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Field Surveys (field + survey)
Terms modified by Field Surveys Selected AbstractsCOMPARISON OF HSPF OUTPUTS USING FTABLES GENERATED WITH FIELD SURVEY AND DIGITAL DATA,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 5 2006Nathan Staley ABSTRACT: The Hydrological Simulation Program-FORTRAN (HSPF) describes discharge from a stream reach based on function tables (FTABLES) that relate stream stage, surface area, volume, and discharge. For this study, five FTABLE scenarios were compared to assess their effect on daily discharge rates predicted using HSPF. Four "field-based" FTABLE scenarios were developed using detailed cross section surveys collected at predefined intervals along 14 reaches in the study watershed. A fifth "digital-based" scenario was developed using digital elevation models (DEMs) and Natural Resource Conservation Service (NRCS) Regional Hydraulic Geometry Curves. The Smirnov k-sample test was used to compare average daily discharge rates simulated with HSPF using the five FTABLE scenarios. No significant difference in simulated stream discharge was found (p = 0.99) between the five FTABLE scenarios. Additional examination of the four field-based scenarios revealed that the number of cross sections per stream reach used to generate FTABLES had little effect on the resulting stage discharge relationship. These findings suggest that FTABLES generated using digital data are a viable option when simulating stream discharge with HSPF and that if field data are used to generate FTABLES, using fewer cross sections will not adversely affect simulated discharge predictions. [source] Environmental mastitis in intensive high-producing dairy herds in New South WalesAUSTRALIAN VETERINARY JOURNAL, Issue 12 2009LWC Shum Objective To determine the prevalence of mastitis pathogens in high-producing intensive dairy herds in New South Wales. Design Field survey. Procedure Milk samples from the mastitis-affected quarter were collected from cows on five high-producing dairy farms in NSW. The 820 samples were cultured using standard microbiological culture techniques. Results Bacteria or fungi were isolated from 83.3% of samples (683/820). More than two colony types were isolated from 16.7% of samples (137/820), two types from 6.6% (54/820), and one type from 52.3% (429/820). No bacteria were isolated from 24.4% (200/820) of the primary cultures, but enrichment cultures of these samples yielded single colony type bacterial isolates from 36.5% (73/200) of samples. Environmental pathogens, including coliforms, environmental Streptococcus and Staphylococcus spp., made up 91% (555/610) of isolates and accounted for 33.6% (205/610), 41.6% (254/610) and 15.7% (96/610), respectively, of isolates. Escherichia coli accounted for 76.1% (156/205) of the coliform isolates, Streptococcus uberis and Streptococcus dysgalactiae accounted for 32.3% (82/254) and 28.0% (71/254), respectively, of the environmental streptococcal isolates. Contagious pathogens were uncommon, comprising only 2.5% (15/610) of the total isolates. Conclusion The incidence and causes of mastitis are largely influenced by farm management. The relatively high prevalence of coliform mastitis in the intensive high-producing herds in this survey contrasts with the low incidence reported in surveys of pasture-based herds in Victoria. If the Australian dairy industry continues its current trend of intensification, coliform intra-mammary infections may emerge as an increasingly important cause of mastitis. [source] Tectonic Landform of Quaternary Lakes and Its Implications for Deformation in the Northern Qinghai-Tibet PlateauACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 1 2009An WANG Abstract: The Hohxil region in the northern Qinghai-Tibet Plateau is occupied by numerous plateau lakes, which have long been inferred as being tectonic products. However, so far little evidence has been found to support this tentative inference. Field survey and morphotectonic analysis of TM satellite images in the eastern segment of the Hohxil region revealed that Kusai Lake and Yelusu Lake are S-shaped pull-apart basins, which were dominated by left strike-slip master faults trending WNW-ESE. The pull-apart distances of the two lakes are analyzed to be <15,20 km and 15 km respectively. Based on studies of the faulting rate, the initiation ages of the pull-apart basins are suggested to be approximately in the Early Pleistocene. The pull-apart basin tectonics is further regarded as a common mechanism for the widely distributed large lake basins in the northern Qinghai-Tibet Plateau. Regional distribution of these pull-apart basins and their substantial intra-block slip suggest that a sinistral shear stress, which is independent of the distinguished strike-slip faults, has been imposed on across the northern Qinghai-Tibet Plateau. Thus, the intra-block slip may be an important expression of the eastward extrusion of the Plateau crustal material in accommodating the ongoing continent-continent convergence between India and Eurasia. The revelation of pull-apart tectonics within the Plateau hinterland provides field evidence and a possible style of deformation for the newly proposed continuous deformation by the global positioning system (GPS) measurement across the northern Qinghai-Tibet Plateau. A model, with respect to systematic tectonic landform development, for pull-apart basins is finally proposed. [source] Viruses of vegetable crops in AlbaniaEPPO BULLETIN, Issue 3 2005M. Finetti-Sialer Field surveys were carried out in the main vegetable-growing areas of Western and Central Albania to evaluate the sanitary status of open-field and protected cultivations of capsicum, tomato, potato, watermelon, cucumber, courgette, aubergine, lettuce, cabbage, chicory, leek and celery. The following viruses were detected: Alfalfa mosaic alfamovirus (AMV), Cucumber mosaic cucumovirus (CMV), Potato Y potyvirus (PVY), Tomato spotted wilt tospovirus (TSWV) and Watermelon mosaic potyvirus 2 (WMV-2). The virus found most frequently was CMV and all the isolates identified were of subgroup IA. AMV was also detected in several areas and all isolates were of subgroup II, suggesting a French origin. Finally, at the time of this survey, TSWV infections appeared to be moderately relevant and absent in protected crops. This is the first documented record of AMV, CMV, PVY, TSWV and WMV-2 in Albania. No infection by Tomato yellow leaf curl begomovirus (TYLCV) or Zucchini yellow mosaic potyvirus (ZYMV) was detected during this survey. [source] Increasing distribution and damage to palms by the Neotropical whitefly, Aleurotrachelus atratus (Hemiptera: Aleyrodidae)JOURNAL OF APPLIED ENTOMOLOGY, Issue 6 2010N. Borowiec Abstract In recent years, the coconut whitefly, Aleurotrachelus atratus Hempel, has been recorded from various islands in the southwestern Indian Ocean. Field surveys in La Réunion, the Seychelles, the Comoros and glasshouses in Paris have allowed us to record this whitefly on 56 palm species, some of which are endemic and/or threatened species. Most of trees showed low infestation levels, except for the coconut palm that is its main