Origin and Aims of this essay It was not by choice but by the misfortunes or fortunes of the last war, that I became involved with rivers. In December 1946 I obtained a lecturing post at the then Gordon Memorial College at Khartoum and the Principal of the college brought me to confluence of the two Niles and urged me to 'do something' on the biology of the river. I was very reluctant, my experience was limited to lakes in Poland up to 1939, and I did not know anything about work on rivers. The 'equipment' was a rowing boat, hired, and a 'home made' plankton net. This limited our first exploratory steps to the immediate vicinity of Khartoum. In both the White and Blue Nile we discovered the presence of a pure plankton. This was contrary to opinions expressed in the limited scientific literature available at Khartoum which stimulated our doubts and the search for the origin of this phenomenon. And so, early in our work, we became aware of the longitudinal sequence of events in running water, a fundamental feature of river ecology. of work were daunting; In the Nile, as in other long rivers, the difficulties the water courses stretch for thousands of kilometers south and north of our base, our work had to be done in time free from lecturing duties, no research grants were available.

Leonard C. Beadle In contrast to the more sta bie oceans, inland waters are, on the geological time scale, short-lived and are subject to great fluctuations in chemical composition and physical features. Very few lakes and rivers have existed continuously for more than a million years, and the life of the majority is to be measured in thousands or less. Earth movements, erosion and long-term climatic changes in the past have caused many of them to appear and disappear. No wonder then that most freshwater organism are especially adapted to great changes and many even to temporary extinction of their environment. Recent studies of residual sediments from existing and extinct lakes in tropical Africa have told us much about their age and the past history of their faunas and floras, from which we may deduce something about the climate and the conditions in the water in the past. The forces that have formed and moulded the African Great Lakes have been catastrophic in their violence and effects. They are not yet finished, but the present rate of change is, in human terms, too slow for direct observation of the ecological effects. The large man-made lakes are providing very good opportunities for studying the chemi cal and biological consequences of the initial filling but, once filled, they are artificially protected against major fluctuations.

Water is Life. Freshwater is one of the most valuable commodities on our planet, and this resource should be managed in a sustainable way. Yet, we are less than careful in the way we use water and many of our non-marine, aquatic habitats are threatened by anthropogenic impacts. Eutrophication, for example, could well turn into one of the major social as well as economic problems of the 21st century.

Reduction of water quality also has a profound effect on the biota that depend on these water bodies, such as micro-organisms, plants and animals. Freshwater Biodiversity is a much underestimated component of global biodiversity, both in its diversity and in its potential to act as models for fundamental research in evolutionary biology and ecosystem studies. Freshwater organisms also reflect quality of water bodies and can thus be used to monitor changes in ecosystem health. The present book deals with all of these aspects of Aquatic Biodiversity. It comprises a unique collection of primary research papers spanning a wide range of topics in aquatic biodiversity studies, and including a first global assessment of specific diversity of freshwater animals. The book also presents a section on the interaction between scientists and science policy managers. A target opinion paper lists priorities in aquatic biodiversity research for the next decade and several reactions from distinguished scientists discuss the relevance of these items from different points of view: fundamental ecology, taxonomy and systematics, needs of developing countries, present-day biodiversity policy at European and at global scales. It is believed that such a platform for the interaction between science and sciencepolicy is an absolute necessity for the efficient use of research budgets in the future.

Lake Baikal is the oldest, largest and deepest lake in the world. Its unique animal life and the beauty of the surrounding landscapes are renowned.
The book discusses the sustainable development of the lake and its use as a model for the rest of the world. It consolidates existing data on the current state of the environment and economy of the region, develops a system of indicators of sustainable developments, makes recommendations on additional components to the existing monitoring system and considers a legal framework and instrument for its implementation.

Proceedings of the 6th International Symposium on Ostracods, Saalfelden (Salzburg), July 30-August 8, 1976

Limnology - the study of inland waters - had its genesis in Europe about the turn of the century. The studies of Fore1 on Lake Geneva were of seminal value at this time. It prospered under the early guidance of Thienemann, Naumann and Wesenberg-Lund in Europe and, soon transplanted, of Birge and Juday in North America (to name just a few early spirits). Now, liminology is a respectable scientific discipline taught at many universities, and limnologists are recognized as important contributors to our understanding of how this fragile spaceship functions. All this acknowledged, it must also be acknowledged that limnology is not yet a globally comprehensive science. To be sure, much is known about globally applicable processes, and the structural elements of aquatic ecosystems worldwide, but limnological emphases, interests and concerns remain essentially European and North American in balance. Much is known about lakes and rivers in less than one fifth of the world's land area (northern temperature regions); rather little is known about inland waters elsewhere.

