Biological and environmental influences on the trophic ecology of leatherback turtles in the northwest Atlantic Ocean

Understanding the causes and consequences of variability in trophic status is important for interpreting population dynamics and for identifying important habitats for protected species like marine turtles. In the northwest Atlantic Ocean, many leatherback turtles (Dermochelys coriacea) from distinct breeding stocks throughout the Wider Caribbean region migrate to Canadian waters seasonally to feed, but their trophic status during the migratory and breeding cycle and its implications have not yet been described. In this study, we used stable carbon and nitrogen isotope analyses of bulk skin to characterize the trophic status of leatherbacks in Atlantic Canadian waters by identifying trophic patterns among turtles and the factors influencing those patterns. δ¹⁵N values of adult males and females were significantly higher than those of turtles of unknown gender (i.e., presumed to be subadults), and δ¹⁵N increased significantly with body size. We found no significant differences among average stable isotope values of turtles according to breeding stock origin. Significant inter-annual variation in δ¹⁵N among cohorts probably reflects broad-scale oceanographic variability that drives fluctuations in stable isotope values of nutrient sources transferred through several trophic positions to leatherbacks, variation in baseline isotope values among different overwintering habitats used by leatherbacks, or a combination of both. Our results demonstrate that understanding effects of demographic and physiological factors, as well as oceanographic conditions, on trophic status is key to explaining observed patterns in population dynamics and for identifying important habitats for widely distributed, long-lived species like leatherbacks.     

Soil-plant nitrogen isotope composition and nitrogen cycling after biochar applications

Environmental Science and Pollution Research - Biochar has strong potential to improve nitrogen (N) use efficiency in both agricultural and horticultural systems. Biochar is usually co-applied with...     

College and university environmental programs as a policy problem (part 1): integrating knowledge, education, and action for a better world?

The environmental sciences/studies movement, with more than 1000 programs at colleges and universities in the United States and Canada, is unified by a common interest??ameliorating environmental problems through empirical enquiry and analytic judgment. Unfortunately, environmental programs have struggled in their efforts to integrate knowledge across disciplines and educate students to become sound problem solvers and leaders. We examine the environmental program movement as a policy problem, looking at overall goals, mapping trends in relation to those goals, identifying the underlying factors contributing to trends, and projecting the future. We argue that despite its shared common interest, the environmental program movement is disparate and fragmented by goal ambiguity, positivistic disciplinary approaches, and poorly rationalized curricula, pedagogies, and educational philosophies. We discuss these challenges and the nature of the changes that are needed in order to overcome them. In a subsequent article (Part 2) we propose specific strategies for improvement.     

When the dark ones become darker: How promotion focus moderates the effects of the dark triad on supervisor performance ratings

The current study adds to a growing body of research on dark personality traits by investigating the moderating role of promotion focus on the relationships among dark triad traits and facets of job performance. Specifically, we investigated the effects of the dark triad (i.e., Machiavellianism, narcissism, and psychopathy) on supervisor ratings of performance, and the moderating effect promotion focus has on those effects. Using field data, we surveyed 549 employees from a manufacturing company in the USA and obtained supervisor ratings of task performance and helping behavior for each employee. We found support for multiple hypotheses, which suggests that managers rated narcissistic and psychopathic employees as having poorer task performance and psychopathic employees as engaging in fewer helping behaviors than employees low in those traits. Furthermore, promotion focus strengthened these negative relationships. We did not find these effects for Machiavellianism. Implications of these findings for future dark personality research as well as the practical implications for managers and organizations are discussed. Copyright © 2015 John Wiley & Sons, Ltd.     

Near term mitigation policy for global change under uncertainty: Minimizing the expected cost of meeting unknown concentration thresholds

An aggregate integrated assessment model is used to investigate the relative merits of hedging over the near term against the chance that atmospheric concentrations of carbon dioxide will be limited as a matter of global policy. Hedging strategies are evaluated given near term uncertainty about the targeted level of limited concentrationsand the trajectory of future carbon emissions. All uncertainty is resolved in the year 2020, and strategies that minimize the expected discounted value of the long term cost of abatement, including the extra cost of adjusting downstream to meet unexpected concentration limits along unanticipated emission trajectories, are identified. Even with uncertainties that span current wisdom on emission futures and restriction thresholds that run from 550 ppm through 850 ppm, the results offer support for at most modest abatement response over the next several decades to the threat of global change.     

VALUE OF WOODY RWER CORRIDORS IN LEVEE PROTECTION ALONG THE MISSOURI RWER IN 19931

ABSTRACT: Following the Midwest flood of 1993, a study was initiated along a 39-mile segment of the Missouri River to determine if there was an association between woody corridors and levee stability. A systematic sample of levee failures revealed that primary levees which did not fail had a significantly wider woody corridor than failed levees. Analysis of the total inventory of failed levees revealed that as the width of the woody corridor decreased, the length of the levee failure increased. Number of levee failures and their severity of damage could be reduced if woody corridors were at least 300 feet wide.