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771. [Article] Ecology of Greenland halibut (Reinhardtius hippoglossoides) during the early life stages in the Eastern Bering Sea and Aleutian Islands
Greenland halibut (Reinhardtius hippoglossoides) have decreased in the eastern Bering Sea and Aleutian Islands since the 1970s. The reasons behind the poor recruitment are unknown, and important knowledge ...Citation Citation
- Title:
- Ecology of Greenland halibut (Reinhardtius hippoglossoides) during the early life stages in the Eastern Bering Sea and Aleutian Islands
- Author:
- Sohn, Dongwha
Greenland halibut (Reinhardtius hippoglossoides) have decreased in the eastern Bering Sea and Aleutian Islands since the 1970s. The reasons behind the poor recruitment are unknown, and important knowledge gaps of the ecology of the early life stages have been identified. The objectives of thesis research were (1) to examine geographic distributions and drift pathways from egg to settled juveniles (age-1) by a retrospective analysis in order to understand connectivity and different habitat utilization through ontogeny, (2) to describe vertical egg distribution using a one-dimensional model in order to understand patterns of vertical egg distribution and their association with water column hydrography and currents through the egg developmental stages, (3) to investigate diet of Greenland halibut larvae and pelagic juveniles diet using stomach content in order to understand foraging behavior, and (4) to examine otolith microstructure of Greenland halibut larvae and pelagic juveniles using otolith analysis in order to establish aging guidelines and other features related to bio-ecological changes (e.g. hatching, mouth opening etc.). The results of the thesis indicate that Greenland halibut early life stages from eggs to newly settled juveniles have a long duration in the plankton and are subject to extended drift pathways. In the eastern Bering Sea and Aleutian Islands, Greenland halibut spawn along the continental slope between Akun Island and the Pribilof Islands, and between Umnak Island and Akun Island in the Aleutian Islands. Spawning most likely occurs in winter from December to January. At-sea observations of egg density ranged from 1023.5 kg/m³ to 1027.8 kg/m³. Based on modeling results, variability of egg density would affect vertical egg distributions. Eggs were found between 50 m and 400 m, in particular, most eggs were concentrated between 200 m and 300 m. Hatching probably occurs in deep water, below 500 m, and larvae rapidly rise in the water column to depths above 45 m. The mechanisms of slope-shelf connectivity appear to be related to the Bering Slope Current in the vicinity of both Bering and Pribilof Canyons. Some larvae cross to the continental shelf from March to May through Bering Canyon, while others are transported through Pribilof Canyon. Pelagic juveniles are mostly found around the Pribilof Islands over the middle shelf (50 m - 100 m isobaths) in July, and settling likely occurs during late summer on the middle shelf near St. Matthew Island. However, given that age-1 juveniles were primarily found on the outer shelf, juvenile Greenland halibut appear to actively move to deeper water, presumably selecting appropriate habitat based on a suite of environmental factors after settlement. Greenland halibut larvae and pelagic juveniles are vigorous carnivores and their feeding habits change as they grow. The clearly defined rings observed in the otoliths might be biological transition marks. This study shows that Greenland halibut have extensive horizontal ontogenetic migrations in the Bering Sea, and utilize a range of geographic areas over the Bering slope and shelf at different life history stages. Based on these results, it is hypothesized that settlement success and recruitment of Greenland halibut may be influenced by variability in currents and flows of the Bering Sea slope and shelf during their transport and by size variations of suitable nursery locations.
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Field biology studies of three grain aphids, Macrosiphum avenae (Fabr.), Acyrthosiphon dirhodum (Walker), and Rhopalosiphum padi (L.) were conducted near Corvallis, Oregon, from 1961 to 1964. Populations ...
Citation Citation
- Title:
- Biology studies of Macrosiphum avenae (Fabr.), Acyrthosiphon dirhodum (Walker), and Rhopalosiphum padi (L.) on Gramineae in western Oregon
- Author:
- Greene, Gerald L.
