Search
Search Results
-
1191. [Article] Riparian forest buffers on agricultural lands in the Oregon coast range : Beaver Creek riparian project as a case study
Riparian areas in the Pacific Northwest have traditionally been a source of natural resources, such as timber and grazing, and have been used as transportation corridors and homestead sites. A primary impact ...Citation Citation
- Title:
- Riparian forest buffers on agricultural lands in the Oregon coast range : Beaver Creek riparian project as a case study
- Author:
- Rogers, William Reinhold, Bishaw, Badege, Emmingham, William H., Oregon State University. Forest Research Laboratory
Riparian areas in the Pacific Northwest have traditionally been a source of natural resources, such as timber and grazing, and have been used as transportation corridors and homestead sites. A primary impact of use has been the removal of riparian trees, the crowns and roots of which provide shade and stream bank protection. Increases in water temperature can be lethal to salmonid fish, and decreasing salmon populations over the past few decades have resulted in an urgent need for improving the management of watersheds, fish habitat, and water quality. Leaving stream-side buffers is now required by state forest practices regulations on forest lands, but no regulations are in place on agricultural lands, where riparian trees have frequently been removed. In 1995, the Beaver Creek Riparian Buffer Project was established to develop better information about how to establish riparian buffers on coastal pastureland near Newport, Oregon. No riparian trees were present when the trial was begun. A replicated tree filter belt trial was established along the south bank of the creek to compare unplanted pasture (controls) with commercially valued red alder (Alnus rubra) planted at 6-ft spacing in belts 1 row, 3 rows, and 6 rows wide. Tree survival and height and diameter growth were compared, as well as the amount of shade produced by the three treatments and control. We used a LI-COR LAI-2000 Plant Canopy Analyzer to quantify shade. We found that intensive site preparation, continued vegetation management, and both fencing and tubing of tree seedlings were necessary to gain survival and protect seedlings from small rodents, beaver, and cattle. Fencing out cattle provided stream bank protection within 1 yr. Significant shading of the stream occurred 2–6 yr after planting, as trees grew tall enough to intercept a significant amount of light. Single row plantings that take a minimal amount of pasture offer significant shading only after 4–7 yr. A wider 6-row filter belt occupies a greater amount of pasture, but provides stream shading sooner than the other treatments.
-
1192. [Article] Effects of stream restoration on macroinvertebrate communities in an Oregon Coast Range system
Stream-restoration projects are usually designed to improve habitat quality for fishes. These projects manipulate flow patterns, substrate distribution, and amount and placement of large woody debris. ...Citation Citation
- Title:
- Effects of stream restoration on macroinvertebrate communities in an Oregon Coast Range system
- Author:
- Christensen, M. Jo
Stream-restoration projects are usually designed to improve habitat quality for fishes. These projects manipulate flow patterns, substrate distribution, and amount and placement of large woody debris. Consequently, they also affect the size and composition of the aquatic macroinvertebrate community. This research evaluates two types of fish habitat restoration: off-channel structures (alcoves) and in-channel structures (log weirs). I compared macroinvertebrate habitats and communities in natural and artificial alcoves in Upper and South Fork Lobster Creeks, Lane Co., and examined the effects of log weirs on in-channel habitat diversity, community composition, drift patterns, and fish consumption of macroinvertebrates. Macroinvertebrate samples were collected from artificial and natural alcoves using hand pumps and D-nets. Within the channel, macroinvertebrates were collected from restored and unrestored reaches with a Hess sampler and using a stratified random sampling scheme. Forty-eight hour invertebrate drift samples were obtained at outlets of log-weir pools. Stomach contents were obtained from coho salmon (Oncorhynchus kisutch) and cutthroat trout (O. clarki) in restored reaches. Although natural alcoves differed from artificial in location within the floodplain, morphology, permanence, and degree of interaction with the stream channel, both alcovetypes provided similar habitats and contained similar macroinvertebrate communities. Average densities and diversity within the alcoves depended on habitat and time of year. Average densities were higher in artificial than in natural. Alcoves contained 29% of species richness within Upper Lobster Creek. Within the stream channel, the diversity of macroinvertebrate habitat was lower in restored than in unrestored sections. Log weirs were associated with reduced taxonomic and functional feeding-group diversity. Composition of drift was not significantly different in restored and unrestored areas; however, drift densities were significantly lower in restored reaches. Diets of fishes in restored areas were composed primarily of organisms produced from outside restored areas. Although in-channel structures may enhance physical habitat for fishes, they may alter or reduce the availability of food for fishes feeding on drifting invertebrates. Recommendations are given for improving the design of stream restoration projects with respect to macroinvertebrates; however stream restoration should focus on restoring whole-system integrity and function, instead of targeting just one or two types of organisms.
