Weapon size versus body size as a predictor of winning in fights between shore crabs, Carcinus maenas (L.)

Relative body size (carapace width) and weapon size (chela length) were used as indicators of resource holding potential (RHP) in the agonistic behaviour of male shore crabs, Carcinus maenas (L.). Weapon size was found to be a more reliable predictor of the outcome of pairwise fights than body size. Crabs with longer chelae than their opponents were more likely to win fights than crabs with relatively larger bodies. Body size had less influence on the outcome of fights. Relative body and weapon size did not influence initiation of contests but did affect the likelihood of winning; however, this was significant only for weapon size. Winning crabs had heavier claws with greater surface area than losing crabs. There was no relationship between relative size and fight duration. The frequency of cheliped display increased with chela length and win- ners performed significantly more displays than losers. Received: 5 February 1997 / Accepted after revision: 20 May 1997     

Effectiveness of high back belt positioning booster seats in side impacts

OBJECTIVE: The objective of this study is to evaluate the potential of high back booster seats to provide effective protection to children in side impacts. METHOD: This article presents a series of side impact sled tests at a velocity change of 30.5 km/h and a peak deceleration of 15.2 g, using the Hybrid III 6-year-old dummy in two styles of commonly used high-back booster seats: a conventional polystyrene booster seat and a convertible child restraint/booster seat. A series of tests were also performed using alternative anchorage systems in combination with the boosters. Simulated side impact tests were conducted at 90 degrees and 45 degrees. RESULTS: The booster seats tested were found to be too short for the 6-year-old dummy and head contact with the side door occurred in all 90 degree tests, resulting in high HIC values. The greatest potential for achieving effective protection in side impact in this test series was observed when the convertible child restraint/booster was used in combination with a rigid anchorage system. Using this system, the body of the dummy was kept farther away from the door which resulted in a softer head impact with the side door. CONCLUSIONS: Results from this work indicate that current booster seats offer poor torso containment and no head protection for children within the recommended age range. They also showed that the level of protection provided by belt positioning booster seats can be improved through the use of rigid anchorage systems. However, for this potential to be fully realized, belt positioning booster seats must offer better containment of the occupant during the impact.     

The relationship between epilithic periphyton (biofilm) bound metals and metals bound to sediments in freshwater systems

Surficial sediments and epilithic periphyton (biofilm) were sampled from six sites on the River Churnet and five sites on the River Manifold in Staffordshire and analysed for cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn). The sites demonstrated a wide range of sediment trace metal concentrations determined by inductively coupled plasma optical emission spectrometry (ICP-OES) and atomic absorbtion spectroscopy (AAS). Biofilm was removed from the substrate using physical abrasion and 0.005 M ethylenediaminoethanetetra-acetic acid (EDTA) extractant. The European Standards, Measurements and Testing Programmes (BCR) operationally defined geochemical speciation scheme was used to determine the exchangeable, acid soluble fraction of the sediments. Significant positive correlations were determined between the EDTA extractable biofilm and the exchangeable sediment fraction for Cd, Cu and Zn but not for Pb. Natural epilithic periphyton may be a potential metal biomonitor particularly of Cu, Cd and Zn in aquatic systems and provide supporting information in relation to potential sediment toxicity.     

Changes in the nature of dissolved organics during pulp and paper mill wastewater treatment: a multivariate statistical study combining data from three analytical techniques

The paper-making process can produce large amounts of wastewater (WW) with high particulate and dissolved organic loads. Generally, in developed countries, stringent international regulations for environmental protection require pulp and paper mill WW to be treated to reduce the organic load prior to discharge into the receiving environment. This can be achieved by primary and secondary treatments involving both chemical and biological processes. These processes result in complex changes in the nature of the organic material, as some components are mineralised and others are transformed. In this study, changes in the nature of organics through different stages of secondary treatment of pulp and paper mill WW were followed using three advanced characterisation techniques: solid-state ¹³C nuclear magnetic resonance (NMR) spectroscopy, pyrolysis-gas chromatography mass spectrometry (py-GCMS) and high-performance size-exclusion chromatography (HPSEC). Each technique provided a different perspective on the changes that occurred. To compare the different chemical perspectives in terms of the degree of similarity/difference between samples, we employed non-metric multidimensional scaling. Results indicate that NMR and HPSEC provided strongly correlated perspectives, with 86 % of the discrimination between the organic samples common to both techniques. Conversely, py-GCMS was found to provide a unique, and thus complementary, perspective.     

