31 research outputs found
Isotopic Turnover and Fractionation of δ15N and δ13C in Captive Pseudopleuronectes americanus (Walbaum)
No full textStable isotope ratios of nitrogen (δ15N) and carbon (δ13C) are ubiquitous ecological tracers used to elucidate an organism’s diet and habitat. However, the application of stable isotope ratios to reconstruct a consumer’s ecology relies upon accurate rates for isotopic turnover at both a tissue and species-specific level. This study estimated isotope turnover rates and trophic discrimination factors in four different tissues (liver, digestive tissue, muscle, and skin) with variable metabolic activity in winter flounder Pseudopleuronectes americanus using a controlled diet-switch experiment. Differences in half-lives were noted among the tissues and between the experimental diets for both δ15N and δ13C. The experimental diets of krill and mysis had variability in nutritional composition, resulting in similar turnovers in δ15N but slower turnovers in δ13C for fish fed krill. Turnovers in both δ15N and δ13C were strongly influenced by metabolism, with the contribution reaching up to 98%, as fish exhibited minimal overall growth. The results of this study demonstrate the importance of considering differences in the catabolic activity of tissue maintenance for fish exhibiting minimal growth, as well as differences in metabolic assimilation of dietary sources that vary in their protein and lipid contents
Life-Span Developmental Psychology: Midlife and Later Years in Western and Non-Western Societies
No full textThis chapter discusses the basis on which studies have been done on the later years of life in Western and non-Western cultures. It suggests that because Westerners value independence, most research on aging in Western societies has focused on how to help the individual maintain his or her functional independence throughout the life-span. Non-Westerners, on the other hand, value interdependence. Therefore, most research on aging has focused on the availability of social support in later life. But with Westernization influences in non-Western societies, there should be a shift in research efforts in order to accommodate a new understanding of aging and human development that includes the promotion of functional independence in later life
Employer Pension Plan Inequality in Canada
No full textThe purpose of this research paper is to contribute to knowledge regarding employer pension plan (EPP) inequality in Canada. Information on EPP coverage and value is analyzed using the 1999 and 2005 Surveys of Financial Security. The results indicate that women, persons who may live alone, landed immigrants, and language minorities are at a disadvantage in their EPP coverage and accrued value. In addition, age, educational attainment, occupation, industry of employment, union membership, total personal income, province, and size of urban residence figure importantly in EPP coverage. Furthermore, age, educational attainment, industry of employment, total personal income, province and size of urban residence are all important determinants of the termination value of EPPs. To identify inequalities in EPP coverage among the sub-populations, the researchers use multivariate analysis. This allows an identification of inequalities that are not a direct result of differences in age, gender, level of education, location, or position in the labour market. Findings indicate that differences in EPP coverage for women, persons who may live alone, landed immigrants and language minorities are primarily due to differences in these other characteristics. However, the lower EPP value witnessed by these sub-populations cannot be explained by individual or labour market characteristics.Employer Pension Plans, Registered Pension Plans, coverage, value, inequality, seniors, landed immigrants, gender differences, minority language
Author's personal copy Risk-sensitive information gathering by cyprinids following release of chemical alarm cues
No full textIn aquatic environments, chemical cues released during a predator attack reliably inform prey about the presence of predation risk. Prey with information about predation risk are more successful in surviving encounters with predators than are unwary prey. To remain prepared for attack, prey should continue to monitor the status of predation risk, presenting a behavioural trade-off for prey: increased distance from areas labelled with alarm cues reduces exposure to predation risk but also reduces access to information about predation risk. In two laboratory experiments we used the presence and absence of water flow in a laboratory fluvarium to test alarm response and subsequent risk-sensitive information gathering by zebrafish (Danio rerio). In response to chemical alarm cues, fish significantly reduced activity and increased use of shelters. In the absence of flow, fish sought out the shelter nearest the cue source. In the presence of flow, fish preferred to seek shelter downstream, but not upstream, of the cue source. This allowed fish to gather information about predation risk from a relatively safe distance. In a field experiment on natural populations of stream fishes, fish avoided areas where chemical alarm cues were released (versus blank water control) but primarily because they avoided the region immediately upstream of the cue source. Fish use of the area immediately downstream of cue release did not decrease. Taken together, these laboratory and field data are consistent with a trade-off between risk avoidance and information gathering.
