Identification of trail pheromone compounds from the labial glands of the stingless bee Geotrigona mombuca

Foragers of several species of stingless bees deposit pheromone spots in the vegetation to guide recruited nestmates to a rich food source. Recent studies have shown that Trigona and Scaptotrigona workers secrete these pheromones from their labial glands. An earlier report stated that species within the genus Geotrigona use citral from their mandibular glands for scent marking. Since convincing experimental proof for this conjecture is lacking, we studied the glandular origin of the trail pheromone of Geotrigona mombuca. In field bioassays, newly recruited bees were diverted by artificial scent trails that branched off from the natural scent trail deposited by their nestmates only when they were baited with extracts from the foragers’ labial glands. Compounds extracted from the mandibular glands, however, did not release trail following behavior. This demonstrates that the trail pheromone of G. mombuca is produced in the labial glands, as in Trigona and Scaptotrigona. Furthermore, in chemical analyses citral was identified exclusively in the foragers’ mandibular glands, which disproves its supposed role as a trail pheromone. The labial glands contained a series of terpene- and wax type esters, with farnesyl butanoate as major constituent. We, therefore, postulate that the trail pheromone of G. mombuca is composed of a blend of esters.     

Effect of environmental flows on deep,anoxic pools

A series of field surveys were carried out on two permanent pools of the upper Glenelg River in SW Victoria, Australia. One was representative of the wider and deeper pools while the other was representative of the more-narrow and shallower pools. Both pools showed a typical seasonal cycle of warm, brackish, oxygen-poor, summer conditions and cool, oxygen-rich, low-salinity, winter conditions. The summer salinity increases were larger than expected, suggesting possible saline groundwater inflow from unidentified springs. Both pools contained anoxic water in their deeper sections but this was permanent only in the deeper pool. A simple model of the flushing rate of such anoxic pools subject to flows, such as environmental flow releases, was developed, based on an energy balance between the potential energy required to lift the anoxic layer and the kinetic energy derived from the river flow. The results were tested against and in agreement with the field measurements. The model also suggests that the anoxic layers are resilient to all but the largest environmental flows.     

Spatial modelling for the development of agri-environmental programs

Spatial modelling of environmental indicators has been well established in landscape ecology and in nature conservation on regional and national scales over the recent past. Yet, using spatial information as a basis for the coordination of environmental measures on a trans-national European level reveals several shortcomings and hindrances, ranging from data quality issues and methodological aspects to discussions on how to define ecological indicators across Europe. This paper analyzes the potential of spatial modelling for the development and implementation of agri-environmental measures as part of rural development policies, discussing critical aspects of spatial environmental modelling as well as chances, trends and demands.     

Hydrologic monitoring tools for freshwater municipal planning in the Arctic: the case of Iqaluit,Nunavut, Canada

Freshwater and the services it provides are vital to both natural ecosystems and human needs; however, extreme climates and their influence on freshwater availability can be challenging for municipal planners and engineers to manage these resources effectively. In Arctic Canada, financial and human capital limitations have left a legacy of freshwater systems that underserve current communities and may be inadequate in the near future under a warming climate, growing population, and increasing demand. We address this challenge to community water resource planning by applying several novel water supply forecasting methods to evaluate the Apex River as an alternative freshwater source for Iqaluit, Nunavut (Canada). Surveys of water isotope composition of the Apex River and tributaries indicated that rainfall is the main source of water replenishment. This information was utilized to calibrate a water resource assessment that considered climate forecasting scenarios and their influence on supply, and alternative scenarios for freshwater management to better adapt to a changing climate. We found that under current climate and demand conditions, the freshwater supply of Iqaluit would be in a perpetual state of drawdown by 2024. Analysis of current infrastructure proposals revealed significant deficiencies in the supply extensions proposed whereby the Apex replenishment pipeline would only provide a 2-year extension to current municipal supply. Our heuristic supply forecast methods allowed for several alternative supply strategies to be rapidly evaluated, which will aid the community planning process by specifically quantifying the service life of the city’s current and future primary water supply.     

Targeting aquatic microcontaminants for monitoring: exposure categorization and application to the Swiss situation

Background, aim, and scope  

Aquatic microcontaminants (MCs) comprise diverse chemical classes, such as pesticides, biocides, pharmaceuticals, consumer products, and industrial chemicals. For water pollution control and the evaluation of water protection measures, it is crucial to screen for MCs. However, the selection and prioritization of which MCs to screen for is rather difficult and complex. Existing methods usually are strongly limited because of a lack of screening regulations or unavailability of required data.     

