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• 761. [Article] Investigation of Crangon spawning behavior, assemblage, and trophic relationships in the estuarine and shelf habitats of the central Oregon coast

  This was a final project for BI 450 Marine Biology, which included a paper and a presentation by myself and Larkin Loewenherz. The presentation was given on June 6th, 2014, to a public audience at Hatfield ...

  Citation × Citation Citation Abstract Copy Title: Investigation of Crangon spawning behavior, assemblage, and trophic relationships in the estuarine and shelf habitats of the central Oregon coast Author: Huff, David D., Danilchik, Nikolai M., Loewenherz, Larkin This was a final project for BI 450 Marine Biology, which included a paper and a presentation by myself and Larkin Loewenherz. The presentation was given on June 6th, 2014, to a public audience at Hatfield Marine Science Center. Title: Investigation of Crangon spawning behavior, assemblage, and trophic relationships in the estuarine and shelf habitats of the central Oregon coast Author: Huff, David D., Danilchik, Nikolai M., Loewenherz, Larkin This was a final project for BI 450 Marine Biology, which included a paper and a presentation by myself and Larkin Loewenherz. The presentation was given on June 6th, 2014, to a public audience at Hatfield Marine Science Center. Close

• 762. [Article] Sedimentary texture--a key to interpret deep-marine dynamics

  The processes responsible for transporting and depositing thick sections of coarse-grained terrigenous clastics on the abyssal floor and for forming associated sedimentary structures are still conjectural. Many ...

  Citation × Citation Citation Abstract Copy Title: Sedimentary texture--a key to interpret deep-marine dynamics Author: Allen, David William The processes responsible for transporting and depositing thick sections of coarse-grained terrigenous clastics on the abyssal floor and for forming associated sedimentary structures are still conjectural. Many workers attribute coarse deep-sea sediments and their probable lithified equivalent, the graywackes of flysch deposits to some type of density movement. Deductions concerning the processes operating in a density flow generally are made from flume studies--in which an artificial situation may develop, or from lithified units--where the magnitude of post-depositional change is unknown. Both approaches contribute to our knowledge, but the unconsolidated elastics themselves should contain a unique key to understanding the dynamics of abyssal sedimentation. To test this theory, divisions of parallel lamination, found in deep-sea sand and silt, were selected for analysis. Since individual laminae closely approach discrete populations of particles assembled under contrasting conditions, their use carries environmental sampling to its practical limits. Northeast Pacific sediments of late Pleistocene and Holocene age, from deep-sea channel and abyssal plain environments, and representing two or three provenances were studied. A total of 115 light-colored and 84 dark-colored laminae were sampled from eight sequences at five locations. Samples averaged about 0.8 gram and were quantitatively processed using quarter-phi calibrated sieves and decantation techniques. Statistical evaluation of the procedure shows better than 95 percent sample recovery, and indicates that textural variance between laminae is significantly greater than within-sample variance. The classic concept of density transport--that coarsest material is carried by the nose of the current, and that clastic size grades tail-ward and upward in a uniformly decreasing manner--is not substantiated by moment measures, sand-silt-clay percentages or factor analysis of grain-size distributions, at least during deposition of the coarse division of parallel lamination. Coarse abyssal lamination develops within a narrow range of current velocity, the limits of which are defined texturally. Absolute velocity values for these limits can only be related, at the present time, to the few flume or in situ bottom current measurements available. Texture indicates that while the total amount of sand carried in suspension varies, lamination does not begin to form until a current is essentially depleted of all material coarser than fine sand--establishing an upper competency limit. At that time, coarse suspended material is distributed throughout the flow mostly in large eddies or vortices whose velocities are estimated on the order of about one meter/sec. Mean current velocity must be sufficient to maintain a dispersed traction carpet without deformation of bedform into ripples. This is postulated at about 50 cm/sec. A current model, based on textural evidence, is proposed to account for lamination. It is suggested that the critical stage in the formation of coarse abyssal lamination occurs while sediment is being dragged along the bottom as bedload. The flowing clastic traction carpet acquires kinetic energy as the current bypasses material lost from suspension. In turn, this energy results in grain shear. When the concentration of granular material in traction is large, it dissipates the energy of bottom shear mostly in collision contacts between gliding grains. The dispersive stresses developed tend to maintain grain separation and prevent settling. Eventually, turbulence in seawater entrapped between grains is suppressed and the net path of grans impelled by repeated collisions becomes quasi-laminar. Within this quasi-laminar traction system, dispersive pressure causes some migration of finer sizes toward the base of the carpet and a concentration of coarser grains in the upper bedload. As new material is introduced in large quantities from suspension, the zone of internal shear--the base of the moving carpet--is displaced progressively upward. As it passes, sediment compacts to a fraction of its dispersed thickness and a population of grains with a slightly finer size distribution than the carpet load comes to rest. This is buried by new deposition and a densely-packed, dark layer continues to accrete upward as long as a moving traction carpet is sustained and a dense rain of clastics is contributed from suspension. When a sand-laden eddy impinges on the bottom, it releases its coarsest load into traction and the dark layer then accreting increases significantly in grains larger than 44 microns. Any eddy, whether laden or not, on striking