-
1193. [Article] Regional Scale Modeling of Climate, Cryosphere, and Freshwater Discharge in Changing Coastal Mountain Environments
The glaciated coastal mountain watersheds that drain into the Gulf of Alaska (GOA) provide a model laboratory to explore the challenges of hydrological modeling and study the impact of climate and glacier ...Citation Citation
- Title:
- Regional Scale Modeling of Climate, Cryosphere, and Freshwater Discharge in Changing Coastal Mountain Environments
- Author:
- Beamer, Jordan P.
The glaciated coastal mountain watersheds that drain into the Gulf of Alaska (GOA) provide a model laboratory to explore the challenges of hydrological modeling and study the impact of climate and glacier cover change on regional hydrology. The region is data-sparse and contains a complex assemblage of topography and land cover, including a system of mountain glaciers that are retreating at some of the highest rates on Earth. The high rates of runoff from precipitation and glacial melt delivered by coastal rivers influence ocean circulation patterns, rates of global sea level rise, and provide spawning habitat for the large salmon populations. Physically-based hydrological modeling of the major water budget components of the GOA, driven using historical reanalysis weather data and land cover, reveals that the modeled water budget components, particularly precipitation input, vary widely between commonly-used weather products. The majority of the large freshwater flux into the GOA is derived from distributed coastal streams rather than the large inland rivers. The modeled seasonal aggregated GOA hydrograph is dominated by the spring and early summer snowmelt, and supplemented by late summer glacial ice melt. Model results demonstrate good agreement with NASA Gravity Recovery and Climate Experiment (GRACE) satellite data in terms of annual amplitudes and long term losses (ice loss), and suggest that existing GRACE solutions, previously reported to represent glacier mass balance alone, are actually measuring the full water budget of land and ice surfaces. An ensemble of climate models and future emissions scenarios were paired with systematically altered land cover to test the sensitivity of the hydrologic system to changes in regional climate patterns and glacier coverage representative of late twenty first century conditions. Compared with the hindcast simulations, the model results forced with increased regional air temperatures and precipitation inputs and reduced glacier cover produce an increase in the annual GOA freshwater discharge volume. The seasonal GOA hydrograph is flattened due to increased winter runoff from more winter rainfall and less snow accumulation, and lower levels of snowmelt and glacier ice contribution. Large uncertainties exist in the direction of change in the glacier runoff component, primarily due to uncertainties that exist in predicting glacier response to climate change. Hydrological modeling with high resolution and inclusion of relevant physical processes can produce significantly improved products that are of high value to and in demand by numerous other scientific communities. However, the value and accuracy of the output from the hydrologic model is highly dependent on the weather forcing quality. Given the considerable importance of quality weather forcing for hydrologic modeling, it is imperative to assess the suitability of multiple products by evaluating local and regional performance and accounting for uncertainty. Additional efforts should be made to improve the spatial resolution of the reanalysis through downscaling and to strategically increase the number of weather stations at high elevations and incorporate that data into weather forcing datasets.
-
An investigation of the fishes of the Willamette River and three of its larger tributaries was made during July, August, September, and November of 1951, to ascertain the possibility of using them as bio-indices ...
