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Various methods have been developed to mitigate the adverse effects of the Federal Columbia River Power System on juvenile Pacific salmon out-migrating through the Columbia River basin. In this study, ...
Citation Citation
- Title:
- An Evaluation of the Influence of Stock Origin and Outmigration History on the Disease Susceptibility and Survival of Juvenile Chinook Salmon
- Author:
- Bravo, Claudia F., Boylen, Deborah A., Loboschefsky, Erik J., Thompson, Donald E., Spangenberg, Dina K., Dietrich, Joseph P., Ylitalo, Gina M., Arkoosh, Mary R., Collier, Tracy K., Loge, Frank J., Fryer, Derek S.
Various methods have been developed to mitigate the adverse effects of the Federal Columbia River Power System on juvenile Pacific salmon out-migrating through the Columbia River basin. In this study, we found that hatchery-reared spring Chinook salmon Oncorhynchus tshawytscha in the river are in varying degrees of health, which may affect delayed mortality and the assessment of the effectiveness of management actions to recover listed stocks (e. g., barging fish downstream versus leaving fish in the river). A laboratory disease challenge with Listonella anguillarum was completed on fish from Rapid River Hatchery and Dworshak National Fish Hatchery (NFH) with different out-migration histories: (1) transported by barge, (2) removed from the river before barging, or (3) left to travel in-river. Barged fish from Rapid River Hatchery experienced less mortality than fish from Dworshak NFH. No statistical differences were found between the hatcheries with fish that had in-river out-migration histories. We suggest that the stressors and low survival associated with out-migration through the hydropower system eliminated any differences that could have been present. However, 18-25% of the fish that were barged or collected before barging died in the laboratory before the disease challenge, compared with less than 2% of those that traveled in-river. Owing to disproportionate prechallenge mortality, the disease-challenged populations may have been biased; thus, they were also considered together with the prechallenge mortalities. The synthesis of prechallenge and disease-challenged mortalities and health characteristics evaluated during out-migration indicated that the benefit of barging was not consistent between the hatcheries. This finding agrees with adult survival and delayed mortality estimates for the individual hatcheries determined fromadult returns. The results suggest that the health status of fish and their history before entering the hydropower system (hatchery of origin and out-migration path) are critical variables affecting the conclusions drawn from studies that evaluate mitigation strategies.
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The early life history stages and metamorphosis in Dover sole (Microstomus pacificus) are described from 201 larvae and juveniles. Unlike other pleuronectids, with the possible exception of the deep-sea ...
Citation Citation
- Title:
- Ontogeny and metamorphosis in the Dover sole (Microstomus pacificus) : a description of the early life history stages, with comments on the sister-group relationship between Microstomus and Embassichthys
- Author:
- Harris, Phillip M.
The early life history stages and metamorphosis in Dover sole (Microstomus pacificus) are described from 201 larvae and juveniles. Unlike other pleuronectids, with the possible exception of the deep-sea sole (Embassichthvs bathvbius), initial migration of the left eye is not associated with metamorphosis or transition from plankton to benthos. The left eye exhibits a stasis during its migration, so that premetamorphic larvae are optically asymmetrical while planktonic. Seven characters are used to quantify the progress of metamorphosis: completed eye migration, dorsal fin position, dentition, pectoral fin development, condition of posterior process of coracoid, pigmentation, and elongation of the intestine into a secondary body cavity. Other characters associated with metamorphosis are reduction in body depth associated with reductions in lengths of neural and hemal spines and associated dorsal- and anal- fin pterygiophores, decreasing interorbital distance, increasing right eye diameter and right premaxilla length, and development of body scales. Metamorphosis appears to require 9- 11 or 12 months to complete. The planktonic period of premetamorphic and metamorphic larvae is about 18-24 months. Metamorphic larvae appear to move inshore into shallower water as metamorphosis progresses. Settlement occurs from about December to April, primarily from January to March. One of the earliest phylogenetic hypotheses about the intergeneric relationships of the pleuronectid genera Microstomus, Embassichthys, Glyotocephalus, and Tanakius was by Norman (1934), who considered Microstomus plus Embassichthvs and Glyotocephalus plus Tanakius to be sister groups. An alternative hypothesis by Richardson (1981) suggested that Embassichthvs larvae resembled larvae of Glyptoceohalus and Tanakius based on a "leptocephaluslike" body shape, and that Microstomus was the primitive sister group of these three genera because of its dorsoventrally deepened body shape. In order to evaluate Richardson's hypothesis of sister group relationships based on body shape, I examined morphological characters associated with eye migration and metamorphosis, and changes in body shape during ontogeny from post-flexion larvae through benthic juveniles. Richardson's-character of a moderate "leptocephalus-like" body shape is an artifact of the paucity and small size range of larvae available for her examination. The body shape of larger Embassichthvs larvae is also dorsoventrally deepened and the larvae appear to undergo changes in body shape during metamorphosis similar to Microstomus. Three synapomorphies that support Norman's hypothesis of an Embassichthys plus Microstomus sister group relationship are dissociation of initial eye migration with metamorphosis, a stasis during eye migration in premetamorphic larvae, and a retention of a larval-like appearance to the eyes of newly settled specimens.
