Now showing items 2114-2133 of 3447

• #### Organic matter sources on the Chukchi Sea shelf in a changing Arctic

Climate-change induced alterations of the organic matter flow from various primary production sources to the benthic system in the Arctic Chukchi Sea could have major implications on carbon cycling, sequestration, and benthic food web structure sustaining upper trophic levels. In particular, the role and contribution of terrestrial matter and bacterial matter could become more prominent, with increasing erosion and permafrost melt being discharged from land, and warming water temperatures raising bacterial metabolism. In this study, I used essential amino acid (EAA) specific stable isotope analysis to trace the proportional contributions of bacterial, phytoplankton, and terrestrial organic matter in sediments, as well as benthic invertebrates on the Chukchi Sea shelf. Across the upper 5 cm of sediments, most organic matter sources were equally distributed, except for a slight decrease with depth in phytoplankton EAA. Terrestrial sources contributed the majority of EAA (~76 %) in all sediment layers, suggesting a potential accumulation of this material due to slow degradation processes. These results indicate a well-mixed upper sediment horizon, possibly due to bioturbation activity by the abundant benthos. Experimental observations of increases in bacterial production, measured as phospholipid fatty acid (PLFA) production, at water temperatures 5 °C above ambient (0 °C) and under sufficient substrate conditions suggest that bacterial organic matter in sediments could become a greater organic matter source in the sediments of a future, warmer Arctic. EAA source contribution to various benthic invertebrate feeding types (FT) were similar but showed significant differences among genera within the same FT, suggesting that feeding habits are more genus-specific rather than FT-specific. These differences were attributed to variations in other characteristics such as mobility, selectivity, and assimilation efficiency. Terrestrial EAA contributed high amounts to all benthic genera, supporting other recent findings that this source is readily utilized by benthic invertebrate consumers. These results of organic matter source contributions across sediments and benthic invertebrate feeding types were then used to better resolve the detrital pathways in an Ecopath mass-balance model of the Chukchi Sea. The incorporation of terrestrial matter as an organic matter source to Chukchi Sea food webs and updated organic matter use in benthic invertebrate diets balanced energy flow from phytoplankton and bacterial production through the food web. Simulations of potential future reductions of the pelagic production to the benthos negatively impacted benthic feeding taxa, which could be partially compensated by a simulated increase in terrestrial and bacterial organic matter supply.
• #### Organizational communication and culture in female predominated workplaces

While equality of the sexes has still not been achieved, the ongoing struggle for parity has paved the way for an influx of females into workplaces. In many organizations this increase has resulted in a higher ratio of females to males. Offices that are predominated by on sex or the other create communication problems, attitudes, and ways of dealing with co-workers on an interpersonal level that organizations with a balance between males and females do not face. This study will explore the perspective of females working in gender predominant organizations, and also observations on organizational culture; intra-organizational communication; communicated support among organizational members; and the overall uniqueness of the organization.
• #### Organizational culture and meanings in tension: an analysis of the Alaska Volcano Observatory

The Alaska Volcano Observatory (AVO) is an organization that is responsible for observing volcanic activity in Alaska and surrounding regions. This organization has a great impact on the public and agencies in Alaska because it is responsible for ensuring the safety of many Alaskans, and to many people who live in neighboring regions. AVO is not only responsible for saving lives, but also responsible for notifying agencies that depend on this organization for volcanic crisis notification. This study is an ethnography of the Alaska Volcano Observatory and through interpretation of my data as research too, I provide a sense of place for this organization. Detailed journals of my experience as a member of this organization have been analyzed to understand the culture of the place.
• #### Organochlorines In Steller Sea Lions (Eumetopias Jubatus)

