1000 resultados para Rivers--Ontario--Niagara Peninsula.
Resumo:
RESUMOSão apresentadas normas DRIS preliminares e derivados níveis críticos de nutrientes no tecido foliar (NC) para a videira ‘NiagaraRosada’ enxertada sobre o porta-enxerto ‘IAC 766’, nas condições de cultivo da região de Jundiaí-SP. As normas DRIS e os NCs foram obtidos a partir de um banco de dados com 116 registros, relacionando produtividade e teores foliares de N, P, K, Ca e Mg das videiras. Esses registros foram obtidos em experimentos de adubação e em um levantamento do estado nutricional de videiras realizados na região de Jundiaí, durante quatro ciclos de produção. Os registros foram separados em duas subpopulações: alto (>26 t/ha), e baixo rendimento (<26 t/ha) e as normas DRIS foram calculadas de acordo com os procedimentos convencionais. Mesmo com a diversidade nas condições de cultivo, a relação entre o índice de balanço nutricional e a produtividade das plantas foi altamente significativa (R2=0,48; p<0,0001), indicando que parte da variação na produtividade dos vinhedos pode ser creditada ao estado nutricional das plantas. Os NCs foram obtidos a partir de regressões múltiplas, relacionando teores foliares de cada nutriente com todos os índices DRIS. Os NCs para teores foliares de N, P, K, Ca e Mg foram 38,0; 3,0; 11,4; 13,7 e 3,5 g kg-1, respectivamente.
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La revisión de las especies ibéricas de Euphorbia sect. Cymatospermum ha precisado de un estudio previo de los caracteres seminales. Se ha examinado la variabilidad morfológica intra e interespecíflca de las semillas y se han definido los caracteres diferenciales para cada taxon. La forma, tamaño y ornamentación epispérmica proporcionan suficientes caracteres para distinguir los táxones reconocidos en este artículo. El estudio de los mucílagos y de los microcaracteres epispérmicos al MEB ha esclarecido las afinidades de las semillas de esta sección respecto a las otras del género, y ha supuesto indagación acerca de su significado funcional y evolutivo.
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Las notas que siguen son un avance de los resultados obtenidos en el estudio que estamos llevando a cabo sobre el género Dianthus L. en el NE de la Península Ibérica, y versan sobre algunos de los táxones que consideramos más conflictivos.
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The distribution of the genus Barbadocladius Cranston & Krosch (Diptera: Chironomidae), previously reported from Chile to Bolivia, has extended northwards. Larvae, pupae and pupal exuviae of this genus have been found in the high mountain tropical streams of Peru to 9°22′56″, but are restricted to very high altitude streams (altitudes over 3,278 m asl) compared to the lower altitude streams (below 1,100 m asl) in which the genus is reported in Chile and Argentina. Based on morphological studies, both described species in the genus, Barbadocladius andinus Cranston & Krosch and Barbadocladius limay Cranston & Krosch, have been found in Peru as pupae or pupal exuviae. Morphological analysis of the larvae and pupae revealed no differences between the two described species from Patagonia and Peru, which are of similar size and with a similar armament of hooklets and spines in pupal tergites and sternites. However, molecular analysis of larvae and pupae revealed that in Peru, there are at least two different evolutionary lines, one distributed widely and another restricted to one site. Phylogenetic analysis (using cox1 mitochondrial sequences) of all available sequences of Barbadocladius shows that the Chilean and Argentinean material differs from that of Peru. Therefore, a total of four molecular segregates are identified, although morphologically, neither larvae nor the pupae may be differentiated.
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El estudio transdisciplinar de la fosa EE1 de la Cova Colomera ha proporcionado un conjunto de datos que aportan importante información sobre las prácticas domésticas y económicas desarrolladas en ella, y sobre las características paleoambientales de esta zona del noreste peninsular en el tránsito III-II milenio cal. AC. Los resultados apuntan a que esta cueva fue ocupada por grupos reducidos, con una economía mixta agropecuaria, que recurrían también a actividades cinegéticas para completar su dieta. En sus cortas estancias en la Cova Colomera, crearon y amortizaron estructuras excavadas en el suelo de la cavidad, como la fosa EE1, bien para almacenar excedentes y después desechar basura, o bien para eliminar residuos de origen doméstico.
