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• 1221. [Article] Crustal shortening and tectonic evolution of the Salt Range in Northwest Himalaya, Pakistan

  The Salt Range is clearly the active participant in the scenario of the progressive southward migration of the Himalayan thrust front. It extends approximately 180 km ENE along strike and is underlain ...

  Citation × Citation Citation Abstract Copy Title: Crustal shortening and tectonic evolution of the Salt Range in Northwest Himalaya, Pakistan Author: Qayyum, Mazhar The Salt Range is clearly the active participant in the scenario of the progressive southward migration of the Himalayan thrust front. It extends approximately 180 km ENE along strike and is underlain by salt. This is manifested by its very narrow (<1°) cross-sectional taper and great (150 km) width. Integration of approximately 450 km of seismic reflection data with available surface geologic, magnetostratigraphic, and exploration well data help in delineating different tectonic features in the Salt Range. These studies reveal a concealed duplex structure under the roof sequence, help to determine the footwall and hangingwall geometries of the leading edge at different successive evolutionary stages, estimate the lateral extent of a basement normal fault, constrain the ages of different structural features, and define lateral variations in the deformational style within the leading edge. The above mentioned features have been synthesized to document an out-of-sequence evolutionary model of the Salt Range. The newly recognized, concealed duplex structure extends more than 40 km along the strike and gradually progrades southward along a décollement that first ramps within the Salt Range Formation and then across the platform sequence and follows the shaley horizons of overlying Murree Formation near the contact. This duplex structure is terminated along the two lateral ramps in the east and west. The northern ramp in the footwall of the roof sequence is localized by a basement normal fault in the central Salt Range, and changes its position and characteristics in the eastern and western Salt Range. In the western Salt Range, it is located 15 km farther south and is entirely within the sedimentary sequence. These two segments are linked by a lateral ramp that developed over the western culmination wall of the lateral ramp associated with the underlying duplex structure. In the eastern Salt Range, however, the northern ramp first continues within the sedimentary sequence beyond the end of the basement normal fault and farther east it changes into an oblique ramp. This oblique ramp is truncated by another N-S trending lateral ramp farther to the east. The monoclinal structure of the Chambal Ridge marks the southernmost extension of this lateral ramp. Along this lateral ramp the roof sequence steps down and joins the basal décollement. Due to the down stepping of the roof sequence the structural style also changes from fault-bend fold to fault propagated fold geometry. Because in fault-bend fold geometry the major component of shortening was accommodated across the northern ramp, very little shortening occurred within the roof sequence. In contrast, all the shortening in the east has been distributed over a region in a prograde fashion. Therefore, the thrust wedge is internally deformed into a fault propagated fold geometry to provide a surface topographic slope necessary to maintain a critical taper. The concealed duplex structure is the earliest structure of the Himalayan thrust front that was formed during 9-7 m.y., and further suggests that out of sequence thrusting has occurred over a region of 150 km during the past 9 m.y. Due to the development of a basement normal fault at 7 m.y., the thrust acquired a high friction front and was unable to move forward. Crustal shortening was then taken up by the Main Boundary Thrust zone in the north, which was quite active during this time. Between 5-6 m.y., the thrust wedge started to ramp over the basement normal fault, facilitated by the development of a thick salt pad on the down-thrown side, during 7-6 m.y. The newly built topography due to the ramping of the thrust wedge resisted the southwards propagation of the roof sequence and caused further out-of-sequence thrusting in the north but was not sufficient to stop its southward progradation. It was followed by the major horizontal translation of the roof sequence over the roof sequence flat. This study also suggests that 13° counter clockwise rotation has occurred along the northern ramp and the concealed duplex structure. Recognition of the concealed duplex structure and better understanding of the footwall geometry of the roof sequence also generates new prospects of oil exploration in the Salt Range. Title: Crustal shortening and tectonic evolution of the Salt Range in Northwest Himalaya, Pakistan Author: Qayyum, Mazhar The Salt Range is clearly the active participant in the scenario of the progressive southward migration of the Himalayan thrust front. It extends approximately 180 km ENE along strike and is underlain by salt. This is manifested by its very narrow (<1°) cross-sectional taper and great (150 km) width. Integration of approximately 450 km of seismic reflection data with available surface geologic, magnetostratigraphic, and exploration well data help in delineating different tectonic features in the Salt Range. These studies reveal a concealed duplex structure under the roof sequence, help to determine the footwall and hangingwall geometries of the leading edge at different successive evolutionary stages, estimate the lateral extent of a basement normal fault, constrain the ages of different structural features, and define lateral variations in the deformational style within the leading edge. The above mentioned features have been synthesized to document an out-of-sequence evolutionary model of the Salt Range. The newly recognized, concealed duplex structure extends more than 40 km along the strike and gradually progrades southward along a décollement that first ramps within the Salt Range Formation and then across the platform sequence and follows the shaley horizons of overlying Murree Formation near the contact. This duplex structure is terminated along the two lateral ramps in the east and west. The northern ramp in the footwall of the roof sequence is localized by a basement normal fault in the central Salt Range, and changes its position and characteristics in the eastern and western Salt Range. In the western Salt Range, it is located 15 km farther south and is entirely within the sedimentary sequence. These two segments are linked by a lateral ramp that developed over the western culmination wall of the lateral ramp associated with the underlying duplex structure. In the eastern Salt Range, however, the northern ramp first continues within the sedimentary sequence beyond the end of the basement normal fault and farther east it changes into an oblique ramp. This oblique ramp is truncated by another N-S trending lateral ramp farther to the east. The monoclinal structure of the Chambal Ridge marks the southernmost extension of this lateral ramp. Along this lateral ramp the roof sequence steps down and joins the basal décollement. Due to the down stepping of the roof sequence the structural style also changes from fault-bend fold to fault propagated fold geometry. Because in fault-bend fold geometry the major component of shortening was accommodated across the northern ramp, very little shortening occurred within the roof sequence. In contrast, all the shortening in the east has been distributed over a region in a prograde fashion. Therefore, the thrust wedge is internally deformed into a fault propagated fold geometry to provide a surface topographic slope necessary to maintain a critical taper. The concealed duplex structure is the earliest structure of the Himalayan thrust front that was formed during 9-7 m.y., and further suggests that out of sequence thrusting has occurred over a region of 150 km during the past 9 m.y. Due to the development of a basement normal fault at 7 m.y., the thrust acquired a high friction front and was unable to move forward. Crustal shortening was then taken up by the Main Boundary Thrust zone in the north, which was quite active during this time. Between 5-6 m.y., the thrust wedge started to ramp over the basement normal fault, facilitated by the development of a thick salt pad on the down-thrown side, during 7-6 m.y. The newly built topography due to the ramping of the thrust wedge resisted the southwards propagation of the roof sequence and caused further out-of-sequence thrusting in the north but was not sufficient to stop its southward progradation. It was followed by the major horizontal translation of the roof sequence over the roof sequence flat. This study also suggests that 13° counter clockwise rotation has occurred along the northern ramp and the concealed duplex structure. Recognition of the concealed duplex structure and better understanding of the footwall geometry of the roof sequence also generates new prospects of oil exploration in the Salt Range. Close