bottom adds to, or deducts its velocity from the velocity of the traction carpet and either increases or decreases bottom shear. Additional impulse given to tractive shear by eddies merely results in more effective size sorting. However, an eddy whose velocity of rotation is opposed to current movement may reduce shear below the critical necessary to maintain a thick carpet by dispersive pressure, The dispersed carpet collapses and instantaneously ceases moving. This less-densely packed layer has a slightly higher sand content than the accreted material below. When partially dried or weathered, alternate layers exhibit different moisture retention properties--the less-porous, accreted layers appearing dark and the more loosely packed layers appearing light. Title: Sedimentary texture--a key to interpret deep-marine dynamics Author: Allen, David William The processes responsible for transporting and depositing thick sections of coarse-grained terrigenous clastics on the abyssal floor and for forming associated sedimentary structures are still conjectural. Many workers attribute coarse deep-sea sediments and their probable lithified equivalent, the graywackes of flysch deposits to some type of density movement. Deductions concerning the processes operating in a density flow generally are made from flume studies--in which an artificial situation may develop, or from lithified units--where the magnitude of post-depositional change is unknown. Both approaches contribute to our knowledge, but the unconsolidated elastics themselves should contain a unique key to understanding the dynamics of abyssal sedimentation. To test this theory, divisions of parallel lamination, found in deep-sea sand and silt, were selected for analysis. Since individual laminae closely approach discrete populations of particles assembled under contrasting conditions, their use carries environmental sampling to its practical limits. Northeast Pacific sediments of late Pleistocene and Holocene age, from deep-sea channel and abyssal plain environments, and representing two or three provenances were studied. A total of 115 light-colored and 84 dark-colored laminae were sampled from eight sequences at five locations. Samples averaged about 0.8 gram and were quantitatively processed using quarter-phi calibrated sieves and decantation techniques. Statistical evaluation of the procedure shows better than 95 percent sample recovery, and indicates that textural variance between laminae is significantly greater than within-sample variance. The classic concept of density transport--that coarsest material is carried by the nose of the current, and that clastic size grades tail-ward and upward in a uniformly decreasing manner--is not substantiated by moment measures, sand-silt-clay percentages or factor analysis of grain-size distributions, at least during deposition of the coarse division of parallel lamination. Coarse abyssal lamination develops within a narrow range of current velocity, the limits of which are defined texturally. Absolute velocity values for these limits can only be related, at the present time, to the few flume or in situ bottom current measurements available. Texture indicates that while the total amount of sand carried in suspension varies, lamination does not begin to form until a current is essentially depleted of all material coarser than fine sand--establishing an upper competency limit. At that time, coarse suspended material is distributed throughout the flow mostly in large eddies or vortices whose velocities are estimated on the order of about one meter/sec. Mean current velocity must be sufficient to maintain a dispersed traction carpet without deformation of bedform into ripples. This is postulated at about 50 cm/sec. A current model, based on textural evidence, is proposed to account for lamination. It is suggested that the critical stage in the formation of coarse abyssal lamination occurs while sediment is being dragged along the bottom as bedload. The flowing clastic traction carpet acquires kinetic energy as the current bypasses material lost from suspension. In turn, this energy results in grain shear. When the concentration of granular material in traction is large, it dissipates the energy of bottom shear mostly in collision contacts between gliding grains. The dispersive stresses developed tend to maintain grain separation and prevent settling. Eventually, turbulence in seawater entrapped between grains is suppressed and the net path of grans impelled by repeated collisions becomes quasi-laminar. Within this quasi-laminar traction system, dispersive pressure causes some migration of finer sizes toward the base of the carpet and a concentration of coarser grains in the upper bedload. As new material is introduced in large quantities from suspension, the zone of internal shear--the base of the moving carpet--is displaced progressively upward. As it passes, sediment compacts to a fraction of its dispersed thickness and a population of grains with a slightly finer size distribution than the carpet load comes to rest. This is buried by new deposition and a densely-packed, dark layer continues to accrete upward as long as a moving traction carpet is sustained and a dense rain of clastics is contributed from suspension. When a sand-laden eddy impinges on the bottom, it releases its coarsest load into traction and the dark layer then accreting increases significantly in grains larger than 44 microns. Any eddy, whether laden or not, on striking bottom adds to, or deducts its velocity from the velocity of the traction carpet and either increases or decreases bottom shear. Additional impulse given to tractive shear by eddies merely results in more effective size sorting. However, an eddy whose velocity of rotation is opposed to current movement may reduce shear below the critical necessary to maintain a thick carpet by dispersive pressure, The dispersed carpet collapses and instantaneously ceases moving. This less-densely packed layer has a slightly higher sand content than the accreted material below. When partially dried or weathered, alternate layers exhibit different moisture retention properties--the less-porous, accreted layers appearing dark and the more loosely packed layers appearing light. 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• 763. [Article] Subsurface densities & lithospheric flexure of the Himalayan foreland in Pakistan, interpreted from gravity data