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It is critical for wildlife managers to understand the population dynamics of a harvested species, particularly for ungulates, which are a valuable wildlife resource. Due to concerns that mule deer (Odocoileus ...
Citation Citation
- Title:
- Survival Rates and Cause-Specific Mortality of Mule Deer in South-Central Oregon
- Author:
- Mulligan, Elizabeth M.
It is critical for wildlife managers to understand the population dynamics of a harvested species, particularly for ungulates, which are a valuable wildlife resource. Due to concerns that mule deer (Odocoileus hemionus) populations in Oregon were declining, more comprehensive data on population vital rates and the factors potentially affecting them were needed by resource managers. To meet this research need, Oregon Department of Fish and Wildlife implemented a seven year study to investigate habitat use and survival of mule deer in eastern Oregon. From 2005-2012, the agency radiocollared 621 mule deer in south-central Oregon in order to gain more comprehensive information about seasonal movement, seasonal and annual survival, and changes in habitat use for the population. I used the radio-telemetry data from this larger study to investigate mule deer survival rates and cause-specific mortality and the effects of deer seasonal distributions, movement behavior, and environmental factors such as annual and climatic variation. I used known-fate data for 408 adult female radio-collared mule deer to estimate monthly survival rates and to investigate a variety of factors that might affect these rates including seasonal distribution, temporal effects (seasonal, annual, and trends across season and year), movement behavior, and climatic covariates on differing scales. Variation in survival rates for this population of female mule deer in eastern Oregon was best explained by an additive effect of migration behavior, fall migration period, and precipitation levels on individual winter ranges. Survival was significantly higher for migratory deer than residents. Both groups had lower survival during the fall migration period (Oct-Nov) and a positive linear relationship between survival and winter precipitation in individual winter ranges. Annual survival estimates for migrants ranged from 0.81-0.82, which is similar to other findings, but survival rates for residents (0.76- 0.77) were low in comparison to survival rates for adult female mule deer in other parts of their range. I used a nonparametric cumulative incidence function estimator (NPCIFE) to generate annual cumulative incidence functions separately for males and females due to differing risks associated with each sex. The four competing sources of mortality I included in this analysis for males were legal harvest, illegal harvest, predation, and starvation, disease, vehicle or fence-collision combined as one category (i.e., other). For females in investigated predation, human-associated mortality (vehicle or fence), illegal harvest, and natural causes (starvation and disease). Annual risk functions were pooled across all years of the study to maximize sample size. For males, the cumulative risk was highest for legal harvest (0.249, 95%CI=0.172-0.326), with predation the next highest cause of mortality for this sex (0.104, 95%CI=0.042-0.611). For females, the cumulative risk was highest for predation, (0.044, 95%CI=0.028-0.065) with anthropogenic causes (0.038, 95%CI=0.021-0.054) and illegal harvest (0.031, 95%CI=0.17-0.054) also important sources of mortality. Higher monthly survival rates of migrants compared to residents (across all months of the biological cycle) suggested that leaving for potentially higher quality summer foraging grounds outweighed the cost of traveling through unfamiliar habitats and energy expenditure from migration. Conversely, it may also imply that the summer ranges for residents had a negative effect on survival due to habitat quality or human disturbance. Both migrants and residents had lower monthly survival during the fall migration period (Oct - Nov). Female mule deer were excluded from the state-managed bow and rifle hunting season during this study, but females may experience the negative effects of human disturbance associated with fall hunting activities. This time of year is also energetically costly for females, being that some may still be nursing, which could have an additive effect to the energy used to migrate or avoid human disturbance. Winter precipitation also had positive effect on survival for both groups, possibly because increased average winter precipitation resulted in increased winter forage quantity and quality. My results suggest that female survival rates observed during my study are on the low end of the range reported for this species and may be