Mercury species measured atop the Moody Tower TRAMP site,Houston, Texas

Atmospheric mercury speciation was monitored within Houston, Texas, USA, August 6–October 14, 2006 as part of the TexAQS Radical and Aerosol Measurement Program (TRAMP). On average, all mercury levels were significantly elevated compared to a rural Gulf of Mexico coastal site. Concentrations varied from very clean to very dirty. Multi-day periods of stagnant or low-wind conditions brought elevated concentrations of all mercury species, whereas multi-day periods of strong winds, particularly southerly winds off the Gulf of Mexico, brought very low values of mercury species. Over the entire mercury measurement period, the daily averages of mercury species showed distinct and consistent relationships with the average planetary boundary layer dynamics, with gaseous elemental and particulate-bound mercury near-surface concentrations enhanced by a shallow nocturnal boundary layer, and reactive gaseous mercury concentration enhanced by midday convective boundary layer air entrainment transporting air aloft to the surface. Mercury concentrations were not significantly correlated with known products of combustion, likely indicating non-combustion mercury sources from the Houston area petrochemical complexes. On the morning of August 31, 2006 an observed emission event at a refinery complex on the Houston Ship Channel resulted in extremely high concentrations of aerosol mass and particulate-bound mercury at the TRAMP measurement site 20 km downwind.     

Assessment of Economic and Water Quality Impacts of Land Use Change Using a Simple Bioeconomic Model

The objective of this study is to assess the economic and water quality impact of land use change in a small watershed in the Wiregrass region of Alabama. The study compares changes in water quality and revenue from agricultural and timber production due to changes in land use between years 1992 and 2001. The study was completed in two stages. In the first stage, a biophysical model was used to estimate the effect of land use change on nitrogen and phosphorus runoff and sediment deposition in the main channel; in the second stage, farm enterprise budgeting tools were used to estimate the economic returns for the changes in land use condition. Both biophysical and economic results are discussed, and a case for complex optimization to develop a decision support system is presented.     

The short-term effects of a routine poisoning campaign on the movements and detectability of a social top-predator

Top-predators can be important components of resilient ecosystems, but they are still controlled in many places to mitigate a variety of economic, environmental and/or social impacts. Lethal control is often achieved through the broad-scale application of poisoned baits. Understanding the direct and indirect effects of such lethal control on subsequent movements and behaviour of survivors is an important pre-requisite for interpreting the efficacy and ecological outcomes of top-predator control. In this study, we use GPS tracking collars to investigate the fine-scale and short-term movements of dingoes (Canis lupus dingo and other wild dogs) in response to a routine poison-baiting program as an example of how a common, social top-predator can respond (behaviourally) to moderate levels of population reduction. We found no consistent control-induced differences in home range size or location, daily distance travelled, speed of travel, temporal activity patterns or road/trail usage for the seven surviving dingoes we monitored immediately before and after a typical lethal control event. These data suggest that the spatial behaviour of surviving dingoes was not altered in ways likely to affect their detectability, and if control-induced changes in dingoes' ecological function did occur, these may not be related to altered spatial behaviour or movement patterns.     

Optimal fire histories for biodiversity conservation

Fire is used as a management tool for biodiversity conservation worldwide. A common objective is to avoid population extinctions due to inappropriate fire regimes. However, in many ecosystems, it is unclear what mix of fire histories will achieve this goal. We determined the optimal fire history of a given area for biological conservation with a method that links tools from 3 fields of research: species distribution modeling, composite indices of biodiversity, and decision science. We based our case study on extensive field surveys of birds, reptiles, and mammals in fire‐prone semi‐arid Australia. First, we developed statistical models of species’ responses to fire history. Second, we determined the optimal allocation of successional states in a given area, based on the geometric mean of species relative abundance. Finally, we showed how conservation targets based on this index can be incorporated into a decision‐making framework for fire management. Pyrodiversity per se did not necessarily promote vertebrate biodiversity. Maximizing pyrodiversity by having an even allocation of successional states did not maximize the geometric mean abundance of bird species. Older vegetation was disproportionately important for the conservation of birds, reptiles, and small mammals. Because our method defines fire management objectives based on the habitat requirements of multiple species in the community, it could be used widely to maximize biodiversity in fire‐prone ecosystems. Historiales de Incendios Óptimos para la Conservación de la Biodiversidad     

Managing water through change and uncertainty: comparing lessons from the adaptive co-management literature to recent policy developments in England

Water management is set to become increasingly variable and unpredictable, in particular because of climate change. This paper investigates the extent to which water policy in England provides an enabling environment for ‘adaptive co-management’, which its proponents claim can achieve the dual objective of ecosystem protection and livelihood sustainability under conditions of change and uncertainty. Five policy categories are derived from a literature review, and are used to conduct a directed content analysis of seven key water policy documents. The findings reveal that although, in part, English water policy serves as an enabling environment for adaptive co-management, there is a level of discrepancy between substantive aspects of the five policy categories and water policy in England. Addressing these discrepancies will be important if English water policy is to allow for the emergence of processes, like adaptive co-management, that are capable of coping with the challenges that lie ahead.     