Citation Citation
- Title:
- The Willamette River fishes as biological indicators of pollution
- Author:
- Noble, Richard Earl
An investigation of the fishes of the Willamette River and three of its larger tributaries was made during July, August, September, and November of 1951, to ascertain the possibility of using them as bio-indices of pollution. Thirteen stations were established on the Willamette River and tributaries. These stations were selected in respect to the major tributaries, cities, and sources of pollution. Two stations were located on the McKenzie river; two on the North Fork of the Santiam River; eight on the main stem of the Willamette River from above Eugene to Oregon City; and one on the Clackamas River. Fishes were collected at each station by means of a seine. The fishes were preserved in a 10 percent formalin solution and returned to Corvallis where they were classified as to species and the numbers of each recorded. Stomach analysis were performed on a portion of the fishes collected from each of the stations. In an attempt to determine the affect of pollution on the fishes of an area, the samples from a clean-water station were compared with those taken from a polluted station. From this survey a tentative list of fishes which were sensitive, intermediate and tolerant to pollution was formed. In general, the trout, salmon, whitefishes and sculpins were found to be sensitive; falcate dace, white crappie, smallmouth black bass, mountain suckers, and longnosed dace were intermediate; and redsided shiner, blacksided dace, coarse-scaled sucker, three-spined stickle back, squawfish, bullhead catfish, chiselmouth, largemouth black bass, Columbia River chub, and larvae of the Pacific lamprey were tolerant. It was found that even the most tolerant fishes disappeared when pollution was excessive. In addition to the biological data collected at each station, certain chemical and physical tests were also determined. Air and water temperatures were taken, along with hydrogen-ion concentration (pH), and dissolved oxygen content of the water. Bio-chemical oxygen demand (B.O.D.) readings were taken at some of the stations by the Oregon State Sanitary Authority. River flow measurements were obtained from U.S.G.S. records for the gage at Salem, Oregon. The physical and chemical tests were used in conjunction with the biological findings to determine the condition of each station. Water flow data was used to determine low water periods. Chemical, physical and water flow data are shown in table form as well as graphically. The numbers of each species of fish and the food organisms found by stomach analysis are listed for each monthly sample and these data are also shown in table form. According to observations from this survey there was a definite indication that pollution can be detected by using the species, numbers and stomach contents of fishes from a waterway.
-
1195. [Article] Continuous monitoring and modeling to assess pesticide exposure in critical habitat for Pacific salmonids
Pacific Northwest and California freshwater resources are key elements in the life history and ecology of Pacific salmon and steelhead listed as threatened or endangered under the Endangered Species Act. ...Citation Citation
- Title:
- Continuous monitoring and modeling to assess pesticide exposure in critical habitat for Pacific salmonids
- Author:
- Janney, Philip Kenton
Pacific Northwest and California freshwater resources are key elements in the life history and ecology of Pacific salmon and steelhead listed as threatened or endangered under the Endangered Species Act. Risk to listed Pacific salmonid species can be assessed by evaluating the spatial and temporal co-occurrence of salmonid species at sensitive life stages and pesticide concentrations at levels that may elicit adverse effects. Understanding the potential for the co-occurrence requires knowledge of pesticide use patterns and application methods, pesticide properties that influence environmental fate, as well as landscape/land management, edaphic, and climatic factors that influence off-site movement into surface water. Reported here is the use of a passive sampling device to monitor selected current use pesticides in surface water on a continuous basis. Passive sampling devices (PSDs) were deployed continuously in 5 watersheds within the Pudding River subbasin, critical habitat for the Upper Willamette River Chinook and Steelhead ESUs, between June 2010 and October 2011 in order to characterize the temporal trends in surface water concentrations. PSDs were deployed in off-channel habitats preferred by juvenile salmonids. The majority of the monitoring results were well below EPA aquatic life benchmarks, as well as levels of concern for listed salmonids. Using the EPA ecoregion framework watershed sensitivity to pesticide surface water loading was characterized. The Soil and Water Assessment Tool (SWAT) was used to assess the relationship between land management practices and PSD monitoring data collected in the Zollner Creek watershed. SWAT was evaluated under different parameterization scenarios representing increasing levels of local knowledge of the system in order to evaluate model performance in relation to average daily stream flow. Using spatially distributed precipitation data and incorporating engineered drainage features into model parameterization resulted in a satisfactory fit of average daily stream flow indicating satisfactory characterization of the watershed hydrology. SWAT was then used to simulate the fate of chlorpyrifos and trifluralin, the two most commonly detected pesticides in the PSD monitoring. The pattern of simulated time-weighted average (TWA) pesticide concentrations was similar to measured values. However, simulated pesticide TWA concentrations consistently underestimated measured values. The most likely source of this bias is underrepresented pesticide use practices.