host plant. Such a wide host range has facilitated the rapid geographical dissemination of this whitefly. A field study was conducted in 2006 in La Réunion, to gain a better understanding of the bioecology of A. atratus in a tropical insular ecosystem. The whitefly was found throughout the island, from sea level to 800-m altitude. Five parasitoid species (Hymenoptera: Aphelinidae) were found associated with the populations of this pest, with Eretmocerus cocois Delvare being the dominant one. A laboratory study showed that the pre-imaginal development of A. atratus is around 48 days at 25,27°C, which is relatively long compared to other whitefly species. With a sex ratio of one male per 1022 females collected in La Réunion, it appears that the whitefly reproduces by thelytoky. It represents a threat to ornamental and agricultural palms as well as to natural palm ecosystems in the absence of effective parasitoids. [source] Species diversity of lepidopteran stem borer parasitoids in cultivated and natural habitats in KenyaJOURNAL OF APPLIED ENTOMOLOGY, Issue 6 2009D. M. Mailafiya Abstract Field surveys were conducted during 2005 to 2007 to assess the species diversity of stem borer parasitoids in cultivated and natural habitats in four agroecological zones in Kenya. In total, 33 parasitoid species were recovered, of which 18 parasitized six stem borer species feeding on cereal crops, while 27 parasitized 21 stem borer species feeding on 19 wild host plant species. The most common parasitoids in cultivated habitats were Cotesia flavipes Cameron, Cotesia sesamiae (Cameron), Pediobius furvus Gahan and the tachinid Siphona sp., whereas in natural habitats, Siphona sp. was the most common. The majority of parasitoids were stenophagous species; only five species ,Cotesia sp., Enicospilus ruscus Gauld and Mitchell, Pristomerus nr. bullis, Sturmiopsis parasitica (Curran) and Syzeuctus ruberrimus Benoit , were monophagous. In both cultivated and natural habitats, parasitoid species diversity was highest on the most dominant stem borers Busseola spp. and Chilo spp. On cereal crops, parasitoid diversity was highest on maize and among wild host plants, it was highest on Setaria spp. The ingress-and-sting attack method was the most common strategy used by parasitoids in both habitats. In all agroecological zones, parasitoid species diversity was significantly higher in natural than in cultivated habitats. Furthermore, the majority of parasitoid species were common to both cultivated and natural habitats. It was concluded that natural habitats surrounding cereal crops serve as refugia for sustaining the diversity of stem borer parasitoids from adjacent cereal fields. [source] Field performance and seasonal changes in the efficacy against Helicoverpa armigera (Hübner) of transgenic cotton expressing the insecticidal protein vip3AAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 2 2007Danny J. Llewellyn Abstract 1,Three years of field experiments in Eastern Australia were carried out on transgenic cotton (Gossypium hirsutum L.) event Cot102 expressing the insecticidal protein gene vip3A from Bacillus thuringiensis to evaluate performance against Helicoverpa armigera Hübner. Efficacy, defined as the capacity of plant tissues to induce larval mortality, was determined with a well-validated leaf bioassay fortnightly through the growth cycle of the cotton in each season. 2,Cot102 plants proved highly efficacious against H. armigera, particularly early in the season, although their efficacy declined as the season progressed, in a manner similar to, but not as dramatic as, that observed with commercial Cry1Ac expressing cotton (Bollgard or Ingard cotton). 3,Field surveys indicated that very few larvae survived beyond first instar on intact growing plants. 4,In one season efficacy declined for a period of approximately 20 days after a cool wet period, suggesting that this may have had a detrimental effect on the expression or efficacy of the gene, but this will need to be verified in further replicated trials. 5,Quantitative enzyme-linked immunosorbent assays indicated that there was no dramatic reduction in production of the vip3A protein during growth and maturation of the crop, suggesting that other host plant factors were affecting the efficacy of the insecticidal protein in the insect gut. 6,These data indicate that Cot102 cotton would provide a useful alternative to Bollgard cotton but, given the similar lytic mode of action of vip3A proteins in the insect midgut, there may be similar inherent vulnerabilities to resistance evolution for these proteins if used alone. Pyramiding of the vip3A trait with a second insecticidal gene would appear to be a high priority for achieving sustainable deployment against H. armigera or similar susceptible species. [source] Occurrence of Pseudomonas syringae pv. coryli on Hazelnut Orchards in Sicily, Italy and Characterization by Fluorescent Amplified Fragment Length PolymorphismJOURNAL OF PHYTOPATHOLOGY, Issue 7-8 2007G. Cirvilleri Abstract Field surveys for ascertaining the sanitary status of hazelnut (Corylus avellana L.) orchards located in the provinces of Catania and Messina, Sicily, were carried out. Twig and branch diebacks were frequently observed on the local hazelnut cultivars. Identification of the bacterial pathogen associated with these symptoms was performed by means of biochemical, pathogenicity and molecular tests as well as by using fluorescent amplified fragment length polymorphic (fAFLP) analysis. The study revealed, for the first time, the presence of Pseudomonas syringae pv. coryli in the Sicilian hazelnut orchards. All the strains obtained did not show the presence of syrB gene. The fAFLP analysis pointed out the presence of three different lineages within the strains of this pathogen. [source] Assessment of occupational health and safety risks of farmworkers in Colorado ,AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue S2 2002Martha Soledad Vela-Acosta MD Abstract Background Migrant farmworkers face a variety of hazards including exposure to pesticides and agricultural chemicals. However, few studies have quantatively evaluated these risks. Methods Hazards were assessed during 32 field surveys conducted in the agricultural fields and 15 surveys at five camps. Observations of 1,461 farmworkers for potential hazards were recorded. Estimated risk was evaluated on a four-point scale (no hazard, minor, serious, and critical). A total of 229 farmworkers were interviewed about field conditions. Results Two out of the five camps did not have safe drinking water. Risks for farmworkers were lower when a manager was living on site. Field surveys estimated higher risk when provision of sanitation was deficient (P,<,0.05). Farmworkers' responses concerning field conditions differed from the survey findings. Conclusions Risks for farmworkers depended largely on the environment provided. Discordances between survey results and farmworkers' interview responses suggested that self-reported data might have limited validity for this population. Working and living conditions require improvement to decrease occupational risks for farmworkers. Am. J. Ind. Med. Suppl. 