Modelling the responses of wildlife to human disturbance: An evaluation of alternative management scenarios for black-crowned night-herons

The impact of anthropogenic disturbance on wildlife is increasing becoming a source of concern as the popularity of outdoor recreation rises. There is now more pressure on site managers to simultaneously ensure the continued persistence of wildlife and provide recreational opportunities. Using ‘Simulation of Disturbance Activities’, a model designed to investigate the impact of recreational disturbance on wildlife, we demonstrate how a simulation modelling approach can effectively inform such management decisions. As an example, we explored the implications of various design and management options for a proposed recreational area containing a historic breeding bird colony. By manipulating the proximity, orientation and intensity of recreation, we were able to evaluate the impact of recreational activities on the behaviour of black-crowned night-heron nestlings (Nycticorax nycticorax). Using a classification and regression tree (CART) procedure to analyse simulation output, we explored the dynamics of multiple strategies in concert. Our analysis revealed that there are inherent advantages in implementing multiple strategies as opposed to any single strategy. Nestlings were not disturbed by recreation when bird-watching facility placement (proximity and orientation) and type were considered in combination. In comparison, proximity alone only led to a <10% reduction in disturbance. Thus we demonstrate how simulation models based on customised empirical data can bridge the gap between field studies and active management, enabling users to test novel management scenarios that are otherwise logistically difficult. Furthermore, such models potentially have broad application in understanding human-wildlife interactions (e.g. exploring the implications of roads on wildlife, probability of bird strikes around airports, etc.). They therefore represent a valuable decision-making tool in the ecological design of urban infrastructures.     

Female lizards discriminate between potential reproductive partners using multiple male traits when territory cues are absent

Female choice can powerfully influence the evolution of male phenotypes. In territorial species, it is challenging to determine the targets of female choice because male traits (e.g., behavior and morphology) are often correlated with territory. We sought to elucidate if and how females specifically evaluate male traits in a territorial species. In this study, we presented female fence lizards, Sceloporus undulatus, with two potential mates to examine mate choice in the absence of territory cues. Females associated more with males possessing better body condition, longer heads, and wider throat badges, and that performed more shudder behavior, which females responded to by approaching shuddering males and performing push-ups. A post hoc decision tree analysis suggests that the strongest predictor of female association was an overall quality index that incorporates all of these traits, rather than individual traits. Male snout–vent length, head width, abdominal badge width, and push-up behavior did not affect female association. Further research on why these traits, which are known to correlate with fitness, do not appear to be used by females when selecting mates would improve our understanding of the evolution of male traits. Our study reveals that females of this territorial species possess the ability to use multiple male traits interactively to make fitness-relevant mate choice decisions in the absence of direct territory cues.     

MACROSCALE HYDROLOGIC MODELING FOR REGIONAL CLIMATE ASSESSMENT STUDIES IN THE SOUTHEASTERN UMTED STATES1

ABSTRACT: A macroscale hydrologic model is developed for regional climate assessment studies under way in the southeastern United States. The hydrologic modeling strategy is developed to optimize spatial representation of basin characteristics while maximizing computational efficiency. The model employs the “grouped response unit” methodology, which follows the natural drainage pattern of the area. First order streams are delineated and their surface characteristics are tested so that areas with statistically similar characteristics can be combined into larger computational zones for modeling purposes. Hydrologic response units (HRU) are identified within the modeling units and a simple three‐layer water balance model, Soil and Water Assessment Tool (SWAT), is executed for each HRU. The runoff values are then convoluted using a triangular unit hydrograph and routed by Muskingum‐Cunge method. The methodology is shown to produce accurate results relative to other studies, when compared to observations. The model is used to evaluate the potential error in hydrologic assessments when using GCM predictions as climatic input in a rainfall‐runoff dominated environment. In such areas, the results from this study, although limited in temporal and spatial scope, appear to imply that use of GCM climate predictions in short term quantitative analyses studies in rainfall‐runoff dominated environments should proceed with caution.     

Defensive and chemical characterization of the froth produced by the cercopid Aphrophora cribrata

Nymphs of the cercopid Aphrophora cribrata cover themselves with a frothy exudate while ingesting sap from their preferred host plant, the eastern white pine, Pinus strobus. Chemical analyses of froth collected from A. cribrata nymphs revealed an array of metabolites belonging to five chemical classes, including fatty acid-derived alcohols, γ-lactones and a single 1-monoacylglycerol, as well as the polyol pinitol and the polyhydroxyalkanoate, poly-3-hydroxybutyrate. Bioassays showed the natural A. cribata froth, as well as a synthetic mixture comprised of representative compound classes identified therein, to be repellent to ants but largely devoid of topical irritancy in tests with cockroaches.     

