The Middle Fork John Day River is composed of low gradient, alluvial valley
segments separated by constrained, canyon-like reaches, and has a history of multiple
land-uses. These factors can alter the physical and biological structure of streams, and
disrupt the longitudinal river continuum. I examined habitat, fish, macroinvertebrates,
Fish assemblage structure was determined along a longitudinal
gradient for three drainages in the upper John Day basin: Middle
Fork, South Fork, and upper Mainstem proper. One or two tributaries
in each drainage were included. Where possible, sites were paired:
those with good versus those with poor riparian habitat. Detrended...
Because riparian canopy controls most energy inputs to stream
ecosystems, it directly affects the structure of aquatic food webs and the
ecological processes that govern interactions among trophic levels. This
study addresses the interdependence among riparian canopy, benthic
community structure, and the carrying capacity of high desert streams for
I examined the relative roles of biotic and abiotic factors in structuring redband trout
Oncorhynchus mykiss distributions in the South Fork John Day. I first examined the
relationship between the biological traits of the fish assemblage and riparian-geomorphic features in context of prevailing theories of stream ecology stemming from the...
Understanding seasonal changes in growth, survival, and movement rates is
crucial to salmonid management. These life history characteristics provide a context for
evaluation of management actions. We evaluated the life history of individually
marked Oncorhynchus mykiss gairdneri in the South Fork John Day River basin in
Northeastern Oregon. This thesis...
The American beaver (Castor canadensis) was nearly extirpated by the late 1800's due to the fur trade. Due to reintroduction efforts, it now occupies much of its former range. Beavers are a keystone species and ecosystem engineers, greatly influencing riparian and instream habitats through selective harvesting of plant materials and...
This thesis focuses on the economic efficiency of alternative habitat, streamfiow, and land use
allocations within a major drainage of the Pacific Northwest. Specifically, productivity of present habitat
and streamfiow conditions is evaluated with respect to anadromous fish species (chinook salmon and
steelhead trout) in the John Day River Basin,...
Water temperature is an important measure of water quality, as well as a dominant factor affecting aquatic life within the stream environment. Elevated water temperatures can decrease the survival rate of fish in each life stage. Cold water species, such as salmonids, are particularly susceptible to elevated water temperatures. For...
This study was an investigation of lotic macroinvertebrate distribution in
northeastern Oregon at two different spatial and biological scales. Examination
of assemblages at a limited spatial scale revealed relationships with natural and
disturbance gradients and led to questions about distribution of a population at
broader spatial scales.
In a 16...