Field biology studies of three grain aphids, Macrosiphum avenae (Fabr.), Acyrthosiphon dirhodum (Walker), and Rhopalosiphum padi (L.) were conducted near Corvallis, Oregon, from 1961 to 1964. Populations of M. avenae were found on grain plants, and alatae entering spring barley may have been from wheat fields. Specimens were found more commonly on plants taller than six inches. Orchardgrass supported the largest numbers of A. dirhodum during the winter. Many grain and grass plants were inhabited by R, padi during mid-winter, and this species survived temperatures below freezing. Aphids of these three species were not found during August and September. Aphid flight was sampled using sticky traps which caught aphids from March 3 to November 14; the major flights of M. avenae and A. dirhodum occurred during July and R. padi during June. M. avenae populations appeared on spring barley in May, peaked in July and declined to zero by July 31. The first appearance of M. avenae was related to planting dates of the barley. A. dirhodum appeared in the barley fields two weeks later than M. avenae and the populations reached less distinct and lower peak numbers. R. padi appeared later in the spring and in lower numbers than the other two species. The number of aphids per infested plant increased as the number of plants infested increased. M. avenae was found on all 200 plants for only one of 40 sampling dates. In conjunctionwiththe abundance study, six life stages of M. avenae and A. dirhodum were recorded for all samples. Aphid populations consisted of progressively smaller numbers of specimens from the first to the fourth nymphal instar. There were more apterous aphids than fourth instar nymphs and the alate group was the smallest. The instar data were used to estimate the reproductive rate under natural field conditions. An estimate of 14.99 young were produced per adult M. avenae and surviving births averaged from 8.08 to 10.69 per adult. It was estimated that adults reproduced for 75% of the expected time and that 50% of the second, third, and fourth instar nymphs died under field conditions. Four areas of the barley plants were sampled; M. avenae frequented the upper growing areas of the plant and migrated to the heads, A. dirhodum inhabited three areas of the plant, and R. padi occurred on the subterranean shoot and lower senescent leaves. Statistical analysis indicated several distribution patterns. All aphids, species combined, were found to infest plants at random for most sampling dates. M. avenae and R. padi were randomly distributed from plant to plant for most samples, and A. dirhodum infested the plants at random in all samples. Specimens of M. avenae were randomly distributed across four quadrants of the fields during most samples. They were clumped within the quadrants, as were the A. dirhodum during 1963. The distribution of aphids per plant area, the number of aphids in each of six life stages, and the interaction of these two classifications showed M. avenae populations unequally distributed on the plant areas, and the number of specimens for each life stage was dissimilar. Estimates of 30, 895 to 16, 266, 718 aphids per acre along with the confidence limits were given. The larger the means the smaller were the confidence ranges relative to the mean. Coccinella trifasciata subversa LeConte and Hippodamia sinuata spuria LeConte were the most abundant Coccinellidae found and Scaeva pyrastri (L.) was the most common Syrphidae associated with the grain aphid populations, primarily M. avenae. From 100 parasitized aphids, 54 Aphidius obscuripes Ashmead emerged and 33 hyper-parasites. An undetermined entomophagus fungus was seen attacking A. dirhodum on orchardgrass.
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Studies were undertaken to determine the extent and rate of binding of Hg-203 labeled phenylmercuric acetate and mercuric ace tate in rat kidney and liver slices and their subcellular fractions after 37°C ...
Citation Citation
- Title:
- A comparative study of the in vitro localization of mercury from phenylmercuric acetate and mercuric salt in rat kidney and liver subcellular fractions and their effect on alkaline phosphatase
- Author:
- Massey, Thomas H.
Studies were undertaken to determine the extent and rate of binding of Hg-203 labeled phenylmercuric acetate and mercuric ace tate in rat kidney and liver slices and their subcellular fractions after 37°C incubation of the slices in Krebs-Ringer -phosphate solutions containing the mercurials at 10⁻⁴ molar. A fast and parallel rate of uptake of both mercurials in kidney slices between 1 to 3 hour periods was observed. The uptake of the two mercurials into liver slices was much less than that found in kidney slices, The binding rate of phenylmercuric acetate was almost double the rate of inorganic mercury. The subcellular fractions (nuclear, mitochondrial, microsomal, and soluble) of the tissue slices were prepared by homogenizing in 0.25 molar sucrose with subsequent differential centrifugation. Even though the two mercurials showed similar binding in kidney slices, it was found that phenylmercuric acetate was bound to almost twice the extent that of inorganic mercury in the mitochondria, micro-somal, and soluble fractions, with the preponderate of the inorganic mercury being bound in the nuclear. Phenylmercuric acetate was also bound to twice the extent of inorganic mercury in the mitochondrial, microsomal, and soluble fractions from incubated liver slices; however, the binding of the two mercurials in the liver nuclear fraction was similar during the first hours. Also, there was a decrease of the binding of inorganic mercury in the soluble fraction from incubated liver slices as the incubation time increased. Sephadex G-100 elution patterns of the soluble protein fractions from incubated kidney and liver slices were determined. The mercury binding patterns in the elution fractions were also determined. There was found to be three main peaks in the elution pattern from liver and kidney soluble proteins. The first peak represents proteins with molecular weights of 100,000 or greater. The second peak consists of 15,000 to 30,000 molecular weight proteins followed by a trough or dip in the pattern representing large polypeptides (molecular weights of 2,000 to 3,000). The last peak consists of small polypeptides. The specific binding of phenylmercuric acetate in the proteins of the elution pattern corresponding to a molecular weight of 100,000 or larger is greater than inorganic mercury by as much as two-fold. The 15,000 to 30,000 molecular weight proteins in the Sephadex G-100 elution patterns show 