A pattern-oriented modelling approach to simulating populations of grey partridge

A number of wildlife species including the grey partridge (Perdix perdix) have shown dramatic post-war population declines. Multiple drivers have been proposed as reasons for the declines, for example agrochemical use and intensification of agricultural practices, climate, predation, and changes in landscape structure. These drivers may interact in non-linear ways and are inherently spatio-temporal in nature. Therefore models used to investigate mechanisms should be spatio-temporal, of proper scale, and have a high degree of biological realism. Here we describe the development and testing of an agent-based model (ABM) of grey partridge using a well documented pre-decline historical data set in conjunction with a pattern-oriented modelling (POM) approach. Model development was an iterative process of defining performance criteria, testing model behaviour, and reformulating as necessary to emulate system properties whilst ensuring that internal mechanisms were biologically realistic. The model was documented using ODdox, a new protocol for describing large agent-based models. Parameter fitting in the model was achieved to within ±2% accuracy for 15 out of 17 field data patterns used, and within 5% for the remaining two. Tests of interactions between input parameters showed that 62% of parameter pairs tested had significant interactions underlining the complex nature of the model structure. Sensitivity analysis identified chick mortality as being the most sensitive factor, followed by adult losses to hunting and adult overwinter mortality, agreeing in general with previous partridge models. However, the ABM used here could separate individual drivers, providing a better understanding of the underlying mechanisms behind population regulation, and allowing factors to be compared directly. The ABM used is rich in output signals allowing detailed testing and refinement of the model. This approach is particularly suited to systems such as the partridge system where data for comparison to model outputs is readily available. Despite the accurate fit between historical data and model output, making use of the predictive power of the approach the model requires further calibration and testing under modern field conditions.     

A Voronoi diagram based population model for social species of wildlife

A population model is presented that accounts for spatial structure within habitat patches. It is designed for social species of wildlife that form social group home ranges that are much smaller than patch size. The model represents social group home ranges by Voronoi regions that tessellate a patch to form a Voronoi diagram. Neighbouring social groups are linked with habitat-confined shortest paths and form a dispersal network. The model simulates population dynamics and makes use of Voronoi diagrams and dispersal networks as a spatial component. It then produces density maps as outputs. These are maps that show predicted animal densities across the patches of a landscape. A construction procedure for the particular Voronoi diagram type used by the model is described. As a test case, the model is run for the squirrel glider (Petaurus norfolcensis), a small arboreal marsupial native to Australia. A time series of density maps are produced that show squirrel glider density changing across a landscape through time.     

Multifoci effects of injustice on counterproductive work behaviors and the moderating roles of symbolization and victim sensitivity

Past research suggests that employees, in response to workplace experiences, selectively engage in targeted counterproductive work behaviors (CWBs). Taking a retributive justice and target similarity perspective, we predict that employee perceptions of unfairness from the organization uniquely predict CWB specifically targeted at the organization whereas employee perceptions of supervisory unfairness uniquely predict CWB specifically targeted at the supervisor. We further hypothesized that moral identity‐symbolization would strengthen these target‐similar relationships. Finally, drawing from the sensitivity to mean intentions model, we hypothesized that victim sensitivity would not only strengthen these target‐similar relationships but also lead to cross‐foci effects of multifoci fairness perceptions on targets of CWB. Results from 3 field studies of full‐time employees provided support for most of our hypothesized relationships.     

Anti-biofilm Activity of Solvent-Cast and Electrospun Polyhydroxyalkanoate Membranes Treated with Lysozyme