2:19,27, 2002. © 2002 Wiley-Liss, Inc. [source] Does biogeographical history matter?AUSTRAL ECOLOGY, Issue 1 2005Diversity, distribution of lotic midges (Diptera: Chironomidae) in the Australian Wet Tropics Abstract We examined broad scale patterns of diversity and distribution of lotic Chironomidae (Diptera) within the Wet Tropics bioregion of northern Queensland, Australia. Field surveys across broad latitudinal and altitudinal gradients within the Wet Tropics revealed a fauna of 87 species-level taxa in 49 genera comprising three main elements: a small genuinely tropical fraction, and larger cosmopolitan and Gondwanan components. The latter group originated when Australia, as part of the ancient Gondwana supercontinent, was situated over Antarctic latitudes with a cooler, wetter climate than today. In the Wet Tropics, cool Gondwanan taxa occurred predominantly in upland and shaded lowland sites, but no species appeared narrowly temperature restricted, and there was no faunal zonation with altitude. Most chironomid species occurred at all latitudes within the Wet Tropics, with no evidence for an enduring effect of the historical rainforest contractions on current-day distribution patterns. These findings contrast with those for aquatic faunas elsewhere in the world and for the terrestrial Wet Tropics fauna. We relate this to the generally broad environmental tolerances of Australian chironomids, and comment on why the latitudinal diversity gradient does not apply to the Australian chironomid fauna. [source] Does biogeographical history matter?AUSTRAL ECOLOGY, Issue 1 2005Diversity, distribution of lotic midges (Diptera: Chironomidae) in the Australian Wet Tropics Abstract We examined broad scale patterns of diversity and distribution of lotic Chironomidae (Diptera) within the Wet Tropics bioregion of northern Queensland, Australia. Field surveys across broad latitudinal and altitudinal gradients within the Wet Tropics revealed a fauna of 87 species-level taxa in 49 genera comprising three main elements: a small genuinely tropical fraction, and larger cosmopolitan and Gondwanan components. The latter group originated when Australia, as part of the ancient Gondwana supercontinent, was situated over Antarctic latitudes with a cooler, wetter climate than today. In the Wet Tropics, cool Gondwanan taxa occurred predominantly in upland and shaded lowland sites, but no species appeared narrowly temperature restricted, and there was no faunal zonation with altitude. Most chironomid species occurred at all latitudes within the Wet Tropics, with no evidence for an enduring effect of the historical rainforest contractions on current-day distribution patterns. These findings contrast with those for aquatic faunas elsewhere in the world and for the terrestrial Wet Tropics fauna. We relate this to the generally broad environmental tolerances of Australian chironomids, and comment on why the latitudinal diversity gradient does not apply to the Australian chironomid fauna. [source] Identification, distribution and current taxonomy of Botryosphaeriaceae species associated with grapevine decline in New South Wales and South AustraliaAUSTRALIAN JOURNAL OF GRAPE AND WINE RESEARCH, Issue 1 2010W.M. PITT Abstract Background and Aims:, Botryosphaeriaceae species are recognised as important pathogens of grapevines both in Australia and overseas. The identity, prevalence and distribution of Botryosphaeriaceae species in vineyards throughout the major winegrowing regions of New South Wales (NSW) and South Australia (SA) was determined to provide a foundation for improved disease prevention and management. Methods and Results:, Field surveys from 91 vineyards across NSW and SA resulted in the collection of 2239 diseased wood samples and subsequent isolation of 1258 Botryosphaeriaceae isolates. Morphological identification along with phylogenetic analysis of ribosomal DNA internal transcribed spacer regions (ITS1-5.8S-ITS2) and partial sequences of the translation elongation factor 1-, gene (EF1-,) showed that eight Botryosphaeriaceae species from four phylogenetic lineages occur on grapevines in eastern Australia, including Diplodia seriata, Diplodia mutila, Lasiodiplodia theobromae, Neofusicoccum parvum, Neofusicoccum australe, Botryosphaeria dothidea, Dothiorella viticola and Dothiorella iberica. Conclusions:, The prevalence of individual species varied according to geography and climate. Species of Diplodia and Dothiorella, characterised by thick-walled, pigmented conidia were the most prevalent and were distributed widely throughout both NSW and SA. Species with hyaline conidia, such as Neofusicoccum and Fusicoccum, were isolated less frequently and displayed more limited geographic ranges, whilst only a single isolate of Lasiodiplodia was recovered, this being from the northern most region of NSW. Significance of the Study:, The identification of eight taxa within the Botryosphaeriaceae, and their distributions throughout south-eastern Australia was established and discussed in context with climate, reported optimum growth temperatures, and more recent taxonomic and nomenclatural revisions. We established a sound base for control strategies based on the prevailing species in Australian viticultural regions. [source] Capturing Flow in the Business ClassroomDECISION SCIENCES JOURNAL OF INNOVATIVE EDUCATION, Issue 2 2008Yi Maggie Guo ABSTRACT This study focuses on the flow experience in business education. Flow experience, characterized by concentration, control, and enjoyment, can lead to better learning outcomes. Leading preconditions of flow include the balance of challenge and skill, feedback, and goal clarity. Other situational factors affect the flow experience through the mediating effects of these three factors. In this article, we extend an existing framework linking flow and learning. Using the model as a guide, we start our research effort of flow in business education by conducting a field survey of student learning experience in terms of flow and influential factors. Data were collected using business students taking an introductory Operations Management course. The analysis reveals that flow does exist in classroom learning. Its key dimensions are concentration, sense of control, and enjoyment. The more important leading factor is having clear feedback. Characteristics of both the instructor and students play a role in the flow experience of students during lecture. It is evident that flow theory offers a useful framework for business education research. Suggestions for future research are made. [source] Diversity and Adaptation of Shelters in Transitional Settlements for IDPs in AfghanistanDISASTERS, Issue 4 2003Joseph Ashmore The diversity of shelters used in transitional settlements for internally displaced persons (IDPs) in Herat, Afghanistan is described. The information is based on a field survey undertaken in March 2002 and highlights the adaptation techniques, which IDPs undertake to improve any provided shelter. Potential areas for improvement are indicated; for example, the possibility for using insulated, demountable liners to prevent cold-related deaths without sacrificing shelter flexibility along with the likely