2.5 to five times as much specific binding of phenylmercuric acetate as compared to mercuric ion. There was no other area in the patterns in which the mercurials were bound to any significant extent. The binding patterns of the two mercury compounds in the soluble proteins of incubated kidney slices filtered through Sephadex G-100 columns, were similar to those of the liver soluble proteins, except for a very high specific binding of both in the region of the elution pattern corresponding to large polypeptides (2,000 to 3,000 molecular weight). Sephadex G-100 filtration of the incubation soluble proteins leached from liver slices indicated that phenylmercuric acetate caused a greater loss of large molecular weight proteins as compared to the control or inorganic mercury incubated slices. The migration characteristics of soluble proteins from kidney slices with and without mercurial treatment were measured by disc electrophorosis on polyacrylamide gel columns. The results indicated that phenylmercuric acetate caused a possible loss of large molecular weight proteins from the soluble fraction as compared to control or inorganic mercury incubated kidney slices. There was found to be no correlation between the specific binding of the two mercurials with the enzymatic activity of alkaline phosphatase in the soluble and microsomal fractions. It was found that kidney slices incubated in solutions of inorganic mercury resulted in approximately 83 percent enhancement of alkaline phosphatase activity in the soluble fraction as compared to control. Phenylmercuric acetate caused about a 40 percent increase. The microsomal fractions from inorganic mercury treated kidney slices showed a greater decrease in the alkaline phosphatase activity than did phenyl-mercuric acetate as compared to that of control. Twenty to 30 percent of the alkaline phosphatase activity of the 35,000 X G soluble fraction was removed by ultracentrifugation at 150,000 X G. It is possible that the apparent activation of alkaline phosphatase in the soluble fraction was due to a solubilization of the enzyme, with its genesis possibly being in the microsomes. Addition of phenylmercuric acetate to the reaction mixture at concentrations up to 10⁻³ molar caused no significant decrease in the activity of alkaline phosphatase from kidney soluble proteins, while inorganic mercury showed 20 percent inhibition at 10⁻⁵ molar and almost 75 percent inhibition at 5 X 10⁻⁵ molar. There was no significant stimulation of the enzyme when either of the mercurials was added to the reaction mixture.
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774. [Article] Characterization of high temperature fatigue mechanisms in Haynes 282 nickel based superalloy
Electric power needs will only grow over the next decades as more humans ascend from poverty into the middle class. Currently, the majority of electric power is generated by burning fossil fuels. To help ...Citation Citation
- Title:
- Characterization of high temperature fatigue mechanisms in Haynes 282 nickel based superalloy
- Author:
- Rozman, Kyle A.
Electric power needs will only grow over the next decades as more humans ascend from poverty into the middle class. Currently, the majority of electric power is generated by burning fossil fuels. To help mitigate the undesirable effects of burning fossil fuels research is being done to increase the efficiency of power produced. In order to increase the efficiency of power production, the operating temperature of steam turbines must be increased, which presents a materials challenge. Haynes 282 is a nickel based superalloy which has been proposed as a potential rotor alloy for steam turbines operating at high temperature (760°C). Other authors have previously looked at creep, oxidation, low cycle fatigue and other properties of Haynes 282; however, lacking from the literature are studies on the fatigue crack growth mechanisms in Haynes 282. This project investigated Haynes 282 from a fatigue crack growth perspective with an aim to fill this literature gap and assess the utility of Haynes 282 as a steam turbine rotor alloy. This dissertation has specifically evaluated the fatigue crack growth rates of Haynes 282 as functions of temperature and frequency. The testing method utilized was ASTM E647, "Standard test method for measuring fatigue crack growth rates." Temperatures investigated were 550°C, 650°C and 750°C. The loading frequencies were both 25 Hz and 0.25 Hz. In general increasing the test temperature increased fatigue crack growth rate. Thermally activated cross-slip and dislocation annihilation were the primary mechanisms responsible for the increased fatigue crack growth rate. The noted activation energy for dislocation jog migration, which is related to dislocation annihilation, was about 12.5 kJ/mol. This value fit with the measured activation energy. The post-test microstructure showed greatly reduced dislocation density at the highest temperature. Fractography of the crack growth region showed transgranular crack growth at 550°C and 650°C with signs of isolated intergranular features at 750°C. The effect of frequency on the fatigue crack growth rates was minor at 550oC but much more significant at 650°C and 750°C. For the temperatures investigated the effect of decreasing loading frequency was to increase the fatigue crack growth rate. At high loading frequency, the isolated intergranular features were present only at stress intensities below about 11 MPa√m. At 0.25 Hz loading frequency, isolated intergranular features persisted into the high stress intensity range. While the isolated intergranular features are of some concern, the measured activation energy was well below published creep and/or oxidation activation energies. This means the crack path did not have enough energy to sustain an intergranular crack path. In summary, the work discussed in this dissertation investigated the fine details of fatigue crack growth of Haynes 282. This study has closed some of the existing gap in the literature regarding the fatigue crack growth rates of Haynes 282. Previous studies have shown no adverse effects during low cycle fatigue and creep for Haynes 282 at temperatures up to and including 760°C. This study has shown no adverse effects in the fatigue crack growth of Haynes 282 up to 650°C. However, some isolated indications of intergranular crack propagation within the crack growth region were observed at 750°C. These isolated regions were observed to arrest, or to revert back to, transgranular crack propagation. This mechanistic aspect, i.e., change back to transgranular crack propagation, is a promising result.
