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Substantial Shift (substantial + shift)
Selected AbstractsEffects of cryptic mortality and the hidden costs of using length limits in fishery managementFISH AND FISHERIES, Issue 3 2007Lewis G Coggins Jr Abstract Fishery collapses cause substantial economic and ecological harm, but common management actions often fail to prevent overfishing. Minimum length limits are perhaps the most common fishing regulation used in both commercial and recreational fisheries, but their conservation benefits can be influenced by discard mortality of fish caught and released below the legal length. We constructed a computer model to evaluate how discard mortality could influence the conservation utility of minimum length regulations. We evaluated policy performance across two disparate fish life-history types: short-lived high-productivity (SLHP) and long-lived low-productivity (LLLP) species. For the life-history types, fishing mortality rates and minimum length limits that we examined, length limits alone generally failed to achieve sustainability when discard mortality rate exceeded about 0.2 for SLHP species and 0.05 for LLLP species. At these levels of discard mortality, reductions in overall fishing mortality (e.g. lower fishing effort) were required to prevent recruitment overfishing if fishing mortality was high. Similarly, relatively low discard mortality rates (>0.05) rendered maximum yield unobtainable and caused a substantial shift in the shape of the yield response surfaces. An analysis of fishery efficiency showed that length limits caused the simulated fisheries to be much less efficient, potentially exposing the target species and ecosystem to increased negative effects of the fishing process. Our findings suggest that for overexploited fisheries with moderate-to-high discard mortality rates, reductions in fishing mortality will be required to meet management goals. Resource managers should carefully consider impacts of cryptic mortality sources (e.g. discard mortality) on fishery sustainability, especially in recreational fisheries where release rates are high and effort is increasing in many areas of the world. [source] Vulnerability of African mammals to anthropogenic climate change under conservative land transformation assumptionsGLOBAL CHANGE BIOLOGY, Issue 3 2006WILFRIED THUILLER Abstract Recent observations show that human-induced climate change (CC) and land transformation (LT) are threatening wildlife globally. Thus, there is a need to assess the sensitivity of wildlife on large spatial scales and evaluate whether national parks (NPs), a key conservation tools used to protect species, will meet their mandate under future CC and LT conditions. Here, we assess the sensitivity of 277 mammals at African scale to CC at 10, resolution, using static LT assumptions in a ,first-cut' estimate, in the absence of credible future LT trends. We examine the relationship between species' current distribution and macroclimatic variables using generalized additive models, and include LT indirectly as a filter. Future projections are derived using two CC scenarios (for 2050 and 2080) to estimate the spatial patterns of loss and gain in species richness that might ultimately result. We then apply the IUCN Red List criteria A3(c) of potential range loss to evaluate species sensitivity. We finally estimate the sensitivity of 141 NPs in terms of both species richness and turnover. Assuming no spread of species, 10,15% of the species are projected to fall within the critically endangered or extinct categories by 2050 and between 25% and 40% by 2080. Assuming unlimited species spread, less extreme results show proportions dropping to approximately 10,20% by 2080. Spatial patterns of richness loss and gain show contrasting latitudinal patterns with a westward range shift of species around the species-rich equatorial zone in central Africa, and an eastward shift in southern Africa, mainly because of latitudinal aridity gradients across these ecological transition zones. Xeric shrubland NPs may face significant richness losses not compensated by species influxes. Other NPs might expect substantial losses and influxes of species. On balance, the NPs might ultimately realize a substantial shift in the mammalian species composition of a magnitude unprecedented in recent geological time. To conclude, the effects of global CC and LT on wildlife communities may be most noticeable not as a loss of species from their current ranges, but instead as a fundamental change in community composition. [source] Changing Patterns in Family Farming: The Case of the Pampa Region, ArgentinaJOURNAL OF AGRARIAN CHANGE, Issue 3 2009CARLA GRAS In the past few decades, Argentine agriculture has been significantly reorganized. Changes include the marked growth of export production, the need for an increasing level of capital investment and technological incorporation into farms and the restructuring of public intervention. This paper examines the dynamics of farm exit and the