Landscape approaches to stream fish ecology, mechanistic aspects of habitat selection and behavioral ecology. Introduction and commentary

The Ecology of Stream Fish Symposium (LobonCervia & Mortensen 1999) was structured as a number sessions destined to showcase the latest developments and prospects for the future in areas of research that, in the opinion of the meeting's Steering Committee and organizers, held particular interest. Convinced of the benefits of research that integrates across fields, the Committee contemplated this division into subtopics as a sort of "necessary evil" imposed by logistics and not without some apprehension about how it may affect the snapshot of current research the Committee hoped the Symposium to offer. The inherent artificiality of this, or any other, rigid scheme was amply confirmed as soon as proposals for presentations started arriving. It was often apparent that slight shifts of emphasis would have allowed the comfortable lodging of the same presentation in different sessions. Fortunately, the Symposium's size did not require^ running sessions simultaneously, and all participants could attend all talks if they so wished. As a consequence, audiences were always diverse in terms of the research areas represented in them, and this greatly helped to bring out the cross-field aspects of presentations in the subsequent periods for comment and discussion. Thus, common ideas and themes that had attracted the attention of researchers with varied perspectives and primary interests were highlighted, and there was abundant opportunity for the enriching insight provided by views of a certain topic from different angles. We, as chairpersons of the sessions Landscape Approaches to Stream Fish Ecology (Gary D. Grossman & Pedro A. Rincon), Mechanistic Aspects of Microhabitat Selection (Pedro A. Rincon & Gary D. Grossman) and Behavioral Ecology (Nicholas F. Hughes) had a particularly good opportunity to experience (and enjoy) the situation described above. We were aware in advance of the strong ties among our sessions: If landscapeoriented research is marked by its representation of the environment as a mosaic of patches of different. characteristics whose geometry (spatial arrangement and connectivity) can be as relevant as their features, the study of habitat selection by stream fishes can be conceived as inquiry about patch choice at small spatial scales of environmental variation (centimeters to tens of meters, usually). Elucidating the mechanisms producing the observed selection patterns typically involves at least rough attempts to estimate organismal performance (such as prey capture and swimming capacities) and integrate it with environmental conditions into sets of constraints within which the fish are, at least hypothetically, expected to operate in ways ultimately producing fitness maximization. However, this expectation of animals to behave optimally under the specific circumstances they 'encounter is the same evolutionary logic considered the basis and hallmark of behavioral ecology and that research in that discipline routinely uses to generate testable predictions about animal behavior. The Symposium turned out to be a good medium for those conceptual links to materialize in a number of more specific research topics and approaches. We take this as a two-fold suggestion: of areas offering exciting opportunities for future research, but also as an indication that such research will be more likely to advance our understanding if it integrates different perspectives'. For