-
1196. [Article] Igneous petrology, structural geology, and mineralization of the central part of the Bayhorse Mining District, Custer County, Idaho
The central part of the Bayhorse Mining District is located in the Salmon River Mountains in north-central Idaho between the towns of Challis and Clayton. The area is underlain by metasedimentary rocks ...Citation Citation
- Title:
- Igneous petrology, structural geology, and mineralization of the central part of the Bayhorse Mining District, Custer County, Idaho
- Author:
- Hodges, Wade Allan
The central part of the Bayhorse Mining District is located in the Salmon River Mountains in north-central Idaho between the towns of Challis and Clayton. The area is underlain by metasedimentary rocks of Early to Middle Paleozoic age that were profoundly affected by the emplacement of a plutonic complex in Middle Cretaceous time, both of which were later intruded and covered by volcanic rocks of Early Tertiary age. Both intrusive events were accompanied by significant mineralization. These basement rocks and the associated mineral deposits have been partly exposed by post-Miocene uplift and subsequent glacial and deep stream erosion. The stratigraphic succession within the Bayhorse area consists of a series of alternating pelitic, carbonate and quartzite units that range from Latest Cambrian to Middle Ordovician in age. Five sedimentary rock units have been described within the area of study and consist, from oldest to youngest, of the Garden Creek Phyllite, Bayhorse Dolomite, Ramshorn Slate, mixed lithology sequence and Clayton Mine Quartzite. The lithologic and textural varieties of the Lower Paleozoic rocks, combined with regional considerations, collectively indicate that the Bayhorse area was transitional between marine shelf areas to the west, north and east and deeper miogeosynclinal areas to the south for most of Paleozoic time. Central Idaho was affected by magmatic activity continually from Late Jurassic to Middle Cretaceous time. Synchronous with the onset of batholithic scale magmatism was folding and thrust faulting of the Paleozoic sedimentary rocks. The magmatic activity culminated in the formation of the Idaho Batholith and related outlying plutons, one of which is locally represented by the Juliette Creek intrusive complex. Geologic evidence indicates that the Juliette Creek intrusive complex represents the upper parts of a much larger and somewhat deeper plutonic mass that was forcefully emplaced into the surrounding sedimentary rocks at depths ranging from 4 to 5 miles along anticlinal axes that paralleled the north-south structural grain of the region. In approximate order of emplacement the exposed part of the intrusive complex consists of quartz diorite, granodiorite grading to granite, and quartz-feldspar porphyry. The effects of thermal metamorphism were variably imposed upon the adjacent sedimentary rocks and the resulting changes in the lithologic characteristics of the country rocks aided in the modification of the pre-existing local structure by the forceful emplacement of the intrusive complex. Hydrothermal alteration and sulfide metallization are predominantly structurally controlled and spatially, temporally and probably genetically related to the Juliette Creek intrusive complex. Fluorite mineralization is related to the later igneous activity of Early Tertiary age. The emplacement of the intrusive complex was of major importance in preparing the ground for the two later episodes of mineralization by significantly altering the pre-existing local structure and lithologic characteristics of the sedimentary rocks The predominant structural feature of the district consists of two parallel elongate folds that formed in the Paleozoic sedimentary rocks by eastwardly directed compressional movement. Subsequent ethplacement of the Juliette Creek intrusive complex has locally modified the pre-existing structure and caused the sedimentary rocks to break along predictable zones of weakness. The sulfide metallization is related to the upper parts of a large hydrothermal system that may be associated with stock-work molybdenum or porphyry-copper type mineralization at depth. After this major period of magmatic, tectonic and hydrothermal activity the rocks of the district were again affected by a later, but similar sequence of events that culminated in the eruption of the rhyodacitic, andesitic and basaltic flows and pyroclastic deposits of the Challis Volcanics and the deposition of significant fluorspar in Early Tertiary time.