contributing to population declines of mule deer in Oregon. Annual estimates of male survival were also low, but it is unclear how that might contribute to overall population declines without more information on annual and seasonal variation in male survival. Surprisingly, I observed high levels of illegal harvest on female deer and evidence that female survival during the fall migration period, which overlaps Oregon’s legal harvest season, was lower than other times of the year. It is unclear why the fall migration period negatively affects both migrants and resident deer similarly, but future research should attempt to determine the specific factors that are negatively impacting mule deer survival during this time period in south-central Oregon. In addition, as human development in the area continues to grow, it is important to consider migration paths and the habitat quality of both summer and winter ranges. My results suggested that conditions may differ between summer ranges in particular, for residents vs. migrants, and understanding these differences may be the key to increasing survival of female mule deer in Oregon. Sharing information from this study with law enforcement and the general public may be the first step towards increasing awareness of, and thereby reducing, the relatively high levels of illegal harvest I documented for the female population. Future research should focus on investigating the differences in habitat quality for residents versus migrants, the factors that decrease survival during fall migration for both groups, and the social and economic factors that contribute to the illegal harvest of female mule deer in eastern Oregon.
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144. [Article] The physiology ecology and run diversity of adult Pacific lamprey, Entosphenus tridentatus, during the freshwater spawning migration
Pacific lamprey, Entosphenus tridentatus, have shown recent and rapid declines in abundance. These anadromous fish return to streams where they mature, spawn and die. It has been inferred that Pacific ...Citation Citation
- Title:
- The physiology ecology and run diversity of adult Pacific lamprey, Entosphenus tridentatus, during the freshwater spawning migration
- Author:
- Clemens, Benjamin Jacob, 1976-
Pacific lamprey, Entosphenus tridentatus, have shown recent and rapid declines in abundance. These anadromous fish return to streams where they mature, spawn and die. It has been inferred that Pacific lamprey enter freshwater and reside for ~ 1 year before spawning. This long exposure to the freshwater environment may affect the plasticity of the maturation process and the migration timing of Pacific lamprey. Diversity in run times and body size has been observed for Pacific lamprey, yet it is unknown if this diversity is induced by the freshwater environment or if it is genetic. My first goal was to describe the maturation and migration characteristics of adult Pacific lamprey during their freshwater migration. My second goal was to use these data to make an estimation of the run diversity in Pacific lamprey. I conducted three complementary studies, in the laboratory and the field, to achieve these goals. I held immature adult lamprey (non-ripe fish that had ceased parasitic feeding in the ocean and had returned to freshwater) in the laboratory at temperatures that mimicked what these fish would experience in the wild, during the summer (mean: 21.8 °C), and another group of lamprey at cooler temperature (mean: 13.6 °C) to compare maturation timing and characteristics. The warm water group of lamprey showed significantly greater proportional decreases in body mass following temperature exposure than fish in the cooler water. All fish exposed to the warm water matured the following spring (8-10 months later) whereas only about half of the fish from the cool water exposure matured. To understand the migration distances and timing of adult Pacific lamprey, I tracked radio-tagged fish throughout the Willamette Basin above Willamette Falls, Oregon, by airplane and recorded their location. Fish migrated primarily during the spring to early summer period before stopping during the remainder of summer, when peak river temperatures (≥ 20°C) occurred. These fish tended to remain stationary through the fall and winter. However, at least a few fish continued to migrate upstream after September. I monitored maturation characteristics of adult Pacific lamprey, over time at Willamette Falls, Oregon and compared these fish with recent migrants collected from the Pacific Ocean as they entered freshwater. The results suggest a unimodal spawn timing between April and June, at water temperatures < 20 °C. Between July and mid-September, as water temperatures peaked at ~ 25 °C, relatively immature fish for both sexes prevailed. Warm