While the reality of the taxon Turbellaria has been called into question lately, turbellarians are nevertheless the subject of active research by a sizable group of biologists. Turbellarians are relatives of the major groups of parasitic platyhelminthes - monogeneans, digeneans, and tapeworms - and most are free-living. Because the ancestors to the major parasitic groups would be classified as turbellarians, strict application of princi- ples of phylogenetic systematics dictates that the Turbellaria is not properly considered a separate taxon; i. e. , it is, in the parlance of systematics, a paraphyletic group. The relationships of turbellarians to other inver- tebrates are even more problematic than their relationships to other platyhelminthes; their relatively simple morphology has been variously interpreted as quintessentially primitive - meaning a turbellarian-like ances- tor would have given rise to most of the major groups of invertebrates - or as secondary simplification, meaning they would essentially be a dead-end group. Modern research on turbellarians covers a broad spectrum. Questions of phylogenetics have inspired ultrastructural studies; the simply structured nervous systems of turbellarians make them good subjects for neurophysiology; simplicity of their tissue structure and the limited number of cell types make them good subjects of embryological and regeneration studies; they are emerging as iIIJ. portant indicator species in ecolo- gy; and improvements in biochemical methodology have meant they are at last amenable - despite their small size - to molecular biological study.

Our understanding of the ecology of running waters has come a long way during the past few years. From being a largely descriptive subject, with a few under tones concerned with such things as fisheries, pollution or control of blackflies, it has evolved into a discipline with hypotheses, such as the River Continuum Concept (Vannote et a/. 1980), and even a book suggesting that it offers opportunity for the testing of ecological theory (Barnes & Minshall 1983). However, perusal of the literature reveals that, although some of the very early studies were concerned with large rivers (references in Hynes 1970), the great mass of the work that has been done on running water has been on streams and small rivers, and information on larger rivers is either on such limited topics as fisheries or plankton, scattered among the journals, or not available to the general limnologist. The only exceptions are a few books in this series of publications, such as those on the Nile (Rz6ska 1976), the Volga (Morduckai Boltovskoi 1979) and the Amazon {Sioli 1984), and the recent compendium by Whitton (1984) on European rivers, among which there are a few that rate as large."

Coastal and marine ecosystems, some severely degraded, other still pristine, control rich resources of inshore environments and coastal seas of Latin America's Pacific and Atlantic margins. Conflicts between the needs of the region's nations and diminishing revenues and environmental quality have induced awareness of coastal ecological problems and motivated financial support for restoration and management.
The volume provides a competent review on the structure, processes and function of 22 important Latin American coastal marine ecosystems. Each contribution describes the environmental settings, biotic components and structure of the system, considers trophic processes and energy flow, evaluates the modifying influence of natural and human perturbations, and suggests management needs. Although the focus of the book is on basic ecological research, the results have application for coastal managers.

Proceedings from a Symposium on Biology and Management of Sturgeon, held during the 113th Annual Meeting of American Fisheries Society at Milwaukee, Wisconsin, USA, August 16-20, 1983

Estuaries are highly dynamic systems subject to changes occurring over a spectrum of time scales ranging from very short periods (e. g. over a tidal cycle) to geologic time scales. The nature of an estuary reflects complex responses to many driving forces, each having a characteristic frequency (or frequencies) of change. For example, freshwater inflow to estuaries varies daily in response to short-term events such as storms, seasonally, and between years as a result of longer-term climatic variability. Other important components of weather, e. g. wind speed/ direction and daily insolation, also vary over time scales ranging from hours to years. Tidal amplitude changes continuously with dominant frequencies associated with the semi-diurnal cycle, the fortnightly neap-spring, and the semi-annual cycle. Temporal dynamics of these driving forces evoke responses in the form of changing (I) circulation patterns and mixing, (2) sediment composition and transport, (3) solute speciation and distribution, (4) composition and abundance of particulates, (5) biomass, species composition, and productivity of plant and animal communities, (6) rates of material exchange between the sediments, water column, and atmosphere, and (7) bioavailability of trace metals and other pollutants. The purpose of this book is to examine the temporal dynamics of these properties and processes in the San Francisco Bay estuary.

