Determinants of paternity success in the spider Pholcus phalangioides (Pholcidae: Araneae): the role of male and female mating behaviour

In double mating experiments, we examined whether and to what extent various male and female behavioural traits influence the course of mating and fertilization success in the cellar spider. In males, we focussed on pre-copulatory behaviour and on the rhythmic twisting movements that the male performs with his pedipalps during copulation. In females, we investigated remating decisions and the effect of female termination of copulation. Second males fertilized a high proportion of the eggs (P ₂: median 89%) despite much shorter second matings, with high variation in relative paternity success. The number of pedipalp movements (PPMs) of either male was a better predictor of paternity than copulation duration. Our results suggest that in second matings, PPMs help to remove sperm from previous males, whereas in first matings a high number of PPMs enhances fertilization success, either due to numerical sperm competition or cryptic female choice. Furthermore, we found a negative male age effect on paternity in second matings, implying that age-related deterioration of spermatozoa may promote variation in fertilization success. Female receptivity decreased significantly in second matings; only 70% of the females remated. Females that accepted a second copulation were found to terminate these much earlier and with higher probability than first matings. This suggests that the intensity of conflict between the sexes is higher in second matings. Increased intensity of sexual conflict may be responsible for stronger selection on male traits, as pre-copulatory behaviour and age only affected male copulatory performance and paternity in second matings. Electronic Publication     

Probabilistic approaches in the effect assessment of toxic chemicals. What are the benefits and limitations?

There is an ongoing discussion whether in the environmental risk assessment for chemicals the so called 'deterministic' approach using point estimates of exposure and effect concentrations is still appropriate. Instead, the more detailed and scientifically sounder probabilistic methods that have been developed over the last years are widely recommended. Here, we present the results of a probabilistic effect assessment for the aquatic environment performed for the pesticide methyl parathion and compare them with the results obtained with the common deterministic approach as described in the EU Technical Guidance Document. Methyl parathion was chosen because a sufficient data set (acute toxicity data for about 70 species) was available. The assumptions underlying the probabilistic effect assessment are discussed in the light of the results obtained for methyl parathion. Two important assumptions made by many studies are: (i) a sufficient number of ecologically relevant toxicity data is available, (ii) the toxicity data follow a certain distribution such as log-normal. Considering the scarcity of data for many industrial chemicals, we conclude that these assumptions would not be fulfilled in many cases if the probabilistic assessment was applied to the majority of industrial chemicals. Therefore, despite the well-known limitations of the deterministic approach, it should not be replaced by probabilistic methods unless the assumptions of these methods are carefully checked in each individual case, which would significantly increase the effort for the assessment procedure.     

Dioxin- and POP-contaminated sites—contemporary and future relevance and challenges

