894 resultados para El Nino Current - Environmental aspects


Relevância:

100.00% 100.00%

Publicador:

Resumo:

Aquaculture of filter-feeding bivalve mollusks involves the fruitful conversion of marine particulate organic matter into premium protein of high nutritive value. Culture performance of bivalves is largely dependent on hydrological conditions and directly affected by e. g. temperature and chlorophyll levels. Accordingly, these parameters may be related with seasonality but also with oceanographic features combined with climate events. Yields of Pacific cupped oyster (Crassostrea gigas) reared at commercial procedures in suspended structures (long-lines) in a sheltered bay in Southern Brazil (Santa Catarina State, 27S 43'; 48 W 30') were evaluated in relation to local environmental conditions: sea surface temperature, chlorophyll a concentration, and associate effects of cold fronts events and El Nino and La Nina periods. Outputs from four consecutive commercial crop years were analyzed (2005/06, 2006/07, 2007/08, 2008/09) in terms of oyster survival and development time during the following grow-out phases of the culture cycle: seed to juvenile, juvenile to adult, adult to marketable. Since culture management and genetics were standardized significant differences verified among crop performance could be mostly related to environmental effects. Time series of temperature and chlorophyll a (remote sensing data) from crop periods displayed significant seasonal and interannual variation. As expected, performance during initial grow-out stages (seed to juvenile) was critical for final crop yield. Temperature was the main factor affecting survival in these initial stages with a trend of negative correlation, though not statistically significant. On the other hand, oyster development rate was significantly and positively affected by chlorophyll a concentration. Chlorophyll a values could be increased by upwelled cold nutrient-rich South Atlantic Central Water (SACW, related to predominant Northern winds) though further dependent on occurrence of Southern winds (cold fronts) to assist seawater penetration into the sheltered farming area. Lower salinity nutrient-rich northward drifted waters from La Plata River discharge may also result in chlorophyll a rise in the farming area. The El Nino period (July 2006 to February 2007) coincided with lower chlorophyll a levels in the farming site that may be related to both decreased number of cold fronts as well as predominance of Northern winds that retain northward spreading of La Plata River discharge waters. In contrast, the La Nina period (August 2007 to June 2008) corresponded to higher chlorophyll a values in the farming area by both upwelling of SACW and penetration of La Plata River discharge water assisted by increased occurrence of Southern winds and cold fronts. The recognition of the potentially changing climate and effects upon the environment will be an important step in planning future development of bivalve aquaculture.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Environmental Management includes many components, among which we can include Environmental Management Systems (EMS), Environmental Reporting and Analysis, Environmental Information Systems and Environmental Communication. In this work two applications are presented: the developement and implementation of an Environmental Management System in local administrations, according to the European scheme "EMAS", and the analysis of a territorial energy system through scenario building and environmental sustainability assessment. Both applications are linked by the same objective, which is the quest for more scientifically sound elements; in fact, both EMS and energy planning are oftec carachterized by localism and poor comparability. Emergy synthesis, proposed by ecologist H.T. Odum and described in his book "Environmental Accounting: Emergy and Environmental Decision Making" (1996) has been chosen and applied as an environmental evaluation tool, in order complete the analysis with an assessment of the "global value" of goods and processes. In particular, eMergy syntesis has been applied in order to improve the evaluation of the significance of environmental aspects in an EMS, and in order to evaluate the environmental performance of three scenarios of future evolution of the energy system. Regarding EMS, in this work an application of an EMS together with the CLEAR methodology for environmental accounting is discussed, in order to improve the identification of the environmental aspects; data regarding environmental aspects and significant ones for 4 local authorities are also presented, together with a preliminary proposal for the integration of the assessment of the significance of environmental aspects with eMergy synthesis. Regarding the analysis of an energy system, in this work the carachterization of the current situation is presented together with the overall energy balance and the evaluation of the emissions of greenhouse gases; moreover, three scenarios of future evolution are described and discussed. The scenarios have been realized with the support of the LEAP software ("Long Term Energy Alternatives Planning System" by SEI - "Stockholm Environment Institute"). Finally, the eMergy synthesis of the current situation and of the three scenarios is shown.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Passive acoustic data have been collected using HARPs (High-frequency Acoustic Recording Packages) and were used to assess (1) the seasonality of blue whale D calls in the Southern California Bight, (2) their interannual abundance during 2007-2012 and (3) their diel variation. This goal has been achieved running the GPL (Generalized Power-Law) automated detector. (1) Blue whale D calls were detected in the Southern California Bight from May through November with a peak in July, even though few detections were from December to April as well. A key predictor for blue whale distribution and movement in the California Current region has been identified with zooplankton aggregations, paying a particular attention to those euphausiid species, such as E. pacifica and T. spinifera, which are blue whale favorite krill. The Southern California Bight experiences seasonal upwelling, resulting in an increase of productivity and prey availability. The summer and early fall have been marked as the most favorable periods. This supports the presence of blue whales in the area at that time, supposing these marine mammals exploit the region as a feeding ground. (2) As to the interannual abundance during 2007-2012, I found a large variability. I observed a great increase of vocalizations in 2007 and 2010, whereas a decrease was shown in the other years, which is well marked in 2009. It is my belief that these fluctuations in abundance of D calls detections through the deployed period are due to the alternation of El Nino and La Nina events, which occurred in those years. (3) The assessment of the daily timing of D calls production shows that D calls are more abundant during the day than during the night with a peak at 12:00 and 13:00. Assuming that D calling is associated with feeding, the daily pattern of D calls may be linked to the prey availability. E. pacifica and T. spinifera are among those species of krill which undertake daily vertical migrations, remaining at depth during the day and slowly coming up towards the surface at night. Because of some anatomical arrangements, these euphausiids are very sensitive to the light. Given that we believe D calls have a social function, I hypothesize that blue whales may recognize the hours at the highest solar incidence as the best moment of the day in terms of prey availability, exploiting this time window to advert their conspecifics.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