• 1222. [Article] Physiological ecology of juvenile Chinook salmon (Oncorhynchus tshawytscha) rearing in fluctuating salinity environments

  Estuaries provide juvenile salmonids with highly productive feeding grounds, refugia from tidal fluctuations and predators, and acclimation areas for smoltification. However, these dynamic, fluctuating ...

  Citation × Citation Citation Abstract Copy Title: Physiological ecology of juvenile Chinook salmon (Oncorhynchus tshawytscha) rearing in fluctuating salinity environments Author: Hackmann, Crystal R. Estuaries provide juvenile salmonids with highly productive feeding grounds, refugia from tidal fluctuations and predators, and acclimation areas for smoltification. However, these dynamic, fluctuating salinity environments may also be physiologically stressful to growing juvenile fish. In order to evaluate the costs and benefits of estuarine marshes to juvenile Chinook salmon, I observed habitat use, diet, and growth of fish in the Nehalem Estuary on the Oregon coast. I also examined physiological costs associated with salmon living in fluctuating salinities and growth rates in laboratory experiments. I collected growth, diet and osmoregulation information from juvenile Chinook salmon in three tidal marsh sites in the Nehalem Bay and from juveniles in the Nehalem River. Stomach contents indicated that a high proportion of the diet is derived from terrestrial prey. These allochthonous prey resources likely become available during the flood stages of tidal cycles when drift, emergent and terrestrial insects would become available from the grasses surrounding the water. This field study confirmed that juvenile Chinook salmon utilized fluctuating salinity habitats to feed on a wide range of items including terrestrial-derived resources. Although field studies indicate that fish in estuarine habitats grow well and have access to quality prey resources, experimental manipulations of salinities were used to quantify the physiological costs of residing in the freshwater-saltwater transitional zone. In the laboratory, I designed an experiment to investigate the physiological responses to fluctuating salinities. Experimental treatments consisted of freshwater (FW), saltwater (SW) (22-25%o); and a fluctuating salinity (SW/FW) (2 - 25%o). These treatments were based on typical salinity fluctuations found in estuarine habitats. I measured length, weight, plasma electrolytes and cortisol concentrations for indications of growth and osmoregulatory function. The fluctuating salinity treatment had a negative effect on growth rate and initial osmoregulatory ability when compared with constant freshwater and saltwater treatments. The results indicated that fluctuating salinities had a small but marginally significant reduction in growth rate, possibly due to the additional energetic requirements of switching between hyper- and hypo-osmoregulation. However, 24-hour saltwater challenge results indicated that all fish were capable of osmoregulating in full-strength seawater. In a second experiment, I manipulated feed consumption rates of juvenile spring Chinook salmon to investigate the effects of variable growth rates on osmoregulatory ability and to test the validity of RNA:DNA ratios as indication of recent growth. The treatments consisted of three different feeding rates: three tanks of fish fed 0.7 5% (LOW) body weight; three tanks fed 3% (HIGH) body weight; and three tanks were fasted (NONE) during the experiment. These laboratory results showed a significant difference in the osmoregulatory ability of the NONE treatment compared to the LOW and HIGH treatments which indicates that a reduction in caloric intake significantly effected osmoregulatory capabilities during a 24 hour saltwater challenge. Furthermore, this suggests that there is a minimum energetic requirement in order to maintain proper ion- and osmoregulation in marine conditions. Estuarine marshes have the potential to provide productive feeding grounds with sufficient prey input from terrestrial systems. However, utilization of these marshes in sub-optimal conditions could alter behavior or impair physiological condition of juvenile Chinook salmon prior to their seaward migration by providing insufficient prey resources in a potentially stressful, fluctuating environment. Therefore, the physiological costs associated with estuarine habitat use should be well understood in order to aid future restoration planning. Title: Physiological ecology of juvenile Chinook salmon (Oncorhynchus tshawytscha) rearing in fluctuating salinity environments Author: Hackmann, Crystal R. Estuaries provide juvenile salmonids with highly productive feeding grounds, refugia from tidal fluctuations and predators, and acclimation areas for smoltification. However, these dynamic, fluctuating salinity environments may also be physiologically stressful to growing juvenile fish. In order to evaluate the costs and benefits of estuarine marshes to juvenile Chinook salmon, I observed habitat use, diet, and growth of fish in the Nehalem Estuary on the Oregon coast. I also examined physiological costs associated with salmon living in fluctuating salinities and growth rates in laboratory experiments. I collected growth, diet and osmoregulation information from juvenile