Transferability of Models to Predict Selection of Cover by Coastal Cutthroat Trout in Small Streams in Western Oregon, USA
Andersen, H.V.

We assessed use and selection of cover by coastal cutthroat trout (Oncorhynchus clarkia clarkii) in six headwater streams in three watersheds in western Oregon, USA during the summer low flow period from 1 August and September 30, 2007. We tagged 1037 coastal cutthroat trout (>100 mm) with passive integrated transponder (PIT) tags across all streams. Selection of cover was analyzed by comparing characteristics of locations used for concealment by relocated fish relative to characteristics of randomly available habitat that could be used for concealment. We measured habitat characteristics for 190 relocated individual fish using cover and 797 randomly points potentially available as cover. Of the latter points, only 235 of 797 were potential cover, based on characteristics of cover actually used by fish. Coastal cutthroat trout used substrate as cover (78%) more often than all other cover types combined (22%). Availability of different cover types was variable, but overall substrate made up 92% of available cover and the remaining 8% represented all other cover types combined. Habitat characteristics measured for both used and available cover included depth at fish location (cm), surface area of cover (m2), proximity to depth of 20 cm for fish located in < 20 cm in depth, b-axis (mm) for substrate >2 mm, and distance under substrate. Each of these habitat characteristics was different for used and available cover.

DISCIPLINE: Fisheries    STUDY: Alsea, Hinkle Creek, Trask    TYPE: Theses    TAGS: coastal cutthroat trout, cover, substrate, habitat selection, Headwater streams, PIT tags, transferability
Experimental Analysis of Intra- and Interspecific Competitive Interactions between Cutthroat Trout and Sculpins in Small Streams
Ramirez, B.S.

In the Pacific Northwest ecoregion of North America, sculpins represent a major constituent of freshwater assemblages in coastal rivers. Little is known of their interactions with co-occurring species, such as widely studied salmon and trout (salmonines). In this study, I evaluated inter- and intraspecific interactions involving cottids (Cottus sp.) and coastal cutthroat trout (Oncorhynchus clarkii clarkii). I used a response surface experimental design to independently evaluate effects of cutthroat trout and sculpin biomass on growth and behavior. There was evidence of both intra- and interspecific interactions between cutthroat trout and sculpins, but the interactions were asymmetrical with biomass of cutthroat trout driving both intra- and interspecific interactions, whereas sculpins had little influence overall. Cutthroat trout biomass was positively related to conspecific aggressive interactions and negatively related to growth. Sculpin exhibited increased use of cover during the day in response to greater biomass of cutthroat trout, but not sculpin biomass. Nocturnal use of cover by sculpins was unaffected by biomass of either species.  This experiment provides insights into the species interactions and the mechanisms that may allow sculpins and salmonines to coexist in nature. As cutthroat trout appear to be superior competitors, coexistence between sculpins and cutthroat trout may depend on some form of refuge.

DISCIPLINE: Fisheries    STUDY: Alsea, Hinkle Creek, Trask    TYPE: Theses    TAGS: sculpins, intraspecific interactions, cottus, Oncorhynchus, coastal cutthroat trout, biomass, Oregon, competition
Seasonal Variability in Diet and Consumption by Cottid and Salmonid Fishes in Headwater Streams in Western Oregon, USA
Raggon, M.F.

Coastal cutthroat trout (Oncorhynchus clarkii clarkii) and cottids (Cottus spp) commonly co-occur in headwater streams in western Oregon. Little is known about the comparative trophic ecology of these species or how they respond to seasonal scarcity of resources. In this study I evaluated the seasonal variability in diets and consumption as it related to food limitation for coastal cutthroat trout and cottids. Over 340 individual diets were quantified from seasonal samples collected in May, July and September of 2008. Diet overlap was relatively low among seasons and species. Coastal cutthroat trout exhibited a more diverse diet in terms of taxonomic richness of prey and consumed both aquatic and terrestrially-derived prey, whereas cottids appeared to specialize on aquatic prey. Based on diet composition and amount consumed, all species appeared to be increasingly food limited from July to September, relative to May. However when diet composition was integrated with a bioenergetic model, coastal cutthroat trout were found to be substantially more food limited than cottids. Differences in the cost of activity between these species may explain this result. Activity costs may be higher for trout, which reside in the water column and rely on active swimming, versus cottids, which lack a swim bladder and are more benthic oriented. Results of this work suggest that cottids are dietary specialists, feeding almost exclusively on benthic prey.