-
1197. [Article] A bioeconomic analysis of altering instream flows anadromous fish production and competing demands for water in the John Day River basin, Oregon
The growing demand for water in the arid regions of the West increases the need for optimal allocation of water among competing uses. An efficient allocation of water between instream and out-of-stream uses ...Citation Citation
- Title:
- A bioeconomic analysis of altering instream flows anadromous fish production and competing demands for water in the John Day River basin, Oregon
- Author:
- Johnson, Neal S.
The growing demand for water in the arid regions of the West increases the need for optimal allocation of water among competing uses. An efficient allocation of water between instream and out-of-stream uses has been impeded by institutional constraints and the scarcity of information regarding instream flow benefits. The objectives of this thesis were to provide preliminary economic data on the value of instream water in "producing" recreational fishing and to examine the effect of forestry, agriculture, and livestock practices on temporal streamflow patterns and anadromous fish production. The steelhead trout (Salmo gairdneri) sport fishery within the John Day River basin in north-central Oregon provided the setting for this research. The interdisciplinary methodology employed in estimating the marginal value of water with respect to steelhead production consisted of two tasks. The first task involved valuing a marginal change in the quality of the steelhead recreational fishery. The contingent valuation method (CVM) was selected for this purpose. Both open- and closed-ended willingness-to-pay (WTP) questions were included in a questionnaire administered to John Day River steelhead anglers during the 1986/87 steelhead fishing season. Survey data were analyzed to arrive at individual and aggregate bid functions relating WTP to expected angling success rates. Results indicate that, under current conditions, the average angler is willing to pay approximately $7.20 to catch an additional steelhead. The second task of the instream water valuation methodology was directed at deriving a streamflow/steelhead production relationship. By including variables influencing steelhead production in a Ricker stock-recruitment model, it was possible to develop a model which could be estimated using linear regression techniques. Some difficulty arose, however, with interpretation of the model due to the unavailability of cohort escapement data and the subsequent use of standing crop data. While possibly masking the true magnitude of streamflow's effect on fish production, this drawback was not deemed limiting within the general context of the interdisciplinary methodology. Results of the biological model conformed to a priori expectations. Increases in summer and winter streamflows led to increased steelhead survival, whereas higher spring flows increased mortality levels. Other results indicate that the John Day Dam was responsible for a 31.5 percent decline in the population index for the 1969-1983 period. Combining the economic and biological results into one equation yielded an estimate of the marginal value of summer instream water in "producing" recreational steelhead angling. Similar equations were developed for winter and spring flows. The marginal value of water in producing recreational steelhead fishing within the John Day basin was estimated at $0.56 per acre-foot for summer flows, $0.046 for winter flows, and -$0.075 for spring flows. By including out-of-basin benefits, these values increased to $2.26, $0.19, and -$0.30, respectively. In comparison, water's value in irrigation within the John Day basin has been estimated at between $10 to $24 per acre-foot. However, nonuse values of steelhead, as well as the increased production of other fish species (such as spring chinook salmon) were not included in the instream water values. In addition, no attempt was made at valuing instream water's contribution to boating, camping, or other benefit-producing activities. A secondary objective of this thesis was to briefly examine the possible benefits accruing to other instream and out-of-stream users due to an alteration in streamflow patterns. In addition, the impact of activities by other resource users -- namely forestry, agriculture, and livestock production --on anadromous fish production was reviewed. Improper management practices by these activities can negatively impact the aquatic and riparian ecosystems. While no firm conclusions were drawn, it appears the quality of these ecosystems, as opposed to the amount of streamflow, has the largest marginal impact on anadromous fish populations.
