Shine a light: Under-ice light and its ecological implications in a changing Arctic Ocean

The Arctic marine ecosystem is shaped by the seasonality of the solar cycle, spanning from 24-h light at the sea surface in summer to 24-h darkness in winter. The amount of light available for under-ice ecosystems is the result of different physical and biological processes that affect its path through atmosphere, snow, sea ice and water. In this article, we review the present state of knowledge of the abiotic (clouds, sea ice, snow, suspended matter) and biotic (sea ice algae and phytoplankton) controls on the underwater light field. We focus on how the available light affects the seasonal cycle of primary production (sympagic and pelagic) and discuss the sensitivity of ecosystems to changes in the light field based on model simulations. Lastly, we discuss predicted future changes in under-ice light as a consequence of climate change and their potential ecological implications, with the aim of providing a guide for future research.     

Evaluation of the potential of applying composting/bioremediation techniques to wastes generated within the construction industry

The objective of the present study was to evaluate the viability of reducing landfill requirements to satisfy EC Landfill Directive requirements by applying composting/bioremediation techniques to the construction and demolition (C&D) industry waste stream at laboratory scale. The experimental study was carried out in nine test rigs to examine different wood mixtures; untreated timber, creosote treated timber and chromated copper arsenate (CCA) treated timber. Several experimental variables affecting the process were characterised and optimised. These include the best nitrogen additive and optimum moisture content required for composting. Poultry manure was found to be the best nitrogen additive. The optimum moisture content was decreased after the addition of poultry manure. The composting/bioremediation process was evaluated through monitoring the microbial activity, carbon dioxide emissions and toxicity examination of the composted product. A typical temperature profile suggested that untreated and CCA treated mix could be classified as hot composting whereas creosote treated mix could be classified as cold composting. The paper reports on the results obtained during this investigation.     

Synergisms among Habitat Fragmentation, Livestock Grazing, and Biotic Invasions in Southwestern Australia

Abstract: The agricultural development of southern Australia over the past 200 years has resulted in extensively fragmented systems, often with only small, isolated remnants of native vegetation remaining. Grazing by sheep and cattle has affected both the remaining fragments and the surrounding matrix, and non-native plant and animal species have had dramatic effects on the native biota. Invasive plant species have the potential to significantly alter ecosystem composition and functioning, and invasive animals, particularly rabbits ( Oryctolagus cuniculatus ), foxes (    Vulpes vulpes ) and cats (    Felis catus ) effectively alter habitat and drive native fauna to local extinction. These different influences often interact. For instance, smaller fragments are often more prone to plant invasion and are more likely to have been grazed in the past. Invasion of plant species is often linked with livestock grazing or rabbit invasion, and other higher-order interactions are also apparent. Classical fragmentation studies that concentrate on parameters such as habitat area and isolation but ignore changes in habitat condition brought about by livestock and invasive species are unlikely to yield meaningful results. Similarly, management of fragmented ecosystems must account for not only the spatial characteristics of the remaining habitat but also the importance of other influences, particularly those that impinge on fragments from the surrounding matrix.     

A Probabilistic Production Costing Analysis of SO2 Emissions Reduction Strategies for Ohio: Emissions,Cost, and Employment Tradeoffs

A new approach for state- and utility-level analysis of the cost and regional economic impacts of strategies for reducing utility SO₂ emissions is summarized and applied to Ohio. The methodology is based upon probabilistic production costing and economic input-output analysis. It is an improvement over previous approaches because it: (1) accurately models random outages of generating units, “must-run” constraints on unit output, and the distribution of power demands; and (2) runs quickly on a microcomputer and yet considers the entire range of potential control strategies from a systems perspective. The input-output analysis considers not only the economic effects of utility fuel use and capital investment, but also those of increased electric rates. Two distinct strategies are found to be most attractive for Ohio. The first, more flexible one, consists of emissions dispatching (ED) alone to meet short run emissions reduction targets. A 75 percent reduction can then be achieved by the turn of the century by combining ED and fuel switching (FS) with flue gas desulfiirization, limestone Injection multistage burners, and physical coal cleaning at selected plants. The second is a scrubber-based strategy which includes ED. By the year 2000, energy conservation becomes a cost effective component of these strategies. In order to minimize compliance costs, acid rain legislation which facilitates emissions trading and places regional tonnage limits on emissions is desirable.     

210Pb-dating of a lake sediment core from Lough Carra (Co. Mayo, western Ireland): use of paleolimnological data for chronology validation below the 210Pb dating horizon

The chronologies and sediment accumulation rates for a lake sediment sequence from Lough Carra (Co. Mayo, western Ireland) were established by applying the constant initial concentration (CIC) and constant rate of supply (CRS) hypotheses to the measured ²¹⁰Pb_excess profile. The resulting chronologies were validated using the artificial fallout radionuclides ¹³⁷Cs and ²⁴¹Am, which provide independent chronostratigraphic markers for the second half of the 20th century. The validity of extrapolating the derived CIC and CRS dates below the ²¹⁰Pb dating horizon using average sedimentation rates was investigated using supplementary paleolimnological information and historical data. Our data confirm that such an extrapolation is well justified at sites characterised by relatively stable sedimentation conditions.     