Using a reverse auction to promote household level stormwater control

Phase II of the US Environmental Protection Agency's (USEPA) National Pollution Discharge Elimination System (NPDES) stormwater regulations requires communities smaller than 100 000 residents to meet new criteria for stormwater runoff reduction. In many cases these smaller communities have no established stormwater utility, and are investigating alternatives for complying with these new, sometimes expensive requirements. We note that it might be cost effective for some communities to encourage homeowners to control stormwater runoff at the parcel level instead of, or in conjunction with more traditional large, infrastructural best management practices (BMP). We go onto argue that in the absence of a strict regulatory cap, an auction is a cost-effective tool for implementing controls on stormwater runoff quantity at the parcel level. In this paper, we test the effectiveness of a procurement auction as the coordinating mechanism for encouraging installation of parcel-scale rain gardens and rain barrels within a small suburban watershed in the Midwest. The auction, which was conducted in spring 2007 and 2008, resulted in installation of 81 gardens and 165 barrels on 107 of the 350 eligible properties. Average cost per liter of runoff detention in both years was $0.36 for gardens and $0.59 for barrels. Interestingly, approximately 55% of the bids were for $0, suggesting that an educational campaign may result in substantial runoff mitigation if utilities paid for the installation of stormwater management practices. However, we found that an auction promoted more participation than education alone and at a cheaper per-unit control cost than a flat stormwater control payment plan. Overall, this study demonstrates that relatively minimal financial incentives can result in homeowners’ willingness-to-accept stormwater management practices on their property, thus opening an important avenue for retrofitting watersheds that are largely in private ownership.     

Experimental and numerical investigation of confined explosion in a blast chamber

An experimental blast program consisting of four tests was conducted in a blast chamber to investigate the effects of cylindrical charges on the peak reflected overpressure and impulse on the wall of the chamber. The charge mass varied from 0.095 kg to 0.2 kg and the standoff distance remained constant at 1.5 m and 1.3 m for the axial and radial directions, respectively. Eight pressure transducers were used in each test to measure the reflected overpressures on confined chamber walls at key locations. A high speed camera was used to record footage of each blast event. The test results indicated that UFC-3-340-02 (Unified Facilities Criteria, 2008) gives a significantly lower prediction for the axially oriented cylindrical charge, and also underestimates the radially oriented cylinder. Another purpose of the blast program was to develop an experimental data set which would validate the AUTODYN model. This would enable the validated AUTODYN model to be used with confidence to generate the overpressure and impulse distribution on a structural element for varying parameters such as the charge shape and charge orientations. Based on the simulated results a new blast model for cylindrical charges has been proposed by considering blast loading on the same level as the charge across the longitudinal direction.     

Seasonal and annual dynamics of harmful algae and algal toxins revealed through weekly monitoring at two coastal ocean sites off southern California, USA

Reports of toxic harmful algal blooms (HABs) attributed to the diatom Pseudo-nitzschia spp. have been increasing in California during the last several decades. Whether this increase can be attributed to enhanced awareness and monitoring or to a dramatic upswing in the development of HAB events remains unresolved. Given these uncertainties, the ability to accurately and rapidly identify an emerging HAB event is of high importance. Monitoring of HAB species and other pertinent chemical/physical parameters at two piers in southern California, Newport and Redondo Beach, was used to investigate the development of a site-specific bloom definition for identifying emerging domoic acid (DA) events. Emphasis was given to abundances of the Pseudo-nitzschia seriata size category of Pseudo-nitzschia due to the prevalence of this size class in the region. P. seriata bloom thresholds were established for each location based on deviations from their respective long-term mean abundances, allowing the identification of major and minor blooms. Sixty-five percent of blooms identified at Newport Beach coincided with measurable DA concentrations, while 36 % of blooms at Redondo Beach coincided with measurable DA. Bloom definitions allowed for increased specificity in multiple regression analysis of environmental forcing factors significant to the presence of DA and P. seriata. The strongest relationship identified was between P. seriata abundances 2 weeks following upwelling events at Newport Beach.     

The chemistry and behaviour of antimony in the soil environment with comparisons to arsenic: A critical review

This article provides a critical review of the environmental chemistry of inorganic antimony (Sb) in soils, comparing and contrasting findings with those of arsenic (As). Characteristics of the Sb soil system are reviewed, with an emphasis on speciation, sorption and phase associations, identifying differences between Sb and As behaviour. Knowledge gaps in environmentally relevant Sb data for soils are identified and discussed in terms of the limitations this imposes on understanding the fate, behaviour and risks associated with Sb in environmental soil systems, with particular reference to mobility and bioavailability.     

Issues in Water Quality Trading: Introduction to Featured Collection1

Heberling, Matthew T., 2011. Issues in Water Quality Trading: Introduction to Featured Collection. Journal of the American Water Resources Association (JAWRA) 47(1):1‐4. DOI: 10.1111/j.1752‐1688.2011.00510.x