This volume contains the papers and abstracts of the posters given at the symposium on Long-term Changes in Coastal Benthic Communities organized by the Commission of the European Communities in Brussels, Belgium from 9 till 12 December 1985. The organization of this symposium came to conclude five years of activities in the COST 647 project on Coastal Benthic Ecology, the rationale of which is explained in the foreword by B. F. Keegan. The importance of this volume is that for the first time special attention is given to long-term data series of relevant biological variables collected in different marine benthic habitats. Many of the data presented here are the result of years of careful data collection by some of the leading scientists in the field of benthic ecology. Some of the series, such as the Macoma balthica data from the Wadden Sea or the macrofauna data from Loch Linnhe, to name just those two, are already classics in the marine biological literature. Other data were collected in the framework of a monitoring programme and are now analyzed for the first time in the different perspective of the COST 647 project. Several papers are from related fields where they represent well known case studies; they were chosen in order to see how problems have been tackled elsewhere.

During the last few years, lake acidification has become a topic of international interest because of the detrimental effects of this problem on lake ecosystems. The stratigraphic record of diatoms and other paleoindicators in lake sediments has been used increasingly to document past limnological conditions. Because many diatom taxa are sensitive indicators of lakewater pH, this approach is especially useful in assessing impacts of atmospheric pollutants and watershed land use on lake pH. The idea that a book be prepared on this subject originated at a workshop entitled 'Reconstructing pH from sedimentary diatom remains - recent insights and update on methods' organized by R.B. Davis and held at the XXII Congress of the International Association of Limnology at Lyon, France in August 1983. At this workshop, presentations were made by many of the authors in this volume. The rapid progress in this field was evident when a second workshop, this time organized by R.W. Battarbee and R.J. Flower, was held one year later at the VII International Symposium on Diatoms at Paris, France. Many individuals helped with the preparation of this volume, most notable were our referees, who thoughtfully reviewed the manuscripts and suggested many improvements. I would also like to thank my colleagues at Queen's University who helped in innumerable ways over the last two years. A special word of gratitude is due to Dr. M.M. Boucherle, Dr. S.R. Brown, Ms. T.C. Oliver, and Mr. P.R. Leavitt. J.

This volume presents selected contributions given to the 38th European Marine Biology Symposium, held in Aveiro, Portugal, in September 2003. Understanding the functioning of marine ecosystems is the first step towards measuring and predicting the influence of Man, and to find solutions for the enormous array of problems we face today. This volume is organised according to the four subthemes of the symposium and to issues commonly perceived as relevant by scientists concerned with the study, protection and management of Marine Biodiversity: patterns and processes, assessment, threats and management and conservation. The 32 papers that make up this book represent current research and concerns about Marine Biodiversity in Europe, and will have wide appeal to all those interested in understanding and preserving the marine ecosystems of the world's oceans.

Handbook of Methods in Aquatic Microbial Ecology is the first comprehensive compilation of 85 fundamental methods in modern aquatic microbial ecology. Each method is presented in a detailed, step-by-step format that allows readers to adopt new methods with little difficulty. The methods represent the state of the art, and many have become standard procedures in microbial research and environmental assessment. The book also presents practical advice on how to apply the methods. It will be an indispensable reference for marine and freshwater research laboratories, environmental assessment laboratories, and industrial research labs concerned with microbial measurements in water.

This book shows how the biological transport, bioaccumulation, disposition, and toxicity of polycyclic aromatic hydrocarbons (PAH) in the aquatic environment are influenced by the ability or inability of organisms to metabolize these environmental pollutants. Written by leading scientists in the fields of PAH metabolism and toxicity in both aquatic and mammalian systems, this book discusses recent advances in the areas of PAH biogeochemistry and bioaccumulation, microbial degradation, enzymes of activation, and detoxication, metabolism of PAH, and laboratory and field studies on carcinogenic/toxic effects. Additionally, important similarities and differences in metabolism of PAH by aquatic and terrestrial organisms are featured. The discussion of bioavailability, metabolism, and subsequent toxic effects should aid in the assessment of the ecological consequences of PAH in the aquatic environment.

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.

