This book argues that the "null model" for describing consumer-resource interactions in ecology must be changed. Evidence is drawn from experiments, from observations and from mathematical models.

Understanding the functioning of ecosystems requires the understanding of the interactions between consumer species and their resources. How do these interactions affect the variations of population abundances? How do population abundances determine the impact of predators on their prey? The view defended in this book is that the "null model" that most ecologists tend to use is inappropriate because it assumes that the amount of prey consumed by each predator is insensitive to the number of conspecifics. The authors argue that the amount of prey available per predator, rather than the absolute abundance of prey, is the basic determinant of the dynamics of predation. This so-called ratio dependence is shown to be a much more reasonable "null model."

This book argues that the "null model" for describing consumer-resource interactions in ecology must be changed. Evidence is drawn from experiments, from observations and from mathematical models.

This book clearly describes the many applications of graph theory to ecological questions, providing instruction and encouragement to researchers.

Running waters are enormously diverse, ranging from torrential mountain brooks, to large lowland rivers, to great river systems whose basins occupy subcontinents. While this diversity makes river ecosystems seem overwhelmingly complex, a central theme of this volume is that the processes acting in running waters are general, although the settings are often unique. The past two decades have seen major advances in our knowledge of the ecology of streams and rivers. New paradigms have emerged, such as the river continuum and nutrient spiraling. Community ecologists have made impressive advances in documenting the occurrence of species interactions. The importance of physical processes in rivers has attracted increased attention, particularly the areas of hydrology and geomorphology, and the inter-relationships between physical and biological factors have become better understood. And as is true for every area of ecology during the closing years of the twentieth century it has become apparent that the study of streams and rivers cannot be carried out by excluding the role of human activities, nor can we ignore the urgency of the need for conservation. These developments are brought together in Stream Ecology: Structure and function of running waters, designed to serve as a text for advanced undergraduate and graduate students, and as a reference book for specialists in stream ecology and related fields.

The dipteran family Chironomidae is the most widely distributed and frequently the most abundant group of insects in freshwater, with rep resentatives in both terrestrial and marine environments. A very wide range of gradients of temperature, pH, oxygen concentration, salinity, current velocity, depth, productivity, altitude and latitude have been exploited, by at least some chironomid species, and in grossly polluted environments chironomids may be the only insects present. The ability to exist in such a wide range of conditions has been achieved largely by behavioural and physiological adaptations with relatively slight morphological changes. It has been estimated that the number of species world-wide may be as high as 15000. This high species diversity has been attributed to the antiquity of the family, relatively low vagility leading to isolation, and evolutionary plasticity. In many aquatic ecosystems the number of chironomid species present may account for at least 50% of the total macroinvertebrate species recorded. This species richness, wide distribution and tolerance to adverse conditions has meant that the group is frequently recorded in ecological studies but taxonomic difficulties have in the past prevented non-specialist identification beyond family or subfamily level. Recent works, including genetic studies, have meant that the family is receiving much more attention globally.