Bøger i Developments in Hydrobiology serien

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.

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.

The present volume comprises aspects of both basic and applied limnology. They include works on physical, chemical, and biological limnology, as well as experimental approaches in selected areas.Contributions from investigators regarding aquatic conservation and biodiversity were specifically not available and therefore, these aspects are considered in various included works. Most manuscripts deal with lentic aquatic resources. This is not surprising since Mexican limnology followed the general study trend of that from temperate limnology. Despite this, we must emphasize that lotic resources in Mexico are quite important both locally and regionally. This does not mean that rivers are not under limnological research in Mexico, just that their study has only recently begun.It is the intention of the volume to stimulate a larger section of limnologists to further research in this field. It is to be hoped that policy-framing governmental authorities in Mexico will benefit from it, and consider some of the aspects described so that further damage to the epicontinental waterbodies can be halted, and remedial measures can be considered in the future.

`Jellyfish', a group that includes scyphomedusae, hydromedusae, siphonophores and ctenophores, are important zooplankton predators throughout the world's estuaries and oceans. These beautiful creatures have come to public attention as featured exhibits in aquaria and in news headlines as invaders and as providers of genes used in biomedical research. Nevertheless, jellyfish are generally considered to be nuisances because they interfere with human activities by stinging swimmers, clogging power plant intakes and nets of fishermen and fish farms, and competing with fish and eating fish eggs and larvae. There is concern that environmental changes such as global warming, eutrophication, and over-fishing may result in increased jellyfish populations. The literature reviews and research papers in this volume explore the interactions between jellyfish and humans. Papers cover the medical aspects of jellyfish stings, jellyfish as human food and jellyfish fisheries, interactions of jellyfish and fish, effects of environmental changes on jellyfish, effects of introduced ctenophores on the Black Sea ecosystem, factors causing increases or concentrations of jellyfish, and others aspects of jellyfish ecology. This is an important reference for students and professional marine biologists, oceanographers, fishery scientists, and aquarists.

Crater Lake is located in the caldera of Mount Mazama in Crater Lake National Park, Oregon. The lake has a surface area of about 53 km2 at an elevation of 1882 m and a maximum depth of 594 m ¿ seventh deepest in the world. Limited studies of this ultraoligotrophic lake conducted between 1896 and 1981, lead to a 10-year limnological study to evaluate any potential degradation of water quality. No long-term variations in water quality were observed that could be attributed to anthropogenic activity. Building on the success of this study, a permanent limnological program has been established with a long-term monitoring program to insure a reliable data base for use in the future. Of equal importance, this program serves as a research platform to develop and communicate to the public a better understanding of the coupled biological, physical, and geochemical processes in the lake and its surrounding environment. This special volume represents our current state of knowledge of the status of this pristine ecosystem including its special optical properties, algal nutrient limitations, pelagic bacteria, and models of the inter-relationships of thermal properties, nutrients, phytoplankton, deep-water mixing, and water budgets.

Ecotones are interface zones between different ecosystems. Their ecological role and significance with regard to ecological management and conservation has become increasingly appreciated. For the management of freshwater resources, for example, an improved understanding of the role of land/inland water interfaces, will be essential for reducing negative human impacts by engineering, nutrient loading, siltation, etc. The management of ecotones, on the other hand, offers the possibility to control aquatic system processes via stock control of fish populations. Fish apparently are both excellent indicators of ecotone quality as well as determiners of its structure and function.

Industrial seaweed use started in Brittany in the XVII century. Today, 700 species have been identified along 1000 km of shoreline, producing 10 million tons of biomass. In the Fourteenth International Seaweed Sumposium the latest developments in the area are discussed. The blending of molecular biology with traditional taxonomy is improving our understanding of phylogeny and species relationships among many of the important algae. A new generation of biologically-based management models is gradually incorporating field testing, concepts from ecological theory and principles from population biology. Prediction is being improved, and an appropriate balance is being struck between commercial exploitation and the preservation of wild seaweed resources. Cell and tissue culture of seaweeds is entering the mass-production phase. Field farming is now entering the large-scale production area. New, biologically active compounds are being described, obtained from algae, and new tools for the characterisation of phytocolloids are described. Microalgal blooms and toxins are also experiencing a flourish of new results.

Members of the gastropod family Littorinidae are common throughout the world. They form a very abundant component of many intertidal and shallow subtidal ecosystems and, by their grazing, often play a central role in shaping these communities. They also display a wide range of life history strategies and many are polymorphic, making them attractive model organisms for ecologists, evolutionary biologists and physiologists alike. Areas of particular interest include ecological interactions with other animals and with algae, the effects of pollutants and the use of littorinids as sentinel species for monitoring pollution, the effects of parasites on growth and ecology, taxonomy, and the study of genotypic/phenotypic responses to environmental factors. There is still much to be done, and the littorinids are proving to be an ideal group on which to work. Audience: Primarily targeted at the research level. Will also provide useful information for advanced first-degree students conducting research projects.

Concentrations of dissolved organic matter (DOM) in lakes are often an order of magnitude greater than concentrations of particulate organic matter; nevertheless, the biogeochemical analysis of DOM is described in only a few textbooks on limnology (most thoroughly by Wetzel). The orgins of dissolved organic substances are largely photosynthetic; DOM is either autochthonously synthesized by littoral and pelagic flora through secretions and autolysis of cellular contents, or allochthonously generated in terrestrial systems of the drainage basin, composing largely of humic substances refractory to rapid microbial degradation. The role of DOM in lacustrine ecosystems, as energy source and system regulator, however, is still poorly known. The aim of this book is: (1) to present state-of-the-art reviews of the role of dissolved autochthonous and allochthonous organic matter in pelagial and littoral zones; and (2) to focus attention on poorly understood but critical topics and hence to provide direction for future research activity.

Mangrove ecosystems are typical formations found in coastal deposits of mud and silt throughout the tropics and some distance into the subtropical latitudes. The total wordwide mangrove area, which is estimated at about 170,000 km2 with some sixty species of trees and shrubs exclusive to the habitat, dominates approximately 75% of the world's coastline between latitudes 25(deg)N and 25(deg)S. Such unique intertidal ecosystems support genetically diverse communities of terrestrial and aquatic organisms that are of direct or indirect socioeconomic values. Mangrove forests play important roles as coastal stabilization and protection against winds and storms; producers of nutrients, forest resources and animal species of economic importance. Recently, the issues on the conservation, proper utilization and management of mangrove forests have been widely discussed. Unfortunately, overexploitation and destruction of mangroves seriously threatens the sustainability of such a unique ecosystem. This volume includes papers on three main areas: recent advances in mangrove ecology; application and utilization of mangrove resources; and conservation and management of the ecosystems.

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.

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.

Proceedings of a Conference on Rutland Water, held in Leicester, 1-3 April 1981

A major concern among ecologists in and outside the ASEAN region is the degradation of the environment, and the overexploitation of freshwater and marine resources. There is as yet no indication that freshwater and marine resources are being managed on a sustainable basis, and loss of wetlands, whether freshwater swamps or mangrove swamps, is a major problem in the ASEAN region. Reclamation of mangrove swamps for aquaculture and agriculture seems to be a continuous activity here and the status of marine parks should also be examined in the light of recent resort development acitivities on small islands. This volume contains numerous recommendations for the promotion of ecological studies and regional cooperation in marine, freshwater ecology and conservation, with special emphasis on the common water masses like the Strait of Malacca, Gulf of Thailand and the South China Sea.