Analysis of spatio-temporal land cover changes for hydrological impact assessment within the Nyando River Basin of Kenya

The spatio-temporal changes in the land cover states of the Nyando Basin were investigated for auxiliary hydrological impact assessment. The predominant land cover types whose conversions could influence the hydrological response of the region were selected. Six Landsat images for 1973, 1986, and 2000 were processed to discern the changes based on a methodology that employs a hybrid of supervised and unsupervised classification schemes. The accuracy of the classifications were assessed using reference datasets processed in a GIS with the help of ground-based information obtained through participatory mapping techniques. To assess the possible hydrological effect of the detected changes during storm events, a physically based lumped approach for infiltration loss estimation was employed within five selected sub-basins. The results obtained indicated that forests in the basin declined by 20% while agricultural fields expanded by 16% during the entire period of study. Apparent from the land cover conversion matrices was that the majority of the forest decline was a consequence of agricultural expansion. The model results revealed decreased infiltration amounts by between 6% and 15%. The headwater regions with the vast deforestation were noted to be more vulnerable to the land cover change effects. Despite the haphazard land use patterns and uncertainties related to poor data quality for environmental monitoring and assessment, the study exposed the vast degradation and hence the need for sustainable land use planning for enhanced catchment management purposes.     

Examining User Comments for Deliberative Democracy: A Corpus-driven Analysis of the Climate Change Debate Online

The public perception of climate change is characterized by heterogeneity, even polarization. Deliberative discussion is regarded by some as key to overcoming polarization and engaging various publics with the complex issue of climate change. In this context, online engagement with news stories is seen as a space for a new “deliberative democratic potential” to emerge. This article examines aspects of deliberation in user comment threads in response to articles on climate change taken from the Guardian. “Deliberation” is understood through the concepts “reciprocity”, “topicality”, and “argumentation”. We demonstrate how corpus analysis can be used to examine the ways in which online debates around climate change may create or deny opportunities for multiple voices and deliberation. Results show that whilst some aspects of online discourse discourage alternative viewpoints and demonstrate “incivility”, user comments also show potential for engaging in dialog, and for high levels of interaction.     

Options for Managing Hypoxic Blackwater in River Systems: Case Studies and Framework

Hypoxic blackwater events occur when large amounts of organic material are leached into a water body (e.g., during floodplain inundation) and rapid metabolism of this carbon depletes oxygen from the water column, often with catastrophic effects on the aquatic environment. River regulation may have increased the frequency and severity of hypoxic blackwater events in lowland river systems, necessitating management intervention to mitigate the impacts of these events on aquatic biota. We examine the effectiveness of a range of mitigation interventions that have been used during large-scale hypoxic blackwater events in the Murray–Darling Basin, Australia and that may be applicable in other environments at risk from hypoxic blackwater. Strategies for hypoxia mitigation include: delivery of dilution flows; enhancement of physical re-aeration rates by increasing surface turbulence; and diversion of blackwater into shallow off-channel storages. We show that the impact of dilution water delivery is determined by relative volumes and water quality and can be predicted using simple models. At the dilution water inflow point, localized oxygenated plumes may also act as refuges. Physical re-aeration strategies generally result in only a small increase in dissolved oxygen but may be beneficial for local refuge protection. Dilution and natural re-aeration processes in large, shallow lake systems can be sufficient to compensate for hypoxic inflows and water processed in off-channel lakes may be able to be returned to the river channel as dilution flows. We provide a set of predictive models (as electronic supplementary material) for estimation of the re-aeration potential of intervention activities and a framework to guide the adaptive management of future hypoxic blackwater events.     

Efficiency of bait usage in the Nova Scotia lobster fishery: a first look

In studies of commercial fishing, little attention has been paid to the use of bait. We examined lobster fishery bait-to-catch ratios in St. Margaret's Bay and Mahone Bay, Nova Scotia. Data were obtained from the Fishermen and Scientists Research Society's Lobster Recruitment Project. Local ecological knowledge of the resource users from within the study area was also gathered using semi-structured interviews. The estimated amount of bait required to catch each lobster, weighing about 480 g, ranged from 185 g (November) to 1455 g (April) for average months during the 2002/3, 2003/4 and 2004/5 fishing seasons. We estimated the overall ratio of bait-to-catch to be about 1.9 units of bait per unit of catch. The eco-efficiency and food-supply implications of consuming more bait than product in a fishery are outlined.