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The average size and age of chinook salmon (Oncorhynchus tshawytscha) caught in commercial fisheries along the Pacific Coast of North America have decreased substantially in this century. These declines ...
Citation Citation
- Title:
- Changes in size and age at maturity of Columbia River upriver bright fall chinook salmon (Oncorhynchus tshawytscha) : implications for stock fitness, commercial value, and management
- Author:
- Beaty, Roy E.
The average size and age of chinook salmon (Oncorhynchus tshawytscha) caught in commercial fisheries along the Pacific Coast of North America have decreased substantially in this century. These declines might be caused in part by changes in size and age at maturity within the stocks contributing to those fisheries. Upriver Brights (Brights), a stock of fall chinook salmon in the Columbia River, are one of those stocks. The purposes of this study were to (1) determine if average size and age at maturity of Brights have declined, (2) gain a better understanding of the factors that may contribute to such declines, and (3) describe potential consequences of these changes. Data from in-river fisheries suggest that the average weight of mature Brights returning to the Columbia River has decreased approximately 2.7 kg since the 1910s, an average rate of about 0.1 lb·yr⁻¹ (45 g·yr⁻¹ ). Most of the potential biases in these data tend to make this estimate conservative. Insufficient data were available to describe changes in average age at maturity. There are many potential causes for the decline in average size of mature Brights, including factors that affect very early life stages. Other researchers have determined that size at maturity appears to be highly influenced by inheritance, gender, and growth rate. I describe how maternal size can influence -- through time of spawning, choice of spawning site, and egg size -- the viability of the young, which carry the dam's genes for size. The size-related ability to produce viable offspring may have been changed by modifications in the environment. Very little is known about how changes in the natural environment for spawning, incubation, and rearing may have contributed to a decline in average size at maturity. Artificial propagation and rearing, such as at Priest Rapids Hatchery, seems to produce adult Brights that are smaller, younger, and more likely to be male than their natural counterparts. The net result is that the average hatchery fish may have only about 0.80 of the reproductive potential of the average natural fish. Changes in growth conditions in the ocean probably did not contribute to the change in size, although the ocean fisheries of Southeast Alaska and British Columbia appear to select, in the genetic sense, against large size and old age in Brights. Since 1978, in-river commercial fisheries have caught larger Brights and a higher proportion of females than are found in the escapement of the Priest Rapids Hatchery component of the stock, but the fisheries impact the two sexes differently by taking the larger males and the smaller females. The effect on the natural component may differ because of their apparently larger average size. I found no evidence that larger fish or more females were caught when 8-in. minimum restrictions were in effect on gillnet mesh size relative to periods when mesh size was not restricted. Impounding the mainstem during the last 50+ yr may have removed obstacles to migration (e.g., Celilo Falls) that selected for large size in Brights, but that hypothesis could not be tested. The perserverance of larger and older phenotypes in the Bright stock suggests that countervailing selection -- perhaps during spawning, incubation, and/or early rearing -- may have resisted the effects of a century of size- and age-selective fisheries. That resistance, however, may reduce the productivity of the stock. Declines in average size and age at maturity can have undesireable consequences. Lower average size means less biomass landed and lower commercial value. Lower average fecundity and a diminished ability to reproduce in some environments are also expected. Loss of size and age classes may reduce the ability of the stock to adapt to environmental variations. These results are relevant to several management practices. A holistic approach to fishery management issues is necessary to avoid erroneous conclusions based on narrow perspectives. Measuring reproductive potential of the catch and escapement would be superior to the conventional practice of simply counting numbers of fish. Many aspects of artificial propagation can be improved, including broodstock aquisition, mating regimes, and rearing practices. Stock abundance is a major factor in determining the effect of many management practices on the stock. In general, fisheries managers must be mindful that they manage very complex natural systems.