-
1198. [Article] Characteristics of two salmonid fish cell lines : glycolytic rates, CO₂ requirements and susceptibility to Reovirus and Reovirus-like agents
The research presented in this thesis is concerned with the characterization of two salmonid cell lines, CSE 119 derived from embryos of coho salmon (Oncorhynchus kisutch) and STE 137 derived from embryos ...Citation Citation
- Title:
- Characteristics of two salmonid fish cell lines : glycolytic rates, CO₂ requirements and susceptibility to Reovirus and Reovirus-like agents
- Author:
- Kleeman, Karl Terrence
The research presented in this thesis is concerned with the characterization of two salmonid cell lines, CSE 119 derived from embryos of coho salmon (Oncorhynchus kisutch) and STE 137 derived from embryos of steelhead trout (Salmo gairdneri). The rates of glucose utilization and lactic acid production during the most active growth phase of each cell line were determined and the results were compared to data from parallel experiments using a human embryonic cell line. The salmonid cells were grown at 23° C and the human cells at 35° C. All cells were grown in Eagle's minimal essential medium supplemented with 20% dialyzed newborn agamma calf The Q[superscript]O₂[subscript]CO₂ serum. values (equivalent microliters CO₂ produced per mg dry weight of cells per hour) were calculated for each cell type, and values of 7.97 and 4.50 were obtained for CSE 119 and STE 137, respectively. These values were somewhat lower than the value of 13.19 calculated for the human cells. In all three cell lines studied, the rates of glucose utilized and lactic acid produced per cell decreased over the growth periods observed. The decreases in the salmonid cells were most likely related to a concomitant increase in population density. In addition, it was shown that the very gradual fall in pH observed during the growth of the salmonid cells is apparently due in part, at least, to the smaller amount of lactic acid produced by these cells. During the course of the studies with the salmonid cell lines, an investigation of the CO₂ requirements of these cells was undertaken. For these experiments, Tris buffer was used to replace the bicarbonate in the medium and 20% dialyzed serum was again used. Results from the salmonid cells grown at 18° C were compared to parallel experiments using He La cells grown at 35° C. It was shown that growth under 2% (salmonid) and 3% (He La) atmospheric CO₂ was comparable to growth in stoppered cultures for CSE 119, STE 137 and the He La cells. The salmonid cells showed good growth in cul- tures that were open to the air (0.03% CO₂), but little or no growth occurred in the He La cells under the same conditions. To determine if CO₂ was actually required for growth of the salmonid cells, CO₂ free cultures were prepared using Conway microdiffusion dishes in which the cells were grown in the center well and a 10% solution of KOH was added to the outer well. The cultures were sealed with high vacuum grease. Under these conditions, both salmonid cell lines demonstrated a growth requirement for CO₂ comparable to that shown by the He La cells. Attempts were made to use oxalacetate to substitute for CO₂ in these cultures. Oxalacetate partially substituted for CO₂ in the He La cell cultures, but little or no growth occurred in the salmonid cell cultures under the same conditions. As part of a continuing effort to determine the viral susceptibility of salmonid cell lines, the coho cells (CSE 119) and the steelhead cells (STE 137) were tested for their susceptibility to Reovirus types 1 and 3, Infectious Pancreatic Necrosis (IPN) virus and Wound Tumor virus (WTV). Neither salmonid cell line nor He La cells were shown to produce infectious virus when inoculated with either reovirus type at 26° C. The salmonid cells would not tolerate 30° C for even short periods of time. Good replication of both reovirus types occurred in He La cells at 35° C. IPN virus replicated well in both salmonid cell lines at 18° C. Phase contrast studies of IPN infected salmonid cells showed an early webbing of the cytoplasm, followed by a rounding up of the cells, shrinkage of the nuclei and a heavy margination of nuclear chromatin. Because of its similarity to the reoviruses and its ability to replicate in an insect cell line, attempts were made to infect the salmonid cells with WTV at 23° C. No indications of WTV inclusion bodies or of a cytopathic effect were found in either salmonid cell line.
-
1199. [Article] From pesticide degradation products to legacy toxicants and emerging contaminants : novel analytical methods, approaches, and modeling
Environmental toxicologists and public health officials are responsible for assisting in the identification, management, and mitigation of public health hazards. As a result, there is a continued need ...Citation Citation
- Title:
- From pesticide degradation products to legacy toxicants and emerging contaminants : novel analytical methods, approaches, and modeling
- Author:
- Forsberg, Norman D.
