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Participatory fisheries management has been increasingly proposed as a useful management approach to address fisheries problems. However, the criteria regarding its applicability and measures of success still seem unclear. This study reviews the main concepts and theory behind two participatory resource-management approaches and compares them to the reality of fisheries management in Costa Rica. The analysis shows that while the implementation of a participatory approach in fisheries management should be encouraged, it is essential to keep in mind the possible limitations these approaches have. Furthermore, it seems important to improve institutional coordination and develop social, legal and economic policies that will allow the state, together with coastal communities, to contribute in an effective way to fisheries management. 相似文献
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Ricardo Sánchez‐Murillo Ana M. Durán‐Quesada Christian Birkel Germain Esquivel‐Hernández Jan Boll 《水文研究》2017,31(4):956-967
The last 2014‐16 El Niño event was among the three strongest episodes on record. El Niño considerably changes annual and seasonal precipitation across the tropics. Here, we present a unique stable isotope data set of daily precipitation collected in Costa Rica prior to, during, and after El Niño 2014‐16, in combination with Lagrangian moisture source and precipitation anomaly diagnostics. δ2H composition ranged from ‐129.4 to +18.1 (‰) while δ18O ranged from ‐17.3 to +1.0 (‰). No significant difference was observed among δ18O (P=0.186) and δ2H (P=0.664) mean annual compositions. However, mean annual d‐excess showed a significant decreasing trend (from +13.3 to +8.7 ‰) (P<0.001) with values ranging from +26.6 to ‐13.9 ‰ prior to and during the El Niño evolution. The latter decrease in d‐excess can be partly explained by an enhanced moisture flux convergence across the southeastern Caribbean Sea coupled with moisture transport from northern South America by means of an increased Caribbean Low Level Jet regime. During 2014‐15, precipitation deficit across the Pacific domain averaged 46% resulting in a very severe drought; while a 94% precipitation surplus was observed in the Caribbean domain. Understanding these regional moisture transport mechanisms during a strong El Niño event may contribute to a) better understanding of precipitation anomalies in the tropics and b) re‐evaluate past stable isotope interpretations of ENSO events in paleoclimatic archives within the Central America region. 相似文献
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Second‐order transgressive–regressive (T–R) cycles, previously recognized using sedimentological criteria in Lower Jurassic hemipelagic deposits from northern Spain, are distinguishable based upon bulk‐rock organic geochemistry [total organic carbon (TOC) and hydrogen index (HI)] and the stable carbon isotope compositions from belemnite rostra. There is a coincidence between regressions and decreasing δ13Cbel, TOC and HI values, and between transgressions and increasing δ13Cbel, TOC and HI values. The δ18O and Mg/Ca records from the belemnite rostra are not always in phase with the T–R cycles. The δ18Obel record reveals, however, a prominent excursion towards higher values within the spinatum Zone that correlates, according to our results, with a regression and with negative shifts in Mg/Ca, δ13Cbel and TOC. On the other hand, an excursion in the δ18Obel towards lower values in the serpentinus Zone also correlates with a peak transgression and with positive shifts in Mg/Ca, δ13Cbel and TOC. These two excursions have been identified in other European regions as geochemical perturbations of the same characteristics. This suggests a link between second‐order relative sea‐level changes and variations in seawater geochemistry that may reflect local and regional palaeoceanographic perturbations in sea‐water temperature, salinity and water circulation during the Early Jurassic. Terra Nova, 18, 233–240, 2006 相似文献
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A photographic survey in four spectral regions (ultraviolet, blue, visible and red) of the Northern Hemisphere of Saturn's atmosphere, has been carried out between 1980 (epoch of the edgewise apparition of the rings) and 1987 (ring's maximum aperture), with the aim of analyzing the changes in the cloud morphology and reflectivity with respect to the spacecraft aspects in 1979 (Pioneer 11) and 1980–1981 (Voyager 1 and 2). Very few variations were detected in the meridional position of the belts and zones ; only a shift of 4000 km toward the North appeared to occur in 1984 in ultraviolet light to the region at latitude 46°N (occupied in 1980–1981 by the “ribbon” feature). Other belts and zones remained stable to ground-based telescopic resolution during the whole period. An increase of 7% in the reflectivity ratio of the belt NEB and the zone EZ, was noted in the spectral interval from 4000 to 6500 Å last year. This can be attributed to the seasonal insolation variation. 相似文献
