Biodiversity of the ground-dwelling spider fauna of afforestation habitats

The aim of this study was to assess spider diversity among habitats that are typically used for afforestation in Ireland, and to identify habitat parameters which could potentially be used as indicators of their biodiversity value. Ground-dwelling spiders were surveyed in 24 sites across Ireland, with eight sites of each of the following habitat types: improved grassland, wet grassland and peatland. The spiders were sampled using pitfall traps which were located within the major vegetation types present in each site as well as within supplementary habitat features which may add to biodiversity value of the whole site such as hedgerows, flushes and the edges of ditches and streams.Each habitat supported distinct spider assemblages that reflect major differences in both environmental conditions and management regime. The improved grasslands had low spider species richness and low variation in assemblage structure which is probably related to the intensive management of this habitat. In this case hedgerows maybe an important aspect of the spider diversity within agricultural landscapes. The peatlands, and to a lesser extent wet grasslands, supported a diverse and specialist spider fauna, including a number of rare species; this may be due to differences in soil moisture and plant architecture. Indicators of biodiversity value identified included wet flushes in the peatlands and low grazing pressure in the wet grasslands. This study suggests that in terms of biodiversity value improved grassland is the preferable habitat for afforestation, because of the poor baseline spider diversity. However, it may be unrealistic to expect land owners to afforest their most productive agricultural land, so the management and habitat indicators identified in this study may be of use for assessing habitat quality among the wet grassland and peatlands to allow sites with lower biodiversity value to be identified.     

Envisioning robust climate change adaptation futures for coastal regions: a comparative evaluation of cases in three continents

The paper reports on a comparative study of three different cases on vision and strategy development for climate change adaptation planning in (i) The South African Breede–Overberg Catchment, (ii) The Mississippi Estuary-New Orleans region and (iii) The Dutch Rhine-Meuse Estuary. The objective of the paper is twofold: to develop a better understanding of such processes and to further develop the Backcasting-Adaptive Management (BCAM) methodology. A framework for case evaluation is developed using six dimensions: (i) inputs and resources, (ii) future vision, (iii) stakeholder engagement, (iv) methodological aspects, (v) pathway development and (vi) impact. Major conclusions based on a cross-case comparison and testing propositions are (i) participatory vision development is a strong tool for climate change adaptation planning in different governance contexts and shows considerable diversity in its application in these contexts; (ii) a single, shared future vision is not a prerequisite for vision and pathway development and endorsement; (iii) broad stakeholder engagement enriches strategy development, but the involvement of marginal groups requires additional efforts and capacity building; (iv) multiple pathways and robust elements are useful but require novel expertise; and (v) more institutional embeddedness and support for participatory processes lead to better implementation of the outcomes of these processes.     

Does contrast between eggshell ground and spot coloration affect egg rejection?

Obligate avian brood parasitic species impose the costs of incubating foreign eggs and raising young upon their unrelated hosts. The most common host defence is the rejection of parasitic eggs from the nest. Both egg colours and spot patterns influence egg rejection decisions in many host species, yet no studies have explicitly examined the role of variation in spot coloration. We studied the American robin Turdus migratorius, a blue-green unspotted egg-laying host of the brown-headed cowbird Molothrus ater, a brood parasite that lays non-mimetic spotted eggs. We examined host responses to model eggs with variable spot coloration against a constant robin-mimetic ground colour to identify patterns of rejection associated with perceived contrast between spot and ground colours. By using avian visual modelling, we found that robins were more likely to reject eggs whose spots had greater chromatic (hue) but not achromatic (brightness) contrast. Therefore, egg rejection decision rules in the American robin may depend on the colour contrast between parasite eggshell spot and host ground coloration. Our study also suggests that egg recognition in relation to spot coloration, like ground colour recognition, is tuned to the natural variation of avian eggshell spot colours but not to unnatural spot colours.     

New tools and strategies for the inspection of the psychosocial working environment: The experience of the Danish Working Environment Authority

In 2007 the Danish Working Environment Authority launched a new strategy to strengthen and qualify primary prevention of work related stress. Part of the strategy consists of increased inspections of the psychosocial working environment as well as the development and implementation of a new inspection tool, namely the “guidance tool”.Twenty-four sector specific guidance tools have been developed to help WEA inspectors assess psychosocial working environment problems in all Danish enterprises. Based on recent research, the guidance tools consist, in each sector, of the three to five most important risk factors (for example quantitative demands, emotional demands, and work related violence), as well as the most important preventive factors, e.g. quality of management, influence/control and training.During the first years of the strategy, an increasing number of inspectors have issued improvement notices regarding work related stress and violence, and there has been an increasing number of notices issued on several risk factors. For some aspects, the tools have helped increase the clarity and comprehensibility of the improvement notices and reduce the WEA’s time consumption per enterprise.The guidance tools seem to be a suitable and efficient way of assessing several health and safety risks concerning work related stress and violence thereby allowing the WEA to detect more of the existing problems. Future challenges projected for the strategy include continuously training all WEA inspectors in the proper use of the tools and continuously refining the tools – or developing new tools – based on further research and experiences from practice.     