Enrichment of <Superscript>15</Superscript>N/<Superscript>14</Superscript>N in wastewater-derived effluent varies with operational performance of treatment systems: implications for isotope monitoring in receiving environments

Stable nitrogen isotope ratios are routinely used to trace the dispersion and assimilation of wastewater-derived N in receiving environments, but few isotope studies have investigated wastewater treatment plants and ponds themselves. An improved understanding of N isotope compositions in effluent will help assess treatment plant processes and performance and will help trace sources of excess nutrients in receiving environments. Here, we assess N budgets and treatment processes in seven wastewater treatment plants and wastewater stabilisation ponds in northern Australia based on concentrations and isotope ratios of N in effluent. We show that δ¹⁵N values in effluent are linked to treatment type, effectiveness of conversion of ammonia and levels of gaseous N emissions. These relationships suggest that N isotope monitoring of wastewater treatment plants and ponds can provide an integrated assessment of treatment performance and gaseous N emissions on a pond- or plant-wide scale that is not readily available through other methods. Our findings further imply that monitoring N isotope ratios in receiving environments cannot be assumed to be universally effective as their sensitivity to uptake of wastewater-derived N will vary with the characteristics of individual treatment systems. Paradoxically, N isotope monitoring is less effective where treatment systems are functioning poorly and where monitoring needs are the greatest.     

Individual variation in the relationship between vigilance and group size in eastern grey kangaroos

The mean vigilance of animals in a group often decreases as their group size increases, yet nothing is known about whether there is individual variability in this relationship in species that change group sizes frequently, such as those that exhibit fission–fusion social systems. We investigated variability in the relationship between group size and vigilance in the eastern grey kangaroo (Macropus giganteus) by testing whether all individuals showed decreased vigilance with increased group size, as has been commonly assumed. We carried out both behavioural observations of entire groups of kangaroos and focal observations of individually recognised wild female kangaroos. As in other studies, we found a collective group-size effect on vigilance; however, individuals varied in their vigilance patterns. The majority (57%) of the identified individual kangaroos did not show significant group-size effects for any of the recorded measures of vigilance. The females that did not show a negative group-size effect were, on average, more vigilant than those females that did show a group-size effect, but this difference was not significant. We propose that some females exhibit higher levels of social vigilance than others, and that this social vigilance increases with group size, cancelling out any group-size effect on anti-predator vigilance for those females. Our results therefore suggest that only some prey individuals may gain anti-predator benefits by reducing their time spent scanning when in larger groups. The large amount of variation that we found in the vigilance behaviour of individual kangaroos highlights the importance of collecting and analysing vigilance data at the individual level, which requires individual recognition.     

Evaluation and in situ assessment of photodegradation of polyaromatic hydrocarbons in semipermeable membrane devices deployed in ocean water

Semipermeable membrane devices (SPMDs) were deployed in water using four different methods: a typical SPMD cage with and without a mesh cover, a bowl chamber and without any protection. In addition to routinely used performance reference compounds (PRCs), perdeuterated dibenz[a,h]anthracene was added. Due to its high sampler to water partition coefficient no measurable clearance due to diffusion was expected during the deployment period, hence any observed loss could be attributed to photodegradation. The loss of PRCs was measured and SPMD-based water concentrations determined. Results showed that a typical SPMD deployment cage covered with mesh provided the best protection from photodegradation. Samplers which had undergone the highest photodegradation underestimated PAH water concentrations by up to a factor of 5 compared to the most protected SPMDs. This study demonstrates that the potential for photodegradation needs to be addressed when samplers are deployed in water of low turbidity.     

Modeling alkene chemistry using condensed mechanisms for conditions relevant to southeast Texas,USA

Alkenes are important in photochemical smog formation in southeast Texas due to their high emissions, especially from industrial sources in and around Houston, and their high reactivities. Therefore, properly characterizing the chemistry of alkenes in condensed mechanisms used in regional photochemical models is important in understanding the formation of ozone and other photochemical air pollutants in Houston. The performance of three versions of the SAPRC condensed chemical mechanism family, for predicting ozone and radical formation, was compared. Simulations were compared to environmental chamber data and ambient data. The analyses showed that separately modeling individual alkenes reactions (especially propene for southeast Texas) has the potential to lead to more accurate simulations of alkene chemistry. Caution must be exercised in un-lumping, however. Testing with different formulations of the 1-butene + O₃ reaction demonstrated the complexity and interconnectedness in choices of stoichiometric parameters for un-lumped species and the extent to which lumped mechanisms are un-lumped.     

Access for all? Barriers to accessing woodlands and forests in Britain

This paper presents results from research that identified and analysed barriers to accessing British woodlands and forests. This paper aims to contribute to an understanding of access and accessibility and to inform the design of policy and management interventions to encourage increased access by under-represented social groups. A brief review of policy and academic literature places the issue of inclusive woodland and forest access in the context of contemporary debates surrounding public health, well-being, diversity and the perceived role of public green space. There follows an analysis of quantitative and qualitative research findings, informing the presentation of a working typology of barriers. The typology is structured around the access needs of various social groups, allowing an analysis of the social distribution of barriers. The findings indicate the deep-seated psychological, emotional and socio-cultural nature of some barriers and highlight the need for carefully designed interventions that may lie outside the conventional remit of woodland management. This paper will be of particular interest to decision-makers and practitioners and to those involved in the design and delivery of policies, programmes and projects aimed at encouraging inclusive use of woodlands, forests and other types of green space.