Existing populations of Steller sea lions (Eumetopias jubatus ) have declined precipitously over the last half-century. Investigations into the cause of this downward trend have focused on many different possible factors. Toxicity caused by the accumulation of organochlorines (OCs), such as polychlorinated biphenyls (PCBs) and 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane or dichlorodiphenyltrichloroethane (DDT), has been demonstrated in marine mammals and was considered here as one possible factor that may have contributed to the decline of Steller sea lions or their failure to recover. The focus of this project was to investigate the relationship of contaminant loads to hormone levels, specifically thyroid hormones and cortisol in Steller sea lions. Two approaches were taken to this study. Firstly, baseline hormone concentrations were identified for the thyroid hormones, thyroxine (T 4) and triiodothyronine (T3), and cortisol. This involves comparison and extrapolation. Secondly, possible risk effects were examined by comparing levels of OCs in captive and free-ranging Steller sea lions to known effects in related species with known physiological thresholds. Serum concentrations of total T4 were highest in Steller sea lions followed by total T3 concentrations. Concentrations of free T4 and free T3 were three to four orders of magnitude lower. Concentrations for all four thyroid hormone measurements tended to a lower level as animals matured beyond the neonatal stage. When thyroid hormones from captive sea lions were evaluated across seasons, all thyroid hormones were highest in the July to September period. Cortisol concentrations were similar in male and female pups. Cortisol varied with age but when considered in regards to time of year when sampled, followed a seasonal pattern. Cortisol was elevated in fall months in captive sea lions (non-pups), which is similar to what is seen in other marine mammals and is likely associated with the annual molt. Male pups from Alaska had lower levels of SigmaPCBs and SigmaDDT when compared to male pups from Russia. Female pups from Alaska were significantly lower in SigmaPCBs than Russian female pups as were female pups for SigmaDDT levels between areas. Anywhere from 12 to 64% (depending on rookery) of Steller sea lion pups investigated for contaminants had concentrations of SigmaPCBs that are high enough to cause physiological problems. Concentrations in blood taken monthly for 2 years in three captive Steller sea lions were similar at any given sampling time and followed a seasonal pattern with levels significantly higher in the summer months of July to September and lower in the three month winter period January to March. Concentrations of OCs in blubber samples collected quarterly for the captive females followed an analogous pattern to blood samples but the captive male sea lion was considerably lower and declined over the study period. A significant relationship between blubber contaminants and lipids was noted in the three captive Steller sea lions. Even though OC contamination has not been hypothesized to be the primary factor that precipitated the population decline, there is a potential for these chemicals to have a negative effect on the health of free-ranging Steller sea lions. These data suggest that concentrations of OCs in Steller sea lions may be high enough to cause endocrine or reproductive dysfunction and could potentially impact fertility or fecundity. Therefore, OC contaminants can not be dismissed as a contributing source to either the decline or the failure to recover of the Steller sea lion population.
• #### The origin and composition of aerosols in the Alaskan airshed

Since the Alaskan airshed north of the Alaska Range receives a substantial portion of its anthropogenic aerosol and gaseous pollutants through long-range transport, Alaskan air quality is influenced to an unusually high degree by the political and economic events of other countries. An understanding of the political and economic forces at work in the various circumpolar nations is key to an understanding of the observed decline in Arctic haze, the present state of Arctic air pollution, and likely future developments. It is shown in this thesis that Arctic haze has declined in Interior Alaska over the last decade and a half. This decline appears to be driven by the widespread emission reductions which have occurred in North America, Europe, and the former Soviet Union (FSU) between 1988 and 1998. If true, this linkage indicates that the story of Arctic haze is not yet a post-mortem. EMEP projections for 2005 foresee a continuing decline in emissions across Europe and a leveling off in North America, but emissions in the European FSU are expected to double by 2005. Events in the FSU, and perhaps Asia as well, threaten to abrogate any further progress made by Europe and North America and could perhaps revive the phenomenon.
• #### Origin, character, application and correlation of tephra partings in tertiary coal beds of the Kenai Peninsula, Alaska