Confronting two-sex demographic models with data

Most population dynamics models explicitly track the density of a single sex. When the operational sex ratio can vary, two-sex models may be needed to understand and predict population trajectories. Various functions have been proposed to describe the relative contributions of females and males to recruitment, and these functions can differ qualitatively in the patterns that they generate. Which mating function best describes the dynamics of real populations is not known, since alternative two-sex models have not been confronted with experimental data. We conducted the first such comparison, using laboratory populations of the bean beetle Callosobruchus maculatus. Manipulations of the operational sex ratio and total density provided strong support for a demographic model in which the birth rate was proportional to the harmonic mean of female and male densities, and females, males, and their offspring made unique contributions to density dependence. We offer guidelines for transferring this approach to other, less tractable systems in which possibilities for sex ratio manipulations are more limited. We show that informative experimental designs require strong perturbations of the operational sex ratio. The functional form of density dependence (saturating vs. over-compensatory) and the relative contributions of each sex to density dependence can both determine in which direction and at which population densities such perturbations would be most informative. Our experimental results and guidelines for design strategies promote synthesis of two-sex population dynamics theory with empirical data.     

Measurement of environmental pollutants using passive sampling devices--a commentary on the current state of the art

Passive sampling devices have been used since the 1970s to measure time-weighted average (TWA) or equilibrium concentrations of pollutants in various environmental matrices (e.g. air, soils and sediments and water). In recent years the popularity of using such samplers has increased and the technology in now well established for the measurement of atmospheric pollutants. This sector has a long experience of using passive samplers in the short- and long-term assessment of air quality in the local environment and on a global scale (e.g. within the United Nations Stockholm Convention on the trans-boundary movement of persistent organic pollutants (POPs) where large networks of samplers on a continental scale have been established). In comparison, the use of passive samplers for monitoring the aquatic environment has been slower to take off. There has, however, been a recent research drive to develop devices for measuring the wide range of pollutants that can be found in environmental waters (e.g. ground, surface, and marine). It is now being recognised that passive samplers can play a valuable role in monitoring water quality within a legislative framework such as the European Union's Water Framework Directive (WFD). The data from these devices can be used alongside the results obtained from conventional spot or bottle sampling to improve risk assessments and to inform decisions on undertaking potentially expensive remedial actions. Such monitoring techniques may have uses within the European Registration, Evaluation, Authorisation & restriction of CHemicals (REACH) Directive and the forthcoming European Marine Strategy Directive. It is expected that the aquatic monitoring sector will follow a transition similar to that which occurred in air monitoring where data obtained from passive samplers can use used within a legal framework. There has also been increased interest in extending the role of passive samplers to both the measurement of equilibrium concentrations and investigating the movement and release of the dissolved fraction of various pollutants in the pore water of sediments and soils.     

Impacts of epigeic, anecic and endogeic earthworms on metal and metalloid mobility and availability

The introduction of earthworms into soils contaminated with metals and metalloids has been suggested to aid restoration practices. Eisenia veneta (epigeic), Lumbricus terrestris (anecic) and Allolobophora chlorotica (endogeic) earthworms were cultivated in columns containing 900 g soil with 1130, 345, 113 and 131 mg kg(-1) of As, Cu, Pb and Zn, respectively, for up to 112 days, in parallel with earthworm-free columns. Leachate was produced by pouring water on the soil surface to saturate the soil and generate downflow. Ryegrass was grown on the top of columns to assess metal uptake into biota. Different ecological groups affected metals in the same way by increasing concentrations and free ion activities in leachate, but anecic L. terrestris had the greatest effect by increasing leachate concentrations of As by 267%, Cu by 393%, Pb by 190%, and Zn by 429% compared to earthworm-free columns. Ryegrass grown in earthworm-bearing soil accumulated more metal and the soil microbial community exhibited greater stress. Results are consistent with earthworm enhanced degradation of organic matter leading to release of organically bound elements. The degradation of organic matter also releases organic acids which decrease the soil pH. The earthworms do not appear to carry out a unique process, but increase the rate of a process that is already occurring. The impact of earthworms on metal mobility and availability should therefore be considered when inoculating earthworms into contaminated soils as new pathways to receptors may be created or the flow of metals and metalloids to receptors may be elevated.