There is increasing evidence that species can evolve rapidly in response to environmental change. However, although land use is one of the key drivers of current environmental change, studies of its evolutionary consequences are still fairly scarce, in particular studies that examine land-use effects across large numbers of populations, and discriminate between different aspects of land use. Here, we investigated genetic differentiation in relation to land use in the annual grass Bromus hordeaceus. A common garden study with offspring from 51 populations from three regions and a broad range of land-use types and intensities showed that there was indeed systematic population differentiation of ecologically important plant traits in relation to land use, in particular due to increasing mowing and grazing intensities. We also found strong land-use-related genetic differentiation in plant phenology, where the onset of flowering consistently shifted away from the typical time of management. In addition, increased grazing intensity significantly increased the genetic variability within populations. Our study suggests that land use can cause considerable genetic differentiation among plant populations, and that the timing of land use may select for phenological escape strategies, particularly in monocarpic plant species.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Evidence of negative conspecific density dependence (NDD) operating on seedling survival and sapling recruitment has accumulated recently. In contrast, evidence of NDD operating on growth of trees has been circumstantial at best. Whether or not local NDD at the level of individual trees leads to NDD at the level of the community is still an open question. Moreover, whether and how perturbations interfere with these processes have rarely been investigated. We applied neighborhood models to permanent plot data from a Bornean dipterocarp forest censused over two 10-11 year periods. Although the first period was only lightly perturbed, a moderately strong El Nino event causing severe drought occurred in the first half of the second period. Such events are an important component of the environmental stochasticity affecting the region. We show that local NDD on growth of small-to-medium-sized trees may indeed translate to NDD at the level of the community. This interpretation is based on increasingly negative effects of bigger conspecific neighbors on absolute growth rates of individual trees with increasing basal area across the 18 most abundant overstory species in the first period. However, this relationship was much weaker in the second period. We interpreted this relaxation of local and community-level NDD as a consequence of increased light levels at the forest floor due to temporary leaf and twig loss of large trees in response to the drought event. Mitigation of NDD under climatic perturbation acts to decrease species richness, especially in forest overstory and therefore has an important role in determining species relative abundances at the site.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

