Predator identity and additive effects in a treehole community

Multiple predator species can interact as well as strongly affect lower trophic levels, resulting in complex, nonadditive effects on prey populations and community structure. Studies of aquatic systems have shown that interactive effects of predators on prey are not necessarily predictable from the direct effects of each species alone. To test for complex interactions, the individual and combined effects of a top and intermediate predator on larvae of native and invasive mosquito prey were examined in artificial analogues of water-filled treeholes. The combined effects of the two predators were accurately predicted from single predator treatments by a multiplicative risk model, indicating additivity. Overall survivorship of both prey species decreased greatly in the presence of the top predator Toxorhynchites rutilus. By itself, the intermediate predator Corethrella appendiculata increased survivorship of the native prey species Ochlerotatus triseriatus and decreased survivorship of the invasive prey species Aedes albopictus relative to treatments without predators. Intraguild predation did not occur until alternative prey numbers had been reduced by approximately one-half. Owing to changes in size structure accompanying its growth, T. rutilus consumed more prey as time progressed, whereas C. appendiculata consumed less. The intermediate predator, C. appendiculata, changed species composition by preferentially consuming A. albopictus, while the top predator, T. rutilus, reduced prey density, regardless of species. Although species interactions were in most cases predicted from pairwise interactions, risk reduction from predator interference occurred when C. appendiculata densities were increased and when the predators were similarly sized.     

Sources of errors in assessing ozone visible symptoms on native vegetation

This paper aims to identify the problems regarding the evaluation of ozone (and ozone-like) symptoms, by examining the results of the 4th UN/ECE ICP-Forests Intercalibration Course for the assessment of ozone-induced visible symptoms. Trees, shrubs and herbaceous species were evaluated in a tree nursery, at Lattecaldo (Switzerland) and under open field conditions at Moggio (Italy). The main findings were: (i) the most expert surveyors tended to be grouped in the same cluster and, during the field exercises, they tended to assess in a more conservative manner compared to the less trained participants; (ii) the agreement was greater in assessing the absence rather than the presence of symptoms; (iii) typical interveinal stippling on the upper leaf surface was more accurately evaluated than discoloration; (iv) uncertainties resulted mainly for species which showed greater variability in their symptom manifestation, and for certain herbaceous species.     

Using EH&S management systems to improve corporate profits

An environmental management system (EMS) approach can improve overall corporate performance and demonstrate this improvement to top management in “dollars and cents” language. This article illustrates the importance of a financial management approach to justify investments in environmental, health, and safety (EH&S) excellence. It also describes in detail the elements of the EH&S management assessment and improvement process.     

The use of terrestrial ecoregions as a regional-scale screen for selecting representative reference sites for water quality monitoring

A process has been developed to select watersheds that are representative of terrestrial ecoregions and that are relatively undisturbed by human activity. Using an existing land classification system at two hierarchical levels of resolution, representative subsets (ecodistricts) of large-scale ecoregions were selected, on the basis of their physiographic, biological, and climatological attributes, to represent the ecoregions. This was achieved using a frequency distribution analysis of existing attribute data and choosing the ecodistrict most closely resembling the most common set of conditions for that ecoregion. Within each ecodistrict, river basins were selected through a best-judgement evaluation of land use, coupled with an assessment of the size and location of each river basin, in order to meet the condition of minimal human impact. Preliminary assessment of water quality data collected from six watersheds selected in this way suggests that the process is effective in targeting regional scale river basins exhibiting the desired characteristics.     

137Cs in marine samples from the Brazilian southeastern coastal region

The present work presents the results of ¹³⁷Cs concentration in seawater, fish and sediments samples collect in 11 sampling points, crossing the Brazilian Southeastern coastal region, from Vitória (ES) to Santos (SP), on a routine basis from 1997 to 2002. This monitoring program was carried out by the Instituto de Radioproteção e Dosimetria (IRD/CNEN/MCT), in cooperation with the Instituto de Estudos do Mar Almirante Paulo Moreira (IEAPM/Brazilian Navy), aiming at determining artificial radionuclides in marine samples. Additionally to the ¹³⁷Cs results, ⁹⁰Sr concentrations in fish samples from 1998 to 2002 are also reported.The ¹³⁷Cs in seawater follows a lognormal distribution, with a geometric mean of 1.8 Bq m^-3 and a geometric standard deviation of 1.4 (n=54), decay corrected to June/2002. For ¹³⁷Cs levels in fish samples a geometric mean of 0.19 Bq kg⁻¹ and a geometric standard deviation of 2.9 (n=39), decay corrected to June/2002, with a range of 0.03 to 1.7 Bq kg⁻¹, were obtained. Based on the ¹³⁷Cs mean concentration in fish as well as in seawater, a transfer factor of 1 × 10² was calculated, which is quite in agreement with the recommended value found in the Safety Report Serie 19.     