need for better agency coordination of the shelter responses they provide. The wider context in which the technical recommendations would be implemented must also be considered. Such issues include agency resources, political impediments to providing the desired option, and the preference of many IDPs that the best shelter would be their home. [source] Soil erosion assessment using geomorphological remote sensing techniques: an example from southern ItalyEARTH SURFACE PROCESSES AND LANDFORMS, Issue 3 2010Sergio Lo Curzio Abstract The aim of this study is to assess of the distribution and map the geomorphological effects of soil erosion at the basin scale identifying newly-formed erosional landsurfaces (NeFELs), by means of an integration of Landsat ETM 7+ remotely sensed data and field-surveyed geomorphological data. The study was performed on a 228·6,km2 -wide area, located in southern Italy. The study area was first characterized from a lithological, pedological, land-use and morpho-topographic point of view and thematic maps were created. Then, the georeferenced Landsat ETM 7+ satellite imagery was processed using the RSI ENVI 4.0 software. The processing consisted of contrast stretching, principal component analysis (PCA), decorrelation stretching and RGB false colour compositing. A field survey was conducted to characterize the features detected on the imagery. Particular attention was given to the NeFELs, which were located using a global positioning system (GPS). We then delimited the Regions of Interest (ROI) on the Landsat ETM 7+ imagery, i.e. polygons representing the ,ground-truth', discriminating the NeFELs from the other features occurring in the imagery. A simple statistical analysis was conducted on the digital number (DN) values of the pixels enclosed in the ROI of the NeFELs, with the aim to determine the spectral response pattern of such landsurfaces. The NeFELs were then classified in the entire image using a maximum likelihood classification algorithm. The results of the classification process were checked in the field. Finally, a spatial analysis was performed by converting the detected landsurfaces into vectorial format and importing them into the ESRI ArcViewGIS 9.0 software. Application of these procedures, together with the results of the field survey, highlighted that some ,objects' in the classified imagery, even if displaying the same spectral response of NeFELs, were not landsurfaces subject to intense soil erosion, thus confirming the strategic importance of the field-checking for the automatically produced data. During the production of the map of the NeFELs, which is the final result of the study, these ,objects' were eliminated by means of simple, geomorphologically-coherent intersection procedures in a geographic information system (GIS) environment. The overall surface of the NeFELs had an area of 22·9,km2, which was 10% of the total. The spatial analysis showed that the highest frequency of the NeFELs occurred on both south-facing and southwest-facing slopes, cut on clayey-marly deposits, on which fine-textured and carbonate-rich Inceptisols were present and displaying slope angle values ranging from 12° to 20°. The comparison of two satellite imageries of different periods highlighted that the NeFELs were most clearly evident immediately after summer tillage operations and not so evident before them, suggesting that these practices could have played an important role in inducing the erosional processes. Copyright © 2009 John Wiley & Sons, Ltd. [source] Fish assemblages as influenced by environmental factors in streams in protected areas of the Czech RepublicECOLOGY OF FRESHWATER FISH, Issue 1 2006M. Humpl Abstract,,, Three streams of comparable size located in different landscape-protected areas were selected for studying the effect of environmental factors on fish assemblages using indirect (detrended correspondence analysis, DCA) and direct (canonical correspondence analysis, CCA) gradient analysis. DCA of species showed well a gradient of assemblage changes in the longitudinal profile. DCA of sites stressed the variability between the fish assemblages of the three streams. This pattern was then confirmed by the highly significant between-stream CCA. In the within-site CCA, environmental factors explained 50.7% variability for presence,absence data and 58.3% for the relative abundance data. The analysis revealed that number of ponds and land use are the most influential factors of the strongest environmental gradient. However, in the partial CCAs, factor substratum type explained the largest proportion of the variability affecting fish in their habitat choice. Generally, presence,absence and relative abundance data of fish gave similar results in both DCA and CCA analyses; the same environmental factors proved to be important in both data type analyses. The environmental factors explain more variability than the regional (between-stream) one. The total proportion of variability explained by the presence,absence data analysis was 71.9% and in the relative abundance analysis even 80.8%. The environmental factors measured during the field survey explain 2.1- and 3.4-times more assemblages' variability than factors measured from a hydrological map. Resumen 1. Tres ríos de tamaño comparable localizados en diferentes áreas de paisaje protegido de la República Checa fueron seleccionados para estudiar el efecto de factores ambientales sobre los ensamblajes de peces. Para ello, utilizando análisis de gradientes indirectos (DCA) y directos (CCA). 2. El DCA para las especies enfatizó la variabilidad entre los ensamblajes de peces de los tres ríos. Este patrón fue confirmado por un CCA altamente significativo. Para la variabilidad dentro de la localidad, un CCA reveló que los factores ambientales explicaron un 50.7% para datos de presencia-ausencia y un 58.3% para las abundancias relativas. 3. Los análisis revelaron que el número de pozas y el uso del suelo fueron los factores de mayor influencia en el gradiente ambiental. Sin embargo, en el CCA parcial, el tipo de sustrato explicó la mayor proporción de la variabilidad que afecta a los peces en la elección de hábitat. 4. Generalmente los datos de presencia-ausencia y abundancia relativa produjeron resultados similares tanto en los análisis DCA como en los CCA; los mismos factores ambientales probaron ser importantes en los análisis de ambos tipos de datos. Los factores ambientales explicaron mas variabilidad que los regionales (entre ríos). La proporción total de variabilidad explicada por el análisis de los datos de presencia-ausencia fue 71.9% mientras que para las abundancias relativas fue de 80.8%. Los factores ambientales medidos durante los muestreos de campo explicaron 2.1 y 3.4 veces mas variabilidad que los factores medidos sobre mapas hidrológicos. [source] Can late summer Landsat data be used for locating Asian migratory locust, Locusta migratoria migratoria, oviposition sites in the Amudarya River delta, Uzbekistan?ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 2 2008Ramesh Sivanpillai Abstract Existing survey methods for assessing the Asian migratory locust, Locusta migratoria migratoria L. (Orthoptera: Acrididae), infestation risk in the Amudarya River delta, Uzbekistan, are largely constrained by economic resources and site accessibility. The surveys are restricted to a few easily accessible areas, which leads to a misinterpretation of the threat of locust infestation. This often results in indiscriminate blanket treatments of vast areas of wetlands with broad-spectrum insecticides, which may adversely impact non-target fauna and flora. In order to minimize the bias during surveys, one approach would be to allocate the sampling locations based on the distribution of the primary food and shelter plant of the locusts, the common reed, Phragmites australis (Cav.) Trin. ex Steud (Poaceae). In this study, we evaluated the utility of satellite-based remotely sensed data (Landsat TM) acquired in August 2006 to characterize reed distribution in the delta and identify potential locust oviposition sites. The overall accuracy of the Landsat data to map land cover classes in the delta was 84%. The Landsat TM data identified 90% of the reeds, but it was less useful in identifying areas where other vegetations (shrubs and grasses) were mixed with reeds. During the following summer field survey in June 2007, we identified 37 sites that were infested with early-instar locusts. The low migration capacity of young nymphs in dense reed vegetation allowed us to presume that these sites were used for oviposition in the previous summer. Twenty-eight (74%) of these 37 sites had reeds in the previous year. Results from these studies demonstrate that reed distribution maps derived from satellite data could be used for targeting locust egg-pod survey locations, in order to minimize sampling bias while predicting locust infestation risks for the following season. [source] Investigating the link between pulp mill effluent and endocrine disruption: Attempts to explain the presence of intersex fish in the Wabigoon River, Ontario, CanadaENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2010Michael S. Pollock Abstract The ability of some pulp mill effluents (PME) to act as reproductive and endocrine disrupters in fish is well documented in the literature. However, changes are not always consistent with regard to species, gender, hormones, or reproductive effects. In the present study, the presence of the first intersexed fish that, to our knowledge, has been found in a Canadian river exposed to PME, is reported. A field survey of the Wabigoon River near Dryden, Ontario, in the fall of 2000 found intersexed walleye (Sander vitreus vitreus) with significantly altered hormone levels and reduced gonad size. The Wabigoon River receives discharge from a bleached kraft pulp and paper mill and a municipal wastewater (MWW) plant. It also has historical sediment contamination (wood fiber mats) contributing to extended periods of low dissolved oxygen under low flow, drought conditions. A mesocosm-based partial life cycle test exposing fathead minnows (Pimephales promelas) to reference water, 20% effluent volume to river volume (v/v), 40% (v/v), or 60% (v/v) PME as well as a field survey of the walleye in the Wabigoon River were conducted. The only change in our mesocosm exposure was a decrease in testosterone in males with increasing effluent concentration and vitellogenin induction in males exposed to 60% (v/v) effluent. These results did not reflect the magnitude of endocrine disruption seen in the wild fish survey. Several hypotheses that may explain these discrepancies are proposed. Specifically, evidence is offered from published studies indicating that either hypoxia or MWW, alone or in combination with PME, may explain the discrepancy between our field experiment and the wild fish survey. The present study illustrates the complexities of multistressor receiving environments and the need for the development of cumulative effects assessment approaches. Environ. Toxicol. Chem. 2010;29:952,965. © 2010 SETAC [source] Butyltin accumulation in two marine bivalves along a pollution gradient,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2008Chuan-Ho Tang Abstract In the present study, we describe a field survey regarding the effect of ambient water conditions in the accumulation of tributyltin (TBT) and its metabolites in green mussels (Perna viridis) and Pacific oysters (Crassostrea gigas). The results showed that following the changes in TBT pollution levels, the accumulation of butyltins exhibited clear differences between oysters and mussels. The ratio of TBT to total butyltin (TBT:,BT) decreased from 0.87 to 0.31 with increasing TBT burdens in the oysters. This status suggests that following the increases of TBT burdens, the metabolic rates of TBT were clearly enhanced in oysters; however, this phenomenon was not shown in mussels. The TBT:,BT remained relatively constant at approximately 0.7 in the mussels despite the TBT burdens. Because of this phenomenon, the opposite status of different TBT burdens between oysters and mussels were present at different TBT pollution levels. These observations may provide valuable insight when evaluating or comparing TBT pollution in the environment using oysters and/or mussels as bioindicators. [source] Habitat selection as a source of inter-specific differences in recruitment of two diadromous fish speciesFRESHWATER BIOLOGY, Issue 11 2008ROBIN HALE Summary 1For aquatic species with highly dispersive offspring, the addition of new individuals into an area (recruitment) is a key process in determining local population size so understanding the causes of recruitment variability is critical. While three general causative mechanisms have been identified (the supply of individuals, habitat selection and mortality), we have a limited understanding of how variation in each is generated, and the consequences this may have for the spatial and temporal distribution of recruits. 2We examined whether active habitat selection during settlement could be the cause of variability in populations of two diadromous fish species using a field survey and laboratory-based choice experiments. If larval behaviour is important, we predicted there would be inter-specific differences in abundance between sites during the survey, and that larvae would prefer water collected from sites with higher conspecific abundances during the experiments. 3During the field survey, significant differences were detected between two rivers (the Cumberland and Grey), with one species (Galaxias maculatus) found in higher abundances at one site (the Cumberland River) while comparable numbers of a closely related species (Galaxias brevipinnis) were caught at both sites. Laboratory choice experiments were conducted to determine whether larval preferences during settlement could be the cause of these differences. G. maculatus larvae showed a preference for freshwater over saltwater, indicating that the fish may be responding to reduced salinities around river mouths during settlement. The results of a second experiment were consistent with the notion that larval preferences could be the mechanism driving differences in the populations of the two rivers, with G. maculatus preferring water collected from the Cumberland River while G. brevipinnis did not prefer water from either river. 