The world's oceans cover 70% of the earth's surface and are home to a myriad of amazing and beautiful creatures. However, the biodiversity of the oceans is incre- ingly coming under serious threat from many human activities including overfi- ing, use of destructive fishing methods, pollution and commercial aquaculture. In addition, climate change is already having an impact on some marine ecosystems. This book discusses some of the major threats facing marine ecosystems by cons- ering a range of topics, under chapters discussing biodiversity (Chapter 1), fisheries (Chapter 2), aquaculture (Chapter 3), pollution (Chapter 4) and the impacts of increasing greenhouse gas emissions (Chapter 5). It goes on to explore solutions to the problems by discussing equitable and sustainable management of the oceans (Chapter 6) and protecting marine ecosystems using marine reserves (Chapter 7). Presently, 76% of the oceans are fully or over-exploited with respect to fishing, and many species have been severely depleted. It is abundantly clear that, in general, current fisheries management regimes are to blame for much of the widespread degradation of the oceans. Many policy-makers and scientists now agree that we must adopt a radical new approach to managing the seas - one that is precautionary in nature and has protection of the whole marine ecosystem as its primary objective. This 'ecosystem-based approach' is vital if we are to ensure the health of our oceans for future generations.

Ecotones, or boundary zones between land and inland waters (such as lakes, streams and rivers), are the principal routes for transport of organic matter and nutrients across landscapes via physical and biological vectors. The ecotone is the place of cumulation and transformation of in situ production as well as of allochthonous material from adjacent aquatic and terrestrial systems. The ecotype functions as an important barrier or filter for principal nutrients, such as phosphorus and nitrogen, responsible for the eutrophication and degradation of surface waters. Intensive forest cutting, agriculture, pollution and bank regulation, urbanization and hydrotechnical constructions seriously endanger the ecotone systems and damage their protective function. It is vital to develop a scientific understanding of the behaviour of phosphorus and nitrogen in these transitional boundary habitats. Such an understanding is important for the rational protection, management and restoration of ecotones connected with lakes and rivers. The importance of nutrient cycling and retention is discussed from the point of view of ecotone function, management and reconstruction in order to sustain its protective role for water bodies. Various types of land/water transitory zones are discussed: wetlands, lake littoral systems, riparian zones of rivers, streams and brooks, the contact zones between groundwater and surface waters of lakes and rivers, air--water interfaces, and patch/ecotone structures in watersheds.

Tidal salt marshes are viewed as critical habitats for the production of fish and shellfish. As a result, considerable legislation has been promulgated to conserve and protect these habitats, and much of it is in effect today. The relatively young science of ecological engineering has also emerged, and there are now attempts to reverse centuries-old losses by encouraging sound wetland restoration practices. Today, tens of thousands of hectares of degraded or isolated coastal wetlands are being restored worldwide. Whether restored wetlands reach functional equivalency to natural' systems is a subject of heated debate. Equally debatable is the paradigm that depicts tidal salt marshes as the great engine' that drives much of the secondary production in coastal waters. This view was questioned in the early 1980s by investigators who noted that total carbon export, on the order of 100 to 200 g m-2 y-1 was of much lower magnitude than originally thought. These authors also recognized that some marshes were either net importers of carbon, or showed no net exchange. Thus, the notion of outwelling' has become but a single element in an evolving view of marsh function and the link between primary and secondary production. The revisionist' movement was launched in 1979 when stable isotopic ratios of macrophytes and animal tissues were found to be mismatched'. Some eighteen years later, the view of marsh function is still undergoing additional modification, and we are slowly unraveling the complexities of biogeochemical cycles, nutrient exchange, and the links between primary producers and the marsh/estuary fauna. Yet, since Teal's seminal paper nearly forty years ago, we are not much closer tounderstanding how marshes work. If anything, we have learned that the story is far more complicated than originally thought. Despite more than four decades of intense research, we do not yet know how salt marshes function as essential habitat, nor do we know the relative contributions to secondary production, both in situ or in the open waters of the estuary. The theme of this Symposium was to review the status of salt marsh research and revisit the existing paradigm(s) for salt marsh function. Challenge questions were designed to meet the controversy head on: Do marshes support the production of marine transient species? If so, how? Are any of these species marsh obligates? How much of the production takes place in situ versus in open waters of the estuary/coastal zone? Sessions were devoted to reviews of landmark studies, or current findings that advance our knowledge of salt marsh function. A day was also devoted to ecological engineering and wetland restoration papers addressing state-of-the-art methodology and specific case histories. Several challenge papers arguing for and against our ability to restore functional salt marshes led off each session. This volume is intended to serve as a synthesis of our current understanding of the ecological role of salt marshes, and will, it is hoped, pave the way for a new generation of research.