summer temperatures coincided with an increase and prevalence of testicular atrophy in males, and I also observed a large die-off of lamprey during this time. The immature fish had maturation stages and phenotypic characteristics similar to recent migrants collected at the mouth of the Klamath River, suggesting that the immature fish at Willamette Falls would spawn the following year, and spawners in any given year may have been recent migrants during the previous year. However there is a temporal overlap in the spring of immature and mature fish, and I found evidence from gonad histology of maturing fish as they entered the river from the ocean, suggesting that a cohort is comprised of recent migrants that spawn within several weeks of entering freshwater, and another cohort is comprised of recent migrants that mature and spawn at least 1 year later. I hypothesize that the recent migrants that would likely spawn shortly after entering freshwater are akin to a winter or "ocean maturing" steelhead, Oncorhynchus mykiss, that optimizes feeding and growth in the open ocean for a few years before entering freshwater to spawn low in the river system shortly afterwards. Alternatively, these lamprey may be similar to coastal cutthroat trout, O. clarki clarki, that feed and grow in the coastal areas of the ocean for a few months before entering freshwater to spawn. There could be other less apparent explanations as well. I also hypothesize that the lamprey that would likely spawn within ~ 1 year of entering freshwater are akin to a "stream maturing" steelhead that foregoes feeding and growth opportunities, enters freshwater during the summer – fall, and accesses spawning grounds to spawn at temperatures that promote evolutionary fitness via successful spawning the following spring. Based on the results of my research, I hypothesize that warm summer temperatures (> 20 °C) can act as a strong selection factor against stream maturing Pacific lamprey in two ways. First, these temperatures may expedite their maturation, while at the same time slowing their migration. If these hypotheses are true, then I predict an uncoupling of spawn timing with optimal habitat characteristics, that would promote fitness, in the upper watershed. Second, summer temperatures may cause gonad atrophy and death prior to spawning. This scenario may select for ocean maturing Pacific lamprey.
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We examine the interactions and feedbacks between bathymetry, waves, currents, and sediment transport. The first two pro jects focus on the use of remote sensing techniques to expand our knowledge of ...
Citation Citation
- Title:
- Development of 2D models to estimate nearshore bathymetry and sediment transport
- Author:
- Splinter, Kristen D.
We examine the interactions and feedbacks between bathymetry, waves, currents, and sediment transport. The first two pro jects focus on the use of remote sensing techniques to expand our knowledge of the nearshore. Due to the plethora of snap-shot data that is available from satellites and their distribution via Google Earth, having a method that can determine bathymetry from spatial wave patterns would be very valuable. Utilizing remotely-sensed wave refraction patterns of nearshore waves, we estimate bathymetry gradients in the nearshore through the 2D irrotationality of the wave number equation. The model, discussed in Chapter 2, uses an augmented form of the refraction equation that relates gradients in bathymetry to gradients in wavenumber and wave angle through the chain rule. The equations are cast in a form that is independent of wave period, so can be solved using wavenumber and direction data from a single snapshot rather than the normally-required time series of images. Synthetic testing of the model using monochromatic waves on three bathymetries of increasing complexity, showed that the model accurately estimated 2D bathymetry gradients, hence bathymetry, with a mean bias of 0.01 m and mean root mean square error over the three beaches of 0.17 m for depths less than 5 m. While the model is not useful for cases of complex seas or small refraction signals, the simplified data requirement of only a single snapshot is attractive. The model is perhaps best suited for shorter period swell conditions (wave periods of 8-10 seconds), for example, where strong refraction patterns are visible and wave number, k, and wave angle, θ, are easily extracted from a single frame image. Secondly, remotely sensed images of wave breaking over complex bathymetry are used to study the nonlinear feedbacks between two-dimensional (horizontal), 2DH, morphol- ogy and cross-shore migration rates of the alongshore averaged bar. We first test a linear model on a subset of 4 years of data at Palm Beach, Australia. The results