Environmental toxicologists and public health officials are responsible for assisting in the identification, management, and mitigation of public health hazards. As a result, there is a continued need for robust analytical tools that can aid in the rapid quantification and characterization of chemical exposure. In the first research phase, we demonstrated that a current tool for estimating human organophosphate pesticide exposure, measuring dialkyl phosphate (DAPs) metabolites in urine as chemical biomarkers of pesticide exposure, could represent exposure to DAPs themselves and not to pesticides. We showed that DAPs are metabolically stable, have high oral bioavailability, and are rapidly excreted in the urine following oral exposure. Results suggest that DAP measurements may lead to overestimates of human organophosphate pesticide exposure. In the second phase of research, a quick, easy, cheap, effective, rugged, and safe (QuEChERS) based analytical method was developed and validated for quantifying polycyclic aromatic hydrocarbons (PAHs) in biotic matrices with fat contents that ranged from 3 to 11%. Our method improved PAH recoveries 50 to 200% compared to traditional QuEChERS methods, performed as well or better than state of the art Soxhlet and accelerated solvent extraction methods, had sensitivity useful for chemical exposure assessments, and reduced sample preparation costs by 10 fold. The validated QuEChERS method was subsequently employed in a human exposure assessment. Little is known about how traditional Native American fish smoke-preserving methods impact PAH loads in smoked foods, Tribal PAH exposure, or health risks. Differences in smoked salmon PAH loads were not observed between Tribal smoking methods, where smoking methods were controlled for smoking structure and smoke source. PAH loads in Tribally smoked fish were up to 430 times greater than those measured in commercially available smoked fish. It is not likely that dietary exposure to non-carcinogenic PAHs at heritage ingestion rates of 300 grams per day poses an appreciable risk to human health. However, levels of PAHs in traditionally smoked fish may pose and elevated of risk of cancer if consumed at high rates over a life time. Accurately estimating PAH exposure in cases where aquatic foods become contaminated is often hindered by sample availability. To overcome this challenge, we developed a novel analytical approach to predict PAH loads in resident crustacean tissues based on passive sampling device (PSD) PAH measurements and partial least squares regression. PSDs and crayfish collected from 9 sites within, and outside of, the Portland Harbor Superfund site captured a wide range of PAH concentrations in a matrix specific manner. Partial least squares regression of crayfish PAH concentrations on freely dissolved PAH concentrations measured by PSDs lead to predictions that generally differed by less than 12 parts per billion from measured values. Additionally, most predictions (> 90%) were within 3-fold of measured values, while state of the art bioaccumulation factor approaches typically differ by 5 to 15-fold compared to measured values. In order to accurately characterize chemical exposure, new analytical approaches are needed that can simulate chemical changes in bioavailable PAH mixtures resulting from natural and/or remediation processes. An approach based on environmental passive sampling and in-laboratory UVB irradiation was developed to meet this need. Standard PAH mixtures prepared in-lab and passive sampling device extracts collected from PAH contaminated environments were used as model test solutions. UV irradiation of solutions reduced PAH levels 20 to 100% and lead to the formation of several toxic oxygenated-PAHs that have been previously measured in the environment. Site specific differences in oxygenated-PAH formation were also observed. The research presented in this dissertation can be used to advance chemical exposure estimation techniques, rapidly and cost-effectively quantify a suite of PAHs in biotic tissues, and simulate the effect of abiotic transformation processes on the bioavailable fraction of environmental contaminants.
-
First introduced to the USA in 1958, Myxobolus cerebralis, the parasite responsible for whirling disease in salmonids, has since spread across the country causing severe declines in wild trout populations ...
