Tropical Stream Ecology

In a certain sense, this book was waiting to be written. There has been a recent surge of interest in tropical streams and rivers. As pointed out in the Preface, several special issues of scientific journals have dealt with tropical streams, e.g., J-NABS 1988 (vol. 7[4]), 1995 (vol. 14[1]), 2006 (vol. 25[1]), and 2009 (vol. 28[2]); Aquatic Conservation: Marine and Freshwater Ecosystems 2006 (vol. 16[7]). Several sessions at recent annual meetings of the North American Benthological Society (NABS) have been devoted to different aspects of tropical stream ecology. However, until now, a textbook addressing the ecology of these systems has not been available. The need and the apparent market notwithstanding, the task of producing a comprehensive reference of tropical stream ecology was a great challenge. The tropics are such a vast area to cover, and the question of a ‘‘typical tropical stream’’ is almost impossible to address. One of the important purposes of this book is to redress the imbalance of available information on temperate vs tropical streams. For a variety of reasons, reports on tropical stream research tend not to reach the general international literature, a situation that further compounds the problem of the relative scarcity of reports of research on tropical streams. David Dudgeon is in an excellent position to tackle this topic. He has had a long and distinguished career in tropical stream research. From his location in tropical Asia, he probably has a more general vision of the field than, say, someone based in the relatively well-known Neotropics. He has chosen the authors of chapters with great care to provide coverage of the different topics that is as balanced as possible. Thus, he has contributors from all the major tropical regions, and within each chapter it seems he has tried to combine authors from different regions. That said, on more than one occasion in the book the paucity of information from the African continent is mentioned. The book has admirable coverage of the many aspects of tropical stream ecology. The definition of stream is taken liberally, and the treatment strays inevitably into rivers and even large rivers. Sensibly, this interpretation allowed treatment of riparian wetlands (Chapter 7). Of course, it was not possible to cover everything in 10 chapters and 300 pages. For example, algae and plants are not given a chapter, and although social and policy issues are mentioned in many parts of the book, they are not specifically addressed. Partly because different people wrote the different chapters and partly because it is in the nature of ecology, certain topics appear repeatedly throughout the book. Authors touch on conservation in many places, and this topic has a chapter of its own (Chapter 10), although Dudgeon states in the Preface that the treatment of conservation was reduced because of recent literature and reviews. The particular question of shredding fauna and their apparent paucity in tropical streams is mentioned in the context of organic matter processing (Chapter 3), macroinvertebrates (Chapter 4), and ecological difference of tropical streams (Chapter 9). In some cases, differences of opinion or treatment by authors of different chapters have not been resolved. This disagreement does not detract from the book as a whole, but rather, serves to enrich the discussion and to indicate that much of the knowledge of tropical stream functioning is still being gathered and is controversial. A recurring theme is the question of whether tropical streams are different from temperate streams. This question is covered in a specific chapter (Chapter 9) and appears in many other chapters. The immediate difficulty is to define what would constitute a significant or emergent difference because many of the differences are trivial products of latitude, warmer temperatures, and more evenly distributed radiation. Andrew Boulton and coauthors (Chapter 9) do an admirable job of delineating the questions and discussing the evidence. They conclude that the available evidence suggests ‘‘no consistent differences in food-web structure, productivity, organic-matter processing or nutrient dynamics. ’’ This conclusion will be contested by others (including me), and I am sure that the debate will remain alive for many years. Apart from the speculative and controversial topics, the book provides a comprehensive treatment of tropical stream ecology, with chapters on physical and chemical features, primary production, organic matter processing, macroinvertebrates, fish, other vertebrates, riparian wetlands, ecological differences, and conservation. One surprise for me in this line-up JNABS Journal, 2010, 29(2):773–774 ’ 2010 by The North American Benthological Society DOI: 10.1899/29.2. BR.774. 1 Published online: 6 April 2010