The idea of producing a book on the activities of sence of bottom versus surface withdrawal all have microorganisms in reservoirs had its origins in an a bearing on microbial processes. In addition, res article published by the editor in ASM News (De ervoirs are often constructed in areas where there cember 1981, 47:527-531). Many individuals ex are few, if any, natural lakes . In this regard, reser pressed an interest in having the article expanded voirs are also often distinct from natural lakes, and into a book on this subject. Several people were that meteorologic, hydrologic, geo to the extent contacted and asked if they would be willing to logic, and edaphic factors make a difference, reser contribute chapters to the book. The interest dis voir microbiology will also be different. Finally, the played by many persons outside the area of reser creation of a new reservoir offers the sediment voir microbiology was encouraging, as was the in microbiologist a unique opportunity to view the spiration of the contributors themselves. We were transformation of terrestrial environments into subsequently approached by Dr. L. Harold Steven aquatic ecosystems."

The Fourth International Symposium on Paleolimnology was held in 1985 from 2 -7 September at Lake Ossiach and close to the Austrian village of Ossiach (mentioned in historical records for the first time in 1028). After the opening speeches a performance by a Carinthian folk-dance group gave the participants a taste of the rural atmosphere of Austria's southernmost federal land. 125 paleolimnologists presented and discussed papers during the meetings and many participated About in the pre-congress excursion devoted to the Salzkammergut, and in the post-congress excursion to Neusied- lersee. There was a half-day trip during the symposium to Langsee which is well known from the pioneer work carried out by Professor D. G. Frey more than 30 years ago. In addition to methodological papers most of the special fields of paleolimnology were covered. Special attention was given a.o. to geochemistry, pigments and meromictic lakes. The geographical range of the sites investigated was quite wide. In this connection it is regrettable that none of the expected Soviet colleagues was able to attent the symposium. Under the presidency of Professor D. G. Frey the present members of the international organizing committee (Prof. S. R. Brown, Prof. E. S. Deevey, Prof. F. Oldfield and Dr. M. Ralska-Jasiewiczowa) contributed considerably to the success of the symposium. Likewise our thanks goes to those who helped behind the scenes (Mr. M. Bobek, Mr. M. Fusko, Mrs. A. Klenner, Ms. B. Stipanits and Ms. K. Wolter).

The structure and functioning of eutrophicated aquatic ecosystems has received considerable attention from limnologists as well as water managers in recent years. Stress has often been on pelagic food webs of deeper lakes whilst littoral systems or shallower lakes have been less thoroughly investigated. Since Dutch aquatic systems are shallow, as a rule, they form a notable exception. But here, too, the orientation was often on pelagic food webs. The present study has a clearly different scope in that it takes the water plant as prime perspective. The editors consider water plants to be the key component in shallow aquatic ecosystems. They have compiled work on one water plant species, Potamogeton pectinatus L., and from one lake, Lake Veluwe, as a typical case, and set out to explain the fluctuations in abundance of this water plant as influenced by eutrophication. A working hypothesis on the mechanism responsible for water plant decline during eutrophication was adopted and tested in a combination of field and laboratory work. A simulation model, SAGAI, for the water plant P.pectinatus was developed and proved to fit independent data very well. The work started out as a joint effort of a single project team in the Department of Nature Conservation of Wageningen Agricultural University, but the present volume has benefited considerably from the inputs of several invited colleagues, as the list of contributors witnesses. The editors have made an invaluable contribution to the understanding of shallow aquatic ecosystems and to their scientifically based and sustainable management.