adjustments made by capitalized family farmers in the Pampa region. We suggest transformations in family farms are the result of a substantial shift in their main characteristics which historically combined the use of family labour, a certain accumulation capacity and ownership status. In particular, we will discuss the different and changing patterns of farm operations and the adjustments made with respect to work and land tenure. [source] Energy Efficiency and Structural Change in the Netherlands, 1980,1995JOURNAL OF INDUSTRIAL ECOLOGY, Issue 1 2000Dematerialization, Economic Structure on National Energy Consumption, Influence of Energy Efficiency Summary International agreement has been reached to reduce greenhouse gas emissions worldwide. One important way of decoupling CO2 emissions from economic growth is by introducing technical measures to improve energy efficiency. In this article, we assess the influence of developments in energy efficiency and economic structure on the total primary energy consumption in the Netherlands over the period 1980, 1995. We find a distinct decoupling of the economic growth and energy consumption of 1.5% per year in the 15-year analysis period. We measure (technical) changes in energy efficiency by changes in the energy consumption per physical unit of production or activity. The aggregate rate of (technical) energy-efficiency improvement was 1.4% per year over the period 1980,1995. The use of physical production indicators makes it possible to measure energy-efficiency developments without detailed surveys at a very low level of aggregation. When we look at economic structural changes over this period, we find that (i) no substantial shift took place at the level of the economic sectors that we distinguish; (ii) the most energy intensive subsectors grew much faster than the total economy; and (iii) at the subsector level, on average, a sizable decoupling of physical production and value added occurred. We conclude that structural changes, that is, changes in the composition of the economy, did not lead to a net decrease in the energy intensity of the Netherlands over the period 1980,1995. [source] Variation of Fungicide Resistance in Czech Populations of Pseudoperonospora cubensisJOURNAL OF PHYTOPATHOLOGY, Issue 3 2007J. Urban Abstract During the growing seasons between the years 2001 and 2004, 98 isolates of Pseudoperonospora cubensis from nine regions of Czech Republic were collected and screened for tolerance/resistance to the three frequently used fungicides (propamocarb, fosetyl-Al, metalaxyl). Fungicides were tested in five different concentrations, using a floating disc bioassay. Fungicide effectiveness varied considerably. Propamocarb appeared most effective and all the isolates collected in the years 2001,2003 were found sensitive to all tested concentrations [607,9712 ,g active ingredient (a.i.)/ml]. In 2004, some strains with increased resistance to propamocarb were detected. These strains were characterized by tolerance at the lowest concentrations (607 ,g a.i./ml, eventually on 1214 ,g a.i./ml); however, they were controlled by 2428 ,g a.i./ml. Fosetyl-Al was effective at the recommended concentration of 1600 ,g a.i./ml against all isolates. However, the occurrence of isolates (collected in 2001) which sporulated at low concentrations (400 and 800 ,g a.i./ml) indicated that the selection for tolerance occurs in the pathogen population. Nevertheless, this phenomenon was not confirmed with the P. cubensis isolates collected between the years 2002 and 2004. Metalaxyl was found ineffective, because 97% of the isolates showed the resistance to the recommended concentration (200 ,g a.i./ml), and the other 3% of isolates expressed tolerant response. The majority of the isolates showed profuse and/or limited sporulation at higher concentrations (400 and 800 ,g a.i./ml). A substantial shift to highly metalaxyl resistant strains was evident in the Czech P. cubensis populations during 2001,2004. [source] Delving into the "Institutional Black Box": Revealing the Attributes of Sustainable Urban Water Management Regimes,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 6 2009Susan J. Van De Meene van de Meene, Susan J. and Rebekah R. Brown, 2009. Delving into the "Institutional Black Box": Revealing the Attributes of Sustainable Urban Water Management Regimes. Journal of the American Water Resources Association (JAWRA) 45(6):1448-1464. Abstract:, This paper is based on the proposition that the transition to sustainable urban water management has been hampered by the lack of insight into attributes of a sustainable urban water regime. Significant progress has been made in developing technical solutions to advance urban water practice, however it is the co-evolution of the socio-institutional and technical systems that enable a system-wide transition. A systematic analysis of 81 empirical studies across a range of practice areas was undertaken to construct a schema of the sustainable urban water regime attributes. Attributes were identified and analyzed