are discussed in Chapter 3. The model requires eight free parameters, solved for using linear regression of the data to model the relationship between alongshore averaged bar position, x, along- shore sinuosity of the bar, a, and wave forcing, F = H 2 o . The linear model suggests that 2DH bathymetry is linked to cross-shore bar migration rates. Nevertheless, the primary limitation is that variations in bar position and variability are required to be temporally uncorrelated with forcing in order to achieve meaningful results. For large storms, this is indeed the case. However, many smaller storms seen at Palm Beach show that changes in bar position and variability are correlated with forcing and bar interaction dynamics are not separable from bar - forcing dynamics. In Chapter 4 a nonlinear model is subsequently developed and tested on the same data set. Initial equations for cross-shore sediment transport are formulated from commonly accepted theory using energetics-type equations. Cross-shore transport is based on the deviations around an equilibrium amount of roller contribution with the nonlinearity of the model forcing sediment transport to zero in the absence of wave breaking. The extension to 2DH is based on parameterizations of bar variability and the associated 2DH circulation. The model has five free parameters used to describe the relation between alongshore averaged bar position, x, 2DH bar variability, a, and wave characteristics (wave height, H , wave period, T , and wave angle, θ). The model is able to span multiple storms, accurately predicting bar migration for both onshore and offshore events. The longest individual data set tested is approximately 6 months. Using manually determined values for the coefficients, bar position is predicted with an R2 value of 0.42 over this time period. The effect of including a 2D dependency both increased rates of onshore migration and prevented highly 2D systems from migrating offshore under moderate wave heights. The model is also compared against a 1DH version by setting the 2D dependency term to unity and using the same values for the five free parameters. The 1DH model showed limited skill at predicting onshore migration rates, suggesting again that the inclusion of 2DH terms is important. The last pro ject (Chapter 5) explored the utilization of changes in bathymetry, ∆h/∆t, to gain further understanding of the feedbacks between 2D sediment transport patterns, Qx and Qy , with respect to existing bathymetry in the nearshore. The model is based on the 2D continuity equation that relates changes in bathymetry to gradients in the cross-shore, ∂ Qx /∂ x, and the alongshore, ∂ Qy /∂ y, directions. The problem is under-determined, having two unknowns (Qy and Qx) and only one known (∆h/∆t) such that a series of constraints must be applied in order to solve for transport. We as- sume that that the cross-shore integral of Qx is closed, such that no sand enters or exits the system in this direction. By conservation of mass, this requires changes in volume of the cross-shore transect to be due to longshore gradients in Qy . We test six rules for distributing Qy : three rules describing the initial longshore transport (Qr y ) and three describing the cross-shore distribution of the excess volume component (Qe y ). Initial re- sults suggest that requiring sediment to travel down slope (Qry = f (βy )) is an intuitive choice for describing transport of distinct perturbations. However, in one example field test this method did not perform well and the approach may need further refinements. Alternatively, having Qrx and Qry depend on spatial correlation lags between two sur- veys showed good results for identifying transport associated with alongshore migrating features. This method, however, did not do well under strict onshore migration of 2D features, where alongshore transport was not predicted. A hybrid approach, using both the down-slope constraint and spatial correlation lags may provide more robust predic- tions of sediment transport patterns in complex environments. Due to the lack of closed boundaries in the alongshore, knowledge of Qy (x, y0 ) is required to obtain sensible net sediment transport patterns. Alternatively, spatial patterns of the transport gradients (∂ Qy /∂ y, ∂ Qx /∂ x), which ultimately determine bar migrations provide useful insight into the system behavior without requiring Qy (x, y0 ).
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Copper migration from treated wood has created concerns within the environmental community because of the potential effects of this heavy metal on aquatic organisms. Migration can be limited, to some extent, ...
Citation Citation
- Title:
- Limiting copper loss from treated wood in or near aquatic environments
- Author:
- Mitsuhashi Gonzalez, June M.