  Gravity data along a N-S profile from Kohistan to the Punjab plain of Pakistan have been incorporated into recent interpretation of the gross structure of the foreland fold and thrust belt of the Himalaya. ...

  Citation × Citation Citation Abstract Copy Title: Subsurface densities & lithospheric flexure of the Himalayan foreland in Pakistan, interpreted from gravity data Author: Duroy, Yannick Gravity data along a N-S profile from Kohistan to the Punjab plain of Pakistan have been incorporated into recent interpretation of the gross structure of the foreland fold and thrust belt of the Himalaya. In northern Pakistan large deviations from Airy Isostatic equilibrium are observed. An excess of mass characterizes the northern Kohistan arc and a deficit of mass underlies a broad area extending from southern Kohistan to the Salt Range, while to the south a slight excess of mass seems to prevail in the region of the Sargodha ridge. This anomalous distribution of mass can be understood if the Indian elastic plate, which is assumed to overlie an inviscid fluid, is flexed down under the weight of both the overthrust mountains and the sediments eroded off the mountain and deposited in the foredeep basin. In many respects the intracontinental subduction of India beneath the Himalaya is similar to island arc formation, including the seismically active Sargodha ridge, an outer topographic rise analogous to the flexural bulge encountered seaward of oceanic trenches. Analysis of Bouguer gravity anomalies along a profile extending from the Sargodha ridge to the main mantle thrust (MMT) show that most of the negative-southward gravity gradient can be attributed to crustal thickening, while short wavelength anomalies are produced by lateral variation of density within the northward thickening sedimentary wedge. In the Sargodha ridge area, an additional contribution of about 25 mgals appears to be due to excess of mass at lower crustal or upper mantle levels. The Moho discontinuity is interpreted to bulge up beneath the Sargodha high, then gradually increase in dip from 1° to 3° beneath the Salt Range and Potwar Plateau (approximately equal to the change in dip of the basement surface). The Moho slope changes from upwardly convex to upwardly concave beneath southern Kohistan. Finally, north of the Main Mantle Thrust (MMT) it bends down again, but at a steeper angle of about 15°. Shorter wavelength anomalies superimposed on the regional gradient are modeled in terms of upper crustal density changes, including those due to: 1) offsets of the basement surface, 2) variable thickness of the Eocambrian evaporite sequence that forms the basal decollement, 3) thrusting and folding of relatively high density, older parts of the stratigraphic section to higher structural levels, particularly in the Salt range and northern Potwar plateau, and 4) thickening of the low density Neogene molasse sequence into the axis of the Soan Syncline, a structural depression between the Salt range and northern Potwar plateau. Subsurface densities of the overthrust wedge, as well as the definition of the shape of the top surface of the Indian plate interpreted from gravity, place bounds on the flexural rigidity of such a plate and the forces that deform it. In northern Pakistan the flexural rigidity of the elastic Indian plate (D = 4.0 x 10²³ Nm) is a factor of 10 smaller than the current values interpreted for the central and eastern Himalaya. Because of the small elastic thickness interpreted for the Indian plate in Pakistan (He [approximately] 30 km), the Bouguer gravity gradient is steeper than in the Himalaya of India. Moreover the maximum flexural stresses are concentrated within the crust which may account for the seismic activity of the Sargodha ridge and southern Kohistan. At the end of the Indian elastic plate (arbitrarily chosen at the MMT), a large positive vertical shear stress, S₀ = 9.2 x 10¹² N/m, is applied to account for the topographic load north of the MMT. In addition, to fit the gravity constraints it was necessary to apply a strong negative bending moment, M₀ = -0.85 x 10¹⁸ N, at the end of the plate. The negative bending moment is due to the combined effect of the northward migration of the Indian plate and the southward differential compressional force generated by the crustal rocks stacked beneath the northern Kohistan arc. Consequently, in southern Kohistan the surface of the Indian plate is concave. The upper portion of the elastic plate is therefore under compressional regime, while the lower portion is subject to extentional stress. High flexural stresses are probably the primary source of the Hazara seismic zone where incipient reverse faulting seems to take place. In contrast, the pronounced convexity developed along the flexural bulge can account for 1) tensional stress in the upper part of the Indian plate, large enough to produce basement normal faults interpreted beneath the Salt range and Sargodha ridge; and 2) compressional stress in the lower portion of the crust that cause the excess of mass and seismicity beneath the Sargodha Ridge. Title: Subsurface densities & lithospheric flexure of the Himalayan foreland in Pakistan, interpreted from gravity data Author: Duroy, Yannick Gravity data along a N-S profile from Kohistan to the Punjab plain of Pakistan have been incorporated into recent interpretation of the gross structure of the foreland fold and thrust belt of the Himalaya. In northern Pakistan large deviations from Airy Isostatic equilibrium are observed. An excess of mass characterizes the northern Kohistan arc and a deficit of mass underlies a broad area extending from southern Kohistan to the Salt Range, while to the south a slight excess of mass seems to prevail in the region of the Sargodha ridge. This anomalous distribution of mass can be understood if the Indian elastic plate, which is assumed to overlie an inviscid fluid, is flexed down under the weight of both the overthrust mountains and the sediments eroded off the mountain and deposited in the foredeep basin. In many respects the intracontinental subduction of India beneath the Himalaya is similar to island arc formation, including the seismically active Sargodha ridge, an outer topographic rise analogous to the flexural bulge encountered seaward of oceanic trenches. Analysis of Bouguer gravity anomalies along a profile extending from the Sargodha ridge to the main mantle thrust (MMT) show that most of the negative-southward gravity gradient can be attributed to crustal thickening, while short wavelength anomalies are produced by lateral variation of density within the northward thickening sedimentary wedge. In the Sargodha ridge area, an additional contribution of about 25 mgals appears to be due to excess of mass at lower crustal or upper mantle levels. The Moho discontinuity is interpreted to bulge up beneath the Sargodha high, then gradually increase in dip from 1° to 3° beneath the Salt Range and Potwar Plateau (approximately equal to the change in dip of the basement surface). The Moho slope changes from upwardly convex to upwardly concave beneath southern Kohistan. Finally, north of the Main Mantle Thrust (MMT) it bends down again, but at a steeper angle of about 15°. Shorter wavelength anomalies superimposed on the regional gradient are modeled in terms of upper crustal density changes, including those due to: 1) offsets of the basement surface, 2) variable thickness of the Eocambrian evaporite sequence that forms the basal decollement, 3) thrusting and folding of relatively high density, older parts of the stratigraphic section to higher structural levels, particularly in the Salt range and northern Potwar plateau, and 4) thickening of the low density Neogene molasse sequence into the axis of the Soan Syncline, a structural depression between the Salt range and northern Potwar plateau. Subsurface densities of the overthrust wedge, as well as the definition of the shape of the top surface of the Indian plate interpreted from gravity, place bounds on the flexural rigidity of such a plate and the forces that deform it. In northern Pakistan the flexural rigidity of the elastic Indian plate (D = 4.0 x 10²³ Nm) is a factor of 10 smaller than the current values interpreted for the central and eastern Himalaya. Because of the small elastic thickness interpreted for the Indian plate in Pakistan (He [approximately] 30 km), the Bouguer gravity gradient is steeper than in the Himalaya of India. Moreover the maximum flexural stresses are concentrated within the crust which may account for the seismic activity of the Sargodha ridge and southern Kohistan. At the end of the Indian elastic plate (arbitrarily chosen at the MMT), a large positive vertical shear stress, S₀ = 9.2 x 10¹² N/m, is applied to account for the topographic load north of the MMT. In addition, to fit the gravity constraints it was necessary to apply a strong negative bending moment, M₀ = -0.85 x 10¹⁸ N, at the end of the plate. The negative bending moment is due to the combined effect of the northward migration of the Indian plate and the southward differential compressional force generated by the crustal rocks stacked beneath the northern Kohistan arc. Consequently, in southern Kohistan the surface of the Indian plate is concave. The upper portion of the elastic plate is therefore under compressional regime, while the lower portion is subject to extentional stress. High flexural stresses are probably the primary source of the Hazara seismic zone where incipient reverse faulting seems to take place. In contrast, the pronounced convexity developed along the flexural bulge can account for 1) tensional stress in the upper part of the Indian plate, large enough to produce basement normal faults interpreted beneath the Salt range and Sargodha ridge; and 2) compressional stress in the lower portion of the crust that cause the excess of mass and seismicity beneath the Sargodha Ridge. Close

• 764. [Article] Distribution of Ceratomyxa shasta (Myxozoa) and habitat preference of the polychaete host, Manayunkia speciosa in the Klamath River

  Ceratomyxa shasta is a myxozoan parasite of salmonids and requires the freshwater polychaete, Manayunkia speciosa to complete its life cycle. The parasite’s distribution is currently limited to the Pacific ...