using a framework of nested management regime spheres: the administrative and regulatory system, inter-organizational, intra-organizational, and human resources spheres. The regime is likely to involve significant stakeholder involvement, collaborative inter-organizational relationships, flexible and adaptive organizational cultures, and motivated and engaging employees. Comparison of the constructed sustainable and traditional regime attributes reveals that to realize sustainable urban water management in practice a substantial shift in governance is required. This difference emphasizes the critical need for explicitly supported strategies targeted at developing each management regime sphere to further enable change toward sustainable urban water management. [source] Modulation of cytokine production by dydrogesterone in lymphocytes from women with recurrent miscarriageBJOG : AN INTERNATIONAL JOURNAL OF OBSTETRICS & GYNAECOLOGY, Issue 8 2005Raj Raghupathy Objective To examine the effects of dydrogesterone on the production of Th1 and Th2 cytokines by lymphocytes from women undergoing unexplained recurrent spontaneous miscarriage (RSM). Design Controlled prospective, clinical study conducted in a maternity hospital and a university-based immunology laboratory. Setting Faculty of Medicine, Kuwait University and Kuwait Maternity Hospital. Sample Thirty women with unexplained RSM. Methods Peripheral blood mononuclear cells (PBMC) from women with unexplained RSM were isolated from venous blood by density gradient sedimentation and stimulated with phytohaemagglutinin (PHA). Culture supernatants assayed for interferon (IFN)-,, tumour necrosis factor (TNF)-,, interleukin (IL)-4, IL-6 and IL-10 by ELISA. Levels of the progesterone-induced blocking factor (PIBF) were also measured. Main outcome measures Cytokine production in the presence and absence of progesterone and dydrogesterone. Results Dydrogesterone significantly inhibited the production of the Th1 cytokines IFN-, (P= 0.0001) and TNF-, (P= 0.005) and induced an increase in the levels of the Th2 cytokines IL-4 (P= 0.03) and IL-6 (P= 0.017) resulting in a substantial shift in the ratio of Th1/Th2 cytokines. The effect of dydrogesterone was blocked by the addition of the progesterone-receptor antagonist mifepristone, indicating that dydrogesterone was acting via the progesterone receptor. Dydrogesterone induced the production of PIBF. Conclusion Dydrogesterone inhibits the production of the Th1 cytokines IFN-, and TNF-, from lymphocytes and up-regulates the production of the Th2 cytokines IL-4 and IL-6, inducing a Th1 to Th2 cytokine shift. [source] Moisture controls on carbon dioxide dynamics of peat- Sphagnum monolithsECOHYDROLOGY, Issue 1 2009M. Strack Abstract Sphagnum moss is the major peat-forming vegetation component in boreal peatlands. The relationship between Sphagnum productivity and moss moisture content has been documented; however, the link between moss moisture content and conditions in the underlying peat column is less clear. We conducted a pilot study in which we monitored volumetric moisture content with depth and gravimetric water content of Sphagnum capitula and CO2 exchange for two peat monoliths with intact moss layer dominated by Sphagnum fuscum and S. magellanicum. Measurements were made under drying conditions and rewetting from below and following simulated precipitation events. Capitulum moisture content was related to water table position but varied between species. Both capitulum moisture content and water table position could be used to explain net CO2 exchange and respiration during drying and rewetting from below, although hysteresis was apparent where respiration was lower on rewetting than drying for the same water table position. Precipitation complicated these relationships because small events (<5 mm) rewetted the upper few centimeters of moss resulting in a change in capitulum moisture content equivalent to a rise in water table position of ,20 cm. This change in capitulum moisture content resulted in substantial shifts in both photosynthesis and respiration rates without affecting water table position or subsurface volumetric water contents as shallow as 5 cm below the surface. While these small events will be difficult to measure in the field, this study suggests they are essential to effectively track or model Sphagnum productivity because they may contribute significantly to seasonal carbon balance. Copyright © 2009 John Wiley & Sons, Ltd. [source] Climate change causes rapid changes in the distribution and site abundance of birds in winterGLOBAL CHANGE BIOLOGY, Issue 11 2008ILYA M. D. MACLEAN Abstract Detecting coherent signals of climate change is best achieved by conducting expansive, long-term studies. Here, using counts of waders (Charadrii) collected from ca. 3500 sites over 30 years and covering a major portion of western Europe, we present the largest-scale study to show that faunal abundance is influenced by climate in winter. We demonstrate that the ,weighted centroids' of populations