Biofilms consist of groups of microorganisms that adhere to surfaces, such as wound and implant surfaces, making it difficult to prevent or remove their formation by antibiotic treatment, due to the innate resistance of the biofilm. Effective treatments of medical biofilms are limited. Polyhydroxyalkanoate (PHA) is a biodegradable and biocompatible polymer that is a suitable alternative to petroleum based polymers for use as a raw material for medical applications. In this study, membranes of the copolymer poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(HB-co-HHx)] containing different HHx monomer contents were used due to its porosity and flexibility, and different sheets were prepared by solvent-casting and electrospinning methods. The sheets were loaded with lysozyme in order to measure the maximum amount of protein adsorption and to examine the ability of immobilized enzyme to inhibit biofilm formation and detach previously established biofilms. Our results have shown maximum loading of 16.1 µg enzyme per 9.5 mm³ discs, and these sheets are effective for inhibiting biofilm formation. Also, lysozyme loaded, eletrospun sheets were observed to more effectively inhibit biofilm formation, as compared to solvent-cast sheets. Based on this study, P(HB-co-HHx) sheets are a suitable material for being used as a potential raw material for fabrication of wound dressings to be used in anti-biofilm treatments.     

Creating sustainable communities: skills and learning in Ontario’s small urban municipalities

This article presents the pilot study results of a province-wide survey of skills and learning in sustainable community development in Ontario, Canada. The pilot project focuses on the testing of an online survey to examine skills building for creating sustainable communities in Ontario’s small urban municipalities. The survey examined the generic, technical and specialist skills, whether they are skills already acquired and/or required by professionals and practitioners for creating sustainable communities. The survey targeted 74 small urban municipalities and 300 respondents by profession. Building sustainable communities require ‘upskilling’ of the workforce as it poses a challenge to those hoping to make a real progress and development at the local level.     

Evaluation of a combined macrophyte–epiphyte bioassay for assessing nutrient enrichment in the Portneuf River,Idaho, USA

We describe and evaluate a laboratory bioassay that uses Lemna minor L. and attached epiphytes to characterize the status of ambient and nutrient-enriched water from the Portneuf River, Idaho. Specifically, we measured morphological (number of fronds, longest surface axis, and root length) and population-level (number of plants and dry mass) responses of L. minor and community-level (ash-free dry mass [AFDM] and chlorophyll a [Chl a]) responses of epiphytes to nutrient enrichment. Overall, measures of macrophyte biomass and abundance increased with increasing concentrations of dissolved phosphorus (P) and responded more predictably to nutrient enrichment than morphological measures. Epiphyte AFDM and Chl a were also greatest in P-enriched water; enrichments of N alone produced no measurable epiphytic response. The epiphyte biomass response did not directly mirror macrophyte biomass responses, illustrating the value of a combined macrophyte–epiphyte assay to more fully evaluate nutrient management strategies. Finally, the most P-enriched waters not only supported greater standing stocks of macrophyte and epiphytes but also had significantly higher water column dissolved oxygen and dissolved organic carbon concentrations and a lower pH. Advantages of this macrophyte–epiphyte bioassay over more traditional single-species assays include the use of a more realistic level of biological organization, a relatively short assay schedule (~10 days), and the inclusion of multiple biological response and water-quality measures.     

Fluvial transport and surface enrichment of arsenic in semi-arid mining regions: examples from the Mojave Desert, California

As a result of extensive gold and silver mining in the Mojave Desert, southern California, mine wastes and tailings containing highly elevated arsenic (As) concentrations remain exposed at a number of former mining sites. Decades of weathering and erosion have contributed to the mobilization of As-enriched tailings, which now contaminate surrounding communities. Fluvial transport plays an intermittent yet important and relatively undocumented role in the migration and dispersal of As-contaminated mine wastes in semi-arid climates. Assessing the contribution of fluvial systems to tailings mobilization is critical in order to assess the distribution and long-term exposure potential of tailings in a mining-impacted environment. Extensive sampling, chemical analysis, and geospatial mapping of dry streambed (wash) sediments, tailings piles, alluvial fans, and rainwater runoff at multiple mine sites have aided the development of a conceptual model to explain the fluvial migration of mine wastes in semi-arid climates. Intense and episodic precipitation events mobilize mine wastes downstream and downslope as a series of discrete pulses, causing dispersion both down and lateral to washes with exponential decay behavior as distance from the source increases. Accordingly a quantitative model of arsenic concentrations in wash sediments, represented as a series of overlapping exponential power-law decay curves, results in the acceptable reproducibility of observed arsenic concentration patterns. Such a model can be transferable to other abandoned mine lands as a predictive tool for monitoring the fate and transport of arsenic and related contaminants in similar settings. Effective remediation of contaminated mine wastes in a semi-arid environment requires addressing concurrent changes in the amounts of potential tailings released through fluvial processes and the transport capacity of a wash.     

