Correspondence Between Ecoregions and Spatial Patterns in Stream Ecosystems in Oregon

Abstract

Multivariate analyses of biotic assemblages and physicochemical measures, species richness, diversity, and composition were used to evaluate the robustness of Omernik's ecoregion classification for small streams in the eight ecoregions of Oregon. Clearest differences were between the montane and nonmontane regions. For the three nonmontane regions, ordinations of fishes, macroinvertebrates, water quality, and physical habitat measures show the clearest differences, with the Willamette Valley ecoregion being consistently most unlike all other regions. Differences between the Columbia Basin and High Desert regions were clearest for water quality and physical habitat measures and fish assemblages. Differences among the montane regions were subtle. Of these regions, the East Cascade Slopes showed the greatest variability, as shown by the ranges of ordination scores for fishes, water quality, and physical habitat. Regional patterns in periphyton assemblages were markedly different from the patterns in the other groups of variables. Ecoregions can be used as a broad-scale geographic framework for classifying streams. This framework provides managers of lotic resources a useful alternative to river basins.

Environmental Factors Influencing Local Fish Species Richness and Differences between Hydroregions in South‐Western France

“…During the last decades, there have been many attempts to produce stream classifications based on aquatic community features (e.g., ILLIES and BOTOSENEANU, 1963;GIBON and STATZNER, 1985;OMERNIK, 1987;WHITTIER et al, 1988;TATE and HEINY, 1995). Nevertheless, few typological systems have had more than local acceptance (PENNAK, 1971).…”

“…Both scientific studies and regional surveys of stream ecosystems have provided large volumes of site-specific data (e.g., WHITTIER et al, 1988;CAYROU et al, 2000), from which local and regional spatial patterns of biological communities can be derived DETHIER and CASTELLA, 2002). Several authors have thus emphasized the importance of geographic differences in biotic and abiotic characteristics of streams (CULP and DAVIES, 1982;ORENDT, 2003), so that classification has become an integral part of efforts to study, monitor and manage ecosystems at a regional scale (WARREN, 1979;OMER-NIK, 1987;TATE and HEINY, 1995;SANDIN and JOHNSON, 2000).…”

Distribution of benthic diatoms in Korean rivers and streams in relation to environmental variables

“…Subsequently, many studies have used the ecoregion concept to interpret regional biological phenomena and ecosystem function Roth et al, 1996;Butcher et al, 2003;Simboura et al, 2005;Borja et al, 2007). However, there is often less correspondence between spatial patterns of biological communities and ecoregional classification (Whittier et al, 1988;Pan et al, 1999;Potapova and Charles, 2002), probably because of the greater impact of local geomorphic factors (e.g., habitat alteration and destruction, channel straightening, and river bed modification) and disturbance factors (e.g., pollution), which interact in a complicated manner (Biggs et al, 1990). The spatial distribution of benthic river diatoms that we found in the present study is worthy of further investigations in relation to ecoregion classification.…”

Associations spécifiques chez les macroinvertébrés benthiques et leur utilisation pour la typologie des cours d'eau. Cas du réseau hydrographique Adour-Garonne (France)

“…Au cours des dernières décennies, de nombreuses classifications des cours d'eau basées sur des associations d'espèces aquatiques ont été proposées (Huet 1949, lilies & Botosaneanu 1963, Omernik 1987, Whittier et al 1988, Tate & Heiny 1995. Un intérêt majeur de telles classifications est que la stabilité spatio-temporelle des ces associations peut être utilisée pour définir des sites ou des stations de référence pour une surveillance biologique des rivières (Hughes et al 1986) : tout changement dans la composition et la structure des assemblages spécifiques pourra être la conséquence de modifications environnementales dans un cours d'eau , appartenant à une section longitudinale ou à une région caractérisée par un peuplement type.…”

“…Cependant, plusieurs auteurs ont souligné la nécessité de considérer les différences géographiques qui existent au niveau des caractéristiques biotiques et abiotiques des cours d'eau (Culp & Davies 1982). Cette hypothè-se peut être vérifiée pour une région donnée en proposant un modèle géographique, c'est-à-dire une carte (Whittier et al 1988). …”