  Citation × Citation Citation Abstract Copy Title: Distribution of Ceratomyxa shasta (Myxozoa) and habitat preference of the polychaete host, Manayunkia speciosa in the Klamath River Author: Stocking, Richard W. Ceratomyxa shasta is a myxozoan parasite of salmonids and requires the freshwater polychaete, Manayunkia speciosa to complete its life cycle. The parasite’s distribution is currently limited to the Pacific Northwest region of North America and has been reported to cause substantial losses of both wild and hatchery salmonids. The spatial and seasonal distribution of C. shasta can vary considerably both within and between river systems. This variation was thought to be a result of specific habitat requirements limiting polychaete distribution and abundance. Field studies were conducted in the Klamath River basin where C. shasta is suspected to have caused high losses in migrating juvenile salmonids. The purpose of this study was to document the host-parasite distribution of C. shasta in the river, assess its ability to cause disease, and study aspects of the polychaetes habitat ecology. This is the first study to report the broad-scale distribution of M. speciosa in a river and the various characteristics of those populations. The seasonal distribution of C. shasta in the Klamath River was investigated by exposing separate groups of C. shasta-susceptible rainbow trout (Oncorhynchus mykiss) at monthly intervals during the study. The spatial distribution was assessed by one basin-wide exposure. The ability of C. shasta to cause disease in native Klamath River salmonids was investigated by exposing fall Chinook salmon (Oncorhynchus tshawytscha; Iron Gate Hatchery strain), along with the known susceptible strains of rainbow trout. The distribution and habitat preferences of M. speciosa were investigated by collecting benthic habitat samples from a variety of habitat types. Where populations were identified, sampling was conducted at a finer scale to study aspects of those populations such as size, density, and age-structure. The distribution and prevalence of C. shasta infection in populations of M. speciosa were determined by using a pooled prevalence strategy on several polychaete populations throughout the Klamath River. Ceratomyxa shasta, with few exceptions, was only detected in exposure groups from the main-stem Klamath. The parasite could be detected from April until November when water temperatures reached 6˚C. It is likely the parasite could be detected beyond the temporal limits of this study. Prevalence of infection was high with little mortality in rainbow trout exposures groups above Iron Gate dam (Upper Klamath River). Mortality was 100% for rainbow trout exposure groups below Iron Gate Dam (Lower Klamath River). Fall Chinook salmon demonstrated a high level of resistance to the parasite above Iron Gate Dam compared to the rainbow trout, but suffered nearly 50% mortality below the dam. This suggests that resistance of native stocks to the parasite can be overwhelmed in the Lower Klamath River and provides further evidence that infectious dose is high relative to the Upper Klamath River. The polychaete host, M. speciosa, was found to occur throughout the Klamath River and was often located in slow flowing depositional habitats such as pools and reservoirs. River populations were highly aggregated into small areas whereas reservoir populations were large, widespread and centered at the inflow area. Sand-organic matter substrates and mat-forming epilithic algae were primary microhabitats. Flow velocity, habitat stability and life traits such as dispersal ability appear to be primary factors limiting distribution and abundance of the polychaete. Populations of M. speciosa tested for the prevalence of C. shasta infection demonstrate a low mean prevalence of 0.27% with areas of elevated infection (4.8 and 8.3%) located just downstream of Iron Gate Dam. This suggests that this area may be the primary source of infectious actinospores contributing to the high juvenile salmonid mortality observed in the Lower Klamath River. Title: Distribution of Ceratomyxa shasta (Myxozoa) and habitat preference of the polychaete host, Manayunkia speciosa in the Klamath River Author: Stocking, Richard W. Ceratomyxa shasta is a myxozoan parasite of salmonids and requires the freshwater polychaete, Manayunkia speciosa to complete its life cycle. The parasite’s distribution is currently limited to the Pacific Northwest region of North America and has been reported to cause substantial losses of both wild and hatchery salmonids. The spatial and seasonal distribution of C. shasta can vary considerably both within and between river systems. This variation was thought to be a result of specific habitat requirements limiting polychaete distribution and abundance. Field studies were conducted in the Klamath River basin where C. shasta is suspected to have caused high losses in migrating juvenile salmonids. The purpose of this study was to document the host-parasite distribution of C. shasta in the river, assess its ability to cause disease, and study aspects of the polychaetes habitat ecology. This is the first study to report the broad-scale distribution of M. speciosa in a river and the various characteristics of those populations. The seasonal distribution of C. shasta in the Klamath River was investigated by exposing separate groups of C. shasta-susceptible rainbow trout (Oncorhynchus mykiss) at monthly intervals during the study. The spatial distribution was assessed by one basin-wide exposure. The ability of C. shasta to cause disease in native Klamath River salmonids was investigated by exposing fall Chinook salmon (Oncorhynchus tshawytscha; Iron Gate Hatchery strain), along with the known susceptible strains of rainbow trout. The distribution and habitat preferences of M. speciosa were investigated by collecting benthic habitat samples from a variety of habitat types. Where populations were identified, sampling was conducted at a finer scale to study aspects of those populations such as size, density, and age-structure. The distribution and prevalence of C. shasta infection in populations of M. speciosa were determined by using a pooled prevalence strategy on several polychaete populations throughout the Klamath River. Ceratomyxa shasta, with few exceptions, was only detected in exposure groups from the main-stem Klamath. The parasite could be detected from April until November when water temperatures reached 6˚C. It is likely the parasite could be detected beyond the temporal limits of this study. Prevalence of infection was high with little mortality in rainbow trout exposures groups above Iron Gate dam (Upper Klamath River). Mortality was 100% for rainbow trout exposure groups below Iron Gate Dam (Lower Klamath River). Fall Chinook salmon demonstrated a high level of resistance to the parasite above Iron Gate Dam compared to the rainbow trout, but suffered nearly 50% mortality below the dam. This suggests that resistance of native stocks to the parasite can be overwhelmed in the Lower Klamath River and provides further evidence that infectious dose is high relative to the Upper Klamath River. The polychaete host, M. speciosa, was found to occur throughout the Klamath River and was often located in slow flowing depositional habitats such as pools and reservoirs. River populations were highly aggregated into small areas whereas reservoir populations were large, widespread and centered at the inflow area. Sand-organic matter substrates and mat-forming epilithic algae were primary microhabitats. Flow velocity, habitat stability and life traits such as dispersal ability appear to be primary factors limiting distribution and abundance of the polychaete. Populations of M. speciosa tested for the prevalence of C. shasta infection demonstrate a low mean prevalence of 0.27% with areas of elevated infection (4.8 and 8.3%) located just downstream of Iron Gate Dam. This suggests that this area may be the primary source of infectious actinospores contributing to the high juvenile salmonid mortality observed in the Lower Klamath River. Close

• 765. [Article] The measurement of nearshore bathymetry on intermediate and dissipative beaches

  In 1996, Beach et al. first proposed the idea of mounting an echo-sounder on a Waverunner to measure nearshore beach profiles. This thesis discusses the Coastal Profiling System, an extension of the original ...