Comparison of precipitation chemistry measurements obtained by the Canadian Air and Precipitation Monitoring Network and National Atmospheric Deposition Program for the period 1995–2004

Precipitation chemistry and depth measurements obtained by the Canadian Air and Precipitation Monitoring Network (CAPMoN) and the US National Atmospheric Deposition Program/National Trends Network (NADP/NTN) were compared for the 10-year period 1995–2004. Colocated sets of CAPMoN and NADP instrumentation, consisting of precipitation collectors and rain gages, were operated simultaneously per standard protocols for each network at Sutton, Ontario and Frelighsburg, Ontario, Canada and at State College, PA, USA. CAPMoN samples were collected daily, and NADP samples were collected weekly, and samples were analyzed exclusively by each network’s laboratory for pH, H^?+?, Ca^2?+?, Mg^2?+?, Na^?+?, K^?+?, $\text{NH}_{4}^{+}$ , Cl^???, $\text{NO}_{3}^{-}$ , and $\text{SO}_{4}^{2-}$ . Weekly and annual precipitation-weighted mean concentrations for each network were compared. This study is a follow-up to an earlier internetwork comparison for the period 1986–1993, published by Alain Sirois, Robert Vet, and Dennis Lamb in 2000. Median weekly internetwork differences for 1995–2004 data were the same to slightly lower than for data for the previous study period (1986–1993) for all analytes except $\text{NO}_{3}^{-}$ , $\text{SO}_{4}^{2-}$ , and sample depth. A 1994 NADP sampling protocol change and a 1998 change in the types of filters used to process NADP samples reversed the previously identified negative bias in NADP data for hydrogen-ion and sodium concentrations. Statistically significant biases (α = 0.10) for sodium and hydrogen-ion concentrations observed in the 1986–1993 data were not significant for 1995–2004. Weekly CAPMoN measurements generally are higher than weekly NADP measurements due to differences in sample filtration and field instrumentation, not sample evaporation, contamination, or analytical laboratory differences.     

Behavioural responses of indigenous benthic invertebrates (Echinogammarus meridionalis, Hydropsyche pellucidula and Choroterpes picteti) to a pulse of Acid Mine Drainage: a laboratorial study

The drainage of abandoned mines leads to several ecological problems, particularly the acidification of surface freshwater systems and heavy metal contamination. In order to study the possibility of using the behavioural early warning responses of Portuguese indigenous benthic invertebrates to detect an acute short-term pulse of Acid Mine Drainage (AMD), experiments with the Multispecies Freshwater Biomonitor MFB™ were performed and locomotion and ventilation were measured as endpoints. AMD was collected from the “São Domingos” mine (Southeast Portugal) and the following species were selected: Echinogammarus meridionalis (Pinkster, 1973), Hydropsyche pellucidula (Curtis, 1834) and Choroterpes picteti (Eaton, 1870). For simulating the pulsed exposure, AMD was added to river water where invertebrates were collected and pH was lowered until reaching 3.5. The effects of H⁺ and heavy metals were discriminated using HCl positive controls. In addition to behaviour, mortality was registered. E. meridionalis was the most sensitive species in terms of mortality and behavioural endpoints, followed by C. picteti and H. pellucidula. E. meridionalis early warning responses consisted of increased locomotion with subsequent increase in ventilation, whereas for C. picteti only an increase in locomotion was observed. H. pellucidula showed no early warning responses. This work demonstrates the suitableness of using benthic invertebrates' behavioural early warning responses for detecting spikes of pollutants like AMD.