Monitoring reproductive success, prey species composition, and colony size of marine birds has been proposed as a method of assessing changes in marine systems that are otherwise difficult to sample (Cairns 1987). I measured inter-annual and intra-seasonal variability in reproductive parameters, taxonomic composition of the diet, and adult body condition...
Factors that influenced the uptake, storage, and elimination of dietary quinoline by rainbow trout (Salmo gairdneri) were studied to obtain an understanding of the mechanisms affecting the bioaccumulation of dietary contaminants in teleosts. Rainbow trout readily absorbed ¹⁴C-quinoline from pelleted food (1% ration at 138 ug quinoline/g food) and most...
Large dams and their respective reservoirs can provide renewable energy and water security, but also profoundly alter riverine ecosystems. In the Pacific Northwest, dams and reservoirs cause discontinuities in river networks that have been particularly problematic for anadromous fishes. As barriers to the upstream and downstream migration of anadromous fishes,...
In grasslands, grazing by large ungulates can influence vegetation structure, composition, primary productivity, and ultimately, ecosystem functioning. While grazing represents a complex disturbance, grazing intensity largely determines the effects of
grazing on vegetation. Structural and compositional changes in the plant community caused by grazing could have bottom-up effects on species...
The performance of an organism or organismic subsystem is
the result of the interaction between the performance capacity of
the system and Its environment. Environmental conditions can
stress an organism and thus affect it's performance. In this
study, three whole organism performances were examined: critical
swimming speed, fatigue time and...
Caspian terns (Hydroprogne caspia) and double-crested cormorants
(Phalacrocorax auritus) nest in large colonies on East Sand Island in the Columbia
River estuary, the largest known colonies for the two species in the world. Both
species of piscivorous colonial waterbirds have been identified as predators with a
significant impact on the...
Genetic, ontogenetic, and environmental factors modified characteristic interrenal and glycemic responses to stress in juvenile salmonid fishes. During continuous confinement stress, plasma cortisol rose more quickly in chinook salmon, Oncorhynchus tshawytscha, acclimated to high rather than medium or low temperatures; hyperglycemia following either acute or chronic stress was also highest...
The northern spotted owl (Strix occidentalis caurina) is one of the most intensively studied raptors in the world; however, little is known about the impacts of wildfire on the subspecies and how they use recently burned areas. Three large-scale wildfires in southwest Oregon provided an opportunity to investigate the short-term...
In 2006–2010, effects of four different cattle stocking rates (0, 14.4, 28.8, and 43.2 animal unit months) were compared, representing 0%, 20%, 32%, and 46% utilization of vegetation by domestic livestock, on vegetation structure (as indexed by visual obstruction), and songbird population and apparent nest density, community composition, and diversity...
The structure of food webs and how they relate to community stability has been an important debate in ecology. Specifically, predictability of web shape and how it influenced by surrounding landscapes is one of the main goals of such discussions. Headwater streams provide a study template that is of interest...