Belgium. In view of the relatively large number of Be1gian by one or more referees. Manuscripts have been adjusted, rotifer workers, many among which are or were active in wherever needed, for grammar, clarity of meaning, and Gent, this proposal sounded acceptable to the attendance length. However, where possible, the flavor of some per­ of the Lunz meeting, who then gave each other rendez sonal styles was left unaltered.

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.

The origins of this volume date back to the 1978 American Society of Limnology and Oceanography (ASLO) meetings in Victoria, British Columbia. Interest in the ecology of mysids, particularly Mysis relieta. was growing rapidly, so a meeting of active workers was held at the ASLO conference. Although the small group of researchers attending that first meeting were primarily North American and interested in Mysis relieta. the group quickly expanded to include researchers from every continent with interests in all aspects of mysid biology (see Appendix). The group, informally called the Mysid Research Group, formed to serve two basic functions·. The first was to facilitate communication among mysid researchers by publishing a member­ ship list and periodic newsletters. The second was to organize an international symposium on mysid ecology. After several false starts, a symposium was successfully held in conjunction with the 1981 ASLO meetings in Milwaukee, Wisconsin. The symposium lasted over parts of two days with an evening workshop the second day. Altogether, 1 poster and 21 oral presentations were given by 42 researchers. This volume is an outgrowth of that symposium and includes 15 of the papers originally presented at the conference. In order to make the volume as comprehensive as possible, contributions from individuals who could not attend the symposium were solicited. Thus, a total of 22 original contributions make up the present work.

At the First International Symposium on Aquatic Oligochaete Biology in Sidney, B. C. , the suggestion was made to hold the second in Pallanza, on Lake Maggiore, at the C. N. R. -Istituto Italiano di Idrobiologia. At the same time it was decided that there should be a symposium every third year. The organization of the symposium was made considerably easier by the Senior Editor's having been in personal contact with several Russian colleagues (courtesy of a kind invitation from the U. S. S. R. Academy of Sciences), the 'Hamburg Group' and the Junior Editor. Correspondence with various students of Oligochaeta also furnished many useful suggestions. The Second International Symposium on Aquatic Oligochaete Biology was therefore held in Pallanza in late September 1982 and was attended by 53 scientists from 16 countries in Europe, North America, Asia and Australia. No review papers were formally invited as this had already been done at the first symposium: all the papers were accordingly allotted the same time for oral presentation. These proceedings contain all papers Hrabe and Slepukhina, which were given in absentia, as it presented at the symposium, including those by was impossible for the authors to join the group. The main topics were taxonomy and evolution of Oligo chaeta, life-cyle and population studies, the role of Oligo chaeta in assessing water pollution, physiolog­ ical studies, community and distribution studies. Special taxonomic workshops took place in the evenings.

Birds are an integral part of most freshwater ecosystems (lakes, rivers, wetlands) but their role in the trophic dynamics of these water bodies has often been overlooked. As a conspicuous part of the biota of water bodies, aquatic birds are indicators of their trophic state both in terms of species composition (quality) as well as occupancy and breeding (quantity). Birds may also influence the trophic state of a water body by importing nutrients (.e.g. resident or migrating birds feeding on adjacent watersheds or the sea). Because of anthropogenic activities, predation or their mobility, birds may not utilize otherwise suitable aquatic habitat. These factors complicate the relationship between aquatic bird production and the trophic status of habitats. As a consequence, the role of aquatic birds in freshwater ecosystems has usually been ignored. This volume contains a wide range of papers selected from those presented at the symposium and reviewed.

Table 1. State variables modeled in MOSES. State variable Units Estuaries are characterized by a strong diversity in car­ bon sources. This is because of the existence of an 3 Fast-decay detritus g- intertidal habitat, the supply of nutrients and organic 3 Slow-decay detritus g- material from the river and from the sea and the input of 3 gCm- Freshwater diatoms matter from human origin. If turbidity remains limited, 3 Freshwater flagellates g- estuaries can also support a high primary production 3 Brackish and marine diatoms g- as nutrients are abundant. Nevertheless, estuaries are 3 Cm- Brackish and marine flagellates usually heterotrophic ecosystems (Billen et aI. , 1991; 3 gCm- Micro-zooplankton Smith & Hollibaugh, 1993) where respiratory process­ 3 Brackish meso-zooplankton gCm- 3 es exceed in situ production. Marine meso-zooplankton gCm- 2 3 gCm- The Westerschelde estuary (260 km in SAWES, Hyperbenthos 3 gSim- Detrital silicate 1991) drains about 21580 square kilometres ofland in 3 gSim- Dissolved silicate one of the most densely populated and highly industri­ 3 gNm- Nitrate and nitrite alised regions of Europe (Wollast, 1988). This estuary 3 gNm- Ammonia is unusual due to the high degree of eutrophication 3 gOm- Oxygen which results from the discharge of untreated wastes 3 gCl m- Chlorides (Heip, 1988) and due to the high residence time of the 3 gm- Suspended matter water masses (Soetaert & Herman, 1995a).