Citation Citation
- Title:
- Potential for dispersal of the non-native parasite Myxobolus cerebralis : qualitative risk assessments for the state of Alaska and the Willamette River Basin, Oregon
- Author:
- Arsan, E. Leyla
First introduced to the USA in 1958, Myxobolus cerebralis, the parasite responsible for whirling disease in salmonids, has since spread across the country causing severe declines in wild trout populations in the intermountain west. Recent development of risk assessment models used to assess the likelihood and consequences of exotic parasite introduction, have strengthened the process of science-based decision-making in aquatic animal health. In the case of M. cerebralis, it is necessary to use a risk assessment model with two unique segments that clearly address the distinct life stages and respective hosts of the parasite separately. The studies described examine the probability of M. cerebralis introduction and establishment for two regions: the state of Alaska, and the Willamette River basin, Oregon. The Alaska risk assessment was based on the assumption that the parasite did not already occur in the state. However, in the process of validating this assumption, we documented the first polymerase chain reaction (PCR) detection of the parasite in the state. The pathogen was identified in hatchery rainbow trout (Oncorhynchus mykiss) from the Anchorage area. Although this is the first detection of the parasite in Alaska, clinical whirling disease has never been documented in the state. To qualitatively assess the risk of further spread of M. cerebralis in Alaska, four potential routes of dissemination were examined: movement of fish by humans, natural dispersal (via migratory birds and stray anadromous salmon), recreational activities, and commercial seafood processing. This research indicates the most likely pathway for M. cerebralis transport in Alaska is human movement of fish. In the Willamette River basin, Oregon, introduction of M. cerebralis has already occurred, though establishment appears limited to a single private hatchery. Introduction in this region was considered the most likely to occur as a result of human movements of fish. Straying anadromous salmonids were also assessed and were present in higher numbers than predicted. However, they were not infected with the parasite, and thus the probability for introduction by this route is low. The probability of introduction of the parasite varies throughout the Willamette River basin. Areas with the highest probability for M. cerebralis introduction were identified as the Clackamas and Santiam River subbasins. The Clackamas River has already experienced an introduction of the parasite, has the largest concentration of hatcheries (state, federal, and private), has a popular sport fishery, and is the closest major tributary to the enormous piscivorous bird-populations in the Columbia River estuary. The Santiam subbasin has a popular sport fishery, received the highest number of stray fish in the Willamette River basin, and has the second largest concentration of hatcheries in the Willamette River basin. Unique from introduction, establishment of the parasite is dependent upon several environmental and biological factors including: water temperatures, spatial/temporal overlap of hosts, and the distribution and genetic composition of the parasite’s invertebrate host, Tubifex tubifex. The distribution, genetic composition and susceptibility of T. tubifex, were considered the most important factor in the ability of M. cerebralis to establish in both systems. Surveys of oligochaete populations were conducted in both study regions. In Alaska, T. tubifex was not detected from the southeast region and the apparent lack of appropriate tubificid hosts may prevent establishment in that part of the state. However, 4 lineages (I, III, IV, and VI) of the species were identified from southcentral Alaska. Lineage IV has not been previously been described in North America and its susceptibility to M. cerebralis was unknown. When lineage IV T. tubifex and 3 mixed-lineage (I, III, IV and VI) groups were exposed to M. cerebralis, only lineage III became infected under our experimental conditions. Thus, if the parasite were dispersed, conditions are appropriate for establishment and propagation of the parasite life cycle in southcentral Alaska, although detrimental effects on fish populations may be reduced as a result of the presence of non-susceptible lineages of T. tubifex. The probability of further establishment in this area is greatest in Ship Creek, where the abundance of susceptible T. tubifex, the presence of susceptible rainbow trout (Oncorhynchus mykiss), and the proximity to the known area of infection make conditions particularly appropriate. Similar to findings in Alaska, the Willamette River basin, Oregon also supports populations of susceptible T. tubifex. If the pathogen were introduced, probability of establishment is high in certain areas of the basin as all conditions are appropriate for propagation of the parasite life cycle. Tributaries to the mainstem Willamette River have the highest probability of establishment as these areas have the greatest numbers of susceptible T. tubifex. However, the abundance of resistant strains of T. tubifex could mitigate the effects of M. cerebralis if introduced. Management recommendations to reduce the likelihood of parasite dissemination are similar for Oregon and Alaska since human movement of fish and angler activities were considered the most likely routes of introduction for both regions. Based on this research, steps should also be taken to limit human movement of fish, whether by restricting carcass planting for stream enrichment in Oregon, or by prohibiting use of fish heads as bait in southcentral Alaska. The states should also allot resources to angler education and awareness of the effects of angler activity and recreation on dispersal of M. cerebralis. This could be done using a combination of brochures and signage at boat ramps describing how to prevent spread of aquatic nuisance species.