This book offers a unique collection of inter- and multidisciplinary studies on river systems. Rivers have been the prime source of sustenance since the advent of civilization and river systems often form the basis for agriculture, transport, water, and land for domestic, commercial, and industrial activities, fostering economic prosperity. A river basin is a basic geographical and climatological unit within which the vagaries of natural processes act and manifest themselves at different spatio-temporal scales. Even if compared side-by-side, no two river basins respond to natural processes in the same way and thus, it has long been recognized that each river basin is unique. Hence, any developmental activity or conservation effort has to be designed and implemented to match each unique river basin. With the burgeoning population and increasing dependency on natural resources, understanding and maintaining river systems has become increasingly important. This book provides a varied reference work on and unprecedented guidelines for conducting and implementing research on river basins, and for managing their ecological development.

Selenium is a naturally occurring trace element that can become concentrated and released by industrial, agricultural, petrochemical and mining activities. At concentrated levels it is toxic and has polluted ecosystems around the world. This book will serve as a comprehensive practical handbook for everyone dealing with selenium in aquatic environments. It offers field-tested approaches and methods for assessment and water quality management. Using his twenty-year experience, the author discusses the effects of selenium on fish and bird populations and presents guidelines for identifying sources of pollution, interpreting selenium concentrations, assessing hazardous conditions, setting water quality criteria and ecosystem loading limits (TMDLs). He also includes a procedure for setting environmentally safe limits that ensure compliance with EPA regulations. Selenium Assessment in Aquatic Ecosystems will interest field scientists, natural resource managers, risk assessors and environmental planners.

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.

Keith Culver and David Castle Introduction Aquaculture is at the leading edge of a surprisingly polarized debate about the way we produce our food. According to the United Nations Food and Agriculture Organization, aquaculture production has increased 8. 8% per year since 1970, far surpassing productivity gains in terrestrial meat production at 2. 8% in the same period (FAO 2007). Like the 'green revolution' before it, the 'blue revolution' in aquaculture promises rapidly increased productivity through technology-driven - tensi?cation of aquaculture animal and plant production (Costa-Pierce 2002; The Economist 2003). Proponents of further aquaculture development emphasize aq- culture's ancient origins and potential to contribute to global food security d- ing an unprecedented collapse in global ?sheries (World Fish Center; Meyers and Worm 2003; Worm et al. 2006). For them, technology-driven intensi?cation is an - dinary and unremarkable extension of past practice. Opponents counter with images of marine and freshwater environments devastated by intensive aquaculture pr- tices producing unsustainable and unhealthy food products. They view the promised revolutionasascam, nothingmorethanclever marketingbypro?t-hungry ?shfa- ers looking for ways to distract the public from the real harms done by aquaculture. The stark contrast between proponents and opponents of modern aquaculture recalls decades of disputes about intensive terrestrial plant and animal agriculture, disputes whose vigor shows that the debate is about much more than food production (Ruse and Castle 2002).

'A lake is the landscape's most beautiful and expressive feature. It is earth's eye; looking into which the beholder measures the depth of his own nature. The fluviatile trees next the shore are the slender eyelashes which fringe it, and the wooded hills and cliffs around are its overhanging brows.' 'A field of water betrays the spirit that is in the air. It is continually receiving new life and motion from above.' 'Nothing so fair, so pure, and at the same time so large, as a lake, perchance, lies on the surface ofthe earth. Sky water. It needs no fence. Nations come and go without defiling it. It is a mirror which no stone can crack, whose quicksilver will never wear off, whose gilding Nature continually repairs; no storms, no dust, can dim its surface ever fresh; - a mirror in which all impurity presented to its sinks, swept and dusted by the sun's hazy brush, - this the light dust-cloth, - which retains no breath that is breathed on it, but sends its own to float as clouds high above its surface, and be reflected in its bosom still.' (Henry David Thoreau: 'Walden; or Life in the Woods'. Fourth printing, April 1953, Ri!lehart & Company, New York).

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.