Volcanic and non-volcanic partings occur in coal beds of the Neogene Beluga and Sterling Formations along the shores of the Kenai lowland, Alaska. The partings were systematically characterized to determine their potential geological applications: Two-thirds of the partings originated as air-fall tephra. Of these, partly altered, Pliocene tephra typically contain volcanic glass + feldspar $\pm$ montmorillonite $\pm$ quartz $\pm$ kaolinite $\pm$ opal-CT. Highly altered Miocene partings are characterized by feldspar $\pm$ kaolinite $\pm$ montmorillonite $\pm$ quartz $\pm$ crandallite $\pm$ altered volcanic glass, where crandallite appears to have formed by replacement of volcanic glass prior to clay formation. About one-third of the partings are of detrital origin and contain detrital chlorite + illite + smectite + quartz $\pm$ feldspar $\pm$ siderite $\pm$ kaolinite. A Pliocene pumice parting near the top of the Sterling Formation was correlated from the northwestern to the southeastern Kenai lowland on the basis of similar glass morphologies, an absence of opaque minerals, and geochemical similarities. A crystal-tuff near the middle of the section could be traced across the Kenai lowland as one or two ash-falls, based on inertinite contents of adjacent coal, mineralogy, and geochemistry. Some other prominent tephras could not be correlated. The tephra partings are time-equivalent to DSDP cores from the Gulf of Alaska and along the Aleutian Island chain. Tephras occur every 125-500 yr in the lower part of the Beluga Formation, and their deposition probably coincides with a volcanic pulse 10.5 m.y. ago. This pulse is not well recorded in nearby DSDP cores. In the upper part of the Beluga Formation, during volcanic quiescence, tephras are recorded at an average rate of one every 9,000 yr. Time equivalent DSDP cores show a near absence of tephras. A volcanic pulse occurred during the deposition of the lower Sterling Formation, about 7.5 m.y. ago, with intervals between volcanism which averages 11,000 yr or longer. Volcanic sources appear to have been distant, which is consistent with an absence of tephra layers in a Gulf of Alaska core. About 5 m.y. ago, concurrent with the deposition of the upper Sterling Formation, the thicknesses of the tephra layers dramatically increase and the frequency increases to an average of one tephra every 2,000 years. This increase is recorded in DSDP cores as well.
• #### Origins And Zoning Of The Buckhorn Gold Skarn, Ne Washington

The Buckhorn Deposit was discovered in the mid 1980's and is composed of two separate Au-Bi deposits: the Gold Bowl and the Southwest Zone. The Southwest Zone is the larger of the two and is blind and stratabound. The Gold Bowl is exposed on the surface. Jurassic and Eocene plutonic rocks are present in the immediate area, indicating a complex geologic history and two potential mineralization ages. To determine the source- and thus the age- of gold mineralization I use chemical analyses of (>300) igneous rocks, X-ray Fluorescence (XRF) determination of (>200) Bi/Au, Cu/Au, and Cu/Pb ratios throughout the ore zones, Fe:Mg ratios of skarn clinopyroxenes determined by EMP analyses, calc-silicate mineral zoning, surface and underground mapping, and Ar40/Ar39 dating of Au-intergrown skarn hornblende. Chemical classification of igneous rocks distinguishes seven potential source intrusions in the immediate Buckhorn area. Metal zoning (Bi/Au, Cu/Au, and Cu/Pb) throughout the entire deposit showcases the lack of relationship between the Gold Bowl and the Southwest Zone, allowing for multiple source and remobilization interpretations. However, the techniques employed all indicate an east to west ore fluid migration across the Southwest Zone and reveal a newly-unrecognized zoned Jurassic pluton SE and below the deposit as the source.
• #### Osteological stress markers and habitual behaviors: analyzing the connection at Hierakonpolis, Egypt

The current project identifies skeletal patterns that indicate habitual behavior using muscle attachment sites, osteoarthritic changes and long-bone robusticity. Using a sample from HK43, a cemetery used by the Naqada II A-C working class (circa 3,800-3,400 B.C.), patterns were determined with respect to sex, and by age group. Those patterns were then compared to hypothesized models of skeletal markers predicted to occur with habitual use of an Egyptian hoe, an ox-drawn ard-style plow, a shaduf (a simple machine used in irrigation), and grinding grain using a saddle quern and grinding stone. The patterns displayed in the sample population correspond to predicted patterns created by habitual activity. Results were determined twice; first by sex, then by age. Females and males were grouped regardless of age, and vice versa. If divided by both, the resulting groups were too small to be compared. Females demonstrated a pattern that was most consistent with grinding grain. Males were determined to have a pattern most consistent with hoeing and using a shaduf The middle adult age group, composed of both males and females, showed a range of skeletal markers that is most consistent with that predicted for plowing. Not all patterns were easily explained, however. The young adult, or 17-24 year old age group displayed a pattern of muscle attachment very similar to the old adult group,>45 years of age. The source of that apparent similarity will have to be addressed by further research at Hierakonpolis, Egypt.
• #### Osteology, relationships and paleoecology of a new Arctic hadrosaurid (Dinosauria: ornithopoda) from the Prince Creek formation of Northern Alaska