  Citation × Citation Citation Abstract Copy Title: The measurement of nearshore bathymetry on intermediate and dissipative beaches Author: Côté, Jessica Magee In 1996, Beach et al. first proposed the idea of mounting an echo-sounder on a Waverunner to measure nearshore beach profiles. This thesis discusses the Coastal Profiling System, an extension of the original work, which has been utilized to measure nearshore bathymetry at selected sites along the coasts of North Carolina, Oregon, and Washington. Position of the Coastal Profiling System is accurately measured five times per second using a differential global positioning system (DGPS), while depth below the hull is measured by an acoustic echo-sounder. Surveys can be conducted in waves up to 3 m and in depths of 1-15 m. The effects of waves, tides, and set-up are eliminated by the co-collection of position and depth data. In October 1997, extensive testing of the system took place at the SandyDuck '97 field experiment in Duck, NC. Nearshore bathymetric surveys were taken simultaneously by the Coastal Research Amphibious Buggy (CRAB) and the Coastal Profiling System (CPS). Comparison of the CPS with CRAB measurements interpolated to the same locations showed a mean bias of 4.6 cm too shallow in the vertical and standard deviations about the bias of 5.5 cm. The largest differences occur over the steeply sloping flanks of sand bars. The bias statistic, of central interest to these tests, is confused by the potential of boat tilt and by possible errors in the CRAB data itself. In July & August 1998, the system was tested as a tool for long-term coastal monitoring by the Southwest Washington Coastal Erosion Study in a regional morphology monitoring program (Ruggiero et al., 1997). A 2-3 km section in approximately the center of each of the four sub-cells of the Columbia River littoral cell, and an anomalous fifth site, was surveyed to map the morphology of each region. Alongshore-averaged profiles were decomposed into underlying AX[superscript m] profiles and deviations from this equilibrium profile. The mean of the exponents was close to 2/3 with m=0.70, but ranged between sites from 0.56 to 0.79. Shape parameters between 0.027 and 0.038 were estimated. Nearshore slopes (0-1 km cross-shore) were calculated from the exponential profile in the dissipative range with a minimum of 0.0067 and a maximum of 0.0089. However, no correlation was seen between the shape parameters and the 1 km nearshore slopes. An analysis of the deviations of the alongshore-averaged profiles from the equilibrium profile provided an objective method to determine sand bar positions from zero-down-crossings. Each site was characterized by a minimum of two sand bars in 2-6.5 m (NAVD 88) depths with heights of 0.2-2 m, lengths of 164-949 m and volumes of 48-534 m³/m. An additional bar in the swash zone between the +1 m elevation and 1 m depth contour was resolved in some cross-shore profiles. The crest of the bar largest in height was located at 3-4.5 NAVD 88 m at four of the five sites suggesting the profiles vary on similar cross-shore length scales amongst the sub-cells. A series of surveys in April, June, and October 1998 at the northern most site in Ocean City, WA demonstrated onshore bar migration and seaward accretion of the foreshore. This seasonal response was further quantified between August and October at Fort Canby. Three nearshore profiles surveyed by Willard Bascom et al. (1954) in the 1940s were reoccupied to compare the shape of the morphology 50 years ago to present. These profiles demonstrate accretion of approximately 2 m elevation gains in the nearshore and 26-165 m of shoreline change. Although the Coastal Profiling System is a highly accurate, mobile and efficient method to obtain nearshore profiles, several improvements have been suggested. Future modifications to the system should include an increase in the precision of the echo-sounder measurements, higher sampling rates, and improvement of the user interface. Additional components may include an onboard navigation system, a thermister to measure temperature and salinity, and a motion sensor to measure roll and pitch of the vehicle. Title: The measurement of nearshore bathymetry on intermediate and dissipative beaches Author: Côté, Jessica Magee In 1996, Beach et al. first proposed the idea of mounting an echo-sounder on a Waverunner to measure nearshore beach profiles. This thesis discusses the Coastal Profiling System, an extension of the original work, which has been utilized to measure nearshore bathymetry at selected sites along the coasts of North Carolina, Oregon, and Washington. Position of the Coastal Profiling System is accurately measured five times per second using a differential global positioning system (DGPS), while depth below the hull is measured by an acoustic echo-sounder. Surveys can be conducted in waves up to 3 m and in depths of 1-15 m. The effects of waves, tides, and set-up are eliminated by the co-collection of position and depth data. In October 1997, extensive testing of the system took place at the SandyDuck '97 field experiment in Duck, NC. Nearshore bathymetric surveys were taken simultaneously by the Coastal Research Amphibious Buggy (CRAB) and the Coastal Profiling System (CPS). Comparison of the CPS with CRAB measurements interpolated to the same locations showed a mean bias of 4.6 cm too shallow in the vertical and standard deviations about the bias of 5.5 cm. The largest differences occur over the steeply sloping flanks of sand bars. The bias statistic, of central interest to these tests, is confused by the potential of boat tilt and by possible errors in the CRAB data itself. In July & August 1998, the system was tested as a tool for long-term coastal monitoring by the Southwest Washington Coastal Erosion Study in a regional morphology monitoring program (Ruggiero et al., 1997). A 2-3 km section in approximately the center of each of the four sub-cells of the Columbia River littoral cell, and an anomalous fifth site, was surveyed to map the morphology of each region. Alongshore-averaged profiles were decomposed into underlying AX[superscript m] profiles and deviations from this equilibrium profile. The mean of the exponents was close to 2/3 with m=0.70, but ranged between sites from 0.56 to 0.79. Shape parameters between 0.027 and 0.038 were estimated. Nearshore slopes (0-1 km cross-shore) were calculated from the exponential profile in the dissipative range with a minimum of 0.0067 and a maximum of 0.0089. However, no correlation was seen between the shape parameters and the 1 km nearshore slopes. An analysis of the deviations of the alongshore-averaged profiles from the equilibrium profile provided an objective method to determine sand bar positions from zero-down-crossings. Each site was characterized by a minimum of two sand bars in 2-6.5 m (NAVD 88) depths with heights of 0.2-2 m, lengths of 164-949 m and volumes of 48-534 m³/m. An additional bar in the swash zone between the +1 m elevation and 1 m depth contour was resolved in some cross-shore profiles. The crest of the bar largest in height was located at 3-4.5 NAVD 88 m at four of the five sites suggesting the profiles vary on similar cross-shore length scales amongst the sub-cells. A series of surveys in April, June, and October 1998 at the northern most site in Ocean City, WA demonstrated onshore bar migration and seaward accretion of the foreshore. This seasonal response was further quantified between August and October at Fort Canby. Three nearshore profiles surveyed by Willard Bascom et al. (1954) in the 1940s were reoccupied to compare the shape of the morphology 50 years ago to present. These profiles demonstrate accretion of approximately 2 m elevation gains in the nearshore and 26-165 m of shoreline change. Although the Coastal Profiling System is a highly accurate, mobile and efficient method to obtain nearshore profiles, several improvements have been suggested. Future modifications to the system should include an increase in the precision of the echo-sounder measurements, higher sampling rates, and improvement of the user interface. Additional components may include an onboard navigation system, a thermister to measure temperature and salinity, and a motion sensor to measure roll and pitch of the vehicle. Close

• 766. [Article] Sediment transport on the northern Oregon continental shelf

  The distribution of surface sediments on the northern Oregon continental shell is characterized by a nearshore sandy facies and an outer shelf muddy facies, separated by a mid-shelf zone of mixed sand ...