4These results demonstrate that active habitat selection may be important in establishing spatial patterns of larvae at settlement, and that multiple cues are likely to be involved. This study also demonstrates that the behaviours exhibited by individuals can strongly influence the structure and dynamics of populations of aquatic species with complex life cycles. [source] How internal waves influence the vertical distribution of zooplanktonFRESHWATER BIOLOGY, Issue 1 2007KARSTEN RINKE Summary 1. We present data with a high spatio-temporal resolution from a 72-h field survey in Bautzen Reservoir (Saxony, Germany). The aims of this survey were to observe hydrophysical processes during a period of unstable stratification in spring and investigate the effect of wind-induced internal waves on the vertical distribution of zooplankton. 2. Wind velocities up to 10 m s,1 caused a strong downwelling event of warm water at the sampling site and led to the generation of internal waves with an amplitude of 4 m. 3. The zooplankton community, which was dominated by Daphnia galeata, inhabited epilimnetic waters. Downwelling enlarged the thickness of the epilimnetic layer and, hence, led to high zooplankton abundances down to relatively deep water strata indicating lateral transport of zooplankton. As a consequence, area-specific zooplankton abundances increased considerably (max. fourfold) during downwelling. 4. We conclude that classical limnological field sampling, such as for monitoring purposes, can lead to severely biased estimates of zooplankton abundance due to the interfering effects of hydrophysical processes like internal waves. 5. Backscattering strengths measured by a simultaneously deployed Acoustic Doppler Current Profiler (600 kHz) were found to be correlated with estimated zooplankton abundances based on plankton samples. [source] Finding the strike direction of fractures using GPRGEOPHYSICAL PROSPECTING, Issue 3 2001Soon Jee Seol GPR reflection energy varies with antenna orientation relative to the strike and dip of the reflector. This directional dependence of GPR responses was investigated through numerical experiments and was used to estimate the azimuth of fractures and joints. Three antenna configurations were considered in this study: perpendicular-broadside (YY mode), parallel-broadside (XX mode) and cross-polarization (YX mode). The reflection energy in the cross-polarization mode shows a shape characteristic similar to the strike, regardless of the dip angle. Those in the other two modes show quite different amplitudes from the strike, depending on the dip angle. We have developed a strike-direction-finding scheme using data obtained from the three different modes for the same survey line. The azimuth angle of each reflector was displayed in colour on the GPR profile. This scheme was applied to a field survey at a granite quarry in southern Korea. The GPR profiles showed different images of the reflectors depending on the antenna configuration. The estimated azimuths of reflectors obtained using our scheme matched fairly well with those of known fractures and joints. [source] Loss of forb diversity in relation to nitrogen deposition in the UK: regional trends and potential controlsGLOBAL CHANGE BIOLOGY, Issue 10 2006CARLY J. STEVENS Abstract In this study we investigate the impact of nitrogen (N) deposition on the diversity of three different vegetation functional groups , forbs, grasses and mosses , using a field survey of acid grasslands across Great Britain. Our aim is to identify the vegetation types that are most vulnerable to enhanced N deposition, and to shed light on the mechanisms that may be driving N-initiated species changes in the UK. Sixty-eight randomly selected grasslands belonging to the UK National Vegetation Classification group U4 (Festuca ovina,Agrostis capillaris,Galium saxatile grassland) were studied along a gradient of atmospheric N deposition ranging from 6 to 36 kg N ha,1 yr,1. At each site, vegetation was surveyed and samples were taken from the topsoil and subsoil. Aboveground plant material was collected from three species: a forb, grass and moss. Both the species richness and cover of forbs declined strongly with increasing N deposition, from greater than eight species/20% cover per m2 quadrat at low levels of N to fewer than two species/5% cover at the highest N deposition levels. Grasses showed a weak but significant decline in species richness, and a trend toward increasing cover with increasing N input. Mosses showed no trends in either species richness or cover. Most of the decline in plant species richness could be accounted for by the level of ammonium deposition. Soil KCl-extractable ammonium concentration showed a significant positive correlation with N input, but there was no relationship between N deposition and extractable nitrate. In the soil O/A horizon, there was no relationship between N deposition and %N, and only a very weak positive relationship between the level of N deposition and the C : N ratio. Finally, in the vegetation, there was no relationship between N deposition and either shoot tissue N concentration or N : P ratio for any of the three reference species. Combining our regional survey with the results of published N-addition experiments provides compelling evidence that there has been a significant decline in the species richness and cover of forbs across Great Britain, and that the primary cause is competition due to an increase in the cover of grasses in response to enhanced deposition of reactive N, primarily NH4+. [source] Effects of plant trichomes on herbivores and predators on soybeansINSECT SCIENCE, Issue 5 2010Hongjun Dai Abstract, Tritrophic interaction in soybean system has received increasing attention recently. However, few studies have investigated the influence of plant trichomes on the population dynamics of soybean herbivores and their natural enemies. We conducted a field survey to investigate whether soybean trichomes affected the abundance of herbivores and their predators. The results of this study show that moderately or densely pubescent trichomes have positive influences on the abundance of some herbivores (e.g., Stollia guttiger) and predators (e.g., Propylaea japonica and Orius similes) although the influence may change over time, while trichome types do not affect the density of soybean aphid, Aphis glycines. [source] The Causes and Consequences of Albanian Emigration during Transition: Evidence from Micro Data,INTERNATIONAL MIGRATION REVIEW, Issue 1 2002Dhori Kule This note reports the results of a field survey of individuals and firms in Albania, carried out during 1998. The surveys were designed to analyze the size, causes and consequences of emigration from Albania during the 1990s. Our results show that emigrants are motivated mainly by the ease of access of neighboring countries and by the prospect of high financial returns. Although most emigrants worked illegally and had part-time, low-skilled jobs, the majority found the overall experience positive, and the skills and earnings abroad have contributed to setting up businesses on return. These results have important