The Liscomb Bonebed (LBB), found in the early Maastrichtian Prince Creek Formation of northern Alaska, is the single most productive site for the Arctic dinosaurs in either hemisphere. From the LBB, thousands of bones representing at least hundreds of individuals of a saurolophine hadrosaur have been collected, but they have not been previously described and their taxonomic status remains unresolved. In part, this stems from the fact that most material comes from individuals approximately one-half to onefourth of adult size. Another long-standing question concerns whether dinosaurs in the Prince Creek Formation overwintered in the paleo-Arctic or migrated elsewhere (presumably south) to escape prolonged darkness and cold. Here, I attempt to determine the taxonomic status of the LBB hadrosaurs using three semi-independent methods: 1) geometric morphometric analysis; 2) comparative morphological analysis; and 3) cladistic analysis. An important component of this work also includes an ontogenetic study of the growth patterns of the genus Edmontosaurus, to which this material has been previously referred, in order to better understand ontogenetic variation within the Alaskan taxon. My results indicate the Alaskan taxon is a new species of the widespread genus Edmontosaurus. For the first time, the Alaskan taxon is described in detail, making it the best known polar dinosaur to date. My cladistic analysis suggests a possible biogeographic scenario in which the common ancestor of Edmontosaurus and Shantungosaurus originated in eastern Eurasia and then dispersed by the Campanian to North America via a land corridor in the area of present day Alaska. Finally, I used a novel method involving strontium isotope geochemistry to test the migration hypothesis of the new species of Alaskan Edmontosaurus. I measured strontium in tooth enamel of Edmontosaurus and a putative non-migratory species (Troodon) using LA-MC-ICP-MS. My results suggest diagenesis had not significantly altered the signal and that Alaskan Edmontosaurus likely did not migrate during approximately the last four months of life. My results lend further support for the existence of a distinct, early Maastrichtian polar dinosaur fauna known as the Paanaqtat Province.
• #### Otters, sea stars, and glacial melt: top-down and bottom-up factors that influence kelp communities

Kelp beds are important features of the Alaska coastline and provide habitat, protect coastlines, and support commercial and subsistence harvests. Kelp beds are affected by top-down and bottom-up factors, which are changing due to human and climate-related impacts. The influences of these top-down and bottom-up factors on kelp beds are investigated in three chapters. My first chapter investigated the influence of glacial discharge on recruitment and early community development in subtidal kelp communities by monitoring benthic sessile algae and invertebrates on cleared rocks across a glacial gradient along with various physical and biological parameters in the summers of 2013-2014. It has been predicted that Alaska's glaciers will lose 30-60% of their volume by 2100. The melt from glaciers increases sedimentation and lowers salinity, impacting important habitat-providing kelp. I found that sites upstream from glacial discharge had higher kelp recruitment than downstream sites, and that up to 72% of the variation in community development was related to mobile invertebrates and kelp in the surrounding community. Glacially-influenced environmental factors did not explain any variation that was not already explained by biological factors. My second chapter explored whether patterns in the recruitment of the dominant canopy kelp, Nereocystis luetkeana and the subcanopy kelp, Saccharina latissima were a result of dispersal limitation or failure to grow to macroscopic size. My goals were to determine 1) whether glacial melt conditions affect adult fecundity (spore production) of either species, 2) how sedimentation affects early gametophyte growth and survival in each species, and 3) whether competitive interaction between species at the gametophyte stage is altered by sediments. I found that glacial melt conditions did not affect the fecundity of either species, but sedimentation affected survival and competition. Saccharina latissima was the superior competitor under high sediment conditions. Because glacially-influenced coastal areas often have little exposed hard substrate and predation by sea otters and sea stars on clams can provide hard substrate for kelp colonization, my third chapter examined methods for determining predation on clams by these predators without direct observation. I found that foraging pits of sea otters and sea stars could not be distinguished using quantitative measurements. In contrast, shell litter proved useful in quantifying relative foraging rates. Clam consumption by sea otters and sea stars was equal at all but one site. Collectively, my thesis chapters provide information on the effects of glacial discharge on microscopic and early kelp life stages in Alaska which can be incorporated into management practices.
• #### Outbreeding depression and inheritance in three generations of geographically distinct southeast Alaska coho salmon (Oncorhynchus kisutch) populations