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Spatially distributed tracer‐aided modelling to explore water and isotope transport,storage and mixing in a pristine,humid tropical catchment 
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下载免费PDF全文 Joni Dehaspe Christian Birkel Doerthe Tetzlaff Ricardo Sánchez‐Murillo Ana María Durán‐Quesada Chris Soulsby 《水文研究》2018,32(21):3206-3224
Rapidly transforming headwater catchments in the humid tropics provide important resources for drinking water, irrigation, hydropower, and ecosystem connectivity. However, such resources for downstream use remain unstudied. To improve understanding of the behaviour and influence of pristine rainforests on water and tracer fluxes, we adapted the relatively parsimonious, spatially distributed tracer‐aided rainfall–runoff (STARR) model using event‐based stable isotope data for the 3.2‐km2 San Lorencito catchment in Costa Rica. STARR was used to simulate rainforest interception of water and stable isotopes, which showed a significant isotopic enrichment in throughfall compared with gross rainfall. Acceptable concurrent simulations of discharge (Kling–Gupta efficiency [KGE] ~0.8) and stable isotopes in stream water (KGE ~0.6) at high spatial (10 m) and temporal (hourly) resolution indicated a rapidly responding system. Around 90% of average annual streamflow (2,099 mm) was composed of quick, near‐surface runoff components, whereas only ~10% originated from groundwater in deeper layers. Simulated actual evapotranspiration (ET) from interception and soil storage were low (~420 mm/year) due to high relative humidity (average 96%) and cloud cover limiting radiation inputs. Modelling suggested a highly variable groundwater storage (~10 to 500 mm) in this steep, fractured volcanic catchment that sustains dry season baseflows. This groundwater is concentrated in riparian areas as an alluvial–colluvial aquifer connected to the stream. This was supported by rainfall–runoff isotope simulations, showing a “flashy” stream response to rainfall with only a moderate damping effect and a constant isotope signature from deeper groundwater (~400‐mm additional mixing volume) during baseflow. The work serves as a first attempt to apply a spatially distributed tracer‐aided model to a tropical rainforest environment exploring the hydrological functioning of a steep, fractured‐volcanic catchment. We also highlight limitations and propose a roadmap for future data collection and spatially distributed tracer‐aided model development in tropical headwater catchments. 相似文献
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A. Eff-Darwich J. Coello R. Viñas V. Soler M. C. Martin-Luis I. Farrujia M. L. Quesada J. de la Nuez 《Pure and Applied Geophysics》2008,165(1):135-145
The spatial distribution of groundwater temperatures in the volcanic island of Tenerife, Canary Islands, has been inferred
through measurements of water temperatures collected in the vast network of wells and subhorizontal tunnels, locally called
“galleries,” which constitutes the main water supply of the island. The spatial coverage of the network of galleries allows
us to reach from depth almost any geological feature of the island. The complex spatial distribution of temperatures in the
interior of Tenerife is the result of the complex geological evolution of the island. Groundwater temperatures are greatly
affected by groundwater flow and are considerably warmer in those galleries located in areas where water circulation is reduced
due to the low permeability of materials and/or to the low infiltration rate of cooling meteoric water. In this sense, groundwater
temperature should be characterized in quiescent conditions (background level), in order to facilitate monitoring changes
in heat flow, such as those induced by ascending gases expected with an increase in volcanic activity. 相似文献
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Summary According to the plate tectonic theory of Le Pichon [1968] we summarized the absolute values of the angular rate of rotation
of the Eurasia and America plates determined by astronomical latitude observations. The authors then tried to use the data
of longitude observation so far available to emphasize the existence of similar crust movements. The analysis of longitude
data has shown the minor homogeneity of these astronomical observations especially as far as the observations obtained by
means of PZT are concerned. By using particularly accurate observational data [Torao & Okasahi, 1965, 1969] the data of longitude
variations confirm the existence of movements in the earth’s crust, exactly equal to those deduced by the analysis of latitude
observations and in agreement with the results of geophysical measurements. 相似文献