MULTIVARIATE CLASSIFICATION OF SMALL ORDER WATERSHEDS IN THE QUABBIN RESERVOIR BASIN,MASSACHUSEVFS1

ABSTRACT: A multivariate approach was used to analyze hydrologic, geologic, geographic, and water-chemistry data from small order watersheds in the Quabbin Reservoir Basin in central Massachusetts. Eighty three small order watersheds were delineated and landscape attributes defining hydrologic, geologic, and geographic features of the watersheds were compiled from geographic information system data layers. Principal components analysis was used to evaluate 11 chemical constituents collected bi-weekly for 1 year at 15 surface-water stations in order to subdivide the basin into subbasins comprised of watersheds with similar water quality characteristics. Three principal components accounted for about 90 percent of the variance in water chemistry data. The principal components were defined as a biogeochemical variable related to wet. land density, an acid-neutralization variable, and a road-salt variable related to density of primary roads. Three subbasins were identified. Analysis of variance and multiple comparisons of means were used to identify significant differences in stream water chemistry and landscape attributes among subbasins. All stream water constituents were significantly different among subbasins. Multiple regression techniques were used to relate stream water chemistry to landscape attributes. Important differences in landscape attributes were related to wetlands, slope, and soil type.     

西印度洋地区海草生态系统

海草是海洋被子植物,广泛分布在温带和热带的海岸带水域,是地球上水生生态系统中最具生产力的生物之一.     

Water and the potential for social instability: Livelihoods, migration and the building of society

In much of the Third World, access to secure water for irrigation, particularly groundwater, reduces vulnerability, stabilizes livelihoods,alleviates poverty and 'entitles' populations to education and other forms of capital accumulation. Water resource development can, as a result, be used as a key tool for addressing the social roots of instability. The reverse is also true — problems such as groundwater overdraft contribute to poverty and are often at the root of forced migration and the creation of underemployed and unstable displaced populations. Water is fundamental to regional as well as local security.
The benefits of water resource development and the risks associated with unsustainable use patterns are particularly critical in arid regions. Patterns of water use that are unsustainable can play a positive role in the transition of populations from nomadic or migratory to stable communities, where people have access to education and asset accumulation. The exit is, however, as important as the entry. In many regions, the majority of the population now need to make the transition from agriculture to non–agricultural livelihoods. Many people, particularly the wealthy, may already be doing this. Understanding and enabling transition represents one of the most important policy challenges for coming decades.
Using examples from India, Yemen, Saudi Arabia and other countries, this article documents some of the connections between water and security and clarifies the importance of effective solutions to water problems and to social transition in arid regions.     

Legitimation Struggles in National Park Spaces: The Banff Bow Valley Round Table

This paper presents an in-depth analysis of a multi-stakeholder process, the Banff Bow Valley Round Table (BBVRT) convened by a federally appointed task force in 1995 to provide public input and participation in the Banff Bow Valley Study (BBVS). The purpose of this initiative was to address environmental concerns and conflict over governance, development and growth in Banff National Park, Canada. A key finding from the analysis discussed in this paper is how various participants struggled for legitimation at the negotiation table, and how the discourses of science and instrumental reason served to empower certain interests and agendas in the process. While the discursive appropriation of ecological science enabled some interests to dominate and to legitimize their concerns, this strategy may have intangible and costly consequences for consensus-based processes and for society overall. Analysis of these discursive struggles demonstrates the challenge of bringing ecology and the general public to the same negotiating table in a meaningful way. It shows the conflicting roles and identities of environmental groups who aspire to re-present nature (as a stakeholder) at the negotiating table. Recommendations for multi-stakeholder processes in planning and governance of national parks are presented, along with social implications in the context of historic human-environment dualism and conflict.