The challenges that the world's running water systems now face have never been more numerous or acute; at the same time, these complex habitats remain absolutely crucial to human wellbeing and future survival. If rivers can ever be anything like sustainable, ecology needs to take its place as an equal among the physical sciences such as hydrology and geomorphology. A real understanding of the natural history and ecology of running waters must now be brought even more prominently into river management. The primary purpose of this textbook is to provide the up-to-date overview that students and practitioners will require to achieve this aim. The book's unifying focus is on rivers and streams as ecosystems in which the particular identity of organisms is not the main emphasis but rather the processes in which they are involved - specifically energy flow and the cycling of materials. It builds on the physicochemical foundations of the habitat templet and explores the diversity and adaptations of the biota, progressing from the population and community ecology of organisms and linking them to ecosystem processes and services in the wider biosphere via the complexities of species interactions and food webs. These include water quality and patterns of river discharge, as well as aesthetics, waste disposal, and environmental health. While the book is not primarily focused on application per se, each chapter addresses how humans affect rivers and, in turn, are affected by them. A final, future-oriented chapter identifies key strategic areas and sets a roadmap for integrating knowledge of natural history and ecology into policy and management. The Biology and Ecology of Streams and Rivers is an accessible text suitable for both senior undergraduate and graduate students taking courses in both lotic and general ecology as well as more established researchers, practitioners, managers, and conservationists requiring a concise and contemporary overview of running waters.

Biogeography may be defined simply as the study of the geographical distribution of organisms, but this simple definition hides the great complexity of the subject. Biogeography transcends classical subject areas and involves a range of scientific disciplines that includes geogra phy, geology and biology. Not surprisingly, therefore, it means rather different things to different people. Historically, the study of biogeogra phy has been concentrated into compartments at separate points along a spatio-temporal gradient. At one end of the gradient, ecological biogeography is concerned with ecological processes occurring over short temporal and small spatial scales, whilst at the other end, historical biogeography is concerned with evolutionary processes over millions of years on a large, often global scale. Between these end points lies a third major compartment concerned with the profound effects of Pleistocene glaciations and how these have affected the distribution of recent organisms. Within each of these compartments along the scale gradient, a large number of theories, hypotheses and models have been proposed in an attempt to explain the present and past biotic distribution patterns. To a large extent, these compartments of the subject have been non-interactive, which is understandable from the different interests and backgrounds of the various researchers. Nevertheless, the distribu tions of organisms across the globe cannot be fully understood without a knowledge of the full spectrum of ecological and historical processes. There are no degrees in biogeography and today's biogeographers are primarily born out of some other discipline."

During the past two decades, there has been a gradual change of emphasis in ecological studies directed at unravelling the complexity of natural communities. Initially, the population approach was used, where interest lay in the way individual populations change and in the identification of factors af fecting these changes. A good understanding of the dynamics of single populations is now emerging, but this has not been a very fruitful approach at the community level. In the natural world, few species can be treated as isolated populations, as most single species are the interacting parts of multispecies systems. This has led to a community approach, involving the study of interrelationships between species within com munities and investigation of the actual organization of natural communities as a whole. The formalization of a number of new concepts and ideas has evolved from this approach, including niche theory, resource allocation, guild structure, limiting similarity, niche width and overlap etc., which, until fairly recently, have been examined mainly from a theoretical point of view. However, a wealth of field data is gradually being added to the literature, especially from the general areas of island biogeography and resource partitioning amongst closely related species. Community structure embodies patterns of resource allocation and spatial and temporal abundance of species of the community, as well a. '1 community level properties such as trophic levels, succession, nutrient cycling etc."