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776. [Article] Constructing a sheeted magmatic complex within the lower arc crust : insights from the Tenpeak pluton, North Cascades, Washington
The sheeted complex of the ~92 Ma Tenpeak pluton, in the Northern Washington Cascades crystalline core, forms a <1.5-km wide zone with a moderate, NE-dip at the SW margin of the pluton. Sheeted magmatic ...Citation Citation
- Title:
- Constructing a sheeted magmatic complex within the lower arc crust : insights from the Tenpeak pluton, North Cascades, Washington
- Author:
- Chan, Christine F.
The sheeted complex of the ~92 Ma Tenpeak pluton, in the Northern Washington Cascades crystalline core, forms a <1.5-km wide zone with a moderate, NE-dip at the SW margin of the pluton. Sheeted magmatic complexes, such as the one in the Tenpeak pluton, are common in plutons and represent examples of incremental growth of plutons. Though it is widely accepted that plutons are constructed incrementally over prolonged timescales of several million years, it is not clear if and to what degree individual batches of magma interact, the timing and size of each magma pulse, and the role, timing, and location of magmatic differentiation. This project uses a combination of field evidence, bulk rock chemistry, and mineral geochemistry to address the (1) role of magma mixing and fractionation, (2) constraints on the relative timing of magma differentiation, (3) diversity of mixing styles preserved, and (4) physical properties that dictate how individual batches of magma interact within this sheeted complex. Rock samples were collected throughout the complex from mafic, felsic, dioritic, thinly-banded, and gradational sheets. Field evidence shows a range of sheet contacts that vary from sharp to diffuse, strong prevalence of mafic enclaves, and localized cases of mechanical mixing in which plagioclase feldspars from a felsic sheet are incorporated into a mafic sheet. In general, sheet thickness increases farther from the contact with the White River shear zone. The bulk rock and mineral chemistry suggests that the felsic magmas in sheets formed independently from the more mafic and hybridized sheets. The composition of the felsic sheets cannot be modeling by binary mixing processes involving mafic and felsic magmas or result from fractionating the most mafic magmas. However, mass-balance calculations using a linear least-squares mass balance calculation and Rayleigh fractionation models indicate that it is possible to explain the range of felsic compositions by internal, crystal fractionation driven mostly by plagioclase crystallization (~40-58%). Negative Eu anomalies in amphiboles from the felsic sheets imply that plagioclase fractionation commenced prior to the onset of amphibole crystallization. With the exception of the most primitive mafic sheet sampled, the mafic and hybridized sheets represent variable proportions of the mafic parental magma and the range of felsic differentiated magmas. Efficient mixing that resulted in these mafic to hybridized magmas must also have occurred prior to mineral growth as the mineral chemistry reflects intermediate, mixed compositions. The bulk rock and mineral chemistry of the most primitive, mafic sheet suggest that it did not mix with any felsic magmas. However there is evidence that the mafic sheet underwent plagioclase fractionation prior to emplacement. This is evident by lower bulk rock Sr/Ba relative to calculated Sr/Bamelt of plagioclase that cannot be reconciled without removing ~40-58% plagioclase. In contrast to the felsic sheets, the amphiboles from this mafic sheet lack Eu anomalies implying that amphibole crystallization occurred prior to major plagioclase fractionation. Chemical evidence reveals that magma mixing played an important role in controlling the chemical composition of individual sheets and field observations suggesting that there was a range of mixing styles. Throughout the sheeted complex, there are localized sites of mechanical mixing where plagioclase phenocrysts from adjacent felsic sheets are mechanically mixed into mafic sheets. Evidence for mechanical mixing is present across both sharp and gradational contacts. This implies varying rheological and viscosity contrasts between different sheets, though in both cases crystallinity and viscosity appears sufficiently low to allow crystals to migrate across sheet contacts. Variability in sheet thickness and contact type suggests that the physical parameters (i.e. temperature, viscosity, rheology, and magma flux) of the system continue to evolve throughout the formation of the sheeted complex. Near the White River, sheets are thin and more heterogeneous but become progressively thicker (>302 m) and more felsic in composition up-section. The composition of plagioclase and amphibole is remarkably uniform in all of the felsic sheets suggesting that each sheet formed from an array of felsic parental magmas. Thicker, felsic sheets most likely reflect hotter conditions where larger magma fluxes could be accommodated or viscosity-temperature contrasts that were low enough to allow for efficient mixing between two adjacent sheets and therefore erase sheet contacts.
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I conducted a study to identify potential spawning habitat for anadromous salmonids above a 60-year-old hydropower dam in the headwaters of the North Umpqua River in Oregon. Like many other historical ...
