Early Benthic Organism Colonization on a Caribbean Coral Reef (Barbados, West Indies): a Plate Experimental Approach     

Victoria Díaz-Castañeda  & Cesar Almeda-Jauregui 《Marine Ecology》1999,20(3-4):197-220

Abstract. Macrofaunal colonization was studied using coral plates fixed at 10 m depth on a fringing reef in Barbados, West Indies. Two sites were compared: Spring Garden, a site that is affected by eutrophication, and Six Men's Bay which is relatively free of this effect. Two sets of plates were immersed in winter and spring 1990 at each site and monitored for 28 and 19 weeks, respectively. Green and brown algae colonized first, followed 2 weeks later by ostracods, cumaceans, amphipods and polychaetes: terebellids, nereidids and syllids. Most colonizers either nestled or encrusted. A total of 11 017 invertebrates belonging to 145 species were collected. Polychaetes were the most abundant and diverse zoological group. Considering polychaetes, crustaceans and molluscs, the study sites shared around 75% of the species. Overall, densities were higher on lower (shaded) surfaces while diversities were higher on upper (illuminated) sides. Similarity coefficients and correspondence analysis showed different macrobenthic assemblages and colonization patterns in light and shaded and in polluted and unpolluted sites. Coral plates were associated according to their 'immersion time' and were closely linked to their stage of development. Spring Garden (polluted) presented a higher number of soft-bottom and deposit-feeder species ( e.g. , Capitella capitata ).  相似文献   

Velocity dispersion estimates of APM galaxy clusters     

M. Victoria Alonso  Carlos Valotto  Diego G. Lambas  Hernán Muriel 《Monthly notices of the Royal Astronomical Society》1999,308(3):618-622

We present 83 new galaxy radial velocities in the field of 18 APM clusters with redshifts between 0.06 and 0.13. The clusters have Abell identifications and the galaxies were selected within 0.75  h ⁻¹ Mpc in projection from their centres. We derive new cluster velocity dispersions for 13 clusters using our data and published radial velocities.
We analyse correlations between cluster velocity dispersions and cluster richness counts as defined in Abell and APM catalogues. The correlations show a statistically significant trend although with a large scatter, suggesting that richness is a poor estimator of cluster mass irrespectively of cluster selection criteria and richness definition. We find systematically lower velocity dispersions in the sample of Abell clusters that do not fulfil APM cluster selection criteria, suggesting artificially higher Abell richness counts owing to contamination by projection effects in this subsample.  相似文献   

The star cluster system of the 3-Gyr-old merger remnant NGC 1316: clues from optical and near-infrared photometry     

Paul Goudfrooij †  M. Victoria Alonso  Claudia Maraston  Dante Minniti 《Monthly notices of the Royal Astronomical Society》2001,328(1):237-256

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STRUCTURAL TENSION,MIGRATION, AND DEVELOPMENT: A CASE STUDY OF VENEZUELA*     

Victoria A. Lawson  Lawrence A. Brown 《The Professional geographer》1987,39(2):179-188

Mismatch of labor demand and supply, resulting from economic growth, is referred to here as structural tension. Spatial variations in structural tension are identified for Venezuelan states in 1971. Positive tension, indicating overutilization of human resources, prevails in urban areas. By contrast, rural locales exhibit underutilization due to rapid labor force growth without parallel increases in employment opportunities. Influence of structural tension, coupled with other migration determinants, upon destination choice by economically active immigrants is explored. Structural tension emerges as strongly significant for the total sample, displacing wages from the model. This is consistent with our contention that wages are a less precise indicator of labor supply and demand.  相似文献   

On Critical Realism,Human Geography,and Arcane Sects!     

