Habitat loss through disruption of constrained dispersal networks.

Large losses of habitat could be caused by land use change that disrupts the dispersal networks used by migratory species. We assessed the relative losses of habitat for diadromous fish (i.e., those migrating between sea and freshwater) due to physical barriers, degradation of migratory passage associated with catchment land use, and site-scale land use characteristics on the West Coast, South Island, New Zealand. Fish occurrence, land use data, and river network models were analyzed in a GIS and subjected to a three-level hierarchical analysis. To identify accessible habitat not restricted by physical barriers, we used the migratory distance and maximum downstream slope encountered to identify accessible sites in least-impacted catchments and applied the results to all catchments within the study area. For two fish species, banded kokopu (Galaxias fasciatus) and koaro (G. brevipinnis), sites modeled as accessible using logistic regression in least-impacted catchments were then used to assess the impacts of catchment-scale deforestation and downstream land uses on habitat loss. Finally, sites not restricted by physical barriers or land-use-related impacts on migratory passage were used to model the effects of local land use. The models indicated that koaro and banded kokopu potentially had access to 28,000 km and 5300 km, respectively, of the 40,600 km of streams within the study area. Impacts due to intensive agricultural land use downstream in catchments affecting migratory passage were predicted to reduce the accessible habitats for koaro and banded kokopu by 55% and 70%, respectively. Local land use further reduced koaro and banded kokopu habitats to 70% and 90%, respectively, of total accessible habitat. Habitat lost through disruption of the dispersal network was disproportionately large because potentially useable habitat was rendered inaccessible.     

Swarming and mating behavior of a mayfly Baetis bicaudatus suggest stabilizing selection for male body size

Large size often confers a fitness advantage to female insects because fecundity increases with body size. However, the fitness benefits of large size for male insects are less clear. We investigated the mating behavior of the mayfly Baetis bicaudatus to determine whether the probability of male mating success increased with body size. Males formed mating aggregations (swarms) ranging from a few to hundreds of individuals, 1-4 m above the ground for about 1.5-2 h in the early morning. Females that flew near swarms were grabbed by males, pairs dropped to the vegetation where they mated and then flew off individually. Some marked males returned to swarms 1, 2 or 3 days after marking. Larger males swarmed near spruce trees at the edges of meadows, but the probability of copulating was not a function of male body size (no large male advantage). Furthermore, the potential fitness advantage of mating with larger, more fecund females was not greater for large males (no size-assortative mating). However, the sizes of copulating males were significantly less variable than those of non-mating males collected at random in swarms. Intermediate male size may be optimal during mating because of trade-offs between flight agility and longevity or competitive ability. Results of this study are consistent with the hypotheses that there is stabilizing selection on adult male body size during mating, and that male body size in this species may be influenced more by selection pressures acting on larvae than on adults.     

Developing a saltmarsh monitoring methodology to meet multiple policy and management objectives in Scotland

To meet Scotland’s conservation and legislative requirements to monitor and set management objectives for saltmarsh habitat, a national survey was developed jointly funded by Scottish Natural Heritage and the Scottish Environment Protection Agency. This national survey focussed on developing a fine scale vegetation map of all Scottish saltmarshes over 3 ha, which was digitised using GIS software. A condition monitoring protocol was also developed to assess the health of key ecological parameters of the saltmarsh system. A total of 7,704 ha of coastal habitat was surveyed as part of the project, which included 5,840 ha of saltmarsh vegetation and 1,864 ha of associated vegetation. The condition monitoring protocol results show that targets relating to the presence of built structures and transition integrity are not achieved more frequently than others. Targets for stock grazing intensity; the maintenance of saltmarsh extent; and poaching damage are also not achieved frequently. Further research is required to accurately reflect the condition of pioneer saltmarsh.     

The effect of vegetation on pesticide dissipation from ponded treatment wetlands: quantification using a simple model

Field data shows that plants accelerate pesticide dissipation from aquatic systems by increasing sedimentation, biofilm contact and photolysis. In this study, a graphical model was constructed and calibrated with site-specific and supplementary data to describe the loss of two pesticides, endosulfan and fluometuron, from a vegetated and a non-vegetated pond. In the model, the major processes responsible for endosulfan dissipation were alkaline hydrolysis and sedimentation, with the former process being reduced by vegetation and the latter enhanced. Fluometuron dissipation resulted primarily from biofilm reaction and photolysis, both of which were increased by vegetation. Here, greater photolysis under vegetation arose from faster sedimentation and increased light penetration, despite shading. Management options for employing constructed wetlands to polish pesticide-contaminated agricultural runoff are discussed. The lack of easily fulfilled sub-models and data describing the effect of aquatic vegetation on water chemistry and sedimentation is also highlighted.     

Distribution and partitioning of depleted uranium (DU) in soils at weapons test ranges - investigations combining the BCR extraction scheme and isotopic analysis

Depleted uranium (DU) has become a soil contaminant of considerable concern in many combat zones and weapons-testing sites around the world, including locations in Europe, the Middle East and the USA, arising from its dispersion via the application of DU-bearing munitions. Once DU is released into the environment its mobility and bioavailability will, like that of other contaminants, largely depend on the type of associations it forms in soil and on the nature of the soil components to which it binds. In this study we used the BCR sequential extraction scheme to determine the partitioning of DU amongst soil fractions of texturally varying soils from locations affected by weapons-testing activities. Isotopic analyses (MC-ICP-MS and alpha-spectrometry) were performed to verify the presence of DU in whole soils and soil fractions and to determine any preferential partitioning of the contaminant. Results identified soil organic matter as being consistently the most important component in terms of DU retention, accounting for 30-100% of DU observed in the soils examined. However, at greater distances from known contamination points, DU was also found to be largely associated with the exchangeable fraction, suggesting that DU can be mobilised and transported by surface and near-surface water and does remain in an exchangeable (and thus potentially bioavailable) form in soils.     

Comparison of levels of polychlorinated biphenyls in edible oils and oil-based products--possible link to environmental factors

Food consumption has been widely reported to be the main source of human exposure to PCBs. A total of 47 samples of food products on sale in supermarkets in the United Kingdom were thus analyzed for PCBs to determine residual levels in oil and oil-based products. The objective was to compare the measured levels of total PCBs (Sigma PCBs) in food products to those reported in various environmental compartments. Combined extraction and online clean up was achieved using Accelerated Solvent Extraction (ASE) to recover target analytes for analysis by GC-MSD (gas chromatography mass spectrometry). Sigma PCBs (ng/g) in each product were in the ranges of 4.73-44.38 edible oil; 1.40-6.18 mayonnaise; 1.21-6.25 salad cream; 1.28-5.64 seafood sauce, and 0.97-15.08 exotic dressing. The level of human exposure to PCBs in all products was < 1 microg/kg body weight/day when considering a 70 kg male or 57 kg female, possibly reflecting the reported decline of PCBs in the environment.     

Recycling Policy in Areas of Low Income and Multi-storey Housing

The paper considers the participation of households in recycling programmes in areas of multi-storey, low income housing which are often considered unattractivefor such programmes.A model of the material recycled is presented together with a review of socio-economic, housing, technological, policy and other factors influencing household recycling. This is followed by a case study of two areas in the city of Edinburgh. Results suggest that the level of recycling is influenced by collection methods, for all materials except glass, with half of the recyclers starting as a result of the introduction of kerbside collection. Housing characteristics such as the storey-level in buildings without lifts , household size and access to cars all influenced recycling participation rates. Housing tenure was not found to be significant. This suggests that well designed kerbside collection programmescan have a significant impact in areas with high levels of multi-storey dwellings, low income and public housing.