I observed no fitness losses among F₂ hybrids of three Southeast Alaska coho salmon (Oncorhynchus kisutch) populations relative to parental controls. Marine survival did not differ among groups in one generation, but was greater for hybrids than controls in another, although the power of these tests was low. Increases in fluctuating asymmetry, which can signal losses in fitness, were not observed. Line cross analyses of length suggested additive and additive plus dominance gene action, and two of three analyses suggested epistasis. In contrast, meristic characters exhibited little variability; and in most cases tests failed to reject a simple additive model. Half- and full-sib analyses provided no evidence of quantitative genetic variation for any trait although the power to detect these effects was low. Comparisons of population divergence measured by quantitative traits (Qst) and molecular markers (Fst) that length is an adaptive trait and that bilateral meristics are highly conserved. Although we did not observe losses in fitness, the power of our tests was low, the among-population differences were unique to our experiment and so results of this study should be interpreted with caution.
• #### Outbreeding depression in hybrids between spatially separated pink salmon (Oncorhynchus gorbuscha) populations: marine survival, homing ability, and variability in family size

Hybridization between distinct populations of salmon can cause fitness loss (outbreeding depression), and may result in reduced survival. The erosion of fitness-related traits such as homing ability and change in family size distribution may underlie reduced survival. Out breeding depression was investigated in two independent experiments that made hybrids between geographically separated and genetically divergent pink salmon populations. Control crosses were made from male and female Auke Creek (Southeast Alaska) pink salmon and hybrid crosses were between Auke Creek females and Pillar Creek (Kodiak Island, about 1000km away) males. Parentage assignment from microsatellite analysis improved estimates of survival and straying, and was used to examine variation in family size. The return rates of even-broodyear F 1 control and hybrid fish were similar, but the odd-broodyear F 1 control returns exceeded hybrid returns. The F 2 control returns exceeded hybrid returns in both the even- and odd broodyears. Hybridization did not impair homing ability; weekly surveys in nearby ( - lkm) Waydelich Creek revealed similar straying rates from Auke Creek by both hybrid and control fish in all years. Family data were available only for even-broodyear returns; hybridization did not increase the index of variability (ratio of variance to mean) in family size in these years. Outbreeding depression in hybrids of geographically separated populations demonstrates the potential for introgression of nonnative fish to erode natural production.
• #### Outdoor education and feminism: a review of the outdoor adventures program at the University of Alaska Fairbanks

This report is an organizational review of the Outdoor Adventures (OA) Program at the University of Alaska Fairbanks (UAF). I will be reviewing the communication strategies within the program as well as the risk mitigation and socialization process of the organization. The goal of this document is to provide a theoretical background to justify decision making and communication practices within the organization based on a feminist critical perspective. This document provides recommendations based upon improving communication dynamics that play a role in the gender disparity as well as the processes through which staff of the organization are socialized. This document provides a brief history of the OA program at UAF and a strengths, weaknesses, opportunities, threats (SWOT) analysis to give perspective on the current state of the program. Next this project contains an overview of the gender disparity in the outdoor field, ways in which risk management is viewed and implemented, and the socialization processes of staff members within the program. Methods used to review the organization included document review, direct observation, and autoethnographic practices. The results of this project include documents to aid in socialization and risk management processes and further explores recommendations to mitigate the gender gap, update risk management practices, and train staff.
• #### Outpatient care in Fairbanks: supporting people with schizophrenia

With the current lack of residential treatment facilities, long-term hospitalization, and mental health agencies that can fully support people with schizophrenia in Fairbanks, Alaska, there are many ethical concerns that must be addressed to best support clients with schizophrenia. The ethical considerations present in the success of outpatient care include: a) promoting the welfare of clients, b) utilizing plans that offer reasonable promise of success, c) understanding the limits imposed on the support networks of these clients, and d) the limitations of employment opportunities for these clients in an outpatient setting. Reviewing literature on the experiences of people with schizophrenia revealed three stages of treatment normally experienced: a) acute care, b) transition care, and c) chronic care. Areas most impacted for people with schizophrenia are socialization and work, memory and intelligence, suicide risk and other disorders, and interactions with family, friends and the community. In Fairbanks, Alaska where weather hinders socializing and available services are limited, building many strong support resources is incredibly important to give people with schizophrenia the best chance of recovery and a stable quality of life.
• #### Overcoming CubeSat downlink limits with VITAMIN: a new variable coded modulation protocol