BACKGROUND, AIM AND SCOPE: Once they have been generated, polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) and other persistent organic pollutants (POPs) can persist in soils and sediments and in waste repositories for periods extending from decades to centuries. In 1994, the US EPA concluded that contaminated sites and other reservoirs are likely to become the major source of contemporary pollution problems with these substances. With this in mind, this article is the first in a new series in ESPR under the title 'Case Studies on Dioxin and POP Contaminated Sites--Contemporary and Future Relevance and Challenges', which will address this important issue. The series will document various experiences from sites contaminated with PCDD/F and other POPs. This article provides an overview of the content of the articles comprising the series. In addition, it provides a review of the subject in its own right and identifies the key issues arising from dioxin/POP-contaminated sites. Additionally, it highlights the important conclusions that can be drawn from these examples. The key aim of this article and of the series as a whole is to provide a comprehensive overview of the types of PCDD/F contaminated sites that exist as a result of historical activities. It details the various processes whereby these sites became contaminated and attempts to evaluate their contemporary relevance as sources of PCDD/Fs and other POPs. It also details the various strategies used to assess these historical legacies of contamination and the concepts developed, or which are under development, to effect their remediation. MAIN FEATURES: Special sessions on 'Contaminated sites--Cases, remediation, risk and policy' were held at the DIOXIN conferences in 2006 and 2007, and this theme will be continued at DIOXIN 2008 to be held in Birmingham. Selected cases from the approximately 70 contributions made to these sessions, together with some additional invited case studies are outlined together with the key issues they raise. By evaluating these cases and adding details of experiences published in the current literature, an overview will be given of the different features and challenges of dioxin and POP-contaminated sites. RESULTS: This article provides a systematic categorisation of types of PCDD/F and POP-contaminated sites. These are categorised according to the chemical or manufacturing process, which generated the PCDD/Fs or POPs and also includes the use and disposal aspects of the product life cycle in question. The highest historical PCDD/F and dioxin-like polychlorinated biphenyl (PCB) contamination burdens have arisen as a result of the production of chlorine and of chlorinated organic chemicals. In particular, the production of chlorinated pesticides, PCBs and the related contaminated waste streams are identified being responsible for historical releases of toxic equivalents (TEQs) at a scale of many tonnes. Along with such releases, major PCDD/F contaminated sites have been created through the application or improper disposal of contaminated pesticides, PCBs and other organochlorine chemicals, as well through the recycling of wastes and their attempted destruction. In some extreme examples, PCDD/F contaminated sites have also resulted from thermal processes such as waste incinerators, secondary metal industries or from the recycling or deposition of specific waste (e.g. electronic waste or car shredder wastes), which often contain chlorinated or brominated organic chemicals. The examples of PCDD/F and dioxin-like PCB contamination of fish in European rivers or the impact of contaminated sites upon fishing grounds and upon other food resources demonstrate the relevance of these historical problems to current and future human generations. Many of the recent food contamination problems that have emerged in Europe and elsewhere demonstrate how PCDD/F and dioxin like PCBs from historical sources can directly contaminate human and animal feedstuffs and indeed highlight their considerable contemporary relevance in this respect. Accordingly, some key experiences and lessons learnt regarding the production, use, disposal and remediation of POPs from the contaminated sites are summarised. DISCUSSION: An important criterion for evaluating the significance and risks of PCDD/Fs and other POPs at contaminated sites is their present or future potential for mobility. This, in turn, determines to a large degree their propensity for off-site transport and environmental accessibility. The detailed evaluation of contaminated site cases reveals different site-specific factors, which influence the varied pathways through which poor water-soluble POPs can be mobilised. Co-contaminants with greater water solubility are also typically present at such sites. Hence, pumping of groundwater (pump and treat) is often required in addition to attempting to physically secure a site. At an increasing number of contaminated sites, securing measures are failing after relatively short time spans compared to the time horizon, which applies to persistent organic pollutant contamination. Due to the immense costs and challenges associated with remediation of contaminated sites 'monitored natural attenuation' is increasingly gaining purchase as a conceptual remediation approach. However, these concepts may well prove limited in their practical application to contaminated sites containing persistent organic pollutants and other key pollutants like heavy metals. CONCLUSIONS: It is inevitable, therefore, that dioxin/POP-contaminated sites will remain of contemporary and future relevance. They will continue to represent an environmental issue for future generations to address. The securing and/or remediation of dioxin/POP-contaminated sites is very costly, generally in the order of tens or hundreds of millions of dollars. Secured landfills and secured production sites need to be considered as constructions not made for 'eternity' but built for a finite time scale. Accordingly, they will need to be controlled, supervised and potentially repaired/renewed. Furthermore, the leachates and groundwater impacted by these sites will require ongoing monitoring and potential further remediation. These activities result in high maintenance costs, which are accrued for decades or centuries and should, therefore, be compared to the fully sustainable option of complete remediation. The contaminated site case studies highlight that, while extensive policies and established funds for remediation exist in most of the industrialised western countries, even these relatively well-regulated and wealthy countries face significant challenges in the implementation of a remediation strategy. This highlights the fact that ultimately only the prevention of contaminated sites represents a sustainable solution for the future and that the Polluter Pays Principle needs to be applied in a comprehensive way to current problems and those which may emerge in the future. RECOMMENDATIONS AND PERSPECTIVES: With the continuing shift of industrial activities in developing and transition economies, which often have poor regulation (and weak self-regulation of industries), additional global challenges regarding POPs and other contaminated sites may be expected. In this respect, a comprehensive application of the "polluter pays principle" in these countries will also be a key to facilitate the clean-up of contaminated areas and the prevention of future contaminated sites. The threats and challenges of contaminated sites and the high costs of securing/remediating the problems highlight the need for a comprehensive approach based upon integrated pollution prevention and control. If applied to all polluting (and potentially polluting) industrial sectors around the globe, such an approach will prove to be both the cheapest and most sustainable way to underpin the development of industries in developing and transition economies.     

Quantification of methane emissions from full-scale open windrow composting of biowaste using an inverse dispersion technique

An inverse dispersion technique in conjunction with Open-Path Tunable-Diode-Laser-Spectroscopy (OP-TDLS) and meteorological measurements was applied to characterise methane (CH₄) emissions from an Austrian open-windrow composting plant treating source-separated biowaste. Within the measurement campaigns from July to September 2012 different operating conditions (e.g. before, during and after turning and/or sieving events) were considered to reflect the plant-specific process efficiency. In addition, the tracer technique using acetylene (C₂H₂) was applied during the measurement campaigns as a comparison to the dispersion model. Plant-specific methane emissions varied between 1.7 and 14.3 g CH₄/m³d (1.3–10.7 kg CH₄/h) under real-life management assuming a rotting volume of 18,000 m³. In addition, emission measurements indicated that the turning frequency of the open windrows appears to be a crucial factor controlling CH₄ emissions when composting biowaste. The lowest CH₄ emission was measured at a passive state of the windrows without any turning event (“standstill” and “sieving of matured compost”). Not surprisingly, higher CH₄ emissions occurred during turning events, which can be mainly attributed to the instant release of trapped CH₄. Besides the operation mode, the meteorological conditions (e.g. wind speed, atmospheric stability) may be further factors that likely affect the release of CH₄ emissions at an open windrow system. However, the maximum daily CH₄ emissions of 1 m³ rotting material of the composting plant are only 0.7–6.5% of the potential daily methane emissions released from 1 m³ of mechanically–biologically treated (MBT) waste being landfilled according to the required limit values given in the Austrian landfill ordinance.     

The alignment of agricultural and nature conservation policies in the European Union

Europe is a region of relatively high population density and productive agriculture subject to substantial government intervention under the Common Agricultural Policy (CAP). Many habitats and species of high conservation interest have been created by the maintenance of agricultural practices over long periods. These practices are often no longer profitable, and nature conservation initiatives require government support to cover the cost for them to be continued. The CAP has been reformed both to reduce production of agricultural commodities at costs in excess of world prices and to establish incentives for landholders to adopt voluntary conservation measures. A separate nature conservation policy has established an extensive series of protected sites (Natura 2000) that has, as yet, failed to halt the loss of biodiversity. Additional broader scale approaches have been advocated for conservation in the wider landscape matrix, including the alignment of agricultural and nature conservation policies, which remains a challenge. Possibilities for alignment include further shifting of funds from general support for farmers toward targeted payments for biodiversity goals at larger scales and adoption of an ecosystem approach. The European response to the competing demands for land resources may offer lessons globally as demands on rural land increase.