A hierarchical evaluation system for characterizing watershed ecosystems for fish habitat

Water Velocity Tolerance in Tadpoles of the Foothill Yellow-legged Frog (Rana boylii): Swimming Performance, Growth, and Survival

“…Abiotic conditions are nested in a hierarchy from small to large spatial and temporal scales, where microhabitat physical characteristics such as velocity, depth and substrate are nested within larger scale features such as mesohabitat morphology (tens of meters in river length), channel slope and reach morphology (hundreds of meters) and proximity to floodplain or tributary habitats (thousands of meters) (Frissell et al 1986;Imhof et al 1996). Biotic factors such as abundance of resources (algae for tadpoles, insects for adult frogs), density of competitors and distribution of predators similarly vary at fine and broad spatial scales (Power et al 1988;Poff 1997).…”

An Ecological Flow Assessment Framework: Building a Bridge to Implementation in Canada

“…Maintain sediment transport capacity Maintain aquatic habitat Maintain profile, spacing and sequences of features Hydraulic biotypes (e.g., riffles, runs, pools, cascades, backwaters and side channels) are integral habitats Maintain cross-sectional shape of channel Maintain capacity of channel Maintain thalweg structure for longitudinal connectivity Maintain wetted perimeter for food production Maintain bank structure for channel stability and habitat provision Maintain floodplain morphology Maintain diversity of floodplain habitats Biological Requirements (Gregory et al, 1991;Imhof et al, 1996) …”

“…These experts traditionally have different approaches and operate at different scales. Hydrologists examine aquatic ecosystems in an analytical way and often employ process-based predictive models whereas because of the complexity of interactions between biota and their habitat, aquatic biologists have traditionally approached aquatic ecosystems in an experimental way and have used empirical models to describe these systems (Dunbar and Acreman, 2001;Imhof et al, 1996). Although many exceptions could be cited, hydrologists tend to operate at the watershed or subwatershed scale, geomorphologists at the reach scale and aquatic biologists at the site scale (Imhof et al, 1996).…”

“…Hydrologists examine aquatic ecosystems in an analytical way and often employ process-based predictive models whereas because of the complexity of interactions between biota and their habitat, aquatic biologists have traditionally approached aquatic ecosystems in an experimental way and have used empirical models to describe these systems (Dunbar and Acreman, 2001;Imhof et al, 1996). Although many exceptions could be cited, hydrologists tend to operate at the watershed or subwatershed scale, geomorphologists at the reach scale and aquatic biologists at the site scale (Imhof et al, 1996). A framework that may provide the basis for a structured process for a multi-disciplinary group of experts to consider potential ecological responses to changes in the flow regime at three scales of management (watershed, reach and site) is referenced later as a context setting tool.…”

“…The hierarchical evaluation system proposed by Imhof et al (1996) provides a tool to structure the consideration of potential ecological responses to changes in the flow regime at three scales of management: watershed, reach and site. It includes a series of tables that identify causal attributes (many of which are flow related), the ecosystem processes affected and the expected manifestation of the response at these three scales.…”