Acipenser brevirostrum female 58 cm long from the Hudson River near Kingston, New York, above Acipenser oxyrinchus male 58 cm long from the Lawrence River near St. Vallier, Quebec, by Paul I. Voevodine from Vladykov & Greeley (1963). 1 Sturgeon landing on the Volga River. From an engraving in Moynet . p. 85. 1 Moynet, M. 1867. LaVolga. LeTourduMonde15: 81-96. Environmental Biology of Fishes 48: 373-380,1997. (c) 1997 Kluwer Academic Publishers. Printed in the Netherlands. Sturgeons and the Aral Sea ecological catastrophe Iliya Zholdasova Institute of Bioecology, Karakalpak Branch of the Academy of Sciences of Uzbekistan, Nukus, Republic Ka- kalpakstan Received5.4.1995 Accepted16.3.1996 Key words: Amu-Dar River, Syr-Dar River, Pseudoscaphirhynchus kaufmanni, P. fedtschenkoi, P. hermanni, Acipenser nudiventris, pollution, acclimatization, Nitzschia Synopsis A short description of the catastrophic changes in the ecology of the Aral Sea basin during the three last decades is presented. These changes have influenced the status oftwo acipenserid endemics to the area, the large Amu-Dar shovelnose, Pseudoscaphirhynchus kaufmanni, and the ship sturgeon,Acipensernudiventris. The main biological characteristics ofboth species in the new environmental conditions are given. Previous unsuccessful attempts to introduce other acipenserid species into the area are also described. International cooperationisneededforsavingthelastsurvivingspeciesrepresentingthegenusPseudoscaphirhynchus.The only twootherspeciesofthe same genus, P.fedtschenkoi and P . hermanni, have alreadybecome victims ofthe Aral Sea catastrophe and are apparently extinct. Introduction 1993). Twosturgeonspecies, the Syr-Dar and small Amu-Dar shovelnose sturgeons, were among the Historically the endemic fauna ofthe Aral Sea ba- first victims of this disaster and seem to be extinct.

The Antarctic continent carries the greatest diversity of lake environments on the planet: freshwater and saline lakes, tidal freshwater epishelf lakes, lakes on ice shelves and glacier surfaces, and over three hundred subglacial lakes; extraordinary ecosystems that have been separated from the atmosphere for up to millions of years. This book provides a unique and cutting edge synthesis of Antarctic limnology, drawing together current knowledge on geomorphology, morphometry, chemistry, community structure and function. It emphasises throughout the value of these near-pristine ecosystems as barometers of climate change, showing how responsive and vulnerable they are to the indirect impacts of anthropogenic activity. Antarctic Lakes begins with an introduction to their physical, chemical, and biological characteristics, providing a basis for understanding the subsequent detailed chapters on different lake types, and ends with a chapter considering the application of new technologies to polar limnology as well as identifying future research directions. This accessible text is suitable for both senior undergraduate and graduate students taking courses in Antarctic and polar limnology, and will also be of broad interest to researchers working in the areas of polar science, microbial ecology (and extremophiles), climatology, glaciology, and astrobiology.

In August of 1980, near the whistlestop of Maltby, Surely, we would plead, the U. S. A. , a wealthy Washington, Don Stewart and I met in my rented nation,can fund our proposal if only as a gesture of house trailer to sketch a proposal to the National support to foreign scientists. Somehow, however, Science Foundation. Our goal was simple: to re we seemed to miss deadlines, fall in-between the quest from the Foundation air fare and per diem for cracks, and miss the right connections. It was not approximately 20 Latin American scientists to at until May, 1982, several weeks before the proposed tend a workshop entitled the 'Systematics and workshop, that we realized we could not find any Evolutionary Ecology of Neotropical Freshwater funds for bringing Latin American scientists to the Fishes' that would follow the 1982 ASIH (Ameri U. S. The programs for the meeting had been can Society of Ichthyologists and Herpetologists) printed, the meal coupons, banquet tickets, and all meeting. We had presented an initial outline for our the other amenities that come with a professional proposal to a number ofcolleagues in . June of 1980 meeting were ready, but we had no Latin American at the ASIH meeting at Texas Christian University ichthyologists as participants. Some abstracts were in Fort Worth, Texas. The steering committee for being received by the program organizers, but the workshop, consisting of a dozen senior scien without U. S.

We are witnessing an alarming, global biodiversity crisis with an ongoing loss of species and their habitats. In response, a number of tools and approaches - including some that are contested - are being explored and promoted. Biodiversity offsets are one such approach, and deserve critical examination since the debate surrounding them has often been oversimplified and lacking practical evidence. As such, this study presents a refined typology including seven types of biodiversity offsets and taking into account different contexts, governance arrangements and drivers. It draws on a detailed analysis of theoretical concepts to explain the voluntary implementation of biodiversity offsets using an internet-based (netnographic) research approach. Furthermore it builds on a broad global explorative base of 72 practical examples and presents in-depth case studies for each type. The results reveal a number of global tendencies that allow recommendations to be made for different locations, contexts and stakeholders. They also encourage the expansion of this research field to respond to the pressing needs of policy and practice.