Biodiversity loss in highly diverse systems such as coral reefs has been linked to significant declines in the ecosystem functions and services provided by marine species. Ecological functioning of coral reefs and the resistance of coral reef fish communities to disturbance depend on the functional traits of species that promotes...
The effects of Marine protected areas (MPAs) on adult fish populations depend on the degree of protection provided, which is partly a function of MPA size and the spatial extent of fish movements. The Redfish Rocks Marine Reserve (RRMR) and MPA, located on the south coast of Oregon near Port...
Tropical coral reef ecosystems are very important from both the ecological and economical
points of view. However, they are also particularly fragile, and have been
declining in recent years in most regions of the world, since they are highly susceptible
to anthropogenic stressors operating at global scales (e.g., global warming...
The feeding ecology of a common temperate mesoherbivore, the oligophagous sea slug Placida dendritica (Gastropoda: Opisthobranchia: Ascoglossa), was examined from April 1985 to June 1989. Along the central coast of Oregon, Placida consumed three host species: the low intertidal green algae Codium setchellii, C. fragile, and Bryopsis corticulans. Individual slugs...
Winters in north-temperate climates impose high
thermogenic demands upon small birds which are met by
seasonal acclimatization. This thesis investigates the
extent and mechanisms of seasonal acclimatization in darkeyed
juncos (Junco hyemalis) inhabiting western Oregon.
Although insulation is significantly increased in
winter, acclimatization is primarily metabolic. Increased
metabolism is required...
We examined the behavioral and physiological responses of wild
and hatchery-reared cutthroat trout Oncorhynchus clarki subjected to
a single electroshock, electroshock plus marking, and multiple
electroshocking in natural and artificial streams. In a natural
stream, trout released after capture by electrofishing and marking
showed distinct behavioral changes: fish immediately sought...
Effects of diet on food energy utilization by grass
carp fed aquatic plants or formulated diets with varied
lipid sources and levels are presented in three
manuscripts. Significant effects of diet on food
consumption, digestion, growth and muscle fatty acid (FA)
composition of fingerling diploid grass carp fed aquatic
macrophytes...
Newly emerged steelhead fry (Oncorhynchus mvkiss) of hatchery and
wild origins were studied in laboratory stream channels and natural
streams. Objectives of the study were to determine if and how earlier
emerging hatchery fry influence the emigration, realized densities,
growth, habitat use, social structure, and activity patterns of
localized populations...
The early life history stages and metamorphosis in Dover
sole (Microstomus pacificus) are described from 201 larvae and
juveniles. Unlike other pleuronectids, with the possible exception
of the deep-sea sole (Embassichthvs bathvbius), initial migration of
the left eye is not associated with metamorphosis or transition from
plankton to benthos. The...
Gradients of physical disturbance are central to
theories of community organization yet rarely are studies
performed in which physical factors are experimentally
manipulated. Pothole tidepool algal communities exhibit
distinct zonation patterns from top to bottom that result
from scouring by rocks and other debris in the pools.
Scouring is easily...
Some parasites may modify the behavior of their
hosts. Altered behaviors may: 1) benefit the host in
that they defend against the pathogen, 2) benefit the
pathogen and represent manipulations of the host
response, and 3) benefit neither the host or the
pathogen and simply be a product of the...
The Mark 0. Hatfield Marine Science Center (HMSC)
public education opportunities include interpretive programs
offered along the Estuary Nature Trail. The purpose of this
study was to determine the effectiveness of three informal
education programs, interpretive signs, a self-guided trail
brochure, and guided naturalist walks, in imparting
information on the...
I examined the biomechanical factors that influence the sizes of intertidal macroalgae by studying a population of Fucus gardneri at Fogarty Creek Point, OR. I constructed a mathematical model to predict optimal sizes and probabilities of survival for Fucus under conditions of high and low wave exposure. Predicted optimal sizes...
As ecologists are being called upon to predict the consequences of human
perturbations to natural communities, an important goal is to understand what factors
drive variability or consistency in nature.
In the rocky intertidal of San Juan Island, Washington, a comparative
experimental approach was used to investigate spatial and temporal...
The influence of loss of diversity on community dynamics and ecosystem functioning has recently received considerable attention. Although study of biodiversity has a long history within ecology, empirical investigations exploring consequences of loss have been rare. Because many factors confound diversity comparisons, experimental manipulations of diversity offer the most direct...
Juvenile steelhead are known to associate with shiner groups, though they also compete for food. Steelhead form dominance hierarchies within cohorts and aggressively defend feeding territories against all other fish. This study focused on the differential effect of shiner competition on steelhead of different social standing.
Survival of subordinate juvenile...
Understanding how large-scale processes (>100 kms) influence ecological communities is currently a major focus in ecology. In marine systems, coastal upwelling, a large-scale oceanographic process in which surface water pushed offshore by winds is replaced by cold, nutrient-rich water from depth, appears to cause variation in rocky intertidal communities. Along...
Once historically widespread throughout the Willamette and Umpqua
River drainages, the Willamette Oregon chub is now restricted to
scattered populations along 15 miles of the Middle Fork of the
Willamette River whereas the Umpqua Oregon chub is still widely
distributed. The decline in the Willamette drainage was more severe
because...
Sympatric steelhead and resident rainbow trout (Oncorhynchus mykiss) are known
to exist in many rivers throughout the Pacific Rim. Whether sympatric steelhead and
resident rainbow trout are polymorphisms within a single gene pool or two reproductively
isolated populations has significant implications concerning the study and conservation of
this polytypic species....
One of the greatest threats to native bull trout Salvelinus confluentus populations is the presence of non-native brook trout S. fontinalis. This study, conducted in two second-order Eastern Oregon streams, investigates the effect of brook trout on the feeding behavior arid diet of bull trout. Feeding behavior, microhabitat use, and...