Citation Citation
- Title:
- Reconnecting aquatic habitats : validating historical habitat use by anadromous fishes using telemetry and stable isotope analysis above barriers
- Author:
- Lewis, Sierra Koch
I conducted a study to identify potential spawning habitat for anadromous salmonids above a 60-year-old hydropower dam in the headwaters of the North Umpqua River in Oregon. Like many other historical salmonid-bearing rivers, little documentation exists for anadromous fish presence above potential natural obstacles upstream of Soda Springs Dam. My prediction was that if migratory salmonids are allowed to move upstream of the dam using a new fish ladder they would utilize available upstream spawning habitat. I captured, radio-tagged, and transplanted wild adult summer steelhead, O. mykiss, above Soda Springs Dam and tracked daily movements for 1 year to observe habitat preferences. I also investigated evidence of historical anadromy throughout the North Umpqua River basin using stable isotope analysis of salmon-derived nitrogen (¹⁵N) in foliar samples from Douglas fir trees, P. menziesii, (>100 years old). I tested the hypothesis that I could identify undocumented, historical salmon spawning reaches above natural and anthropogenic obstacles based solely upon δ¹⁵N foliar deposition patterns. While tracking radio-tagged steelhead, I documented holding locations, the timing of spawning activities, and the outmigration of kelts. Tagged fish did not show any extensive movement in the river or tributaries above the dam. Most of the tagged adults showed incremental daily movements near the release site or downstream into the hydropower reservoir but did not travel further than 1 kilometer upstream in the main river channel. I recorded movements and localized activities that suggested some of the fish spawned and subsequently moved downstream towards the Pacific Ocean. My observations indicated that spawning behavior of tagged fish above Soda Springs Dam was delayed several weeks relative to fish spawning below the dam. There was no evidence from telemetry that any fish moved upstream in Fish Creek, the newly accessible habitat of interest in this project. My data suggest that steelhead will use restored habitat above dams, but that re-colonization activities are variable and may be affected by altered flow regimes within the restored habitat upstream of the dam and intra-specific density dependence. My stable isotope data indicated that the foliar δ¹⁵N deposition patterns were confounded with elevation. I documented potential "salmon-derived" false positives on the Umpqua National Forest above impassable waterfalls. Overall I found that foliar δ¹⁵N deposition patterns were highly variable and unexpectedly indicated a statistically significant negative correlation of foliar δ¹⁵N values with historical salmon presence. My linear mixed-effects modeling suggests that the presence of salmon is the most important indicator of foliar δ¹⁵N values, rather than the proximity of a sampled tree to stream flow above or below migratory barriers. I was not able to use the mixed effects model to identify previously undocumented salmon spawning habitat. My results from the foliar technique suggest that the method may not be universally applicable as has been previously suggested in the literature.
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778. [Article] Effects of boron rates and differential irrigation on bush green beans and cauliflower
Five boron rates and seven water levels were applied to bush green beans (Phaseolus vulqaris cv Oregon 91G) and to cauliflower (Brassica olereacea var. botrytis, cultivar "Snowball Y") in 1989 and 1990 ...Citation Citation
- Title:
- Effects of boron rates and differential irrigation on bush green beans and cauliflower
- Author:
- Grealish, William J.
Five boron rates and seven water levels were applied to bush green beans (Phaseolus vulqaris cv Oregon 91G) and to cauliflower (Brassica olereacea var. botrytis, cultivar "Snowball Y") in 1989 and 1990 to evaluate their effects on total yield of both crops and on outer quality, head hollowness and internal discoloration of cauliflower curds. Of the five B rates (0,1,3,6 and 9kg/ha) three (0, 3 and 9 kg/ha) were monitored to evaluate B concentrations at soil depths of 0-15, 15-30, 30-45 and 45-60 cm. In each season, B concentrations were analyzed at a high (wet) level of applied water. An overall evaluation comparing the starting and ending levels of B after two years was conducted at two levels of applied water (high and low). Soil applied B rates of 9 kg/ha significantly reduced bean yields in 1989 and 1990. Boron concentrations in the trifoliate leaf tissue at the highest (wet) water level in 1989 and 1990 ranged between 22 to 72 mg/kg for the five B rates. Tissue concentrations at the lowest (dry) Water level in 1990 ranged from 23 to 32 mg/kg B. Soil B levels for both years had an overall range of 0.22 to 1.81 mg/kg. Injury to beans occurred at soil concentrations equal to or greater than 1.0 mg/kg B. An added experiment (0,9,18 and 36 kgB/ha) in 1990 produced highly significant reductions in bean yields at B rates of 18 and 3 6 kg/ha. Yields did not vary significantly, however, between 0 and 9 kgB/ha. Boron concentrations in whole plant samples at the first trifoliate leaf stage ranged from 4 3 to 3 52 mg/kg. Soil B levels ranged from 0.3 5 to 4.07 mg/kg. Applied water levels of 77% and 69 to 87% of a calculated reference evapotranspiration coefficient (ETo) produced highest yields of bean pods in 1989 and 1990 respectively. Optimum yields for both seasons occurred when soil moisture levels (% moisture/ volume) were depleted to no less than 50% of available soil moisture. Total yields, inner quality and outer quality of cauliflower were not