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Registros recuperados: 12
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CLIMATE CHANGE SENSITIVITY ASSESSMENT ON UPPER MISSISSIPPI RIVER BASIN STREAMFLOWS USING SWAT AgEcon
Jha, Manoj K.; Arnold, Jeffrey G.; Gassman, Philip W.; Gu, Roy.
The Soil and Water Assessment Tool (SWAT) model was used to assess the impacts of potential future climate change on the hydrology of the Upper Mississippi River Basin (UMRB). Calibration and validation of SWAT were performed on a monthly basis for 1968-87 and 1988-97, respectively; R2 and Nash-Sutcliffe simulation efficiency (E) values computed for the monthly comparisons were 0.74 and 0.65 for the calibration period and 0.81 and 0.75 for the validation period. The impacts of eight 20-year (1971-90) scenarios were then analyzed, relative to a scenario baseline. A doubling of atmospheric CO2 concentrations was predicted to result in an average annual flow increase of 35 percent. An average annual flow decrease of 15 percent was estimated for a constant...
Tipo: Working or Discussion Paper Palavras-chave: Climate change; Flow; Hydrology; Simulation; Spatial patterns; Watershed; Environmental Economics and Policy.
Ano: 2004 URL: http://purl.umn.edu/18419
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Eastern English Channel fish assemblages: measuring the structuring effect of habitats on distinct sub-communities ArchiMer
Vaz, Sandrine; Carpentier, Andre; Coppin, Franck.
Multivariate and spatial analyses are used to identify and locate fish, cephalopod, and macrocrustacean species assemblages in the eastern English Channel from 1988 to 2004. Four sub-communities with varying diversity levels were identified in relation to depth, salinity, temperature, seabed shear stress, sediment type, and benthic community nature. From 1997 to 2004, some 25% of overall community structure variance could be related to the available environmental descriptors and 20% to persistent factors such as depth, seabed shear stress, sediment, and macro-invertebrate community type. Although there may be significant interannual shifts in overall community structure and composition, the sub-communities identified persisted over time, reflecting the...
Tipo: Text Palavras-chave: Structuring environment; Spatial patterns; Fish community; Eastern English Channel; Diversity.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/2007/publication-2829.pdf
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Fish assemblage in a dammed tropical river: an analysis along the longitudinal and temporal gradients from river to reservoir Neotropical Ichthyology
Terra,Bianca de Freitas; Santos,Alex Braz Iacone dos; Araújo,Francisco Gerson.
We analysed changes in the fish assemblage structure along a longitudinal gradient of the Paraíba do Sul River and Funil Reservoir. We tested the hypothesis that shifts from lotic to lentic environment affect the richness and structure of the assemblage which are modulated by seasonal rainfall changes. Standardised monthly samplings were carried out from October 2006 to September 2007 in four zones: 1) river upstream from the reservoir; 2) upper part of the reservoir; 3) lower part of the reservoir, and 4) river downstream from the reservoir. Fishes were caught using gillnets deployed for 15 hours. We collected a total of 4550 specimens, representing 35 species and 5 orders. The highest richness and diversity were recorded in zone 2, the transitional zone...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Spatial patterns; Physico-chemical variables; Reservoirs.
Ano: 2010 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-62252010000300004
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Fish assemblage structure in a port region of the Amazonic coast Iheringia, Sér. Zool.
Silva,Marcelo H. L.; Torres Júnior,Audálio R.; Castro,Antonio C. L.; Azevedo,James W. J.; Ferreira,Cássia F. C.; Cardoso,Rayssa L.; Nunes,Jorge L. S.; Carvalho-Neta,Raimunda N. F..
ABSTRACT: The fish assemblage structure in a port area in São Marcos Bay (Amazonic coast) was evaluated based on the spatial and temporal distributions to identify potential changes in response to anthropic pressure increases associated with industrial and port activities in region. The samples were taken between March 2011 and November 2015. The ichthyofauna was represented by a total of 56 species, distributed in 15 orders and 29 families. Captures were dominated by Genyatremus luteus (Bloch, 1790), but Sciades proops (Valenciennes, 1840) was the most representative in terms of biomass. Seasonal distributions of fish assemblage did not reveal significant differences. However, there was a difference between catch sites, abundance, biomass and Shannon...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Ichthyofauna; Estuary; Seasonal variability; Spatial patterns; Maranhão Amazon.