P. G. Sly Canada Centre Inland Waters, P.O. Box 5050, Burlington, Ontario L7R 4A6, Canada Keywords: symposium, sediments, freshwater Following the highly successful First Symposium work of the symposium: on Research into the Interactions between Sedi- I. Summary of sediment dynamics and distribu- ments and Freshwater held in Amsterdam, in 1976, tion in fluvial and lacustrine environments. it was decided that a second symposium in this 2. Land use effects on sediment yields,and quality. series should be held to continue the discussions on 3. Sediments in mass balance models, including progress in this rapidly expanding field of aquatic total loadings. science. The Second Symposium was held at 4. Sediments as concentrating mechanisms of nat- Queen's University, Kingston, Ontario, between 15 ural and anthropogenic, organic and inorganic and 18 June 1981. It was originally intended to hold materials. the meeting in Toronto a year earlier, but because 5. Release mechanisms, and transfer to biosystem, of difficulties in planning and the high cost of ac- from bed and suspended solids. commodation it was necessary to revise the original 6. Short- and long-term dating methods, spatial program and schedule. and temporai consistency, bioturbation and dif- The symposium received generous support from fusion.

This is the first comprehensive study of an east African lake for thirty years. It represents the culmination of research expeditions which stretch back twenty years and is thus able to pick up long term changes which the individual research activities do not reveal. Lake Naivasha is a tropical lake whose natural fluctuations are now dwarfed by human impacts. Papers show how the irrigation for horticulture and power cooling has reduced the lake depth significantly; exotic arrivals have altered the plant community beyond recognition and its commercial value as a fishery and a tourist feature are reduced by over use. Despite this, the lake has considerable conservation value at present. It provides a different case study in the ever-growing library of the effects of human follies. Lake Naivasha has achieved global importance in the past ten years because its waters are used to sustain the largest horticultural industry in Africa. The book highlights its fragility under such pressure and points out the way towards sustainable use of the water and the ecosystem.

The southwestern Amazon basin, centering on the Territory of Rondoenia and the State of Acre, is symbolically if not exactly geographically, the Wild Wild West of Brazil's northern rainforest fron tier. In Brazil the name Rondoenia evokes exaggerated images of lawlessness, land feuding, and indigent peasants in search of a homestead. Despite the problems and the perception, the region has pushed ahead, in the view of the govern ment, with large-scale deforestation and the establishment of cattle ranches and agricultural farms raising manioc, rice, bananas, and other cash crops. The mining industry has been launched with the exploitation oftin stone, and the recent gold rush has attracted thousands of miners that are sifting alluvial deposits along the rivers for the precious ore. In an energy-short world, the region boasts of its large hydroelectric potential waiting development in the rivers falling off the Brazilian Shield and draining into the Rio Madeira. Planners are optimistic that Rondoenia's resources, once developed, will more than justify, at least in this corner of the rainforest frontier, the Economic Conquest ofthe Amazon. Sandwiched between the economic take-off and the dream, however, are the biological resources - the plants and animals - that must serve as sources of energy and food until human dominated ecosystems replace naturaiones. These resources are, ofnecessity, being heavily attacked to support the shaky economy of the region, but they are very poorly understood in terms of potential productivity and proper management.

The recent progress achieved in aquatic genomics research has important implications in science and aquaculture. Researchers' success in genome sequencing of the fugu has provided a foundation not only for comparative fish genomics but also for genetic studies of other vertebrates. This volume, with contributions by leading scientists from around the world, provides the latest information on genomic studies of a variety of aquatic organisms including fish, crustaceans, and shellfish, with descriptions of such methodologies as genome analysis, gene mapping, DNA markers, and EST analysis. Other topics include regulation of gene expression, stress and immune responses, sex differentiation, hormonal control, and transgenic fish. This book is a valuable resource for all scientists whose work involves aquatic organisms, especially for those in the fields of aquatic genomics, fish immunology, and aquatic biotechnology.

The fourth international rotifer symposium was Wednesday afternoon a tour of Edinburgh, includ held in Edinburgh, Scotland, August 18 - 25, 1985, ing a visit to the Palace of Holyrood, was arranged. hosted by the Institute of Terrestrial Ecology. This This was followed by an evening banquet with meeting continued the tradition of holding rotifer traditional Scottish entertainment. On Thursday symposia at three-year intervals. The first an evening most participants attended a fireworks dis nouncement of the fourth meeting was circulated at play which was part of the Edinburgh Festival. Fi the end of 1983 to almost 300 people whose names nally, an excursion to Loch Lomond and the Tros appeared on the mailing list of the international sach hills was arranged for the Saturday after the newsletter, Rotifer News. In total, 68 people from meeting. 23 countries attended the meeting. It is interesting The organisers would like to thank Mr. C. J. to note that, of these 68 participants, 21 had at Place and colleagues at the Institute of Terrestrial tended the first meeting, held in Linz, Austria, Ecology for their invaluable help in organising the 1976, and 13 had attended all three previous meet meeting and preparing the symposium volume for ings. publication. We are also grateful for financial sup As in previous symposia, some research topics port from the Royal Society, the British Council were identified in advance of the meeting as being and British Petroleum (Scotland).