Chinook salmon in three tidal marsh sites in the Nehalem Bay and from juveniles in the Nehalem River. Stomach contents indicated that a high proportion of the diet is derived from terrestrial prey. These allochthonous prey resources likely become available during the flood stages of tidal cycles when drift, emergent and terrestrial insects would become available from the grasses surrounding the water. This field study confirmed that juvenile Chinook salmon utilized fluctuating salinity habitats to feed on a wide range of items including terrestrial-derived resources. Although field studies indicate that fish in estuarine habitats grow well and have access to quality prey resources, experimental manipulations of salinities were used to quantify the physiological costs of residing in the freshwater-saltwater transitional zone. In the laboratory, I designed an experiment to investigate the physiological responses to fluctuating salinities. Experimental treatments consisted of freshwater (FW), saltwater (SW) (22-25%o); and a fluctuating salinity (SW/FW) (2 - 25%o). These treatments were based on typical salinity fluctuations found in estuarine habitats. I measured length, weight, plasma electrolytes and cortisol concentrations for indications of growth and osmoregulatory function. The fluctuating salinity treatment had a negative effect on growth rate and initial osmoregulatory ability when compared with constant freshwater and saltwater treatments. The results indicated that fluctuating salinities had a small but marginally significant reduction in growth rate, possibly due to the additional energetic requirements of switching between hyper- and hypo-osmoregulation. However, 24-hour saltwater challenge results indicated that all fish were capable of osmoregulating in full-strength seawater. In a second experiment, I manipulated feed consumption rates of juvenile spring Chinook salmon to investigate the effects of variable growth rates on osmoregulatory ability and to test the validity of RNA:DNA ratios as indication of recent growth. The treatments consisted of three different feeding rates: three tanks of fish fed 0.7 5% (LOW) body weight; three tanks fed 3% (HIGH) body weight; and three tanks were fasted (NONE) during the experiment. These laboratory results showed a significant difference in the osmoregulatory ability of the NONE treatment compared to the LOW and HIGH treatments which indicates that a reduction in caloric intake significantly effected osmoregulatory capabilities during a 24 hour saltwater challenge. Furthermore, this suggests that there is a minimum energetic requirement in order to maintain proper ion- and osmoregulation in marine conditions. Estuarine marshes have the potential to provide productive feeding grounds with sufficient prey input from terrestrial systems. However, utilization of these marshes in sub-optimal conditions could alter behavior or impair physiological condition of juvenile Chinook salmon prior to their seaward migration by providing insufficient prey resources in a potentially stressful, fluctuating environment. Therefore, the physiological costs associated with estuarine habitat use should be well understood in order to aid future restoration planning. Close

• 1223. [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 Citation Abstract Copy 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. 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. Close

• 1224. [Article] Biology studies of Macrosiphum avenae (Fabr.), Acyrthosiphon dirhodum (Walker), and Rhopalosiphum padi (L.) on Gramineae in western Oregon

  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 Citation Abstract Copy 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. 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. Close

• 1225. [Article] 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

  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 Citation Abstract Copy 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. 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. Close

• 1226. [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 Citation Abstract Copy 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. 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. Close

• 1227. [Article] 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

  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 Citation Abstract Copy 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. 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. Close

• 1228. [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 Citation Abstract Copy 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. 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. Close

• 1229. [Article] Reconnecting aquatic habitats : validating historical habitat use by anadromous fishes using telemetry and stable isotope analysis above barriers

  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 Citation Abstract Copy 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. 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. Close

• 1230. [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 Citation Abstract Copy 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%. 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%. Close