Planting woody crops on dredged contaminated sediment provides both positive and negative effects in terms of remediation

There is currently a requirement for studies focusing on the long-term sustainability of phytoremediation technologies. Trace element uptake by Salix, Populus and Alnus species planted in dredged contaminated canal sediment and concentrations in sediment and pore waters were investigated, eight years after a phytoremediation trial was initiated in NW England. Soil biological activity was also measured using invertebrate and microbial assays to determine soil quality improvements. Zinc was the dominant trace metal in foliage and woody stems, and the most mobile trace element in sediment pore water (∼14 mg l⁻¹). Biological activity had improved; earthworm numbers had increased from 5 to 24, and the QBS index (an index of microarthropod groups in soil) had increased from 70 to 88. It is concluded that biological conditions had improved and natural processes appear to be enhancing soil quality, but there remains a potential risk of trace element transfer to the wider environment.     

Characterization of hydrocarbon contaminated areas by multivariate statistical analysis: Case studies

Analysis of soil gases is a relatively rapid and inexpensive method to delineate and measure hydrocarbon contamination in the subsurface caused by diesel or gasoline. Techniques originally developed for petroleum exploration have been adapted to tracking hydrocarbons which have leaked or spilled at or below the earth's surface.Discriminant analysis (a multivariate statistical technique) is used to classify soil gas samples of C₁ to C₇ hydrocarbons as biogenic (natural soil gases) or thermogenic (contaminant hydrocarbons). Map plots of C₁ to C₇ total interstitial hydrocarbons, C₂ to C₇ interstitial hydrocarbons, and C₁/C _n rations are used to further delineate and document the extent and migration of contamination.Three case studies of the technique are presented: each involves leakage of hydrocarbons from underground storage tanks. Soil gas analysis clearly defines the spread of contamination and can serve as the basis for the correct placement of monitoring wells. The method proved to be accurate, rapid, and cost-effective; it therefore has potential for widespread application to the identification of soil and groundwater contaminated by hydrocarbons.     

Comparative analysis using EIA for developed and developing countries: case studies of hydroelectric power plants in Pakistan,Norway and Sweden

Environmental impact assessment (EIA) is an important legislative and scientific tool that may assist and improve the quality assistance for the decision-making process in sustainable development. Here, a comparison of EIAs from three cases of hydropower projects in Pakistan, Norway and Sweden is reported. A huge difference concerning the incorporation of environmental considerations into the decisionmaking process between developed and developing countries is observed. The EIA system of Pakistan appears to be less efficient in the application and review process. In addition, the appraisal of issues, the decision-making process and evaluation through post-monitoring is not as well performed in Pakistan as in cases of hydroelectric power plants in Sweden and Norway. The key reason for this shortcoming is misconceptions about the EIA process, which initially receives intense attention but becomes weakened by the time of implementation. This implies that there is a need to adopt simplified and flexible EIA techniques suitable for the infrastructure and resources of a specific country, taking into account institutional, technical and financial constraints. Improvements are required in public participation, awareness, as well as in environmental control and data system sectors in Pakistan, besides simply enacting legislation to achieve the goals of the EIA system.     

Pregnancy patterns of pantropical spotted dolphins (Stenella attenuata) in the eastern tropical Pacific determined from hormonal analysis of blubber biopsies and correlations with the purse-seine tuna fishery

The northeastern offshore population of the pantropical spotted dolphin (Stenella attenuata) in the eastern tropical Pacific remains listed as depleted under the Marine Mammal Protection Act, and recent estimates of abundance show that recovery has been slow. One hypothesis for the slow recovery is that continued chase and encirclement by the tuna fishery negatively affects reproduction. Insufficient life-history sampling in this region over the last two decades makes traditional estimates of reproductive rates impossible. Here, we examine the current reproductive patterns of these dolphins by measuring blubber progesterone (BP) concentrations in biopsy samples to assess pregnancy state. BP was quantified in 212 biopsies from female offshore spotted dolphins sampled between 1998 and 2003 in the northeastern tropical Pacific, and we found that 11.5 % of the biopsied females (mature and immature) were pregnant. The relationship between pregnancy and fishery exposure was analyzed, and we found that pregnant females were exposed to significantly less fishery activity than non-pregnant ones (p = 0.022), suggesting that the fishery may have an inhibitive effect on pregnancy. Spatial analysis indicated that pregnancy was more aggregated than random (p < 0.05) at a scale up to 180-nmi, with the highest proportion pregnant in the mouth of the Gulf of California, an area with relatively low reported fishery activity.     