DISCIPLINE: Fisheries    STUDY: Trask    TYPE: Theses    TAGS: coastal cutthroat trout, cottus, diet composition, bioenergetic models, food limitation, seasonal variation, ecology, Oregon
Suspended Sediment Concentrations and Turbidity Responses from Contemporary Road Crossings in the Trask River Watershed
Arismendi I., J. D. Groom, S. L. Johnson, M. Reiter, L. De

Road-related turbidity and suspended sediments is a concern for both commonly occurring and higher magnitude storm events with the potential to negatively affect in-stream biota. Here, we present preliminary results that address whether forest road crossings deliver fine sediments into streams. Specifically, we evaluate evidence of sediment routing before/after road interventions (including new roads and road upgrades - surfacing with gravel) and above/below road crossing within forest harvest units. We hypothesize that newly constructed and upgraded roads will increase turbidity and suspended sediments where roads have hydrologic connections to streams. This response will be heightened during high intensity precipitation. We measured suspended sediment and turbidity above and below road crossing and before (June 2010-Apr 2011) and after (July 2011-June-2012) road upgrades using ISCO samplers in five headwater streams from small-sized watersheds (5-36 ha). We complemented this information with available data from hydrology (four flume stations) and precipitation (two climate stations) during the same time periods. We examined statistical differences of in-stream turbidity and concentrations of suspended sediments below and above road crossing and characterized the behavior of sites before and after road upgrades.

DISCIPLINE: Hydrology & Water Quality    STUDY: Trask    TYPE: Presentations    TAGS:
Stream Temperature Pattern and Process in the Trask Watershed Study: Pre-Harvest
Reiter M., S. Johnson, and P. James

The Trask Watershed Study is a multi-disciplinary, long-term research project in the Oregon Coast Range that is designed to examine the effects of current forest management practices on aquatic ecosystems. Extensive physical (e.g., water quantity and quality, channel morphology) and biological data (e.g., primary productivity, macro-invertebrate communities, amphibian movement and fish populations and behavior) has been collected in both the small and large watersheds since 2006 and will continue until 2016. One of these key parameters we have been collecting at multiple scales is stream temperature.
Understanding the variability in stream temperature patterns and processes prior to harvest in both small non-fish headwater streams and downstream in larger fish-bearing basins allows us to anticipate potential responses to harvest and subsequent potential changes in biota. Using the pre-harvest stream temperature data we examine variability in maximum and minimum temperatures across the 15 small headwater streams. We also examine how well both small treatment streams and the larger downstream basins correlate to un-harvested reference streams to determine the best match to compare post-harvest response. Finally we examine how stream temperature patterns vary longitudinally in the downstream direction through time.

DISCIPLINE: Hydrology & Water Quality    STUDY: Trask    TYPE: Presentations    TAGS:
Examining the Effects of Contemporary Forest Practices on Aquatic Ecosystems at Multiple Scales
Reiter, M.

The Trask watershed study is an extensive pre- and post-harvest study to quantify effects of forest harvest on the physical, chemical and biological characteristics of small non-fish headwater streams and the extent to which harvest on these small streams influences downstream fish reaches. The effects on fish, amphibians, macro invertebrates, birds, hydrology, stream temperature, sediment routing, are considered in this long-term and multidisciplinary project.  This project also offers tours for public, research,  regulatory and environmental groups.

DISCIPLINE: Hydrology & Water Quality    STUDY: Trask    TYPE: Presentations    TAGS:
Headwater Riparian Habitat: Prime Real Estate For Birds
Hagar, J., J. Li, and J. Sobota

Management strategies along headwater streams typically focus on aquatic resources, but riparian forests also are habitat for many terrestrial wildlife species. Increasing the understanding of mechanisms that underlie the riparian associations of these species can help integrate management of aquatic and terrestrial environments in headwater forests. We investigated the diets of and food availability for four bird species associated with riparian habitats in the headwaters of the Trask River, in northwestern Oregon. We tested the hypotheses that 1) emergent aquatic insects were a food source for insectivorous birds in headwater riparian areas, and 2) the abundance of arthropod prey did not differ between streamside and upland areas during the bird breeding season. We found that adult aquatic insects represented a relatively small proportion of available prey abundance and biomass and were present in less than 1% of the diet samples from the four riparian-associated bird species. Nonetheless, arthropod prey, comprised primarily of insects of terrestrial origin, was more abundant in streamside than upland samples. We concluded that food resources for birds in headwater riparian areas are primarily associated with terrestrial vegetation, and that bird distributions along the gradient from streamside to upland may be related to variation in arthropod prey availability.