INTRODUCTION Out-migration from mountain areas is leaving behind half families and elderly to deal with managing the land alongside daily life challenges. A potential reduction of labour force as well as expertise on cropping practices, maintenance of terraces and irrigation canals, slope stabilization, grazing, forest and other land management practices are further challenged by changing climate conditions and increased environmental threats. An understanding of the resilience of managed land resources in order to enhance adaptation to environmental and socio-economic variability, and evidence of the impact of Sustainable Land Management (SLM) on the mitigation of environmental threats have so far not sufficiently been tackled. The study presented here aims to find out how land management in mountains is being affected by migration in the context of natural hazards and climate change in two study sites, namely Quillacollo District of Bolivia and Panchase area of Western Nepal, and which measures are needed to increase resilience of livelihoods and land management practices. The presentation includes draft results from first field work periods in both sites. A context of high vulnerability According to UNISDR, vulnerability is defined as “the characteristics and circumstances of a community, system or asset that make it susceptible to the damaging effects of a hazard”.Hazards are another threat affecting people’s livelihood in mountainous area. They can be either natural or human induced. Landslides, debris flow and flood are affecting peopleGood land management can significantly reduce occurrence of hazards. In the opposite bad land management or land abandonment can lead to negative consequences on the land, and thus again increase vulnerability of people’s livelihoods. METHODS The study integrates bio-physical and socio-economic data through a case study as well as a mapping approach. From the social sciences, well-tested participatory qualitative methodologies, typically used in Vulnerability and Capacity Analyses, such as semi-structured interviews with so-called ‘key informants’, transect walks, participatory risk and social resource mapping are applied. The bio-physical analysis of the current environmental conditions determining hazards and structural vulnerability are obtained from remote sensing analysis, field work studies, and GIS analysis The assessment of the consequences of migration in the area of origin is linked with a mapping and appraisal of land management practices (www.wocat.net, Schwilch et al., 2011). The WOCAT mapping tool (WOCAT/LADA/DESIRE 2008) allows capturing the major land management practices / technologies, their spread, effectiveness and impact within a selected area. Data drawn from a variety of sources are compiled and harmonised by a team of experts, consisting of land degradation and conservation specialists working in consultation with land users from various backgrounds. The specialists’ and land users’ knowledge is combined with existing datasets and documents (maps, GIS layers, high-resolution satellite images, etc.) in workshops that are designed to build consensus regarding the variables used to assess land degradation and SLM. This process is also referred to as participatory expert assessment or consensus mapping. The WOCAT mapping and SLM documentation methodologies are used together with participatory mapping and other socio-economic data collection (interviews, questionnaires, focus group discussions, expert consultation) to combine information about migration types and land management issues. GIS and other spatial visualization tools (e.g. Google maps) will help to represent and understand these links. FIRST RESULTS Nepal In Nepal, migration is a common strategy to improve the livelihoods. Migrants are mostly men and they migrate to other Asian countries, first to India and then to the Gulf countries. Only a few women are migrating abroad. Women migrate essentially to main Nepali cities when they can afford it. Remittances are used primarily for food and education; however they are hardly used for agricultural purposes. Besides traditional agriculture being maintained, only few new practices are emerging, such as vegetable farming or agroforestry. The land abandonment is a growing consequence of outmigration, resulting in the spreading of invasive species. However, most impacts of migration on land management are not yet clear. Moreover, education is a major concern for the respondents; they want their children having a better education and get better opportunities. Linked to this, unemployment is another major concern of the respondents, which in turn is “solved” through outmigration. Bolivia Migration is a common livelihood strategy in Bolivia. In the area of study, whole families are migrating downward to the cities of the valleys or to other departments of Bolivia, especially to Chapare (tropics) for the coca production and to Santa Cruz. Some young people are migrating abroad, mostly to Argentina. There are few remittances and if those are sent to the families in the mountain areas, then they are mainly used for agriculture purpose. The impacts of migration on land management practices are not clear although there are some important aspects to be underlined. The people who move downward are still using their land and coming back during part of the week to work on it. As a consequence of this multi-residency, there is a tendency to reduce land management work or to change the way the land is used. As in Nepal, education is a very important issue in this area. There is no secondary school, and only one community has a primary school. After the 6th grade students have therefore to go down into the valley towns to study. The lack of basic education is pushing more and more people to move down and to leave the mountains. CONCLUSIONS This study is on-going, more data have to be collected to clearly assess the impacts of out-migration on land management in mountain areas. The first results of the study allow us to present a few interesting findings. The two case studies are very different, however in both areas, young people are not staying anymore in the mountains and leave behind half families and elderly to manage the land. Additionally in both cases education is a major reason for moving out, even though the causes are not always the same. More specifically, in the case of Nepal, the use of remittances underlines the fact that investment in agriculture is not the first choice of a family. In the case of Bolivia, some interesting findings showed that people continue to work on their lands even if they move downward. The further steps of the study will help to explore these interesting issues in more detail. REFERENCES Schwilch G., Bestelmeyer B., Bunning S., Critchley W., Herrick J., Kellner K., Liniger H.P., Nachtergaele F., Ritsema C.J., Schuster B., Tabo R., van Lynden G., Winslow M. 2011. Experiences in Monitoring and Assessment of Sustainable Land Management. Land Degradation & Development 22 (2), 214-225. Doi 10.1002/ldr.1040 WOCAT/LADA/DESIRE 2008. A Questionnaire for Mapping Land Degradation and Sustainable Land Management. Liniger H.P., van Lynden G., Nachtergaele F., Schwilch G. (eds), Centre for Development and Environment, Institute of Geography, University of Berne, Berne