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Streams and rivers in mediterranean-climate regions (med-rivers in med-regions) are ecologically unique, with flow regimes reflecting precipitation patterns. Although timing of drying and flooding is predictable, seasonal and annual intensity of these events is not. Sequential flooding and drying, coupled with anthropogenic influences make these med-rivers among the most stressed riverine habitat worldwide. Med-rivers are hotspots for biodiversity in all med-regions. Species in med-rivers require different, often opposing adaptive mechanisms to survive drought and flood conditions or recover from them. Thus, metacommunities undergo seasonal differences, reflecting cycles of river fragmentation and connectivity, which also affect ecosystem functioning. River conservation and management is challenging, and trade-offs between environmental and human uses are complex, especially under future climate change scenarios. This overview of a Special Issue on med-rivers synthesizes information presented in 21 articles covering the five med-regions worldwide: Mediterranean Basin, coastal California, central Chile, Cape region of South Africa, and southwest and southern Australia. Research programs to increase basic knowledge in less-developed med-regions should be prioritized to achieve increased abilities to better manage med-rivers.
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Data about breeding populations of birds in the Antarctica are rare and fragmented. Thus, information about the status of the breeding populations of Antarctic birds is crucial given the current scenario of climate change, which is particularly acute in Antarctica. This paper presents new information about the populations of the Antarctic tern Sterna vittata, the kelp gull Larus dominicanus, the southern giant petrel Macronectes giganteus, the Antarctic skua Catharacta antarctica lonnbergi, the chinstrap penguin Pygoscelis antarctica and the gentoo penguin Pygoscelis papua on Byers Peninsula (Livingston Island, South Shetland Islands). We used line transects counts to estimate both densities and numbers of nests of the different species. We estimate that there are 398.96 birds km-2 of southern giant petrels (2793 individuals), 62.4 birds km-2 of Antarctic tern (3746 individuals) and 269.1 birds km-2 of kelp gull (1884 individuals). Furthermore, we found 15 nests of Antarctic skua in 25 km2, from which we can estimate that 6091 birds must breed on Byers Peninsula. We also censused two colonies of gentoo penguins (3000 and 1200 pairs) and 50 pairs of chinstrap. Compared to previous estimates, gentoo penguins seem to have increased whereas chinstrap penguin have decreased. Finally, the populations of Antarctic tern, southern giant petrel and kelp gull have stabilized or slightly increased.
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Majolica pottery was the most characteristic tableware produced in Europe during the Medieval and Renaissance periods. Because of the prestige and importance attributed to this ware, Spanish majolica was imported in vast quantities into the Americas during the Spanish Colonial period. A study of Spanish majolica was conducted on a set of 186 samples from the 10 primary majolica production centres on the Iberian Peninsula and 22 sherds from two early colonial archaeological sites on the Canary Islands. The samples were analysed by neutron activation analysis (NAA), and the resulting data were interpreted using an array of multivariate statistical approaches. Our results show a clear discrimination between different production centres, allowing a reliable provenance attribution of the sherds from the Canary Islands.
