Geographic and Ontogenetic Variation in the Trophic Ecology of Lingcod (Ophiodon elongatus) Along the U.S. West Coast

Dietary studies of fishes provide an understanding of predator-prey interactions and may be used to inform resource managers about food web dynamics. Along the West Coast of North America, Lingcod (Ophiodon elongatus) are top marine predators in rocky-reef habitats and support an economically important fishery. In this study, gut content and stable isotope analyses were used to evaluate differences in the diets of Lingcod collected in U.S. waters from Alaska to Southern California during 2016 and 2017. Overall, Lingcod consumed a wide variety of prey and exhibited both generalist and opportunist feeding strategies. Significant variability in Lingcod diets was driven by factors such as depth, region, sex, and total length. Male Lingcod caught in shallow depths consumed more lower trophic level prey items (e.g. cephalopods) and had more diverse diets. Female Lingcod caught in deep depths consumed more higher trophic level prey items (e.g. groundfishes) and had less diverse diets. Geographic variation in trophic level was associated with environmental conditions of sea surface temperature and primary productivity (i.e., chlorophyll a). Southern Lingcod fed more on cephalopods while northern Lingcod fed more on various fish groups. This study fills in data gaps in the trophic ecology of a top marine predator and can inform food web models and fisheries management

Decision Making in Corporate Taxation

This dissertation is comprised of three experimental studies that examine corporate tax aggressiveness through an investigation of judgment and decision making in the corporate tax environment. Studies 1 and 2 examine individual judgment involved in decision making (i.e., assessments of tax positions based upon tax scenario facts and tax authority). Study 1 examines how advice from external tax advisors and a tax advisor\u27s association with the company\u27s audit firm influences the aggressiveness of experienced in-house corporate tax decision makers. Study 2 examines how situational factors in the corporate tax environment interact with individual traits to affect individual-level tax aggressiveness, focusing in greater depth upon the process of individual judgment and decision making. Study 3 extends the investigation of situational factors from individual-level decision making to a group-level analysis, examining individual-level and group-level decision making in a tax setting (i.e., tax compliance decisions). Overall, results reflect the complexity of the corporate tax environment. The effects of the situational factors examined in the dissertation generally influence decision makers\u27 own perceptions. For example, Study 1 results suggest that tax advisor identity influences how corporate tax directors weight advice only if the advice is conservative and if the tax directors agree with the advice. Additionally, in Studies 2 and 3, decision maker perceptions are found to mediate the effects of manipulated situational factors. In Study 2, regulatory focus state indirectly influences individual tax aggressiveness through the perception of the tax advisor\u27s level of client advocacy. In Study 3 decision maker type, a situational factor, affects tax compliance decision riskiness indirectly through feelings of responsibility for the possible outcomes of the decision. Collectively these studies contribute to the nascent literature on decision making in a corporate tax environment, helping to lay the groundwork for future studies in this area

Population Variation in the Mitochondrial-DNA of Two Marine Organisms: The Hard Shell Clam \u3ci\u3eMercenaria spp.\u3c/i\u3e and the Killifish, \u3ci\u3eFundulus Heteroclitus\u3c/i\u3e

The two major topics are covered in this dissertation: the integration of molecular genetic tools with applied aquacultural research and short-term evolutionary dynamics. The first study investigated the extent of geographic differentiation of native clam stocks along the U.S. east and Gulf coasts. Clam mitochondrial DNA (mtDNA) demonstrated size polymorphism (16.5-19.0 kb) and restriction site heteroplasmy. Size heteroplasmic individuals occurred at a frequencies of 0-89% in clam populations. Restriction site heteroplasmy occurred in 12% of the 317 individuals assayed. Results of the study indicated that although harbouring a wealth of genetic variation, clams from northern regions were similar and lacked evidence of geographic differentiation. Northern populations exhibited high probabilities of gene identity (average I = 0.882), low percent nucleotide sequence divergence (δ = 0.003), and high levels of gene flow (average Nem = 3.6). All other populations were geographically differentiated. Phylogenetic analysis of the clam taxa Mercenaria mercenaria, M. campechiensis and M. mercenaria texana detected similar degrees of divergence between all three taxa (ranging from $\delta$ = 0.053 to 0.020), indicated that the texana group may be of multiple maternal origin, and concluded that in all probability texana deserves species distinction separate from M. mercenaria. In the second section, the effect of restricted gene flow was evaluated as a possible explanation for maintenance of morphological and gene frequency clines in killifish. Effective migration rate was concluded using mtDNA haplotype frequencies for five partially isolated populations. From Fst, Nem was estimated to be 24.09. The corresponding value from a private alleles-type analysis was Nem= 18.47. These estimates indicated a very large potential for gene flow necessitating that substantial selection pressures be invoked to account for the present-day clinal distributions in F. heteroclitus