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Using US National Centers for Environmental Prediction/US National Center for Atmospheric Research re-analysis data, we investigate the relationships between crustal ion (nssCa(2+)) concentrations from three West Antarctic ice cores, namely, Siple Dome (SD), ITASE00-1 (IT001) and ITASE01-5 (IT015), and primary components of the climate system, namely, air pressure/geopotential height, zonal (u) and meridional (v) wind strength. Linear correlation analyses between nssCa(2+) concentrations and both air-pressure and wind fields for the period of overlap between records indicate that the SD nssCa(2+) variation is positively correlated with spring circumpolar zonal wind, while IT001 nssCa(2+) has a positive correlation with circumpolar zonal wind throughout the year (r > 0.3, p < 0.01). Intensified Southern Westerlies circulation is conducive to transport of more crustal aerosols to both sites. Further correlation analyses between nssCa(2+) concentrations from SD and IT001 and atmospheric circulation suggest that the high inland plateau (represented by core IT001) is largely influenced by transport from the upper troposphere. IT015 nssCa(2+) is negatively correlated with westerly wind in October and November, suggesting that stronger westerly circulation may weaken the transport of crustal species to IT015. Correlations of nssCa(2+) from the three ice cores with the Antarctic Oscillation index are consistent with results developed from the wind-field investigation. In addition, calibration between nssCa(2+) concentration and the multivariate El Nino-Southern Oscillation (ENSO) index shows that crustal species transport to IT001 is enhanced during strong ENSO events.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