Copper migration from treated wood has created concerns within the environmental community because of the potential effects of this heavy metal on aquatic organisms. Migration can be limited, to some extent, by more controlled treatments and by post-treatment processing, but these actions cannot completely overcome the problem. An alternative approach to limit copper migration is to incorporate additives into the formulations that would either block or slow copper loss. Preliminary trials suggest that adding small amounts of Di(hydrogenated tallowalkyl)dimethyl ammonium chloride (2HT), a common fabric softener, to the treating solution can reduce copper losses in service. Reducing copper losses may also allow the use of lower initial preservative loadings. In this research, the potential for using 2HT was examined to reduce copper losses while maintaining preservative efficacy. The effect of the additive on leaching was assessed by soaking blocks in water over a 14-day period, then examining the resulting leachate. The incorporation of 2HT to alkaline copper-based and DDAC preservative solutions reduced the rate of copper migration from southern pine blocks subjected to laboratory leaching procedures by 5% to 14%. 2HT had no effect on loss rates for isothiazolone. Biological efficacy was assessed by exposing treated blocks to decay fungi in a soil block test. 2HT did not enhance the biological efficacy of copper azole nor isothiazolone in standard laboratory trials with a brown rot fungus, P. placenta. The potential for chemical interactions was assessed using Fourier Transform Infrared Spectroscopy (FTIR) analysis. Results indicated that 2HT did not change the structure of wood, suggesting that 2HT reduces copper losses due to ionic interactions between the organic cationic end of the quaternary ammonium compound and the negatively charged surface of wood. This interaction leaves the hydrophobic end of the 2HT exposed to act as a water repellent, thereby excluding the water that would otherwise solubilize and remove copper from the wood. Results provide support for using this additive to limit copper losses into the environment.
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During early embryonic development, endodermal cells leave the inner cell mass (ICM) and migrate over an extracellular matrix (ECM), located on the blastocoelic side of the trophectoderm, to form a continuous layer ...
Citation Citation
- Title:
- Expression of extracellular matrix proteins during blastulation in bovine embryos and factors affecting bovine endodermal cell outgrowth In Vitro
- Author:
- CoreyAyne, Singleton
During early embryonic development, endodermal cells leave the inner cell mass (ICM) and migrate over an extracellular matrix (ECM), located on the blastocoelic side of the trophectoderm, to form a continuous layer of extraembryonic endoderm. Cell migration events depend on a family of cell surface proteins known as integrins that bind specific ECM proteins. In an effort to understand the mechanisms involved in bovine endodermal cell migration, two experiments were conducted. In the first experiment, expression of the ECM proteins fibronectin, laminin and vitronectin was evaluated by immunofluorescent staining in in vivo and in vitro developing embryos during Day 6-10 and Day 7-10, respectively (Day 0=onset of estrus). Fibronectin was detected in all stages of in vivo and in vitro embryos, however no difference (P>0.10) was observed due to day or developmental stage. Laminin staining was moderately expressed in all stages of in vivo embryos, with an increase (P<0.05) in Day 10 in vivo embryos. Laminin staining in Day 9 in vitro embryos was less intense (P<0.05) than Day 7 and 8 in vitro embryos. Higher (P<0.05) expression of laminin was observed in Day l0 in vivo embryos as compared to Day 10 in vitro. Vitronectin staining was expressed throughout all stages of development. Day 6 in vivo embryos exhibited more intense (P<0.05) staining compared to Day 8 in vivo embryos. Day 10 in vivo embryos expressed more (P<0.05) vitronectin than Day 10 in vitro embryos. In the second experiment, the effects of ECM-type and inhibitors of integrin binding on bovine endodermal cell outgrowth from the ICM were evaluated. Day 7 embryos were nonsurgically collected and cultured for 96 h on either fibronectin-layered microdrops containing 0 (control), 0.5 or 1.0 mg/ml RGD and/or EILDV peptides or vitronectin-layered microdrops containing 0, 0.5 or 1.0 mg/ml RGD peptides. At 24-h intervals, ICM were photographed and the numbers of cells leaving the ICM were counted. Areas of cellular outgrowth were calculated from the photomicrographs. Compared to the control, addition of 0.5 or 1.0 mg/ml RGD, EILDV or RGD and EILDV did not (P>0.10) reduce the areas of cellular outgrowth from the ICM on matrices of fibronectin. Numbers of cells in outgrowths were greater (P<0.05) in control ICM compared to 0.5 mg/ml RGD, but this effect was eliminated (P>0.10) when the inhibitor concentration was increased to 1.0 mg/ml. Addition of 0.5 or 1.0 mg/ml RGD did not reduce (P>0.10) the area of cellular outgrowth from the ICM on vitronectin and had no effect (P>0.10) on numbers of cells in the outgrowths. Detection of fibronectin, laminin and vitronectin by immunofluorescence suggests these proteins are present in the developing bovine embryo to support endodermal cell migration and stabilization in extraembryonic endoderm formation. Because cell migration over fibronectin and vitronectin was not inhibited by the RGD and EILDV peptides, endodermal cells must use either an integrin that recognizes alternative binding sites in fibronectin and vitronectin or an alternative cell adhesion system.