Birds as predators in tropical agroforestry systems

Insectivorous birds reduce arthropod abundances and their damage to plants in some, but not all, studies where predation by birds has been assessed. The variation in bird effects may be due to characteristics such as plant productivity or quality, habitat complexity, and/or species diversity of predator and prey assemblages. Since agroforestry systems vary in such characteristics, these systems provide a good starting point for understanding when and where we can expect predation by birds to be important. We analyze data from bird exclosure studies in forests and agroforestry systems to ask whether birds consistently reduce their arthropod prey base and whether bird predation differs between forests and agroforestry systems. Further, we focus on agroforestry systems to ask whether the magnitude of bird predation (1) differs between canopy trees and understory plants, (2) differs when migratory birds are present or absent, and (3) correlates with bird abundance and diversity. We found that, across all studies, birds reduce all arthropods, herbivores, carnivores, and plant damage. We observed no difference in the magnitude of bird effects between agroforestry systems and forests despite simplified habitat structure and plant diversity in agroforests. Within agroforestry systems, bird reduction of arthropods was greater in the canopy than the crop layer. Top-down effects of bird predation were especially strong during censuses when migratory birds were present in agroforestry systems. Importantly, the diversity of the predator assemblage correlated with the magnitude of predator effects; where the diversity of birds, especially migratory birds, was greater, birds reduced arthropod densities to a greater extent. We outline potential mechanisms for relationships between bird predator, insect prey, and habitat characteristics, and we suggest future studies using tropical agroforests as a model system to further test these areas of ecological theory.     

Exploring Environmental Data in a Highly Immersive Virtual Reality Environment

Geography inherently fills a 3D space and yet we struggle with displaying geography using, primarily, 2D display devices. Virtual environments offer a more realistically-dimensioned display space and this is being realized in the expanding area of research on 3D Geographic Information Systems (GISs). Traditionally, a GIS has only limited tools for statistical analysis, and 3D GIS research has concentrated on the visualization of the geographical terrain. Here we discuss linking multivariate statistical graphics to geography in the highly immersive C2 virtual reality environment at Iowa State University using mid-Atlantic streams data.     

Effects of interactions among genotypically diverse nestmates on task specialization by foraging honey bees (Apis mellifera)

Summary Recent studies have shown that differences in patterns of task specialization among nestmate honeybee workers (Apis mellifera) can be explained, in part, as a consequence of genotypic variability. Here, we present evidence supporting the hypothesis that an individual's pattern of task specialization is affected not only by her own genotype, but, indirectly, by the genotypes of her nestmates. Workers from two strains of honey bees, one selected for high pollen hoarding, the other for low pollen hoarding, were observed in colonies of their respective parent strains and in colonies of the other strain. Worker genotype and host-colony type affected foraging activity. Workers from the high strain fostered in low-strain colonies returned with pollen on 75.6% of total foraging trips, while workers from the high strain fostered in high-strain colonies returned with pollen on 53.5% of total trips. Workers from the low strain fostered in low-strain colonies returned with pollen on 34.8% of total foraging trips while workers from the low strain fostered in high-strain colonies returned with pollen on 2.6% of total trips. Similar results were obtained in a second experiment. We suggest that workers influence the behavior of their nestmates indirectly through their effects on the shared colony environment. The asymmetry seen in the response of workers from these strains to the two types of colony environments also suggests that these genotypes exhibit different norms of reaction. Offprint requests to: N.W. Calderone