policy implications for both EU countries and other transition countries in the region. [source] Irrigation and drainage systems research and development in the 21st century,IRRIGATION AND DRAINAGE, Issue 4 2002Bart Schultz irrigation; drainage; développement durable; système de réseau Abstract One critical problem confronting mankind today is how to manage the intensifying competition for water between expanding urban centres, traditional agricultural activities and in-stream water uses dictated by environmental concerns. In the agricultural sector, the dwindling number of economically attractive sites for large-scale irrigation and drainage projects limits the prospects of increasing the gross cultivated area. Therefore, the required increase in agricultural production will necessarily rely largely on a more accurate estimation of crop water requirements on the one hand, and on major improvements in the construction, operation, management and performance of existing irrigation and drainage systems, on the other. The failings of present systems and the inability to sustainably exploit surface and groundwater resources can be attributed essentially to poor planning, design, system management and development. This is partly due to the inability of engineers, planners and managers to adequately quantify the effects of irrigation and drainage projects on water resources and to use these effects as guidelines for improving technology, design and management. To take full advantage of investments in agriculture, a major effort is required to modernize irrigation and drainage systems and to further develop appropriate management strategies compatible with the financial and socio-economic trends, and the environment. This calls for a holistic approach to irrigation and drainage management and monitoring so as to increase food production, conserve water, prevent soil salinization and waterlogging, and to protect the environment. All this requires, among others, enhanced research and a variety of tools such as water control and regulation equipment, remote sensing, geographic information systems, decision support systems and models, as well as field survey and evaluation techniques. To tackle this challenge, we need to focus on the following issues: affordability with respect to the application of new technologies; procedures for integrated planning and management of irrigation and drainage systems; analysis to identify causes and effects constraining irrigation and drainage system performance; evapotranspiration and related calculation methods; estimation of crop water requirements; technologies for the design, construction and modernization of irrigation and drainage systems; strategies to improve irrigation and drainage system efficiency; environmental impacts of irrigation and drainage and measures for creating and maintaining sustainability; institutional strengthening, proper financial assessment, capacity building, training and education. Copyright © 2002 John Wiley & Sons, Ltd. Résumé Aujourd'hui le problème critique pour l'humanité est comment manier la compétition intensifiante pour de l'eau entre les centres urbains en expansion, pour des activités traditionnellement agricoles et pour l'usage de l'eau fluviale prescrit par des conditions écologistes. Dans le secteur agricole les perspectives d'agrandir les champs cultivés bruts sont limitées par le nombre diminuant des terrains économiquement attractifs pour des projets d'irrigation et du drainage de grande envergure. Par conséquent l'augmentation nécessaire de la production agricole comptera surtout sur une évaluation plus précise du besoin des plantes d'un côté, et de l'autre sur de grandes améliorations dans la construction, dans l'opération, dans le management et dans la performance des systèmes d'irrigation et du drainage. On peut attribuer les défauts des systèmes actuels et l'incompétence d'exploiter durablement les ressources hydriques de surface et souterraines au planification, au système de la gestion de l'eau et au système du développement. Cela est partiellement dû à l'incapacité des ingénieurs, des planificateurs et des gérants, de quantifier adéquatement les effets des projets d'irrigation et de drainage sur les ressources hydriques et d'utiliser ces résultats pour améliorer la technologie, la planification et la gestion de l'eau. Pour profiter le mieux possible des investissements dans l'agriculture, on exige un effort considérable pour moderniser les systèmes d'irrigation et de drainage et pour développer des stratégies de gestion de l'eau qui doivent être appropriées et compatibles avec les tendances financières et socio-économiques et avec l'environnement. Ceci a besoin d'une procédure holistique pour la gestion et le monitorage de l'eau, pour augmenter la production d'aliments, pour conserver l'eau, pour prévenir la salination du sol et pour protéger l'environnement. Tout cela demande, entre autres choses, une recherche d'avant-garde et une variété d'instruments comme les contrôles du régime hydrique et les appareils de régulation, la télédétection, les systèmes de l'information géographique, les systèmes et les modèles de support de décision et de même les levés sur le terrain et les techniques d'évaluation. Pour entreprendre ce défi nous devons nous concentrer sur les questions suivantes: capacité de mettre enoeuvre des technologies nouvelles; le développement des procédures pour intégrer la planification et la gestion des systèmes d'irrigation et de drainage; l'analyse pour identifier les causes et les effets de forcer à la performance des systèmes d'irrigation et de drainage; l'évapotranspiration et les méthodes de calcul en question; l'évaluation des exigences hydriques des cultures; les technologies pour le dessein, la construction et la modernisation des projets d'irrigation et de drainage; les stratégies pour améliorer l'efficacité des systèmes d'irrigation et de drainage; les impacts des projets d'irrigation et de drainage et des mesures appropriées pour créer et entretenir la durabilité; l'amélioration du contexte institutionnel, l'évaluation financière, la formation et l'amélioration des compétences techniques. Copyright © 2002 John Wiley & Sons, Ltd. [source] Institutional Diversity and Capitalist Transition: The Political Economy of Agrarian Change in Arunachal Pradesh, IndiaJOURNAL OF AGRARIAN CHANGE, Issue 4 2009BARBARA HARRISS-WHITE This paper contributes a preliminary analysis of the process of agrarian capitalist transition in Arunachal Pradesh, one of the least studied regions of India. Primarily based on information collected through a field survey in eleven villages, the paper seeks to explain the nature and implications of institutional unevenness in the development of capitalism. Institutional diversity is not simply mapped across space, it is also manifested in the simultaneous existence of market and non-market institutions across the means of production within the same village or spatial context. In addition, there is a continuous and complex interaction among these institutions which both shapes and is shaped by this capitalist transition. Primitive accumulation emerges as a continuing characteristic of the