An annually dated ice core recovered from South Pole (2850 in a.s.l.) in 1995, that covers the period 1487-1992, was analyzed for the marine biogenic sulfur species methanesulfonate (MS). Empirical orthogonal function analysis is used to calibrate the high-resolution MS series with associated environmental series for the period of overlap (1973-92). Utilizing this calibration we present a similar to500 year long proxy record of the polar expression of the El Nino-Southern Oscillation (ENSO) and southeastern Pacific sea-ice extent variations. These records reveal short-term periods of increased (1800-50, 1900-40) and decreased sea-ice extent (1550-1610., 1660-1710, 1760-1800). In general, increased (decreased) sea-ice extent is associated with a higher (lower) frequency of El Nino events.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Time series of satellite measurements are used to describe patterns of surface temperature and chlorophyll associated with the 1996 cold La Nina phase and the 1997-1998 warm El Nino phase of the El Nino - Southern Oscillation cycle in the upwelling region off northern Chile. Surface temperature data are available through the entire study period. Sea-viewing Wide Field-of-view Sensor (SeaWiFS) data first became available in September 1997 during a relaxation in El Nino conditions identified by in situ hydrographic data. Over the time period of coincident satellite data, chlorophyll patterns closely track surface temperature patterns. Increases both in nearshore chlorophyll concentration and in cross-shelf extension of elevated concentrations are associated with decreased coastal temperatures during both the relaxation in El Nino conditions in September-November 1997 and the recovery from EI Nino conditions after March 1998. Between these two periods during austral summer (December 1997 to March 1998) and maximum El Nino temperature anomalies, temperature patterns normally associated with upwelling were absent and chlorophyll concentrations were minimal. Cross-shelf chlorophyll distributions appear to be modulated by surface temperature frontal zones and are positively correlated with a satellite-derived upwelling index. Frontal zone patterns and the upwelling index in 1996 imply an austral summer nearshore chlorophyll maximum, consistent with SeaWiFS data from I 1998-1999, after the El Nino. SeaWiFS retrievals in the data set used here are higher than in situ measurements by a factor of 2-4; however, consistency in the offset suggests relative patterns are valid.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Una reciente transición en el campo del desarrollo rural es el movimiento desde un enfoque reducido del sector agrícola hasta uno que adopta una visión territorial más amplia. Este pasaje intenta interpretar las interacciones entre los mundos urbano y rural de una manera más comprensiva. Esta perspectiva teórica relativamente nueva interesa particularmente a los académicos y los políticos en los países latinoamericanos donde, a partir de la mitad de los años noventa, el concepto de una nueva ruralidad se ha visto como la fuente de un nuevo enfoque para el desarrollo rural. Por lo tanto, el propósito teórico de esta investigación es explicitar los indicadores analíticos del nuevo enfoque de la ruralidad en América Latina e identificar las diferencias entre los acercamientos sectoriales y territoriales, considerando los aspectos socio-económicos, institucionales y medioambientales involucrados. La transición del enfoque sectorial a uno territorial significa también, desde un punto de vista operativo, el reconocimiento de la existencia de áreas homogéneas a partir de las cuales pueden proponerse estrategias de desarrollo rural. El propósito operativo de esta investigación consiste en proponer una metodología para identificar estas áreas con una aplicación a la Región del Maule en Chile. La conclusión subraya algunos elementos críticos que se deben considerar en la definición de estrategias del desarrollo rural territorial.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

El concepto de sustentabilidad implica una relación a largo plazo entre los seres humanos y la naturaleza. Un sistema productivo sustentable es aquel capaz de permanecer en el tiempo ya que promueve la conservación de los recursos naturales, del capital social y genera una renta económica suficiente para la subsistencia de los mismos. La vitivinicultura brinda numerosos beneficios al sector agrícola, sector responsable del uso y contaminación de recursos naturales de la provincia de Mendoza (Argentina). Si bien existen algunos indicadores inherentes al sector vitivinícola, la mayoría se concentran en aspectos físicos y económicos. El trabajo consiste en elaborar indicadores para evaluar la sustentabilidad de la producción de vid en Mendoza, sobre la base del concepto de sustentabilidad que integra las tres dimensiones de un sistema: la económica, la social y la ambiental. Esto se aplicó a la producción vitícola, para lo cual se construyeron indicadores que caracterizaron al sistema siguiendo el concepto de sustentabilidad. Los indicadores se probaron con encuestas a productores (estudio de caso). Los indicadores seleccionados resultaron apropiados para determinar en qué estado de sustentabilidad está un viñedo respecto de cada una de las dimensiones (económica, social y ambiental); fáciles de obtener y de interpretar.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

El trabajo presenta los problemas y oportunidades de la agricultura ecológica en Aragón, España. Con esta finalidad, se compara la agricultura ecológica con la convencional tanto en los aspectos socioeconómicos como medioambientales. Como base de esta comparativa, se presentan algunos de los principios básicos de la agricultura ecológica y su estructura contable de costes, obtenida a través de un trabajo de campo en Aragón y bases de datos oficiales, así como datos sobre su consumo y distribución; finalmente se sugieren algunas vías de actuación pública que pueden apoyar las oportunidades de la agricultura ecológica.

Relevância:

100.00% 100.00%

Publicador:

Relevância:

100.00% 100.00%

Publicador:

Relevância:

100.00% 100.00%

Publicador: