An ecological framework for contextualizing carnivore–livestock conflict

Carnivore predation on livestock is a complex management and policy challenge, yet it is also intrinsically an ecological interaction between predators and prey. Human–wildlife interactions occur in socioecological systems in which human and environmental processes are closely linked. However, underlying human–wildlife conflict and key to unpacking its complexity are concrete and identifiable ecological mechanisms that lead to predation events. To better understand how ecological theory accords with interactions between wild predators and domestic prey, we developed a framework to describe ecological drivers of predation on livestock. We based this framework on foundational ecological theory and current research on interactions between predators and domestic prey. We used this framework to examine ecological mechanisms (e.g., density-mediated effects, behaviorally mediated effects, and optimal foraging theory) through which specific management interventions operate, and we analyzed the ecological determinants of failure and success of management interventions in 3 case studies: snow leopards (Panthera uncia), wolves (Canis lupus), and cougars (Puma concolor). The varied, context-dependent successes and failures of the management interventions in these case studies demonstrated the utility of using an ecological framework to ground research and management of carnivore–livestock conflict. Mitigation of human–wildlife conflict appears to require an understanding of how fundamental ecological theories work within domestic predator–prey systems.     

Maximum nitrogen removal in the step-feed activated sludge process.

This paper presents a mathematical framework that can be used to determine the flow distributions for a step-feed activated sludge process that result in maximum nitrogen removal. The model indicates that nitrogen removal efficiency in a step-feed activated sludge process is highly dependent on the ultimate biochemical oxygen demand (BOD(L))-to-total Kjeldahl nitrogen (TKN) ratio of the wastewater. For typical domestic wastewater, which has a relatively high BOD(L)-to-TKN ratio, the step-feed process will outperform the Modified Ludzack-Ettinger process for nitrogen removal, when the flow to each step is optimally distributed. Using plant-specific water quality data and operating conditions from a 1-year period, nitrogen removal performance for four step-feed activated sludge plants operated by the Sanitation Districts of Los Angeles County (California) was calculated using the developed model. The calculated nitrogen removal efficiencies match well with the actual plant performance data. These results validate the model as a useful tool for predicting nitrogen removal in a step-feed activated sludge process. Other analyses revealed that improvements in nitrogen removal at existing facilities are achievable by adjusting the split of primary effluent flow to each anoxic zone several times during the day. The timing of the adjustments and the optimal flow splits can be determined from data on diurnal fluctuations in BOD(L) and TKN concentrations. An example is provided to illustrate the application of such an operating strategy and the potential enhancement of nitrogen removal.     

Discrimination between nestmate and non-nestmate kin by social wasps (Polistes fuscatus,Hymenoptera: Vespidae)

Summary The threespine stickleback,Gasterosteus aculeatus is a voracious cannibal of both its own eggs and those of conspecific neighbours. Females, but not males, can distinguish their progeny from those of other fish and attacked alien eggs more frequently. In experiments to examine nest raiding, females that initiated raids on nests resulting in cannibalism were the first females to spawn in the reconstructed nest. These results support the hypothesis that cannibalism by females may be adaptive in situations where intense female competition for male guardians occurs.     

Synergistic interactions between chemical alarm cues and the presence of conspecific and heterospecific fish shoals

Chemical and visual sources of information are used by aquatic prey during risk assessment. Here, we test the behavioral response of littoral prey fish to combinations of chemical alarm cues (skin extract) and the visual presence of a fish shoal. We scented minnow traps with either alarm cues or water (control) placed inside the trap, a jar that contained either a fish shoal or nothing (control), and recorded the number and species of fish captured. We predicted that chemical alarm cues would reduce the number of fish captured and that a fish shoal would increase the number of fish captured. The predicted effect of chemical and visual cues combined depended on the nature of the interaction. We found that the lowest catch rate was for the combination of alarm cue + no shoal, but the highest catch rate occurred for the combination of alarm cue + shoal. Fish shoal + water had the second highest catch rate and no shoal + water had the second lowest catch rate. We conclude that chemical alarm cues induce area avoidance in the absence of a shoal, but a strong behavioral proclivity to increase shoal cohesion in the presence of a shoal. The presence of a shoal in the traps induced alarmed fish to shoal with them and thus, enter the traps. This occurred even though traps were the source of the alarm cue.Communicated by A. Mathis     

Taproot™ technology: Tree coring for fast,noninvasive plume delineations

In efforts to evaluate the use of plants as a forensic tool for delineating contaminated soil and groundwater, a laboratory experiment and a field sampling effort were undertaken. Site assessments are often costly and inaccurate, requiring multiple mobilizations to hone in on source areas and getting accurate estimates of contaminant extent and distribution. As these extensive site delineations take place, valuable time and resources are lost. The findings of this study show that plants can be used as a tool to evaluate a variety of subsurface contaminants, either in the vadose zone or in the saturated zone. In the first field application of Taproot? Technology, a large, heavily forested site was sampled in one day and the contamination on‐site was more accurately delineated than had been generated at the site in over a decade, with more than 26 wells installed. New source zones were detected on the site, and the presence of new waste depositions was uncovered for the first time showing the great value of tree coring as a contaminant detection tool. © 2009 Wiley Periodicals, Inc.     

Marijuana trajectories and associations with driving risk behaviors in Canadian youth

Objective: Research on risky driving practices involving marijuana use among youth and young adults often relies on cross-sectional data, which fail to account for longitudinal changes in substance use patterns. A better understanding of the longitudinal patterns of marijuana use and its effect on risky driving practices during young adulthood is needed in order to better inform prevention efforts. The current study examined whether different longitudinal patterns of marijuana use across the transition from adolescence to young adulthood are associated with impaired driving risks in young adulthood.

Methods: Data were from the longitudinal Victoria Healthy Youth Survey, which interviewed youth biennially on 6 occasions across 10 years (2003 to 2013).

Results: Youth who reported consistently high levels of marijuana use from adolescence to young adulthood (chronic users) and youth who reported increasing levels of use across this period (increasers) were more likely to engage in risky impaired driving behaviors compared to the other 3 user groups (occasional users, decreasers, and abstainers). Frequency of marijuana use was also predictive of impaired driving risks in young adulthood after controlling for individual characteristics (age, sex, socioeconomic status, age of onset of marijuana use), frequency of other substance use (heavy episodic drinking and illicit drug use), and simultaneous use of marijuana and other substances (alcohol and illicit drugs). By young adulthood, youth who use marijuana more than once a week are more likely to simultaneously use alcohol and engage in heavy episodic drinking. They are also more likely take driving risks.

Conclusions: Harm reduction strategies and legislative approaches targeting impaired driving risks associated with marijuana use should include approaches to target these high-risk groups and to reduce simultaneous use of alcohol.     

Development of Sediment and Nutrient Export Coefficients for U.S. Ecoregions

Water quality impairment due to excessive nutrients and sediment is a major problem in the United States (U.S.). An important step in the mitigation of impairment in any given water body is determination of pollutant sources and amount. The sheer number of impaired waters and limited resources makes simplistic load estimation methods such as export coefficient (EC) methods attractive. Unfortunately ECs are typically based on small watershed monitoring data, which are very limited and/or often based on data collected from distant watersheds with drastically different conditions. In this research, we seek to improve the accuracy of these nutrient export estimation methods by developing a national database of localized EC for each ecoregion in the U.S. A stochastic sampling methodology loosely based on the Monte‐Carlo technique was used to construct a database of 45 million Soil and Water Assessment Tool (SWAT) simulations. These simulations consider a variety of climate, topography, soils, weather, land use, management, and conservation implementation conditions. SWAT model simulations were successfully validated with edge‐of‐field monitoring data. Simulated nutrient ECs compared favorably with previously published studies. These ECs may be used to rapidly estimate nutrient loading for any small catchment in the U.S. provided the location, area, and land‐use distribution are known.