7405

• UCREFRP Catalog Number: 7405
• Author: Bain, M. B., ed. 1990.
• Title: Workshop Synopsis,
• USFW Year: Ecolog
• USFW - Doc Type: U.S. Department of the Interior,
• Copyright Material: NO

Ecological Research

Presentations by stream ecologists address a variety of organisms, physical characteristics, and tem-
poral properties of stream systems. Despite the wide differences in research topics and background of
speakers, four recurrent themes are evident. First, the need to understand the extent and causes of natural
variation in biological communities is stressed as a prerequisite for developing effective management
methods. Many studies have identified that populations, trophic organization, interspecific interactions,
and species compositions are dynamic and change through time in stream systems. The magnitude of
natural change is recognized as considerable and difficult to predict but not solely a random phenomenon.
Second, the importance of natural variability and timing of flow events (especially floods and floodplain
inundation) is recognized. Much of the variability in stream biota probably comes from the natural variability
in streamflows. Research shows that organisms are adapted to seasonal cycles in stream discharge, and
maintaining these cycles will be necessary to preserve natural system properties. Third, the critical im-
portance of early life stages in determining adult population dynamics is discussed. Although several
speakers identified this area as integral for explaining the natural dynamics of stream fish populations,
they also agree that present knowledge of early life biology is poor and hampered by the continued em-
phasis on studies of adults and late juveniles. Finally, the complexity observed in warmwater communities
and species-habitat relations is emphasized. Despite high complexity, the presentations include some
generalized patterns (e.g., invertebrate production, faunal declines, fish-habitat organizations) that are
useful for stream management. In general, recent research and probable future emphasis seem to center
on relations among different types of aquatic habitats, causes of variance in the biological characteristics
of streams, and the role of temporal habitat variability in communities.

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