significantly affected by soil applied B rates as high as 9 kg/ha (as compared to 0, 1, 3 and 6 kgB/ha) during both the 1989 and 1990 seasons. Boron concentrations in leaf tissue at the highest (wet) water level ranged from 13.2 to 23.8 and 34.8 to 70.9 mg/kg in 1989 and 1990 respectively. Boron concentrations in leaf tissue were higher at the highest water level than at the lowest water level. Post harvest soil B concentrations ranged from 0.31 to 0.82 mg/kg at the highest water level in 1989 and 1990 respectively. In general, soil B concentrations were higher at the lowest (dry) water levels than at the highest water level. Highest yields were achieved at applied amounts of water that equaled 104 and 80% of ETo in 1989 and 1990 respectively. Corresponding soil moisture data (% moisture/volume) showed optimum yields occurring when available moisture remained above 50%. The frequency of good outer quality curds increased as water amounts increased. The frequency of good inner quality curds decreased as water amounts increased. Marketable yields at the lower moisture regimes, however, were marginal. Internal quality appeared to be a function of harvest date in this experiment. The frequency of head-hollowness and internal discoloration both decreased as the harvest season progressed. Percent good inner quality ranged from 48.5 to 84.7 and 34.9 to 91.1 between first and last harvests in 1989 and 1990 respectively. Boron migration or loss through the soil profile was greatest out of the top 0-15 cm depth and at the 9 kgB/ha rate. Losses as high as 39 and 49% in 1989/1990 and 1990/1991 seasons respectively, were found as a result of differential dates of soil sampling. In an additional experiment in the mid-summer of 1990 where rates of 9, 16 and 32 kgB/ha were applied, losses of B from the 0-15 cm depth ranged from 35 to 49%.
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779. [Article] Nearshore distribution of barnacle and mussel larvae and oceanographic mechanisms of onshore transport and delivery
Recruitment of larvae from the plankton is an important determinant of community structure in marine systems. In populations of many marine species, recruitment determines the basic demographic parameters ...Citation Citation
- Title:
- Nearshore distribution of barnacle and mussel larvae and oceanographic mechanisms of onshore transport and delivery
- Author:
- Tyburczy, Joe
Recruitment of larvae from the plankton is an important determinant of community structure in marine systems. In populations of many marine species, recruitment determines the basic demographic parameters of immigration, emigration, and reproduction. Moreover, the effect of recruitment as an "ecological subsidy" can determine the strength of interactions among species and whether populations are limited by recruitment itself, or by competition or predation. For this reason, understanding the transport of larvae is essential for management and conservation. In Chapter 2, my coauthors and I investigated the vertical and cross-shelf distribution of barnacle and bivalve larvae with a series of paired day/night sampling cruises off the coast of central Chile. Barnacle larvae were generally found close to shore (within 1.5 km), and the cross-shelf distribution of all taxa varied little despite contrasting upwelling conditions. Since current velocities decrease quickly with proximity to shore, larvae distributed in the nearshore are less likely to be dispersed long distances. Further, the consistent cross-shelf distribution of larvae suggests that they are not necessarily swept on- or offshore by upwelling or relaxation. Depth distributions consistent with classical diel vertical migration (DVM; swimming deeper during the day, shallower at night) were found in barnacle nauplii, but not barnacle cyprids or in bivalve larvae. One potential advantage of DVM is that it may limit offshore transport and thereby increase the odds that larvae will reach suitable habitat when they are competent to settle. Another possible benefit of DVM is that it may increase feeding opportunity in shallow water at night when visual predation risk is low, while providing refuge at depth during the day when visual predation in the upper water column is greater. In Chapter 3, my coauthors and I undertook a large-scale study in northern Monterey Bay, CA that integrated high-frequency physical and biological sampling to allow resolution of multiple different potential mechanisms of onshore larval transport and settlement. Depending on location within Monterey Bay, three processes were found to be associated with onshore barnacle settlement: regional upwelling, local diurnal upwelling driven by afternoon sea breezes, and the passage of an upwelling shadow front. Based on these findings we propose a novel conceptual model that encompasses oceanographic processes at multiple scales and reconciles apparent inconsistencies between empirical results and existing theories. In Chaper 4, my coauthors and I developed a simple larval transport model using data on currents, offshore flux of barnacle larvae, and onshore settlement of barnacles from the empirical study in Chapter 3. A parameter set was found that produced model settlement correlated with observed settlement. The fit of modeled and observed settlement was sensitive to model parameters. However, for all parameter sets examined, onshore transport of particles was much greater at depth. This result from the larval transport model is consistent with the conceptual model proposed in Chapter 3. Further, during intervals when onshore transport was observed, model particle trajectories clearly show onshore transport only at depth via two of the mechanisms identified in Chapter 3 (local diurnal upwelling and passage of the upwelling shadow front).