Atmospheric oxidation capacity in the summer of Houston 2006: Comparison with summer measurements in other metropolitan studies

Both similarities and differences in summertime atmospheric photochemical oxidation appear in the comparison of four field studies: TEXAQS2000 (Houston, 2000), NYC2001 (New York City, 2001), MCMA2003 (Mexico City, 2003), and TRAMP2006 (Houston, 2006). The compared photochemical indicators are OH and HO₂ abundances, OH reactivity (the inverse of the OH lifetime), HO_x budget, OH chain length (ratio of OH cycling to OH loss), calculated ozone production, and ozone sensitivity. In terms of photochemical activity, Houston is much more like Mexico City than New York City. These relationships result from the ratio of volatile organic compounds (VOCs) to nitrogen oxides (NO_x), which are comparable in Houston and Mexico City, but much lower in New York City. Compared to New York City, Houston and Mexico City also have higher levels of OH and HO₂, longer OH chain lengths, a smaller contribution of reactions with NO_x to the OH reactivity, and NO_x-sensitivity for ozone production during the day. In all four studies, the photolysis of nitrous acid (HONO) and formaldehyde (HCHO) are significant, if not dominant, HO_x sources. A problematic result in all four studies is the greater OH production than OH loss during morning rush hour, even though OH production and loss are expected to always be in balance because of the short OH lifetime. The cause of this discrepancy is not understood, but may be related to the under-predicted HO₂ in high NO_x conditions, which could have implications for ozone production. Three photochemical indicators show particularly high photochemical activity in Houston during the TRAMP2006 study: the long portion of the day for which ozone production was NO_x-sensitive, the calculated ozone production rate that was second only to Mexico City's, and the OH chain length that was twice that of any other location. These results on photochemical activity provide additional support for regulatory actions to reduce reactive VOCs in Houston in order to reduce ozone and other pollutants.     

Science, Power, and System Dynamics: the Political Economy of Conservation Biology

Abstract: Frustration with the lack of action on conservation issues by governments has sparked debate around the policy role of conservation biologists. We analyzed the political economy of conservation biology, that is, of the dynamics of the political and economic structures within which conservation biology operates, and we suggest more productive means for conservation biologists to achieve conservation goals. Within the modern state, conservation goals are marginalized because the growth needs of industrial capital have the highest priority. Environmental advocacy within this system largely addresses only proximate concerns and has limited success. Science is a product of modern society, but scientists now need to foster novel institutional arrangements in which humans can function within the limits of natural systems. This entails a larger recognition of the inherent contradictions residing within current institutions that themselves depend on unsustainably high resource flows. As one critical counterbalance to these institutions, we discuss community-based management and research as primary institutions through which sustainable use of natural resources might be achieved.     

The Northwest U.S. Dam Breaching Decision: Factors, Costs and Benefits

Northwestern United States' salmon populations have fallen precipitously. Attempts at salmon restoration are going on and dam breaching is being considered. Costs associated with the continued restoration attempts including hatchery stocking, barging and trucking salmon around the dams are high while benefits are unclear. Those costs may be greater than dam breaching. An additional impetus for dam removal is the revival of the commercial salmon fishing industry. This may not occur for both ecological and economic reasons. Ecologically complete restoration may not be feasible. Economically, the rise of competitively priced salmon aquaculture will reduce the value of any future commercial catch. A statistical relationship between falling prices for wild salmon and rising salmon aquaculture output is shown.     

Dust Deposit Profiles in a High Velocity Pulse-Jet Fabric Filter

Dust deposit profiles in a pilot-scale pulse-jet fabric filter were measured using a beta gauge. Fly ash was collected on polyester needled felt bags, and the dust profiles were measured after the test system was operated to equilibrium at superficial filtration velocities of 50, 75,100,125, and 150 mm/s. The profiles measured show that a large mass of dust is retained on the fabric of a pulse-jet filter when operated at high filtration velocities. This dust mass retention can be caused by two mechanisms: the failure to remove dust from the fabric during a cleaning pulse, and the redeposition of suspended dust onto the fabric after a cleaning pulse. The dust deposit measured at the highest test velocity was found to be much different from the deposits measured at all other velocities. The deposit found at 150 mm/s had almost twice the average areal density and was more evenly distributed than the deposits found at lower velocities.