Seasonal variations in lipid composition of the hydrothermal vent mussel Bathymodiolus azoricus from the Menez Gwen vent field     

Ana Colaço  Catarina Prieto  Ana Martins  Miguel Figueiredo  Virginie Lafon  Margarida Monteiro  Narcisa M. Bandarra 《Marine environmental research》2009,67(3):146-152

Specimens of the hydrothermal mussel Bathymodiolus azoricus collected in Menez Gwen hydrothermal vent field (NE Atlantic) during 2002–2003 were examined for feeding patterns variations through three seasons. The fatty acid profile and lipid classes of the mussels were studied, together with the MODIS/AQUA-derived near-surface chlorophyll a to test the hypothesis that surface productivity might be related to the feeding patterns of this species. The lipid levels showed pronounced seasonal fluctuations with the highest values occurring in January and August. Seasonal variations in lipid classes and fatty acid composition of neutral and polar lipids in the mussels are presented. Differences in the fatty acid profile of lipid classes in different seasons suggest that the higher energy requirements in summer and winter were supplied by bacterial biomarkers ω7 MUFA (monounsaturated fatty acids), whereas ω6 PUFA (polyunsaturated fatty acids) and NMI (non-methylene-interrupted) fatty acids predominated during the spring. The MODIS/AQUA data show marked seasonal variability and an anomalous peak during January of 2003, although this cannot be directly linked to lipid composition variation.  相似文献   

Sandy beach macrofaunal communities on the western coast of Portugal – Is there a steady structure under similar exposed conditions?     

Sílvia C. Gonalves  Pedro M. Anastcio  Miguel A. Pardal  Patrícia G.Cardoso  Susana M. Ferreira  Joo C. Marques 《Estuarine, Coastal and Shelf Science》2009,81(4):555-568

The structure of macrofaunal communities at two similar exposed sandy beaches on the western coast of Portugal was monitored for approximately 18 months by sampling all the beach area, from the shoreline to the base of the dunes. The beaches’ physical environment, as well as community density and composition, seasonal variations and the potential relationships between biological data and environmental parameters were studied. The two beaches had similar exposure to wave action, but differed in terms of sediment grain size, extent of the intertidal area, sediment moisture content and, especially, in the potential food availability in the form of allochthonous debris. Differences were observed with regard to the communities’ structure, namely regarding composition and relative contribution of the dominant species. Seasonality, especially temperature variations, and the interaction between seasons and the beach zones (supralittoral vs. intertidal) also had a strong influence on communities: controlling dominant species’ density and the horizontal distribution of the dominant species, and promoting a differential utilization of the beach by several resident macrofaunal animals. The present study allows the identification of key species in exposed sandy beaches of western Portugal and demonstrates that a steady community structure does not persist in the similarly exposed conditions observed, which may be mainly a response to distinct detritus subsidies, combined with differences in sediment grain size, sediment moisture content and extent of the intertidal area.  相似文献   

Possibilities of discriminating tropical secondary succession in Amazônia using hyperspectral and multiangular CHRIS/PROBA data     

Lênio Soares Galvão  Flávio Jorge PonzoniVeraldo Liesenberg  João Roberto dos Santos 《International Journal of Applied Earth Observation and Geoinformation》2009

CHRIS/PROBA data collected in the Brazilian Amazônia in 4 view angles (−36°, nadir, +36°, +55°) and 62 bands (410–1000 nm range) were evaluated for the discrimination between primary forest and 3 stages of secondary succession after deforestation: initial (SS1; <5 years), intermediate (SS2; 5–15 years) and advanced (SS3; >15 years). Single view angle and multiangular approaches (nadir plus anisotropic information derived from reflectance ratios between view angles) were tested for discrimination. Both approaches used principal components analysis (PCA) applied to pixel spectra representative of each class in order to reduce data dimensionality at each dataset, to enhance separability between the classes, and to provide input variables for multiple discriminant analysis (MDA). The results showed that the off-nadir viewing improved discrimination between the successional stages. Discrimination between SS2 and SS3 was enhanced with PCA at +36° view angle. Primary forest and SS3 presented a more anisotropic behavior than SS2 and SS1, especially in the backward scattering direction (positive view angles) in which great amounts of sunlit canopy components were viewed by the sensor. MDA classification results showed that the multiangular approach produced an overall improvement in the discrimination. From the single (nadir) to the multiangular approach, classification accuracy using a separate set of pixels increased from 83.3% to 98.3% for SS1, 53.3% to 70.0% for SS2, and 58.3% to 76.7% for SS3. The nadir and multiangular classifications were statistically different at a 0.05% level of significance. Kappa statistics increased from 0.63 to 0.82. The results showed that multiangular data can improve the differentiation between primary forest and old stages of natural vegetation regrowth, which have been reported in the literature as the most difficult classes to be mapped in the Amazonian environment.  相似文献   

H.- J. TREDER: Elementare Kosmologie. Bd.154 der Reihe „Wissenschaftliche Taschenbücher”︁, Akademie-Verlag,Berlin 1975, 153 S., kl. go,broschiert 8.- M     

o. Heckmann 《Astronomische Nachrichten》1976,297(3):165-165

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Metamorphic evolution of the Karakaya Complex in northern Turkey based on phyllosilicate mineralogy     