  Citation × Citation Citation Abstract Copy Title: Sediment transport on the northern Oregon continental shelf Author: Harlett, John Charles The distribution of surface sediments on the northern Oregon continental shell is characterized by a nearshore sandy facies and an outer shelf muddy facies, separated by a mid-shelf zone of mixed sand and mud. Currents which have been measured at 130 centimeters above the bottom indicate that the distribution of the surface sediment is a reflection of the hydraulic regime. The strongest bottom currents which were measured were in the nearshore region at a depth of 36 meters. Here currents of over 40 cm/sec generated by surface waves are capable of placing the nearshore sands in suspension, where they are transported shoreward by the wave surge. At mid-shelf, in 90 meters of water, the bottom current veolcity ranges from zero to over 25 cm/sec, although the mean is normally about 10 cm/sec. The strongest currents at this depth are capable of eroding some of the fine sediments, but probably do not rework the older sediments which have been compacted. Currents which are similar in character to those at mid-shelf were observed at the shelf edge in a depth of 165 meters. A significant departure, however, is the difference in frequency where the most energy is found. At the shelf edge the dominant frequency was about four cpd whereas the dominant frequency at mid-shelf was two cpd or lower. The dominant frequencies indicate that tides are important in the generation of continental shelf bottom currents. The twelve - hour period is that of the semi-diurnal tide; the six-hour period is the second harmonic of the semi-diurnal component. No indication of surface wave influence was found at mid-shelf or shelf-edge depths. Profiles of turbidity made at four east-west transects of the continental shelf indicate suspended sediment transport occurs principally at three levels in the water column. An upper layer is at the level of the seasonal thermocline, a mid-water layer is located at the level of the permanent pycnocline, and the third layer is at the bottom. The surface layer is important in transporting suspended sediment of the Columbia River plume, although there is also a contribution to the surface layer from the surf zone by the process of diffusion of fine particles. The mid-water layer thickens vertically and becomes less intense seaward, indicating a nearshore source for the suspended material. This source is diffusion of fine particles from the surf zone at mid-water depths. The mid-water layer is located at the level of the permanent pycnocline. The layer is sub-parallel to the bottom over the shelf but becomes diffuse at the shelf edge. Sediment transport in the mid-water layer provides a mechanism by which sediment bypasses the outer shelf and upper slope area. The bottom layer receives its suspended material from erosion of the bottom, from the water column above, and from fine material moving seaward from the surf zone. The amount of eroded material contributed to the bottom layer depends on the bottom current strength and on the bottom roughness characteristics. Over a rough bottom the erosive power of a given bottom current is increased drastically. For this reason, the presence or absence of rippling is important to sediment transport on the shelf. The fine material of the bottom layer may concentrate by settling during quiescent periods, allowing low-density flows to initiate. Several time-series observations of turbidity indicate that the bottom layer thickens and thins in response to increases and decreases in current velocity. The mid-water layer migrated somewhat in a vertical direction, but its thickness and intensity remained nearly the same. The thickness and intensity of the upper layer responded to changes in the structure of the thermocline, becoming thick and dispersed when the upper part of the water column is mixed. A model of sediment transport proposes that mid-water and bottom currents transport suspended sediments diagonally across the shelf toward the south-southwest. The sediments of the Columbia River plume are also transported in a southerly direction in the surface waters. Relatively little deposition takes place on the shelf and upper slope, with the bulk of the sediments bypassing the shelf and depositing on the lower slope and continental rise. Title: Sediment transport on the northern Oregon continental shelf Author: Harlett, John Charles The distribution of surface sediments on the northern Oregon continental shell is characterized by a nearshore sandy facies and an outer shelf muddy facies, separated by a mid-shelf zone of mixed sand and mud. Currents which have been measured at 130 centimeters above the bottom indicate that the distribution of the surface sediment is a reflection of the hydraulic regime. The strongest bottom currents which were measured were in the nearshore region at a depth of 36 meters. Here currents of over 40 cm/sec generated by surface waves are capable of placing the nearshore sands in suspension, where they are transported shoreward by the wave surge. At mid-shelf, in 90 meters of water, the bottom current veolcity ranges from zero to over 25 cm/sec, although the mean is normally about 10 cm/sec. The strongest currents at this depth are capable of eroding some of the fine sediments, but probably do not rework the older sediments which have been compacted. Currents which are similar in character to those at mid-shelf were observed at the shelf edge in a depth of 165 meters. A significant departure, however, is the difference in frequency where the most energy is found. At the shelf edge the dominant frequency was about four cpd whereas the dominant frequency at mid-shelf was two cpd or lower. The dominant frequencies indicate that tides are important in the generation of continental shelf bottom currents. The twelve - hour period is that of the semi-diurnal tide; the six-hour period is the second harmonic of the semi-diurnal component. No indication of surface wave influence was found at mid-shelf or shelf-edge depths. Profiles of turbidity made at four east-west transects of the continental shelf indicate suspended sediment transport occurs principally at three levels in the water column. An upper layer is at the level of the seasonal thermocline, a mid-water layer is located at the level of the permanent pycnocline, and the third layer is at the bottom. The surface layer is important in transporting suspended sediment of the Columbia River plume, although there is also a contribution to the surface layer from the surf zone by the process of diffusion of fine particles. The mid-water layer thickens vertically and becomes less intense seaward, indicating a nearshore source for the suspended material. This source is diffusion of fine particles from the surf zone at mid-water depths. The mid-water layer is located at the level of the permanent pycnocline. The layer is sub-parallel to the bottom over the shelf but becomes diffuse at the shelf edge. Sediment transport in the mid-water layer provides a mechanism by which sediment bypasses the outer shelf and upper slope area. The bottom layer receives its suspended material from erosion of the bottom, from the water column above, and from fine material moving seaward from the surf zone. The amount of eroded material contributed to the bottom layer depends on the bottom current strength and on the bottom roughness characteristics. Over a rough bottom the erosive power of a given bottom current is increased drastically. For this reason, the presence or absence of rippling is important to sediment transport on the shelf. The fine material of the bottom layer may concentrate by settling during quiescent periods, allowing low-density flows to initiate. Several time-series observations of turbidity indicate that the bottom layer thickens and thins in response to increases and decreases in current velocity. The mid-water layer migrated somewhat in a vertical direction, but its thickness and intensity remained nearly the same. The thickness and intensity of the upper layer responded to changes in the structure of the thermocline, becoming thick and dispersed when the upper part of the water column is mixed. A model of sediment transport proposes that mid-water and bottom currents transport suspended sediments diagonally across the shelf toward the south-southwest. The sediments of the Columbia River plume are also transported in a southerly direction in the surface waters. Relatively little deposition takes place on the shelf and upper slope, with the bulk of the sediments bypassing the shelf and depositing on the lower slope and continental rise. Close

• 767. [Article] The association of DNA with other cellular materials in Escherichia coli lysates

  The association of other materials with DNA has been studied extensively in higher organisms and more recently in bacteria. However, investigation of these complexes in bacteria have for the most part ...