of seven species of wader occurring in internationally important numbers have undergone substantial shifts of up to 115 km, generally in a northeasterly direction. To our knowledge, this shift is greater than that recorded in any other study, but closer to what would be expected as a result of the spatial distribution of ecological zones. We establish that year-to-year changes in site abundance have been positively correlated with concurrent changes in temperature, but that this relationship is most marked towards the colder extremities of the birds' range, suggesting that shifts have occurred as a result of range expansion and that responses to climate change are temperature dependent. Many attempts to model the future impacts of climate change on the distribution of organisms, assume uniform responses or shifts throughout a species' range or with temperature, but our results suggest that this may not be a valid approach. We propose that, with warming temperatures, hitherto unsuitable sites in northeastern Europe will host increasingly important wader numbers, but that this may not be matched by declines elsewhere within the study area. The need to establish that such changes are occurring is accentuated by the statutory importance of this taxon in the designation of protected areas. [source] Comparison of phenology trends by land cover class: a case study in the Great Basin, USAGLOBAL CHANGE BIOLOGY, Issue 2 2008BETHANY A. BRADLEY Abstract Direct impacts of human land use and indirect impacts of anthropogenic climate change may alter land cover and associated ecosystem function, affecting ecological goods and services. Considerable work has been done to identify long-term global trends in vegetation greenness, which is associated with primary productivity, using remote sensing. Trend analysis of satellite observations is subject to error, and ecosystem change can be confused with interannual variability. However, the relative trends of land cover classes may hold clues about differential ecosystem response to environmental forcing. Our aim was to identify phenological variability and 10-year trends for the major land cover classes in the Great Basin. This case study involved two steps: a regional, phenology-based land cover classification and an identification of phenological variability and 10-year trends stratified by land cover class. The analysis used a 10-year time series of Advanced Very High Resolution Radiometer satellite data to assess regional scale land cover variability and identify change. The phenology-based regional classification was more detailed and accurate than national or global products. Phenological variability over the 10-year period was high, with substantial shifts in timing of start of season of up to 9 weeks. The mean long-term trends of montane land cover classes were significantly different from valley land cover classes due to a poor response of montane shrubland and pinyon-juniper woodland to the early 1990s drought. The differential response during the 1990s suggests that valley ecosystems may be more resilient and montane ecosystems more susceptible to prolonged drought. This type of regional-scale land cover analysis is necessary to characterize current patterns of land cover phenology, distinguish between anthropogenically driven land cover change and interannual variability, and identify ecosystems potentially susceptible to regional and global change. [source] Synthesis of Polystyrene- block -Poly(methyl methacrylate) with Fluorene at the Junction: Sequential Anionic and Controlled Radical Polymerization from a Single CarbonMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 24 2009Nathan D. Contrella Abstract Polystyrene- block -poly(methyl methacrylate) (PS- b -PMMA) has been synthesized by sequential anionic and reverse atom transfer radical polymerization (ATRP) or a variation of nitroxide mediated polymerization (NMP) from a single initiating site, specifically the 9-carbon on 2,7-dibromofluorene or fluorene. The addition of the second arm (PS) relied on thermal decomposition of 2,2,-azoisobutyronitrile (AIBN) to generate radicals, abstracting the 9-H on the polymer-bound fluorene species to form the initiating radical. Styrene was not present in the reaction mixture when AIBN was decomposed, preventing competition between addition across the monomeric alkene and hydrogen abstraction from the fluorene. After 1,h, styrene was introduced and mediation of the subsequent radical polymerization was achieved by the presence of CuCl2/ligand or TEMPO. Characterization of the diblock copolymers by gel permeation chromatography (GPC) revealed substantial shifts in number average molecular weight () values compared to the anionically prepared PMMA macroinitiator, while polydispersity indices (PDI's) remained relatively low (typically,<,1.5). Characterization by UV detection with GPC (at 310,nm) verified that the diblock polymer is chromophore-bound, which was further verified by UV-vis spectroscopy of the isolated diblock. [source] | |||||||||||||