Victoria A. Lawson  Lynn A. Staeheli 《The Professional geographer》1991,43(2):231-233

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Phytoplankton assemblages in the CoOP-WEST coastal upwelling area     

Adria M. Lassiter  Frances P. Wilkerson  Richard C. Dugdale  Victoria E. Hogue 《Deep Sea Research Part II: Topical Studies in Oceanography》2006,53(25-26):3063

Elevated levels of phytoplankton were observed at the Northern California coastal upwelling ecosystem studied as part of the CoOP-WEST project during monthly summer surveys in 2000, 2001 and 2002. The high concentrations of chlorophyll were made up mostly of larger cells; the phytoplankton communities that resulted were dominated by centric diatoms. The highest chlorophyll a concentrations were observed when large diatoms or small colony-forming species dominated the assemblages. In contrast, when smaller nano-flagellates and picoplankton were dominant, total chlorophyll a concentrations were over four or five-fold lower than when diatoms were prevalent, illustrating the importance of large diatoms to total phytoplankton biomass. Each year, when chlorophyll concentrations were greatest, Chaetoceros species created a Chaetoceros-dominated system. A few other genera contributed to the upwelling diatom community, mostly the centric diatoms Asterionella, Thalassiosira, Rhizosolenia (including Guinardia and Proboscia), and the pennate Nitzschia. These diatoms have been described in other coastal upwelling ecosystems, and at this study site form a functional group that are apparently well adapted to the high-nutrient, turbulent conditions that are typical of these coastal regions.  相似文献   

The need to understand the behaviour of fish reared for mariculture or restocking     

Gro Vea Salvanes  Anne; Braithwaite  Victoria 《ICES Journal of Marine Science》2006,63(2):345-354

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Millennial timescale resolution of rhyolite magma recharge at Tarawera volcano: insights from quartz chemistry and melt inclusions   总被引：4，自引：4，他引：0  

Phil Shane  Victoria C. Smith  Ian Nairn 《Contributions to Mineralogy and Petrology》2008,156(3):397-411

Most rhyolite eruption episodes of Tarawera volcano have emitted several physiochemically distinct magma batches (∼1–10 km³). These episodes were separated on a millennial timescale. The magma batches were relatively homogeneous in temperature and composition at pumice scale (>4 cm), but experienced isolated crystallisation histories. At the sub-cm scale, matrix glasses have trace element compositions (Sr, Ba, Rb) that vary by factors up to 2.5, indicating incomplete mixing of separate melts. Some quartz-hosted melt inclusions are depleted in compatible trace elements (Sr, Ti, Ba) compared to enclosing matrix glasses. This could reflect re-melting of felsic crystals deeper in the crystal pile. Individual quartz crystals display a variety of cathodoluminescence brightness and Ti zoning patterns including rapid changes in melt chemistry and/or temperature (∼50–100°C), and point to multi-cycle crystallisation histories. The Tarawera magma system consisted of a crystal-rich mass containing waxing and waning melt pockets that were periodically recharged by silicic melts driven by basaltic intrusion. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

Rivers of North-Rhine Westphalia revisited: Tracing changes in river chemistry   总被引：1，自引：0，他引：1  

Andrea Stgbauer  Harald Strauss  Julia Arndt  Victoria Marek  Florian Einsiedl  Robert van Geldern 《Applied Geochemistry》2008,23(12):3290-3304

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Toward a participatory VGI methodology: crowdsourcing information on regional food assets     

Victoria Fast  Claus Rinner 《International journal of geographical information science》2018,32(11):2209-2224

Local knowledge has been underrepresented in food-related policies and planning. The goal of this research was to engage members of a local food community and generate volunteered geographic information (VGI) on community food assets. During active data collection, over 200 food assets were reported. This paper details the systematic approach used to create VGI, which emphasizes the socio-cultural context surrounding the mapping technology. The project began with an identified need to connect to and learn from the local food community. The participants were drawn from active food system stakeholders, and a Geoweb infrastructure was selected based on publicly available crowdsourcing tools. The resulting VGI is presented according to system functions: input (Web traffic, contributors, input types), management (contribution vetting, privacy), analysis (typology of input), and presentation (sharing the submitted data). Despite limitations, this study revealed a hyper-local and community-driven perspective on food assets, opened access to government and private data, and increased the transparency and accessibility of information on the regional food system. This research also revealed that there is a growing need for intermediaries who can bridge the gap between experts in the subject matter and experts in digitally enabled participation, and a need for non-government open data repositories.  相似文献