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Numerous populations of salmon and trout undergo extensive migrations, migrating from freshwater to the sea and throughout ocean basins. Years later they return to their natal streams with remarkable accuracy ...
Citation Citation
- Title:
- An Evaluation of the Effects of Hatchery and Management Practices on Geomagnetic Orientation Behavior in Juvenile Pacific Steelhead Trout (Oncorhynchus mykiss)
- Author:
- Scanlan, Michelle M.
Numerous populations of salmon and trout undergo extensive migrations, migrating from freshwater to the sea and throughout ocean basins. Years later they return to their natal streams with remarkable accuracy and precision. The outward migration is accomplished without the benefit of following experienced migrants or prior individual experience. Evidence suggests that Pacific salmon and trout use the earth's geomagnetic fields when undertaking these migrations. My study evaluated current hatchery and management practices that may influence the ability of Pacific steelhead trout (Oncorhynchus mykiss) to perceive or respond to geomagnetic fields. Magnetized coded wire tags (CWT) were implanted into Alsea river steelhead pre-smolts (juveniles that have not undergone the physiological transition to prepare for oceanic life stage) during the fall of 2013. Test subjects were exposed to simulated magnetic fields at the latitudinal periphery of their oceanic foraging range in the North Pacific. Orientation responses were recorded and compared to non-tagged individuals. However, due to fish illness or other factors, control test subjects did not exhibit the north/south orientation responses observed during previous studies and results were inconclusive. Magnetic susceptibility, total magnetic field intensity, and median destructive field were assessed by analyzing 48 CWTs from five injection units. The total field intensity was consistent among machines and tags within a single machine. The strength of the fields produced by the tags relative to the known magnetic sensitivity of steelhead trout suggest that they are unlikely to pose major problems for large-scale navigation in fish. Sex differences in geomagnetic orientation response were evaluated based on work that documented early movement downstream by female steelhead. Experiments documented no significant difference in geomagnetic orientation responses based on genetic sex, though these results may also have been confounded by the same problems associated with the CWT orientation experiments. Lastly, effects of rearing juvenile steelhead in concrete raceways (subject to magnetic distortion due to iron rebar) were examined following similar "simulated magnetic displacement" protocols. These juvenile steelhead exhibited random orientation responses. The inability of fish reared in raceways to distinguish between fields at the periphery of their oceanic foraging range could pose potential problems for homing and navigation in hatchery fishes. The duration of these affects is unknown and warrants further study. Based on these findings, there is evidence to suggest that some current hatchery and management practices may influence the ability of juvenile salmon and trout to perceive geomagnetic fields. In turn, this may influence successful navigation to foraging grounds in the Pacific, subsequent return rates, as well as homing and straying behavior.
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It is essential to study the relationship between environmental features and human land-use activities that can provide a better understanding of human-environment interactions. In a response, this dissertation ...