on-going agrarian and non-agrarian capitalist transition. Institutional adaptation, continuity and hybridity are as integral to the emergence of the market economy as are the processes of creation of new institutions and demise of others. There is no necessary correspondence between the emerging commercialization of the different productive dimensions of the agrarian economy. These uneven processes are deeply influenced by existing and emerging power relations and by the state. Framed by the Bernstein,Byres debate about the contemporary (ir)relevance of the agrarian question, evidence is presented to justify the conclusion that although the processes at work are far from the classical models of the transition to capitalism, all aspects of the agrarian question remain relevant. [source] Class and the Politics of Participatory Rural Transformation in West Bengal: An Alternative to World Bank OrthodoxyJOURNAL OF AGRARIAN CHANGE, Issue 3 2007SUDIPTA BHATTACHARYYAArticle first published online: 3 JUN 200 Based on a primary field survey and secondary sources of information, this study analyzes the West Bengal experience of participatory rural transformation in relation to the changing class structure in a differentiated rural economy, the rise in class-consciousness among the rural poor and the participation of different classes in the political process of decision-making. Utsa Patnaik's (1987) labour exploitation criterion is used in order to rank rural households in class terms, alongside the standard acreage groupings. This study strongly refutes the neo-liberal (World Bank) idea of social capital and civil society as sources of ,people's participation'. It is argued that ,people's participation' is a meaningless concept, since the ,people' as a category includes different classes with conflicting interests. Though subordinate classes in West Bengal have achieved a higher level of class consciousness than in the past, and have resisted extra economic coercion, and while their political participation has risen, their involvement at the grass roots level of administrative decision-making is very weak. Panchayat Raj has so far failed to initiate a second phase of institutional reform in West Bengal, encompassing education, gender justice and above all the co-operative movement. This partial failure is the outcome of short-term electoral benefit being given priority over and so undermining class struggle. [source] Short-term transformation of matrix into hospitable habitat facilitates gene flow and mitigates fragmentationJOURNAL OF ANIMAL ECOLOGY, Issue 6 2007NIELS BLAUM Summary 1Habitat fragmentation has major implications for demography and genetic structure of natural plant and animal populations as small and isolated populations are more prone to extinction. Therefore, many recent studies focus on spatial fragmentation. 2However, the temporal configuration of suitable habitat may also influence dispersal and gene flow in fragmented landscapes. We hypothesize that short-term switching of inhospitable matrix areas into suitable habitat can mitigate effects of spatial fragmentation in natural and seminatural ecosystems. 3To test our hypothesis, we investigated the hairy-footed gerbil (Gerbillurus paeba, Smith 1836), a ground-dwelling rodent, in fragmented Kalahari savannah areas. Here, rare events of high above mean annual rainfall suggest short-term matrix suitability. 4During the field survey in ,matrix' areas in the Kalahari (shrub encroachment by heavy grazing) we never observed the hairy-footed gerbil in years of average rainfall, but observed mass occurrences of this species during rare events of exceptionally high rainfall. 5In a second step, we developed an agent-based model simulating subpopulations in two neighbouring habitats and the separating matrix. Our mechanistic model reproduces the mass occurrences as observed in the field and thus suggests the possibly underlying processes. In particular, the temporary improvement in matrix quality allows reproduction in the matrix, thereby causing a substantial increase in population size. 6The model demonstrates further how the environmental trigger (rainfall) impacts genetic connectivity of two separated subpopulations. We identified seasonality as a driver of fragmentation but stochasticity leading to higher connectivity. 7We found that our concept of temporal fragmentation can be applied to numerous other fragmented populations in various ecological systems and provide examples from recent literature. We conclude that temporal aspects of fragmentation must be considered in both ecological research and conservation management. [source] The role of trout in stream food webs: integrating evidence from field surveys and experimentsJOURNAL OF ANIMAL ECOLOGY, Issue 2 2006KRISTIAN MEISSNER Summary 1We evaluated the effects of brown trout on boreal stream food webs using field surveys and enclosure/exclosure experiments. Experimental results were related to prey preference of uncaged trout in the same stream, as well as to a survey of macroinvertebrate densities in streams with vs. without trout. Finally, we assessed the generality of our findings by examining salmonid predation on three groups of macroinvertebrate prey (chironomid midges, epibenthic grazers, invertebrate predators) in a meta-analysis. 2In a preliminary experiment, invertebrate predators showed a strong negative response to trout, whereas chironomids benefited from trout presence. In the main experiment, trout impact increased with prey size. Trout had the strongest effect on invertebrate predators and cased caddis larvae, whereas Baetis mayfly and chironomid larvae were unaffected. Trout impact on the largest prey seemed mainly consumptive, because prey emigration rates were low and independent of fish presence. Despite strong effects on macroinvertebrates, trout did not induce a trophic cascade on periphyton. Uncaged trout showed a strong preference for the largest prey items (predatory invertebrates and aerial prey), whereas Baetis mayflies and chironomids were avoided by trout. 3Densities of invertebrate predators were significantly higher in troutless streams. Baetis mayflies also were less abundant in trout streams, whereas densities of chironomids were positively, although non-significantly, related to trout presence. Meta-analysis showed a strong negative impact of trout on invertebrate predators, a negative but variable impact on mobile grazers (mainly mayfly larvae) and a slightly positive impact on chironomid larvae. 4Being size-selective predators, salmonid fishes have a strong impact on the largest prey types available, and this effect spans several domains of scale. Discrepancies between our experimental findings and those from the field survey and meta-analysis show, however, that for most lotic prey, small-scale experiments do not reflect fish impact reliably at stream-wide scales. 5Our findings suggest that small-scale experiments will be useful only if the experimental results are evaluated carefully against natural history information about the experimental system and interacting species across a wide array of spatial scales. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||