Natural Resource Management at Four Social Scales: Psychological Type Matters

Understanding organisation at different social scales is crucial to learning how social processes play a role in sustainable natural resource management. Research has neglected the potential role that individual personality plays in decision making in natural resource management. In the past two decades natural resource management across rural Australia has increasingly come under the direct influence of voluntary participatory groups, such as Catchment Management Authorities. The greater complexity of relationships among all stakeholders is a serious management challenge when attempting to align their differing aspirations and values at four social institutional scales—local, regional, state and national. This is an exploratory study on the psychological composition of groups of stakeholders at the four social scales in natural resource management in Australia. This article uses the theory of temperaments and the Myers-Briggs Type Indicator (MBTI^®) to investigate the distribution of personality types. The distribution of personality types in decision-making roles in natural resource management was markedly different from the Australian Archive sample. Trends in personality were found across social scales with Stabilizer temperament more common at the local scale and Theorist temperament more common at the national scale. Greater similarity was found at the state and national scales. Two temperaments comprised between 76 and 90% of participants at the local and regional scales, the common temperament type was Stabilizer. The dissimilarity was Improviser (40%) at the local scale and Theorist (29%) at the regional scale. Implications for increasing participation and bridging the gap between community and government are discussed.     

Regulating overabundant ungulate populations: an example for elk in Rocky Mountain National Park, Colorado

In many areas of the world, populations of native ungulates have become so abundant that they are believed to be harming vegetation and disrupting ecosystem function. Methods for controlling overabundance populations include culling animals from the population and controlling fertility using contraceptives. However, understanding the feasibility these alternatives requires insight into their long-term effects on populations. We constructed a simulation model to evaluate options for regulating elk populations in and around Rocky Mountain National Park and used the model to compare different treatment options. Methods were evaulated with respect to the time required to reduce the population to a target level, the number of animals treated and/or culled and the risk of extinction. We contrasted culling with lifetime-effect contraceptives and yearlong contraceptives. Lifetime contraceptives required treating the fewest animals to maintain the population at desired targets. However, this approach also causes the greatest population variability and potential risk of extinction. Yearlong contraceptives required treatment of dramatically more animals but had essentially no extinction risk whereas culling produced intermediate levels of both extinction risk and number of animals treated. These results characterize the risks and benefits of alternative control strategies for overabundant wildlife. They emerge from a modeling approach that can be broadly useful in helping managers in choose between alternatives for regulating overabundant wildlife.     

Additives to reduce ammonia and odor emissions from livestock wastes: a review

This paper reviews the use of additives to reduce odor and ammonia (NH3) emissions from livestock wastes. Reduction of NH3 volatilization has been shown to be possible, particularly with acidifying and adsorbent additives, and potential exists to develop further practical and cost-effective additives in this area. Masking, disinfecting, and oxidizing agents can provide short-term control of malodor, but as the capacity of these additives is finite, they require frequent reapplication. Microbial-based digestive additives may offer a solution to this problem as they are regenerative, but they appear to have been developed without a thorough understanding of microbiological processes occurring in livestock wastes. Currently, their use to reduce odor or NH3 emissions cannot be recommend. If the potential of these types of additives is to be realized, research needs to shift from simply evaluating these unknown products to investigating known strains of bacteria or enzymes with known modes of action. To protect the farmers' interest, standard independent test procedures are required to evaluate efficacy. Such tests should be simple and quantify the capacity of the additive to perform as claimed. The principle use of additives needs to be identified and addressed during their development. Producers may not use effective additives in one area if they further compound other problems that they perceived to be more important. There is the potential to use additives to treat other problems associated with livestock wastes, particularly to improve handling properties, reduce pollution potential to watercourses, and reduce pathogenic bacteria. Further work is required in these areas.     

Disturbance, Diversity, and Invasion: Implications for Conservation

Disturbance is an important component of many ecosystems, and variations in disturbance regime can affect ecosystem and community structure and functioning. The "intermediate disturbance hypothesis" suggests that species diversity should be highest at moderate levels of disturbance. However, disturbance is also known to increase the invasibility of communities. Disturbance therefore poses an important problem for conservation management, Here, we review the effects of disturbances such as fire grazing, soil disturbance and nutrient addition on plant species diversity and invasion with particular emphasis on grassland vegetation. Individual components of the disturbance regime can have marked effects on species diversity, but it is often modifications of the existing regime that have the largest influence. Similarly, disturbance can enhance invasion of natural communities, but frequently it is the interaction between different disturbances that has the largest effect. The natural disturbance regime is now unlikely to persist within conservation areas since fragmentation and human intervention have usually modified physical and biotic conditions. Active management decisions must now be made on what disturbance regime is required and this requires decisions on what species are to be encouraged or discouraged.     

Native predators reduce harvest of reindeer by Sámi pastoralists

Contemporary efforts to protect biological diversity recognize the importance of sustaining traditional human livelihoods, particularly uses of the land that are compatible with intact landscapes and ecologically complete food webs. However, these efforts often confront conflicting goals. For example, conserving native predators may harm pastoralist economies because predators consume domestic livestock that sustain people. This potential conflict must be reconciled by policy, but such reconciliation requires a firm understanding of the effects of predators on the prey used by people. We used a long-term, large-scale database and Bayesian models to estimate the impacts of lynx (Lynx lynx), wolverine (Gulo gulo), and brown bear (Ursus arctos) on harvest of semi-domesticated reindeer (Rangifer tarandus) by Sami pastoralists in Sweden. The average annual harvest of reindeer averaged 25% of the population (95% credible interval = 19, 31). Annual harvest declined by 96.6 (31, 155) reindeer for each lynx family group (the surveyed segment of the lynx population) in a management unit and by 94.3 (20, 160) for each wolverine reproduction (the surveyed segment of the wolverine population). We failed to detect effects of predation by brown bear. The mechanism for effects of predation on harvest was reduced population growth rate. The rate of increase of reindeer populations declined with increasing abundance of lynx and wolverine. The density of reindeer, latitude, and weather indexed by the North Atlantic Oscillation also influenced reindeer population growth rate. We conclude that there is a biological basis for compensating the Sámi reindeer herders for predation on reindeer.