Ano: 2018 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0073-47212018000100218
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Fish assemblages along a morphodynamic continuum on three tropical beaches Neotropical Ichthyology
Oliveira,Ronnie E. M. C. C.; Pessanha,André L. M..
A comparative study involving three mesotidal beaches from reflective to estuarine states was conducted between October 2010 and September 2011 in the estuary of Mamanguape River, northeastern Brazil. The aim was to test for differences in fish assemblages along a morphodynamic continuum, particularly the effects of wave action. In total, 3,732 fish from 71 species were examined; Rhinosardinia bahiensisand Atherinella brasiliensisdominated the estuarine beach, whereas Trachinotus carolinus dominated the reflective beach. Fish assemblages were structured by spatial differences among the sites, and overall abundance, richness and biomass demonstrated a clear increasing trend from the reflective to the estuarine beaches, indicating a primary influence of wave...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Community descriptors; Juveniles; Nursery; Spatial patterns; Wave action.
Ano: 2014 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-62252014000100165
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Historical fluctuations in spawning location of anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) in the Bay of Biscay during 1967-73 and 2000-2004 ArchiMer
Bellier, Edwige; Planque, Benjamin; Petitgas, Pierre.
The spatial extent of small pelagic fish spawning habitat is influenced by environmental factors and by the state of the adult population. In return, the configuration of spawning habitat affects recruitment and therefore the future structure of the adult population. Interannual changes in spatial patterns of spawning reflect variations in adult population structures and their environment. The present study describes the historical changes in the spatial distribution of spawning of anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) in the Bay of Biscay during two periods: 1967-72 and 2000-2004. Using data from egg surveys conducted in spring, the spatial distributions of anchovy and sardine eggs are characterized by means of geostatistics....
Tipo: Text Palavras-chave: Spawning habitat; Spatial patterns; Sardine; Long term changes; Bay of Biscay; Anchovy.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/2007/publication-2179.pdf
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Local extinction of an important seed disperser does not modify the spatial distribution of the endemic palm Astrocaryum aculeatissimum (Schott) Burret (Arecaceae) Acta Botanica
Zucaratto,Rodrigo; Pires,Alexandra dos Santos.
Spatial pattern of the palm Astrocaryum aculeatissimum was investigated in an urban Atlantic Forest fragment (Tijuca National Park, Brazil) where its main seed disperser, the red-rumped agouti Dasyprocta leporina, is locally extinct. A 120 × 130 m plot (1.56 ha) was established in which all A. aculeatissimum individuals were quantified, georeferenced, and classified by ontogenetic stages, namely, seedling, infant, juvenile, immature individual, and adult. Analyses were performed using Ripley's K function. We recorded 376 individuals, most of which were in the juvenile stage (n = 228). The spatial pattern was aggregated as observed for other palm species. Seedlings and infants were not associated with adults, whereas juveniles and immature individuals were...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Atlantic Forest; Palm; Recruitment distances; Ripley's K function; Spatial patterns.
Ano: 2015 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-33062015000200244
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Notes on survey-based spatial indicators for monitoring fish populations ArchiMer
Woillez, Mathieu; Rivoirard, Jacques; Petitgas, Pierre.
This paper presents the spatial indicators used in the European project FISBOAT. These are statistics intended to capture spatial patterns of fish populations, using fish density data collected during scientific surveys. To handle diffuse population limits, indicators are designed not to depend on arbitrary delineation of the domain. They characterize the location (centre of gravity and spatial patches), occupation of space (inertia, isotropy, positive area, spreading area and equivalent area) and microstructure. Collocation between different populations is summarized by a global index of collocation. These spatial indicators have the potential to be used in a monitoring system to detect changes in spatial distribution. They could be helpful for relating...
Tipo: Text Palavras-chave: Fish populations; Spatial patterns; Monitoring; Spatial indicators.
Ano: 2009 URL: http://archimer.ifremer.fr/doc/2009/publication-6687.pdf
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Spatial patterns of the Citrus leprosis virus and its associated mite vector in systems without intervention. Repositório Alice
BASSANEZI, R. B.; CZERMAINSKI, A. B. C.; BARBOSA, F. F. L.; MOREIRA, A. S.; RIBEIRO JUNIOR, P. J.; KRAINSKI, E. T.; AMORIM, L..
Leprosis is caused by the Citrus leprosis virus cytoplasmic type and is vectored by the mite Brevipalpus yothersi . Miti- cide applications, which cost $54 million annually, are based on inspection for the presence of mites. The aim of the present study was to characterize the spatial patterns of B. yothersi-infested trees and trees with leprosis symptoms for further improvement in sampling and disease control. The presence of mites and the occurrence of leprosis were assessed over two years in 1160 Valencia trees and 720 Natal trees in a commercial sweet orange grove in Sao Paulo State, Brazil. To assess the natural growth and dispersal of mites and leprosis, mite populations were not controlled during the experimental period. Maps of mite-infested trees...
Tipo: Artigo em periódico indexado (ALICE) Palavras-chave: Brevipalpus yothersi; Citrus leprosis virus; Flat mite; Spatial analysis; Spatial patterns; Leprosis; Fruta Cítrica; Citrus Sinensis; Epidemiology.
Ano: 2018 URL: http://www.alice.cnptia.embrapa.br/alice/handle/doc/1103966
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Spatial patterns of two co-occurring savanna and forest tree species in a dense fire-protected savanna fragment Acta Botanica
Costa,Rafael Carvalho da; Santos,Flavio Antonio Maës dos.
ABSTRACT Savanna-forest transition under fire-exclusion could be explained by differential competitive performance of savanna and forest species under shading/fire-exclusion. Aiming to understand strategies related to either habitat affinity, we investigated spatial patterns of a savanna and a forest species in a fire-protected savanna. We predicted that: savanna species would have lower abundance than the forest species due to a restriction in the number of open microsites; segregation of size classes and a trend from clumping to regularity with size for forest species due to absence of microsite limitation and intra-specifc competition; and spatial association and increasing clustering with size for savanna species due to microsite limitation. To test...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Cerrado; Competition; Fire; Microsite limitation; Recruitment; SADIE; Savanna; Spatial patterns.
Ano: 2016 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-33062016000400577
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Testing CPUE-derived spatial occupancy as an indicator for stock abundance: application to deep-sea stocks ArchiMer
Trenkel, Verena; Beecham, Jonathan A.; Blanchard, Julia L.; Edwards, Charles T. T.; Lorance, Pascal.
The status of an exploited population is ideally determined by monitoring changes in abundance and distributional range and pattern over time. Area of occupancy is a measure of the current distribution. Unfortunately, for many populations, scientific abundance and distribution information is not readily available. To evaluate the reliability of commercial fishing data for deriving occupancy indicators that could serve as proxies for stock abundance, we investigated four questions: 1) Occupancy changes with stock biomass, but is this change strong enough to make occupancy a sensitive indicator of population biomass? 2) Fishing boats follow fish, but when does such activity alter the positive macroecological relationship between occupancy and abundance? 3)...
Tipo: Text Palavras-chave: Catch per unit effort; Spatial patterns; Macroecology; Fisheries management; Marine Strategy Framework Directive; MSFD.
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00176/28759/27232.pdf
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The role of terrestrial bromeliads in determining the spatial organization of plant life forms in a tropical coastal forest Acta Botanica
Lopes,Celio M.; Misaki,Flora; Santos,Karina; Evangelista,Carlos A. P.; Carrijo,Tatiana T.; Garbin,Mário L..
ABSTRACT The interplay between plant-plant interactions and light heterogeneity in the understory of tropical forests has rarely been examined. We aimed to identify the relative importance of the understory light environment and terrestrial bromeliads in explaining the abundance and spatial organization of different plant life forms along a coastal forest gradient from seashore inland in southeastern Brazil. We estimated the abundance of various life forms (herbs, woody plants, bromeliads, climbers, and palms) and the degree of light availability using hemispherical photographs in 165 plots (1 m2) within a 1.75 ha site. We used ordination methods, partial redundancy analysis (pRDA), spatial filtering using Moran’s eigenvector mapping, and Moran’s I...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Community assembly; Hemispherical photographs; Herb layer; Shrub layer; Spatial patterns.
Ano: 2017 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-33062017000100084
Registros recuperados: 12
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