Bücher der Reihe Developments in Hydrobiology

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).

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.

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.

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.

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.

Chrysophycean algae are a diverse and often abundant group of primarily freshwater phytoplankton, characterized by the endogenous formation of siliceous cysts or stomatocysts (also called statospores or statocysts). Cyst morphology is highly variable, but believed to be species-specific. Recently, cysts have received considerable attention from phycologists and especially paleoecologists who wish to use these indicators for assessments of environmental change. Nonetheless, attempts at using cysts have often been hampered by taxonomic problems. This Atlas dispels some of the mystery surrounding stomatocysts, facilitating the accurate identification of individual cyst morphotypes, and encouraging other workers to begin using these important indicators. The terminology used to describe cysts is outlined in detail, followed by detailed descriptions of cyst morphotypes, following International Statospore Working Group (ISWG) guidelines, complemented by scanning electron and light micrographs, as well as line illustrations. Any available biogeographical and ecological information is also provided. These descriptions will further accelerate the continued effort to link cyst morphotypes to the algae that produce them. For paleoecologists who wish to include stomatocysts in their studies, researchers working with living chrysophycean algae, and those interested in the morphology and ultrastructure of cyst morphotypes.

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).

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.

Ponds are an exceptional freshwater resource around the world and represent thirty percent of the global surface area of standing water. Furthermore, the millions of ponds which exist exhibit a particularly high biodiversity and have a high potential for ecosystem functions and services. Despite these impressive features, ponds face many threats from a variety of human activities and receive little or no protection under European and national legislation. Consequently, there is an urgent need to protect, consolidate and increase the pond resource in Europe. In order to achieve these objectives, the European Pond Conservation Network (EPCN) was launched 2004 in Geneva. Its aim is to promote the awareness, understanding and conservation of these small water bodies in the European landscape. This volume of "e;Developments in Hydrobiology"e; presents a selection of 31 papers presented during EPCN conferences held in 2006 in France (Toulouse) and in 2008 in Spain (Valencia). They represent a diverse collection of themes from across the continent and North Africa and present new and original insights into topics as wide ranging as pond biodiversity; human disturbance; landscape ecology; ecological assessment and monitoring; practical management measures; ecological restoration; hydrology and climate change; invasive species and threatened species.

This volume reports on the findings of experts on tropical zooplankton gathered at a meeting in Kariba, Zimbabwe, in 1991. Some basic questions were asked on community composition and biodiversity in the tropics versus the non-tropics. Old ideas on the nature of zooplankton, which were found to be wider than the `classical' rotifers, cladocerans and copepods, as well as on the number of species in tropical waters, are now beginning to break down accordingly as more and more blank spots in the tropics are explored and as more in-depth studies on the zooplankton of tropical lakes are becoming available. This volume contains a mix of papers discussing the two alternative controls (bottom-up and top-down) of zooplankton community structure and these constitute another step towards a coherent theory of tropical ecosystem theory.

As in previous symposia, some current research topics were selected for review and eight invited papers were presented. For the first time a paper was presented on the historical aspects of Rotiferology, covering European research between 1680-1950. A special workshop session was devoted to a debate on a controversial topic: Rotifer Phylogeny. The workshop resulted in a very successful discussion and the integration of scattered evidence and hypotheses on the phylogenetic origin of rotifers, the relationships between major rotifer groups, and the mechanisms of evolution.