  Citation × Citation Citation Abstract Copy Title: The association of DNA with other cellular materials in Escherichia coli lysates Author: Porter, Bruce Wallace The association of other materials with DNA has been studied extensively in higher organisms and more recently in bacteria. However, investigation of these complexes in bacteria have for the most part been restricted to the study of a specific function this association may serve, or a specific kind of association. The degree of protein, RNA and membrane association of DNA within a given species has not been compared at one time under the same experimental conditions. These studies were undertaken in order to compare DNA associated with protein, RNA and cell membrane fractions in a single bacterial system. Escherichia coli strain CR34 (requiring thymine, leucine, threonine, and B₁) or strain TAU bar (requiring thymine, arginine, uracil, methionine, proline and tryptophan) were grown 5-5.5 hours in media containing ³H thymidine, ¹⁴C uracil, ³H tryptophan or ¹⁴C arginine, harvested, washed three times with buffer and lysed with 1 percent sodium lauryl sulfate (SLS) or sarkosyl. Untreated, sonicated, RNAse and pronase treated lysates were then subjected to starch block electrophoresis or CsC1 density gradient analysis. After electrophoresis of a ³H thymidine labeled SLS lysate, about 30 percent of the DNA was found at the origin. This association with materials of low electrophoretic mobility was not found when phenol-extracted, ³H labeled DNA was added to cells prior to lysis and electrophoresis. In electrophoresis of sonicated lysates virtually none of the DNA was found at the origin, while over 80 percent of the DNA appeared 20 or more cm from the origin, showing a distribution very similar to that of unsonicated, phenol-extracted DNA. These results indicated that DNA association with materials of low electrophoretic mobility occurs in the cell prior to lysis and that sonication will remove DNA from this complex. Treatment of unsonicated SLS lysates with pronase prior to electrophoresis decreased by about one fifth the amount of DNA retained at the origin. Similar treatment with RNAse reduced the amount of DNA remaining at the origin by about one half. Electrophoretic profiles for ³H tryptophan and ¹⁴C arginine labeled lysates were similar, with most of the radioactivity at or near the origin. Sonication did not release radioactivity to faster migrating fractions. Electrophoresis of cell lysates labeled with ¹⁴C uracil showed that only 4 percent of the ¹⁴C label was found at the origin. From these findings it seemed that about 30 percent of the DNA was bound to materials of low electrophoretic mobility, in conjunction with protein and a minor amount of the cells' RNA. Enzymatic destruction of protein or RNA affected the amount of DNA bound to this complex and thus either may function as a linker of DNA to substances of low electrophoretic mobility, possibly the cell membrane. CsC1 density gradient analysis of ³H thymidine-labeled lysates showed that most of the DNA was associated with a mucous film of light density floating on top of the gradient. From this appearance and the reports of others, this pellet was identified as the cell membrane fraction. If the lysate was sonicated before centrifugation, most of the DNA was not found in the floating pellet, but was distributed in a broad band throughout the center of the gradient. Pooling and recentrifugation of widely separated portions of this broad density band resulted in a single peak, indicating all portions to be of similar density. Treatment of a ³H thymidine- labeled SLS lysate with pronase before centrifugation reduced the amount of label in the floating pellet by 10 percent. Similar treatment with RNAse reduced the total radioactivity in the floating pellet by 4 percent. After centrifugation of a ³H tryptophan or ¹⁴C arginine-labeled lysate, virtually all of the radioactivity was found in the top few fractions and sonication of a lysate before centrifugation did not change this. After centrifugation of a ¹⁴C uracil-labeled lysate, ¹⁴C label was found in all portions of the tube, with about 50 percent of the label in the floating pellet. Sonication of a lysate prior to centrifugation reduced by 10 percent the ¹⁴C in the floating pellet. Paper chromatography of hydrolysed top, intermediate and bottom fractions from a density gradient of a sonicated, ¹⁴C uracil labeled lysate revealed the ¹⁴C label to be mostly in RNA in the top and bottom fractions, and to be largely in DNA, by the conversion of ¹⁴C uracil to ¹⁴C cytosine, in the intermediate fractions. A small amount of ¹⁴C uracil was found in fractions of intermediate density, probably indicating RNA-DNA hybrids. Similar studies showed the floating pellet to contain a greater percent of RNA which may be released by sonication to the positions of intermediate density than does the lysate as a whole. Thus the membrane fraction may be a preferential location of RNA-DNA hybrids. Title: The association of DNA with other cellular materials in Escherichia coli lysates Author: Porter, Bruce Wallace The association of other materials with DNA has been studied extensively in higher organisms and more recently in bacteria. However, investigation of these complexes in bacteria have for the most part been restricted to the study of a specific function this association may serve, or a specific kind of association. The degree of protein, RNA and membrane association of DNA within a given species has not been compared at one time under the same experimental conditions. These studies were undertaken in order to compare DNA associated with protein, RNA and cell membrane fractions in a single bacterial system. Escherichia coli strain CR34 (requiring thymine, leucine, threonine, and B₁) or strain TAU bar (requiring thymine, arginine, uracil, methionine, proline and tryptophan) were grown 5-5.5 hours in media containing ³H thymidine, ¹⁴C uracil, ³H tryptophan or ¹⁴C arginine, harvested, washed three times with buffer and lysed with 1 percent sodium lauryl sulfate (SLS) or sarkosyl. Untreated, sonicated, RNAse and pronase treated lysates were then subjected to starch block electrophoresis or CsC1 density gradient analysis. After electrophoresis of a ³H thymidine labeled SLS lysate, about 30 percent of the DNA was found at the origin. This association with materials of low electrophoretic mobility was not found when phenol-extracted, ³H labeled DNA was added to cells prior to lysis and electrophoresis. In electrophoresis of sonicated lysates virtually none of the DNA was found at the origin, while over 80 percent of the DNA appeared 20 or more cm from the origin, showing a distribution very similar to that of unsonicated, phenol-extracted DNA. These results indicated that DNA association with materials of low electrophoretic mobility occurs in the cell prior to lysis and that sonication will remove DNA from this complex. Treatment of unsonicated SLS lysates with pronase prior to electrophoresis decreased by about one fifth the amount of DNA retained at the origin. Similar treatment with RNAse reduced the amount of DNA remaining at the origin by about one half. Electrophoretic profiles for ³H tryptophan and ¹⁴C arginine labeled lysates were similar, with most of the radioactivity at or near the origin. Sonication did not release radioactivity to faster migrating fractions. Electrophoresis of cell lysates labeled with ¹⁴C uracil showed that only 4 percent of the ¹⁴C label was found at the origin. From these findings it seemed that about 30 percent of the DNA was bound to materials of low electrophoretic mobility, in conjunction with protein and a minor amount of the cells' RNA. Enzymatic destruction of protein or RNA affected the amount of DNA bound to this complex and thus either may function as a linker of DNA to substances of low electrophoretic mobility, possibly the cell membrane. CsC1 density gradient analysis of ³H thymidine-labeled lysates showed that most of the DNA was associated with a mucous film of light density floating on top of the gradient. From this appearance and the reports of others, this pellet was identified as the cell membrane fraction. If the lysate was sonicated before centrifugation, most of the DNA was not found in the floating pellet, but was distributed in a broad band throughout the center of the gradient. Pooling and recentrifugation of widely separated portions of this broad density band resulted in a single peak, indicating all portions to be of similar density. Treatment of a ³H thymidine- labeled SLS lysate with pronase before centrifugation reduced the amount of label in the floating pellet by 10 percent. Similar treatment with RNAse reduced the total radioactivity in the floating pellet by 4 percent. After centrifugation of a ³H tryptophan or ¹⁴C arginine-labeled lysate, virtually all of the radioactivity was found in the top few fractions and sonication of a lysate before centrifugation did not change this. After centrifugation of a ¹⁴C uracil-labeled lysate, ¹⁴C label was found in all portions of the tube, with about 50 percent of the label in the floating pellet. Sonication of a lysate prior to centrifugation reduced by 10 percent the ¹⁴C in the floating pellet. Paper chromatography of hydrolysed top, intermediate and bottom fractions from a density gradient of a sonicated, ¹⁴C uracil labeled lysate revealed the ¹⁴C label to be mostly in RNA in the top and bottom fractions, and to be largely in DNA, by the conversion of ¹⁴C uracil to ¹⁴C cytosine, in the intermediate fractions. A small amount of ¹⁴C uracil was found in fractions of intermediate density, probably indicating RNA-DNA hybrids. Similar studies showed the floating pellet to contain a greater percent of RNA which may be released by sonication to the positions of intermediate density than does the lysate as a whole. Thus the membrane fraction may be a preferential location of RNA-DNA hybrids. Close

• 768. [Article] River-dependent bird species as potential indicators of ecosystem response to removal of dams on the Elwha River, Washington

  If two dams on the Elwha River are removed, the ecosystem will be open to the downstream flow of sediments and the upstream flow of marine nutrients in the form of anadromous fish. Nutrient enrichment ...