Many space missions, including low earth orbit CubeSats, communicate in a highly dynamic environment because of variations in geometry, weather, and interference. At the same time, most missions communicate using fixed channel codes, modulations, and symbol rates, resulting in a constant data rate that does not adapt to the dynamic conditions. When conditions are good, the fixed date rate can be far below the theoretical maximum, called the Shannon limit; when conditions are bad, the fixed data rate may not work at all. To move beyond these fixed communications and achieve higher total data volume from emerging high-tech instruments, this thesis investigates the use of error correcting codes and different modulations. Variable coded modulation (VCM) takes advantage of the dynamic link by transmitting more information when the signal-to-noise ratio (SNR) is high. Likewise, VCM can throttle down the information rate when SNR is low without having to stop all communications. VCM outperforms fixed communications which can only operate at a fixed information rate as long as a certain signal threshold is met. This thesis presents a new VCM protocol and tests its performance in both software and hardware simulations. The protocol is geared towards CubeSat downlinks as complexity is focused in the receiver, while the transmission operations are kept simple. This thesis explores bin-packing as a way to optimize the selection of VCM modes based on expected SNR levels over time. Working end-to-end simulations were created using MATLAB and LabVIEW, while the hardware simulations were done with software defined radios. Results show that a CubeSat using VCM communications will deliver twice the data throughput of a fixed communications system.
• #### An overview on the author's graduate recital program

The following project paper consists of three chapters, examining the works in my Graduate Recital Program. The first chapter analyzes the form, structure and particular interesting elements that Aram Khachaturian uses in his Sonata for Piano. The second chapter gives a brief historical information of the term Fantasy and examines two examples of the genre, Chopin's Fantasy in F minor op. 49 and Carl Vine's Sonata no. 3 "Fantasia". The third chapter covers some biographical information of Elliott Carter and examines the form and structure of his work for solo piano, 90+.
• #### Overwintering Physiology Of Arctic And Subarctic Insects From Interior Alaska

This dissertation focuses on the overwintering of three insects from Interior Alaska: a hemipteran, Elasmostethus interstinctus, and a coleopteran, Cucujus clavipes puniceus, that are freeze avoiding in the strict sense of the phrase, and a dipteran, Exechia nugatoria, that is simultaneously partially freeze avoiding and freeze tolerant. The variability within the freeze avoidance strategy itself is a key theme throughout this dissertation. Two significant contributions to comparative physiology are the confirmation of insect vitrification (glass formation) with its attendant extension of freeze avoidance and survival into a new, extreme low temperature record of -100�C and the simultaneous coupling of freeze avoidance and tolerance within an individual, which may more properly be described as a new overwintering strategy. Vitrification is the process by which ice crystallization is circumvented, resulting in a supercooled amorphous solid. Through a combination of antifreeze proteins that inhibit ice nucleation, dehydration tolerance, presence of high glycerol concentration, and low temperatures, the mobility of the remaining liquid water molecules is reduced, effectively by-passing the crystalline state. The second contribution is the discovery of a new overwintering strategy that combines freeze avoidance and freeze tolerance within an individual. In this case, the abdomen freezes (and the insect survives), while the contiguous head/thorax remains supercooled. These findings lead to the following evolutionary and trans-disciplinary questions. Is vitrification an adaptation? What is the selective advantage of compartmentalizing ice between body sections of an individual insect? Is this new overwintering strategy an example of a species transitioning between either becoming exclusively freeze avoiding or free tolerant? Applying new understanding of mechanisms of insect vitrification and avoidance of devitrification to cryomedicine may extend preservation of human tissues and organs. Similarly, for physical and material scientists, by understanding the patterns of ice formation within insects that tolerate, inhibit, and/or impede ice formation below the homogeneous ice nucleation temperature of water (-40�C), new biomimetic possibilities can be envisioned.
• #### Oxidative stress is transient and tissue-specific during cold acclimation of threespine sticklebacks

