Sixteen populations of guppies (Poecilia reticulata) were established
in laboratory aquariums. Eight populations were exposed to
dieldrin at a mean concentration of 0.525 ppb in the water and 2.11
ppm in the food, tubificid worms. Eight populations received control
water and food. All populations were fed three grams of tubificid...
Aquatic communities consisting of guppies, amphipods, copepods, snails, nematodes, rotifers, protozoans, euglenoid flagellates, and other microorganisms were established in sixteen laboratory microcosms. Guppies were exploited at four different levels (0 percent, 10 percent, 20 percent, and 40 percent of the population biomass) with four communities at each level of exploitation....
Organization and the adaptation of aquatic laboratory ecosystems
to resource availability, exploitation, and a toxicant were examined in
a 34-month study. Sixteen 560-liter microcosms including prey,
predator, and competitor populations were employed over a wide range
of energy and habitat resource availability and exploitation of the top
predator. Chronic exposure...
Adequate management and scientific investigation of ecosystems
depends on classification of landscape systems based on all significant
bio-physical and associated cultural properties. The present
classification is a hierarchical systems design that can be modeled in
terms of a natural system interacting with its level-specific
environment. A watershed system in this...
A possible form of a theory of exploitation of fish populations was examined. The exploitation theory was derived from a theory of community dynamics that represents the interactions between populations in a biological community with complex interrelated systems of isoclines on phase planes. The isocline systems are deduced, with a...
Acute toxicity bioassays and growth studies, with juvenile salmon
as test animals, were used to identify and characterize the major
toxic components of a zirconium process effluent (ZPE) produced by
Teledyne Wah Chang Albany Corporation.
The major toxic component of the ZPE is ammonia. Although
other components of the ZPE...
Acute toxicity bioassays (96-hr TL₅₀) were employed to determine
the tolerance of coho salmon (Oncorhynchus kisutch) to inorganic
chloramines at the alevin (yolk sac fry), yolk absorption, and early
juvenile life stages. Any influence of changes in temperature, pH,
and total alkalinity on the tolerance of juvenile coho for chloramines...
In a native prairie of Oregon (363 km²) red-tailed (Buteo jamaicensis), ferruginous (Buteo regalis), and Swainson's hawks (Buteo swainsoni) coexist in one of the highest nesting Buteo densities in North America. In 1979 and 1980, the distribution, density, and productivity of the three species was studied in relation to availability...
Historical aerial photos were used to examine the early phase of forest succession after stand replacement disturbance, covering the Coast Ranges Province (CRP) and the western Cascades Province (WCP) of western Oregon. The study consisted of two components: characterizing the pattern of forest succession in western Oregon; analyzing the influence...
Biometric and gas exchange techniques were used to measure soil respiration (soil surface CO₂ efflux) and NEP (Net Ecosystem Production) across three climatically-distinct forest chronosequences in Oregon. Results indicate significant forest type, age, and forest type x age interaction effects on annual soil respiration. A regional age class distribution skewed...