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Assessing ecological connectivity of blacktip sharks (Carcharhinus limbatus) in the Gulf of Mexico using stable isotope analysis of multiple tissues
No full textEffective management of blacktip sharks relies on a comprehensive understanding of population distribution and stock structure. Previous stock separations and the implementation of regional quotas have proven successful in maintaining the sustainable harvest of blacktip sharks in both the Western North Atlantic and United States Gulf of Mexico (US GoM), in commercial and recreational fisheries. Within the US GoM, finer scale biological separation between blacktips in western and eastern regions has been supported through tagging, genetic, and diet data. This study provides additional evidence of unique ecological isotopic niche areas and δ15N and δ13C values for blacktip sharks from the western, central, and eastern US GoM across muscle and vertebral tissues that reflect different isotope turnover rates. Blacktip sharks from western and central regions exhibited isotope values and niches that were significantly smaller compared to eastern sharks, with enriched δ13C and depleted δ15N west of 88ºN. Ontogenetic shifts were noted for most regions and there was no crossover or overlap in average isotope values from early to recent life between regions. These spatiotemporal patterns suggest that in the year following birth and prior to the time of capture, blacktip sharks on the central and western shelves have separated ecologically from blacktips on the eastern US GoM Florida shelf
Employer Pension Plan Inequality in Canada
No full textThe purpose of this research paper is to contribute to knowledge regarding employer pension plan (EPP) inequality in Canada. Information on EPP coverage and value is analyzed using the 1999 and 2005 Surveys of Financial Security. The results indicate that women, persons who may live alone, landed immigrants, and language minorities are at a disadvantage in their EPP coverage and accrued value. In addition, age, educational attainment, occupation, industry of employment, union membership, total personal income, province, and size of urban residence figure importantly in EPP coverage. Furthermore, age, educational attainment, industry of employment, total personal income, province and size of urban residence are all-important determinants of the termination value of EPPs. To identify inequalities in EPP coverage among the sub-populations, the researchers use multivariate analysis. This allows an identification of inequalities that are not a direct result of differences in age, gender, level of education, location, or position in the labour market. Findings indicate that differences in EPP coverage for women, persons who may live alone, landed immigrants and language minorities are primarily due to differences in these other characteristics. However, the lower EPP value witnessed by these subpopulations cannot be explained by individual or labour market characteristics.Employer Pension Plans, Registered Pension Plans, coverage, value, inequality, seniors, landed immigrants, gender differences, minority language
How Much Help Is Exchanged in Families? Towards an Understanding of Discrepant Research Findings
No full textResponding to claims that contemporary families had abandoned their elderly members, gerontologists over the past 30 years have provided extensive documentation of intergenerational familial support. These studies have been lodged within conceptual frameworks of the modified extended family, intergenerational solidarity, and, more recently, intergenerational equity. By and large, studies claim to have found extensive levels of support. Closer examination of findings from various studies, however, reveals widely discrepant findings in terms of amounts of help given to and received by older family members. This paper examines the findings from four representative Canadian and American studies spanning four decades. Factors contributing to discrepant findings are identified at both methodological and conceptual levels, and implications for future research are discussed.intergenerational support
How Much Help Is Exchanged in Families? Towards an Understanding of Discrepant Research Finding
No full textResponding to claims that contemporary families had abandoned their elderly members, gerontologists over the past 30 years have provided extensive documentation of intergenerational familial support. These studies have been lodged within conceptual frameworks of the modified extended family, intergenerational solidarity, and, more recently, intergenerational equity. By and large, studies claim to have found extensive levels of support. Closer examination of findings from various studies, however, reveals widely discrepant findings in terms of amounts of help given to and received by older family members. This paper examines the findings from four representative Canadian and American studies spanning four decades. Factors contributing to discrepant findings are identified at both methodological and conceptual levels, and implications for future research are discussed.intergenerational support
The Economic Casualties of Retiring Because of Poor Health
No full textThis multimethod study investigated the effect of involuntary retirement on retirement income. Using the General Social Survey 1994, a secondary data analysis was carried out which examined the economic effects of retiring because of poor health. When the men and women who retired for reasons of poor health were compared to those who retired for other reasons, there was little doubt that the health retirees were disadvantaged on human capital variables, in terms of their work history, and ultimately, in their retirement income, whether personal or household. The men who retired because of ill health did not appear to benefit from government transfer payments and were less likely to receive income from a private pension or from interest and dividends. The women retirees suffered from the same disadvantages as the men, however, when they reached retirement they were more likely to rely on government transfer payments as a major source of income. Like the men, they were more likely to believe that their retirement income had gotten worse since the day they retired, and, over two-thirds believed that their financial situation had become much worse. In the multivariate analyses, however, any effect that poor health might have had on household income was offset by the benefits associated with marriage, and their own sociodemographic characteristics. This is further confirmed when personal income is considered, since marriage has the strong and negative influence on personal income. The interviews with the retirees indicated that retiring for reasons of poor health was seen by most people as a somewhat unpleasant transition that had long lasting and negative effects on retirement income.GSS; poor health; retirement