We sought to determine if oxidative stress occurs in liver, oxidative muscle or glycolytic muscle of threespine sticklebacks during cold acclimation. Fishes were held at 20°C for 12 wks and then acclimated to 8°C for 9 wks or held at 20°C for an additional 9 wks. Animals were harvested during the first four days of cold acclimation, and at wk 1, 4 and 9. Protein carbonyls were quantified as an indirect measure of the production of reactive oxygen species (ROS). The activity of superoxide dismutase (SOD), levels of SOD mRNA, and glutathione levels were quantified as indices of protection against ROS. All measurements were made in liver, glycolytic muscle and oxidative muscle. Protein carbonyl levels increased in livers of fishes after 1 wk at 8°C and decreased after wk 4. Total glutathione levels increased in livers on day 3 of cold acclimation and then decreased by wk 4. Measured at a common temperature, SOD activity increased early in all tissues and remained elevated throughout cold acclimation. Measured at the acclimation temperature, SOD activity increased only in oxidative muscle after 9 wks of cold acclimation. Together, these results indicate that oxidative stress is transient and tissue-specific during cold acclimation of fishes.
• #### Oxytetracycline tags in pink salmon fry applied by immersion and detected by fluorescence spectrometry

I investigated the feasibility of using spectrophotofluorescence as a quantitative method of analyzing pink salmon fry otoliths for the presence of oxytetracycline (antibiotic). I exposed twenty-four groups of pink salmon fry (approximately 250 individuals each) to solutions of oxytetracycline ranging in concentration from unexposed to 2000 ppm, and in duration of exposure from one to twelve hours. Otoliths from unexposed fry had the lowest mean fluorescence (log e [mean flu. units] = -1.77). Otoliths from fry exposed to 500 ppm for twelve hours had the highest fluorescence (log e [mean flu. units] = 0.899). Fluorescence increased nonlinearly with duration of exposure. There is a linear increase of fluorescence with exposure up to 500 ppm; above which fluorescence decreases. Pink salmon fry exposed to OTC in solution absorb detectable amounts of OTC in their otoliths. These amounts of OTC can be quantitatively measured by spectrofluorometry.
• #### Ozone depletion and biologically relevant ultraviolet radiation

An atmospheric radiative transfer model is used to calculate surface spectral ultraviolet irradiance under cloud-free conditions, and compared with measurements made at Lauder, New Zealand (45$\sp\circ{S}$, 170$\sp\circ{E})$ before and after the eruption of Mt. Pinatubo, and including a snow-covered surface. The ratios of diffuse to direct irradiance depend critically on solar elevation, surface albedo, and aerosol extinction. Ozone changes have pronounced effects on the global UVB irradiance, but have only a minor effect on these ratios. The comparison suggests that the ultraviolet radiation exposure can be computed with confidence for clear sky conditions, if the appropriate atmospheric pressure and temperature profiles, ozonesonde data, surface albedo, and aerosol optical properties are available. The total ozone abundances are derived by using ground-based UV irradiance measurements and compared with TOMS in Antarctica and the Arctic from 1990 to 1994. The comparisons show that they are generally in good agreement. Possible reasons for the discrepancies between the two methods are discussed. The equivalent cloud optical depths are also inferred from these data. Ozone depletion can also increase the penetration of ultraviolet radiation into the aquatic system. A coupled atmosphere-ocean radiative transfer model is used to investigate the effect of ozone depletion on UV penetration through the atmosphere and into the underlying water column. Comparisons between model computations and in situ measurements of irradiances made in Antarctic water show good agreement in the UV spectral range between 300 and 350 nm. The ratio of UVB (280-320 nm) to total (280-700 nm) irradiance also compared well. For a given ozone reduction the largest relative increase of UVB radiation arriving at the surface and penetrating to various depths in the ocean occurs at large solar zenith angles. At high latitudes the most pronounced increase in UVB exposure due to an ozone depletion occurs in the early spring, when ozone depletion is expected to be the most severe. The sensitivities of irradiance reflectance and diffuse attenuation coefficients to solar zenith angle, sky conditions, and chlorophyll concentration are discussed by using a coupled atmosphere-ocean radiative transfer model. The irradiance reflectance is sensitive to solar zenith angle, cloud cover, and chlorophyll concentration; the diffuse attenuation coefficient is sensitive to solar zenith angle and chlorophyll concentration, but less sensitive to sky conditions.