DISCIPLINE: Wildlife    STUDY: Trask    TYPE: Presentations    TAGS:
Short-term Relationship of Timber Management and Pacific Giant Salamander Populations, and the Response of Larval Stream Amphibian to Predators Under Different Sediment Levels
Leuthold, N.

In the Pacific Northwest, multiple studies have found negative effects of timber harvest on stream amphibians, but the results have been highly variable and region-specific. Over the last 30 years forest management practices have changed substantially, yet little work examines how modern forest management relates to the abundance or density of stream amphibians. I examined the influences of contemporary forest practices on Pacific giant salamanders as part of the Hinkle Creek paired watershed study. Density was positively associated with substrate, negatively associate with upstream area drained, and had a weak positive association with fish density, but I found no evidence of an effect of harvest. Pacific Northwest stream amphibians are often negatively associated with sedimentation, but the mechanism underlying this relationship is not clear. I found amphibian larvae were more visible as sediment level increased and some evidence that larvae were less visible in the presence of fish. These patterns are consistent with the hypothesis that sediment affects larval stream amphibians by increasing vulnerability to predation.

DISCIPLINE: Amphibians    STUDY: Alsea, Hinkle Creek, Trask    TYPE: Theses    TAGS: timber harvest, stream amphibians, Pacific giant salamanders, mark-recapture analysis, predation, Larva
Local and Downstream Effects of Contemporary Forest Harvesting on Streamflow and Sediment Yield
Zégre, N. P.

This dissertation is a collection of three manuscripts that serve to fill the knowledge gaps and advance methods of detecting the effects of contemporary forest harvesting in experimental catchment studies. The objective of this research was to develop change detection models using time-series records to detect and quantify the effects of forest harvesting on streamflow and sediment yield. To accomplish this, it was necessary to characterize streamflow and sediment processes at a temporal scale capable of describing daily, monthly, and seasonal dynamics following forest harvesting; increase sample sizes used to construct regression-based change detection models; and develop alternative methods to the paired-catchment approach in order to discern changes in streamflow and sediment using highly variable time-series data. The paired-catchment approach was used to detect and quantify relative changes in streamflow and sediment yield in 5 harvested catchments. The ability to detect statistically significant changes at certain time-steps was a function of accounting for all sources of variability in change detection models. In this study, we aimed to develop robust change detection models using time-series data to increase sample size and decrease false/missed detections of true treatment effects.

DISCIPLINE: Hydrology & Water Quality    STUDY: Alsea, Hinkle Creek, Trask    TYPE: Theses    TAGS: forest harvesting, contemporary harvesting practices, detection models, paired-catchment, sediment yield
On the Estimation and Application of Spatial and Temporal Autocorrelation in Headwater Streams
Som, N.

This collection of three manuscripts serves to improve methods for collecting, interpreting, and utilizing autocorrelated data from headwater stream networks. Two chapters of this work relied on a unique and comprehensive set of data which constitutes a complete census of habitat unit fish counts from 40 randomly selected headwater basins in western Oregon. The first objective of this work was to evaluate how different sampling designs captured spatial autocorrelation, given the samples were drawn from a population of spatially autocorrelated observations. The second objective was to investigate spatial autocorrelation model range parameters as measures of patch sizes. The third objective was to refine the analysis of temporally autocorrelated hydrology data from paired watershed studies. These  are used to evaluate forest harvesting effects on stream biota and hydrology (i.e. fish, amphibians, insects, stream flow, and sediment yield).

DISCIPLINE: Hydrology & Water Quality    STUDY: Alsea, Hinkle Creek, Trask    TYPE: Theses    TAGS: autocorrelated data, headwater stream networks, Spatial autocorrelation, patch size, paired watershed studies


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