Sema Tetiker  Hüseyin Yalçın  Ömer Bozkaya  M. Cemal Göncüoğlu 《Mineralogy and Petrology》2015,109(2):201-215

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The new CutSprof sampling tool and method for micromorphological and microfacies analyses of subsurface salt marsh sediments,Algarve, Portugal     

João Araújo-Gomes  Ana Ramos-Pereira 《Geo-Marine Letters》2015,35(1):69-75

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Water balance,nutrient and carbon export from a heath forest catchment in central Amazonia,Brazil          下载免费PDF全文

Fabrício B. Zanchi  Maarten J. Waterloo  Andrés Peralta Tapia  Maria S. Alvarado Barrientos  Marcos A. Bolson  Flávio J. Luizão  Antônio O. Manzi  Albertus J. Dolman 《水文研究》2015,29(17):3633-3648

Carbon storage values in the Amazon basin have been studied through different approaches in the last decades in order to clarify whether the rainforest ecosystem is likely to act as a sink or source for carbon in the near future. This water balance, dissolved organic carbon (DOC) and nutrient export study were carried out in a micro‐scale heath forest (Campina) catchment in central Amazonia, Brazil. For a 1‐year study period (18 March 2007 until 19 March 2008), rainfall amounted to 3054 mm; of which, 1532 mm was evaporated by the forest (4.1 mm day^?1). Rainfall interception loss amounted to 15.6% of gross rainfall. Surface runoff amounted to 485 mm, whereas another 1071 mm was discharged as regional groundwater outflow. Accumulated DOC exports in surface runoff amounted to 15.3 g m^?2 year^?1, whereas the total carbon exported was 55.9 g m^?2. This is much higher than that observed for a nearby tall rainforest catchment in central Amazonia (DOC export < 20 g m^?2). As Campina heath forest areas cover a significant proportion of the Amazon Basin, these differences in ecosystem hydrological carbon exports should be taken into account in future studies assessing the carbon budget for the Amazon Basin. Macro‐nutrient exports were low, but those of calcium and potassium were higher than those observed for tall rainforest in the Amazon, which may be caused by a lower retention capacity of the heath forest ecosystem. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

The Dramas of the Marine Extractive Reserve Managers in Brazil: Navigating through Multiple Institutions     

Deborah Santos Prado  Fábio de Castro  Cristiana Simão Seixas 《社会与自然资源》2020,33(5):651-668

Abstract

In this paper, we describe and analyze the co-management institutional framework at 21 Brazilian Marine Extractive Reserves (MERs) and present the dramas of its implementation from the local manager’s perspective. We categorized the governance instruments of MERs into (i) instruments for land/sea tenure and beneficiaries’ recognition, (ii) territorial use planning, (iii) institutional arenas for discussion and deliberation, as well as (iv) public policies. Although the legal arrangements of these protected areas address fundamental dimensions of governance, we present the challenges of its implementation based on the voice of local managers. The managers are the bridge between the central government and communities, dealing with the implementation of the institutional framework in a reality of multi-level and multi-scale drama: from local to national dilemmas, from organizational to structural ones. We explore these dramas and highlight the institutional dilemmas based on the paradoxes between legalism and social emancipation.  相似文献   

Correction to: Spatiotemporal variability of vegetation due to drought dynamics (2012–2017): a case study of the Upper Paraíba River basin,Brazil     

da Silva  Glauciene Justino Ferreira  de Oliveira  Nádja Melo  Santos  Celso Augusto Guimarães  da Silva  Richarde Marques 《Natural Hazards》2020,102(3):965-965

Natural Hazards - This correction stands to support the updating of the original article for changing the name Glauciene Justino Ferreira to Glauciene Justino Ferreira da Silva. The author group...  相似文献   

Dimensionality reduction in drought modelling     

João Filipe Santos  Maria Manuela Portela  Inmaculada Pulido‐Calvo 《水文研究》2013,27(10):1399-1410

For monitoring hydrological events characterized by high spatial and temporal variability, the number and location of recording stations must be carefully selected to ensure that the necessary information is collected. Depending on the characteristics of each natural process, certain stations may be spurious or redundant, whereas others may provide most of the relevant data. With the objective of reducing the costs of the monitoring system and, at the same time, improving its operational effectiveness, three procedures were applied to identify the minimum network of rain gauge stations able to capture the characteristics of droughts in mainland Portugal. Drought severity is characterized by the standardized precipitation index applied to the timescales of 1, 3, 6 and 12 consecutive months. The three techniques used to reduce the dimensionality of the network of rain gauges were as follows: (i) artificial neural networks with sensitivity analysis, (ii) application of the mutual information criterion and (iii) K‐means cluster analysis using Euclidean distances. The results demonstrated that the best dimensionality reduction method was case dependent in the three regions of Portugal (northern, central and southern) previously identified by cluster analysis. All the reduction techniques lead to the selection of a subset of rain gauges capable of reproducing the original temporal patterns of drought. For specific severe drought events in Portugal in the past, the comparison between drought spatial patterns obtained with the original stations and the selected subset indicated that the subset produced statistically satisfactory results (correlation coefficients higher than 0.6 and efficiency coefficients higher than 0.5). Copyright © 2012 John Wiley & Sons, Ltd.  相似文献