Local disappearance of bivalves in the Azores during the last glaciation     

Sérgio P. Ávila  Patrícia Madeira  C. Marques da Silva  Mário Cachão  Bernard Landau  Rui Quartau  A. M. de Frias Martins 《第四纪科学杂志》2008,23(8):777-785

The Pleistocene (Eemian) outcrops of Lagoinhas and Prainha, located at Santa Maria Island (Azores), were investigated and their fossil mollusc content reported. These studies revealed that the last glaciation affected two groups of molluscs: the ‘warm‐guest’ gastropods with West African or Caribbean affinities (e.g. Conus spp., Cantharus variegatus, Bulla amygdala, Trachypollia nodulosa) and shallow bivalve species mainly associated with sandy habitats (Ensis minor, Lucinella divaricata, and probably Laevicardium crassum). In this paper we focus on this group of bivalves, which has since locally disappeared from the Azores. We relate the local disappearance of these bivalves in the Azores with the lack of sand in the shelf. The specific characteristics of the Santa Maria shelf combined with the sea‐level drop during the Weichselian prevented deposition of the lowstand deposits and permitted erosion of the previous ones, leaving the shelf without a sediment cover. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Concurrent imaging of chlorophyll fluorescence,Chlorophyll a content and green fluorescent proteins‐like proteins of symbiotic cnidarians          下载免费PDF全文

Miguel Costa Leal  Bruno Jesus  João Ezequiel  Ricardo Calado  Rui Jorge Miranda Rocha  Paulo Cartaxana  João Serôdio 《Marine Ecology》2015,36(3):572-584

Research on photosynthetic cnidarians has been mainly focused on the symbiosis established between the cnidarian host and its dinoflagellates endosymbionts from genus Symbiodinium. Despite the potential of imaging techniques for assessing the spatial distribution of key parameters of cnidarian photobiology, such as photochemical activity, chlorophyll a content or green fluorescent proteins (GFPs), to our best knowledge, no study has ever attempted to simultaneous map these three features. In this study, we developed a modified imaging pulse amplitude fluorometer by applying excitation light of different wavelengths and selectively detecting short spectral bands through bandpass filters. The imaging system was used to sequentially excite and quantify chlorophyll variable fluorescence (maximum quantum yield of photosystem II, F_v/F_m), Chl a content (normalized difference vegetation index) and relative content of GFPs. The spatial distribution of these photophysiological parameters was mapped both horizontally, across the surface of the soft corals Sarcophyton cf. glaucum and Sinularia flexibilis and the zoanthid Protopalythoa sp., and vertically, throughout a vertical section of S. cf. glaucum. Results showed bleached areas within each individual coral colony and registered photophysiological changes with S. cf. glaucum tissue depth. Analysis of Protopalythoa sp. polyps’ expansion revealed differential surface patterns of NDVI and GFP concentration, and a negative relation between these latter parameters within each polyp. This novel non‐invasive approach allowed a high‐resolution characterization of the spatial relationship between these key parameters through the analysis of image information on a pixel‐by‐pixel basis, which has great potential for investigating the physiological state of symbiotic associations.  相似文献   

Optical archival spectra of blazar candidates of uncertain type in the 3rd Fermi Large Area Telescope Catalog     

N. Álvarez Crespo  F. Massaro  R. D’Abrusco  M. Landoni  N. Masetti  V. Chavushyan  E. Jiménez-Bailón  F. La Franca  D. Milisavljevic  A. Paggi  V. Patiño-Álvarez  F. Ricci  Howard A. Smith 《Astrophysics and Space Science》2016,361(9):316

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Links between teleconnection patterns and mean temperature in Spain     

David Ríos-Cornejo  Ángel Penas  Ramón Álvarez-Esteban  Sara del Río 《Theoretical and Applied Climatology》2015,122(1-2):1-18

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Contribution of SHRIMP U–Pb zircon geochronology to unravelling the evolution of Brazilian Neoproterozoic fold belts     

Miguel Angelo Stipp Basei  Benjamim Bley Brito Neves  Oswaldo Siga Junior  Marly Babinski  Marcio Martins Pimentel  Colombo Celso Gaeta Tassinari  Maria Helena Bezerra Hollanda  Allen Nutman  Umberto Giuseppe Cordani 《Precambrian Research》2010

The South-American continent is constituted of three major geologic–geotectonic entities: the homonym platform (consolidated at the end of the Cambrian), the Andean chain (essentially Meso-Cenozoic) and the Patagonian terrains, affected by tectonism and magmatism through almost all of the Phanerozoic. The platform is constituted by a series of cratonic nuclei (pre-Tonian, fragments of the Rodinia fission) surrounded by a complex fabric of Neoproterozoic structural provinces.  相似文献   

Introduction     

María dos Santos Afonso  Miguel A. Blesa 《Aquatic Geochemistry》2010,16(2):223-224

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Medium- and Long-term Recovery of Estuarine and Coastal Ecosystems: Patterns,Rates and Restoration Effectiveness   总被引：1，自引：0，他引：1  

Ángel Borja  Daniel M. Dauer  Michael Elliott  Charles A. Simenstad 《Estuaries and Coasts》2010,33(6):1249-1260

Many estuarine and coastal marine ecosystems have increasingly experienced degradation caused by multiple stressors. Anthropogenic pressures alter natural ecosystems and the ecosystems are not considered to have recovered unless secondary succession has returned the ecosystem to the pre-existing condition or state. However, depending upon the scales of time, space and intensity of anthropogenic disturbance, return along the historic trajectory of the ecosystem may: (1) follow natural restoration though secondary succession; (2) be re-directed through ecological restoration, or (3) be unattainable. In order to address the gaps in knowledge about restoration and recovery of estuarine and coastal ecosystems, this special feature includes the present overview and other contributions to provide a synthesis of our knowledge about recovery patterns, rates and restoration effectiveness. From the 51 examples collated in this contribution, we refine the recovery from the list of stressors into six recovery mechanisms: (1) recovery from sediment modification, which includes all aspects of dredging and disposal; (2) recovery by complete removal of stressors limiting natural ecosystem processes, which includes tidal marsh and inundation restoration; (3) recovery by speed of organic degradation, which includes oil discharge, fish farm wastes, sewage disposal, and paper mill waste; (4) recovery from persistent pollutants, which includes chemical discharges, such as TBT; (5) recovery from excessive biological removal, related to fisheries and (6) recovery from hydrological and morphological modification. Drawing upon experience both from these many examples and from an example of one comprehensive study, we show that although in some cases recovery can take <5 years, especially for the short-lived and high-turnover biological components, full recovery of coastal marine and estuarine ecosystems from over a century of degradation can take a minimum of 15–25 years for attainment of the original biotic composition and diversity may lag far beyond that period.  相似文献   

Soil and vegetation seasonal changes in the grazing Andean Mountain grasslands     

MU?OZ María ángeles  FAZ ángel 《山地科学学报》2014,11(5):1123-1137

Andean grasslands ecosystems are fragile environments with rigorous climatologic conditions and low and variable food for the grazing. The Apolobamba area is located in the Bolivian Andean Mountains. Its high grasslands provide a natural habitat for wild and domestic camelids such as vicuna（Vicugna vicugna） and alpaca（Lama pacos）. The botanical diversity plays an essential role in maintaining vital ecosystem functions. The objectives of this research were to determine the seasonal changes in soil properties, to study the vegetation changes during the wet and dry seasons and the influence of soil properties and camelid densities on the vegetation in the Apolobamba grasslands. Four zones with different vicuna populations were selected to be studied. The following soil parameters were determined： total organic carbon, total nitrogen, available phosphorous, cation exchange capacity, exchangeable cations, pH and texture. The vegetation season changes were studied through botanical identification, above-ground biomass, plant cover and species richness. Results showed that some soil properties such as C/N ratio, CEC, silt and clay percentages kept stable against the seasonal changes. Generally, soil nutrients were relatively higher during the dry season in the surface and subsurface. The results did not point out the predominant vegetation growth during the wet season. The seasonal vegetation growth depended on each species. Thegood soil fertility corresponded to the highest plant cover. Soil fertility presented no influence on the above-ground biomass of the collected species. The negative influence of camelid grazing on soil properties could not be assessed. However, overgrazing could affect some plant species. Therefore, protection is needed in order to preserve the biodiversity in the Andean mountain grasslands.  相似文献   

Mushroom production as an alternative for rural development in a forested mountainous area     

José A. BONET  José R. GONZáLEZ-OLABARRIA  Juan MARTíNEZ DE ARAGóN 《山地科学学报》2014,11(2):535-543

Wild mushrooms are recognized as important non-wood forest products in mountainous ecosystems, but their real potential for generating rural economies has not been fully evaluated due to the difficulties in obtaining reliable productivity data, minimizing their true potential as contributor to rural economies. Mushroom yield models based on large data series from Pinus forest ecosystems in the region of Catalonia(Spain), combined with data from the Spanish National Forest Inventory allow us to estimate the potential mushroom productivity by forest ecosystems. The results of 24,500 tons/yr of mushrooms of which 16,300 tons are classified as edible and 7,900 tons are commonly marketed demonstrate the importance of mushroom productions in Catalonian pine forests, mostly located in mountainous areas where the development of agricultural activities is limited. Economic mushroom value is estimated at 48 million € for the edible mushroom and 32 million € for those corresponding to marketable yields, confirming the potential of this non-wood forest product. These production results and corresponding economic values provide a basis for the incorporation of wild mushrooms as significant non-wood forest products in the development of forest policies in mountainous areas.  相似文献   

Technical, financial and location criteria for the design of land application system treatment     

Juana María Sanz  Ángel de Miguel  Irene de Bustamante  Alberto de Tomás  José Luis Goy 《Environmental Earth Sciences》2014,71(1):13-21

Conventional water treatments when downsized to cover the demands of small and scattered populations are costly and ineffective. In fact, many small towns cannot afford the high average treatment costs nor provide the skill and complex management requirements. Even when these facilities are available, waste water might not be properly treated. Land application system treatments (LAST) have been shown to be preferable on the basis of their technical effectiveness and financial viability. The recently approved Spanish regulations (RDL 1620/2007, pp 50369–50661) represent an opportunity for the implementation of well-designed LASTs. This paper presents an assessment methodology for the design of LASTs by combining technical, financial and location criteria. The method is applied to the design of LASTs to cover the water disposal demand of twelve municipalities located within the protected natural landscape, and surrounding areas of ‘El Rebollar’, Salamanca, Spain.  相似文献