Citation Citation
- Title:
- Essays on the interactions between land use, natural amenity and wildfire risk
- Author:
- Xu, Wenchao
It is essential to study the relationship between environmental features and human land-use activities that can provide a better understanding of human-environment interactions. In a response, this dissertation addresses the human-environment issues from different perspectives in three essays. The first essay conducts an integrated analysis to investigate the impacts of human activities and environmental features on wildfire occurrence at the Wildland-Urban Interface in a changing climate. We focus on the impacts of land use changes as measured by their density, connectivity, and mix. The conceptual model builds on a theoretical framework developed by Woodward (1987) and Neilson (1995) that characterizes the functioning mechanism of ecosystems. The empirical models identify the key factors that influence wildfires. Hypotheses are tested to demonstrate the spatial heterogeneity of human land-use impacts on wildfires. Results can inform the design of policies that aim to identify community vulnerabilities, reduce wildfire uncertainties, strengthen firewise community development, and inform future land-use decision making in response to wildfire threats. The second essay analyzes the impacts of wildfire risk on urban development. It builds on and expands the monocentric-city framework developed by Wu (2006) and Wu (2010) by introducing wildfire risk into this model. We calibrate the model and examine the urban spatial profiles changes under different assumptions of wildfire risks and natural amenities. We find that wildfire risk can take on various aspects of urban spatial profiles at a much broad scale that go beyond the fire-prone areas and affects both households and public decision sectors. Even without inconsistency in fire-zone designation policy, over-development can occur in fire-hazardous area. The third essay models the role of amenity in interregional migration and spatial distribution of economic activities. Extending the new economic geography model of Helpman (1998) by including locational amenities, we present a multi-market equilibrium framework that includes consumption, production, and trade. Results suggest that the effects of amenities are significantly affected by household preferences, trade barriers, and other regional economic characteristics. This study contributes to the amenity-driven migration literatures and informs the debate about the effect of amenities on interregional migrations and regional economic development.
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150. [Article] An investigation into the genetic basis of migration timing in Chinook salmon (Oncorhynchus tshawytscha)
The genetic basis of adaptation is complex as many fitness-related traits are quantitative and likely influenced by multiple genes with variable effects across different selective environments. One important ...Citation Citation
- Title:
- An investigation into the genetic basis of migration timing in Chinook salmon (Oncorhynchus tshawytscha)
- Author:
- O'Malley, Kathleen Gallen, 1976-
The genetic basis of adaptation is complex as many fitness-related traits are quantitative and likely influenced by multiple genes with variable effects across different selective environments. One important adaptation for anadromous Chinook salmon (Oncorhynchus tshawytscha) is the time at which individuals return to natal breeding sites within a reproductive season. Here, I tested for adaptive genetic differentiation among temporally divergent migratory runs using candidate loci. First, I isolated and characterized two copies of the circadian rhythm gene, Clock, from Chinook salmon (OtsClock1a and OtsClock1b). Phylogenetic analysis revealed that these copies likely arose subsequent to the salmonid genome-wide duplication event. Each copy contains a polyglutamine repeat motif (PolyQ), an essential binding domain of this transcription factor. However, a 1200bp non-coding segment, showing >90% sequence identity to the Salmo salar Transferrin gene, is located downstream of the OtsClock1a PolyQ, yet absent from OtsClock1b providing evidence for nonhomologous recombination. Another candidate, Ots515NWFSC, shows sequence identity to three salmonid genes central to reproductive development: Gonadotropin-releasing hormone, CYP19b-I, and Ghrelin. I employed OtsClock1b and Ots515NWFSC to test for differentiation in two unique systems: Feather River, California; and Waitaki and Poulter Rivers, New Zealand. Based on length variation in these candidate genes, Feather River fall and spring run Chinook salmon are genetically differentiated. In contrast, these seasonal runs are genetically indistinguishable based on neutral microsatellite loci. Correspondingly, temporally divergent Chinook salmon runs in the Waitaki and Poulter Rivers show greater differentiation based on variation in OtsClock1b and Ots515NWFSC than microsatellite loci. Tests for selective neutrality indicate that OtsClock1b and Ots515NWFSC are likely under selection in both systems. In addition, I found evidence for a latitudinal cline in two OtsClock1b PolyQ alleles among 42 Chinook salmon runs which is likely maintained by selection and thus may reflect an adaptation to photoperiodic parameters. Lastly, a hierarchical gene diversity analysis of OtsClock1b PolyQ variation revealed that run timing explained 43.7% of the overall genetic variance which contrast sharply with the 8.1% calculated for microsatellite loci. Evidence presented here suggests that OtsClock1b and Ots515NWFSC may influence migration timing of Chinook salmon.