Basic Living Expenses for the Canadian Elderly

Our research undertakes to determine the basic living expenses required by Canadian seniors living in different circumstances in terms of age, gender, city of residence, household size, homeowner or renter, means of transportation and health status. The paper develops required expenses for food, shelter, health care, transportation and miscellaneous. The research identifies the typical expenses of seniors in each of these categories. Using 2001 as our base year, we follow the US Elder Standard to build an elderly threshold for Halifax, Montreal, Toronto, Calgary and Vancouver. The research is unique because it is the first Canadian study of absolute basic living expenses tailored to seniors, rather than simply to adults in general. This information is important to seniors, prospective retirees, financial planners, policy makers and actuaries in assessing the minimum level of income required in retirement and the adequacy of savings and income security programs. Our conclusions suggest that individual circumstances, rather than age, are the primary drivers in determining the cost of these basic expenses. Seniors are a diverse group, particularly with respect to health, so it is important that seniors and financial planners do not blindly rely on a fixed replacement ratio or universal level of income when projecting the level of finances needed to retire. This research enables the reader to determine the threshold that is suited to a senior’s general circumstances.Retirement Income Adequacy; Absolute Measure; Elder Standard; Canadian Data

The Canadian Elder Standard - Pricing the Cost of Basic Needs for the Canadian Elderly

We determined the after-tax income required to fi nance basic needs for Canadian elders living with different circumstances in terms of age, gender, city of residence, household size, homeowner or renter status, means of transportation, and health status. Using 2001 as our base year, we priced the typical expenses for food, shelter, medical, transportation, miscellaneous basic living items and home-based long-term care for elders living in fi ve Canadian cities. This is the fi rst Canadian study of basic living expenses tailored to elders instead of adults in general, prepared on an absolute rather than a relative basis. We also accounted for an individual’s unique life circumstances and established the varying effect that they have on the cost of basic expenses, particularly for home care. We found that the maximum Guaranteed Income Supple ment and Old Age Security benefi t did not meet the cost of basic needs for an elder living in poor circumstances.Canadian seniors, poverty measure, economic security, aging-in-place, cost-of-living, absolute measure, home care

Analysis of Change in Central Texas Using Image Differencing and Unsupervised Classification

An image differencing algorithm was applied to two Landsat MSS scenes in central Texas to assess its ability to identify change in the greater Austin, Texas metropolitan area. Near infrared data from a Landsat MSS scene acquired September 9, 1972 were subtracted from a Landsat MSS scene acquired August 24, 1990 to produce a difference image representing change in and around Austin, Texas covering a twenty year period. Results indicate that use of empirical analysis to visually identify change within a difference image is highly effective. Unsupervised classification of a difference image to identify change is dependent upon time requirements and the sensitivity of the classified image. While an unsupervised classification of a difference image with a small number of classes was shown to be time saving, it was determined to possess less subtle areas of change. Therefore, it became evident that the greater number of classes used resulted in a higher degree of identified subtle areas of change

Accuracy of Land Cover Maps Derived From Remotely Sensed Data

Accurate knowledge of land cover and land cover change is essential for a wide range of objectives. Since the 1970\u27s, remotely sensed data have been used increasingly as a means to classify and characterize the earth\u27s land use and land cover. This project compares the accuracy of results of classifying data from mid-level to very high spatial resolutions (Landsat ETM+, SPOT 4, ASTER, SPOT 5, QuickBird). Data from all of these sensors were classified for both urban and rural settings. The project examines accuracy levels between spatial and spectral resolution