  Citation × Citation Citation Abstract Copy Title: River-dependent bird species as potential indicators of ecosystem response to removal of dams on the Elwha River, Washington Author: Blackie, Barbara If two dams on the Elwha River are removed, the ecosystem will be open to the downstream flow of sediments and the upstream flow of marine nutrients in the form of anadromous fish. Nutrient enrichment may influence trophic dynamics of the entire ecosystem, extending beyond the aquatic boundary. I assessed the current relative densities of five river dependent bird species on the Elwha and three other rivers in Olympic National Park in Washington State to describe pretreatment reference conditions as a basis for assessment of post-treatment ecosystem responses. I also compared the amount of time that non-breeding and failed-breeding (NBIFB) female Harlequin Ducks (Histrionicus histrionicus) spent foraging on different rivers and on adjacent coastal habitat to determine whether time spent foraging could be used as an indicator of habitat preference. Surveys of key river-dependent bird species were conducted on two rivers in 1996 and on four rivers in 1997. The benthivorous foraging guild was represented by the American Dipper (Cinclus mexicanus), Harlequin Duck and Spotted Sandpiper (Actitis macularia). Harlequin Ducks had higher relative densities on the Elwha than the Hoh and Soleduck Rivers, but densities were similar to those found on the Duckabush River. There were greater numbers of Harlequin Ducks per linear kilometer above the two dams than between or below them. Relative densities of American Dippers on the Elwha were lower than on the Duckabush but not statistically different from those on the Hoh and Soleduck Rivers. Spotted Sandpipers had similar densities on all rivers except the Soleduck River where their numbers were lower. The piscivorous foraging guild was represented by the Common Merganser (Mergus merganser) and Belted Kingfisher (Ceryle alcyon). Common Mergansers were relatively more abundant on the Elwha River than on the other rivers due to their high numbers below the lowest dam where wild and hatchery anadromous fish are present. Belted Kingfisher relative densities showed no significant differences between rivers as they were found in low numbers on all rivers. Using relative abundances of some river dependent bird species as indicators of ecosystem recovery after dam removal may be useful tool surveys are continued throughout the process. In spite of lack of anadromy, the Elwha River ecosystem supports a significant population of Harlequin Ducks when compared to other Olympic rivers. American Dippers are also well represented on the Elwha River, specifically above the dams. Because of their relative abundance, these benthivore populations may have a measurable, upriver response to any nutrient enrichment as a result of dam removal and both species should be monitored. The Duckabush River, with a similar Harlequin Duck relative abundance in the lower reaches, should be monitored concurrently to account for region-wide population shifts of that species over time. The Common Merganser may be the best indicator of below dam effects on the Elwha River and numbers could be compared with the lower Soleduck River, however alternative survey methods, specifically drift boat surveys, should be considered to improve count accuracy. During June and July of 1997, time-activity budget data were gathered on NB/FB Harlequin Ducks on the Elwha, Duckabush and Dosewallips Rivers and at their mouths and at the mouth of Salt Creek. Time spent foraging by NBIFB Harlequin Ducks was similar among the three rivers examined. NB/FB Harlequin Ducks on the spent 33.1%, 33.2%, 36.4% of their time feeding, on the Elwha, Duckabush Dosewallips Rivers respectively. The Elwha River system was the only system where time activity budgets could be compared between river and adjacent coastal habitats. Time spent foraging at the mouth of the Elwha was significantly higher (52.5%) than on the Elwha River proper. Food availability on river habitat may be a factor in NB/FB females' decision to remain on river habitat during the breeding season or migrate to the ocean. Time-activity budgets provide information on Harlequin Duck life history but a better understanding of their foraging behavior and the role of food availability in habitat selection is needed before time-activity budgets alone can be used as a tool for assessing ecosystem response to dam removal. Time-activity budget data collected concurrently with food availability data from field studies, along with energetics and food preference data from field or laboratory studies may establish a clearer link between time spent feeding and habitat quality and preferences. Title: River-dependent bird species as potential indicators of ecosystem response to removal of dams on the Elwha River, Washington Author: Blackie, Barbara If two dams on the Elwha River are removed, the ecosystem will be open to the downstream flow of sediments and the upstream flow of marine nutrients in the form of anadromous fish. Nutrient enrichment may influence trophic dynamics of the entire ecosystem, extending beyond the aquatic boundary. I assessed the current relative densities of five river dependent bird species on the Elwha and three other rivers in Olympic National Park in Washington State to describe pretreatment reference conditions as a basis for assessment of post-treatment ecosystem responses. I also compared the amount of time that non-breeding and failed-breeding (NBIFB) female Harlequin Ducks (Histrionicus histrionicus) spent foraging on different rivers and on adjacent coastal habitat to determine whether time spent foraging could be used as an indicator of habitat preference. Surveys of key river-dependent bird species were conducted on two rivers in 1996 and on four rivers in 1997. The benthivorous foraging guild was represented by the American Dipper (Cinclus mexicanus), Harlequin Duck and Spotted Sandpiper (Actitis macularia). Harlequin Ducks had higher relative densities on the Elwha than the Hoh and Soleduck Rivers, but densities were similar to those found on the Duckabush River. There were greater numbers of Harlequin Ducks per linear kilometer above the two dams than between or below them. Relative densities of American Dippers on the Elwha were lower than on the Duckabush but not statistically different from those on the Hoh and Soleduck Rivers. Spotted Sandpipers had similar densities on all rivers except the Soleduck River where their numbers were lower. The piscivorous foraging guild was represented by the Common Merganser (Mergus merganser) and Belted Kingfisher (Ceryle alcyon). Common Mergansers were relatively more abundant on the Elwha River than on the other rivers due to their high numbers below the lowest dam where wild and hatchery anadromous fish are present. Belted Kingfisher relative densities showed no significant differences between rivers as they were found in low numbers on all rivers. Using relative abundances of some river dependent bird species as indicators of ecosystem recovery after dam removal may be useful tool surveys are continued throughout the process. In spite of lack of anadromy, the Elwha River ecosystem supports a significant population of Harlequin Ducks when compared to other Olympic rivers. American Dippers are also well represented on the Elwha River, specifically above the dams. Because of their relative abundance, these benthivore populations may have a measurable, upriver response to any nutrient enrichment as a result of dam removal and both species should be monitored. The Duckabush River, with a similar Harlequin Duck relative abundance in the lower reaches, should be monitored concurrently to account for region-wide population shifts of that species over time. The Common Merganser may be the best indicator of below dam effects on the Elwha River and numbers could be compared with the lower Soleduck River, however alternative survey methods, specifically drift boat surveys, should be considered to improve count accuracy. During June and July of 1997, time-activity budget data were gathered on NB/FB Harlequin Ducks on the Elwha, Duckabush and Dosewallips Rivers and at their mouths and at the mouth of Salt Creek. Time spent foraging by NBIFB Harlequin Ducks was similar among the three rivers examined. NB/FB Harlequin Ducks on the spent 33.1%, 33.2%, 36.4% of their time feeding, on the Elwha, Duckabush Dosewallips Rivers respectively. The Elwha River system was the only system where time activity budgets could be compared between river and adjacent coastal habitats. Time spent foraging at the mouth of the Elwha was significantly higher (52.5%) than on the Elwha River proper. Food availability on river habitat may be a factor in NB/FB females' decision to remain on river habitat during the breeding season or migrate to the ocean. Time-activity budgets provide information on Harlequin Duck life history but a better understanding of their foraging behavior and the role of food availability in habitat selection is needed before time-activity budgets alone can be used as a tool for assessing ecosystem response to dam removal. Time-activity budget data collected concurrently with food availability data from field studies, along with energetics and food preference data from field or laboratory studies may establish a clearer link between time spent feeding and habitat quality and preferences. Close

• 769. [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

• 770. [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