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780. [Article] The 1951 Alsea River silver salmon tagging program
During a tagging operation conducted in 1951 on the Alsea River, 1,142 adult silver salmon were tagged with plastic Petersen-type tags and stainless steel jaw tags. An attempt was made to determine whether ...Citation Citation
- Title:
- The 1951 Alsea River silver salmon tagging program
- Author:
- Oregon. Fish Commission, Cleaver, Fred C. (Frederick Charles), 1916-, Morgan, Alfred R.
During a tagging operation conducted in 1951 on the Alsea River, 1,142 adult silver salmon were tagged with plastic Petersen-type tags and stainless steel jaw tags. An attempt was made to determine whether tagged fish released in different apparent conditions suffered differential mortalities. Under the hypothesis that the recovery of the fish in the commercial fishery was independent of the apparent condition of the fish when it was released, a significant value of chi-square was obtained. However, it was concluded that this significance was a result of sampling differences and not actually due to differences in mortality. The number of fish taken in the commercial catch each week was calculated by dividing the number of pounds in the weekly catch by the average weight of the fish in the samples for that week. It was calculated that the commercial fishery took approximately 14,000 fish during the season, which was only about 15 per cent of the run available to the fishery. This is an extremely low fishing mortality and is considerably lower than had been expected. The number of tags taken each week by the commercial fishery was calculated by dividing the number of fish in the catch each week by the number of fish per tag in the samples for the week. It was calculated that 67 tags were taken during the season by the commercial fishery. This number of recoveries was 15.5 per cent of the 438 tags available to the fishery. With the cooperation of a number of boat moorages on the Alsea River, an estimate of the sport catch of silver salmon was made. It was calculated that the lower river sport fishery took approximately 3,000 adult silvers with an additional 500 fish being taken by the bank fishery. The weight of the total catch of 3,500 fish was calculated to be about 33,000 pounds. This weight formed 20.2 percent of the combined commercial and sport catches. It was calculated that 18 tagged fish were taken in the sport catch. A total of 44 numbered Petersen and jaw tags were recovered from both dead and live fish which had reached spawning areas. This number includes three tags recovered from the spawning grounds of adjacent streams. When the tagged fish were examined according to areas recovered, it was found that Drift Creek had a smaller number of fish per tag than any other area with one exception. Recoveries appeared to be distributed throughout the drainage from any particular time of tagging. Fish enter the lower river together, then separate to the various spawning areas in the system. Several fish moved from the tagging location in the Alsea River to adjacent streams. About 7 percent of the total recoveries in Table 12 were made from streams other than the Alsea River. The Petersen and jaw tag recoveries in the samples of the commercial catch were examined for selection of the Petersen tags by the nets. The percentage by size group in the catch of fish with each type of tag was about the same as the percentage by size group with each type of tag at the time of release. Large losses of tags in the fishery would have been reflected by a higher number of fish per tag on the spawning grounds. Since the gill-nets did not appear to be selective on either type of tag, the Petersen tags, jaw tags, and tag scars were combined in the calculations involving tag recoveries. After the fish moved beyond the fishing area, many still did not move rapidly to the spawning grounds. Several were taken in tidewater or in the vicinity of tidewater 48-58 days after they had been tagged. The average time between tagging and recovery on the spawning grounds was 63 days for live fish and 70 days for dead fish. Using the method proposed by Schaefer (1951a) for obtaining a population estimate from spawning ground recoveries, an estimate of the population available to the fishery was made from the number of tags recovered by sampling the commercial catch. It was calculated that approximately 90,000 fish were available to the fishery. About 89,000 fish were calculated to be available to the fishery when the equation N = nt/s was used, where N = the population, n = the sample size, t = the number of fish tagged, and s = the number of tag recoveries. The 95 percent limits of confidence for the population estimate derived from the equation N = nt/s were calculated using the method developed by Chapman (1948). The lower limit was found to be 63,736 fish, and the upper limit was 119,371 fish. Approximately 63,000 of the fish available to the commercial fishery continued the migration to the spawning grounds. Spawning ground tag recoveries provided an estimate of the population in the lower river which was in close agreement with the estimate of the population made from tag recoveries in the commercial fishery.