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Mediterranean endemic freshwater fish are among the most threatened biota in the world. Distinguishing the role of different extinction drivers and their potential interactions is crucial for achieving conservation goals. While some authors argue that invasive species are a main driver of native species declines, others see their proliferation as a co-occurring process to biodiversity loss driven by habitat degradation. It is difficult to discern between the two potential causes given that few invaded ecosystems are free from habitat degradation, and that both factors may interact in different ways. Here we analyze the relative importance of habitat degradation and invasive species in the decline of native fish assemblages in the Guadiana River basin (southwestern Iberian Peninsula) using an information theoretic approach to evaluate interaction pathways between invasive species and habitat degradation (structural equation modeling, SEM). We also tested the possible changes in the functional relationships between invasive and native species, measured as the per capita effect of invasive species, using ANCOVA. We found that the abundance of invasive species was the best single predictor of natives’ decline and had the highest Akaike weight among the set of predictor variables examined. Habitat degradation neither played an active role nor influenced the per capita effect of invasive species on natives. Our analyses indicated that downstream reaches and areas close to reservoirs had the most invaded fish assemblages, independently of their habitat degradation status. The proliferation of invasive species poses a strong threat to the persistence of native assemblages in highly fluctuating environments. Therefore, conservation efforts to reduce native freshwater fish diversity loss in Mediterranean rivers should focus on mitigating the effect of invasive species and preventing future invasions
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Species structure and composition in Mediterranean riparian forests are determined by hydrological features, longitudinal zonation, and riverbank topography. This study assesses the distribution of four native riparian plants along the riverbank topographic gradient in three river stretches in southern Spain, with special emphasis on the occupation of adult and young feet of each species. The studied stretches suffered minimal human disturbances, displayed semi-arid conditions, and had wide riparian areas to allow the development of the target species: black alder (Alnus glutinosa), salvia leaf willow (Salix salviifolia), narrow-leafed ash (Fraxinus angustifolia), and oleander (Nerium oleander). Thalweg height was used to define the riverbank topographic gradient. The results showed a preferential zone for black alder and salvia leaf willow in the range of 0-150 cm from the channel thalweg, with adult alders and willows being more common between 51 and 150 cm and young alders being more common under 50 cm. Conversely, narrow-leafed ash and oleander were much more frequent, and showed greater development, in the ranges of 151-200 cm and 201-250 cm, respectively, whereas the young feet of both species covered the entire topographic range. Adult feet of the four species were spatially segregated along the riverbank topographic gradient, indicating their differential ability to cope with water stress from the non-tolerant alders and willows to more tolerant narrow-leafed ash trees and oleanders. Young feet, however, showed a strategy more closely linked to the initial availability of colonisation sites within riparian areas to the dispersion strategy of each species and to the distribution of adult feet. In Mediterranean areas, where riparian management has traditionally faced great challenges, the incorporation of species preferences along riverbank gradients could improve the performance of restoration projects.
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Research on limnology in southern Europe had achieved a notable presence in the international arena before the onset of the current dramatic cuts in public investment in science. We assessed the limnological research published in peer-reviewed journals by Spanish and Portuguese (i.e., Iberian) researchers during the decade prior to the economic recession (2000 to 2009). The Thompson Reuters Web of Knowledge database was used to retrieve all publications on limnology authored by researchers affiliated with Spanish or Portuguese institutions independently of the geographical setting of the study. The publishing pattern was characterised in terms of authors, journals, and citation statistics. In addition, a thematic characterisation of the research was performed by a manual assignation of several categorical descriptors combined with a blind word count analysis. Iberian researchers produced an annual mean of 278 papers on limnology. Papers were published in journals that had impact factors ranging from 0.1 to 31.4, with a mean of 2.0. Based on citations, the impact of the Iberian limnological research was not due to a few highly cited papers but rather to a wide number of publications; each paper received a mean of 8 citations. The Iberian limnological research involved up to 5460 researchers, with a mean of 4.3 authors per paper. The research largely focused on fluvial systems, with 47 % of total publications (2778) devoted to these ecosystems. There was a dominant focus on local, within-system aspects of study sites and the research was mostly restricted to the Iberian Peninsula; larger spatial scales of analysis (i.e., landscape, regional, or global) tended to be overlooked. Iberian research addressed fundamental (75 %) rather than applied (17 %) or methodological (5 %) questions and was vastly dominated by observational approaches (75 %). Interestingly, Iberian limnological research increased its scientific productivity during the analysed decade at a higher rate than its international counterpart (increase of 119 %). Overall, Iberian research on limnology appeared to be in good health during the analysed decade. Certain areas have been more studied than others, which opens opportunities to develop new research.
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This study aimed to describe patterns of diversity of Baetidae (Ephemeroptera) at the ommunity and population levels within the Montseny Mountain range (North-East Iberian Peninsula). We studied both the distribution of 4 species of baetids in 20 sites among three catchments along the altitudinal gradient (350-1700 masl); and the genetic diversity of the mtDNA cytochrome c oxidase subunit I (cox1) gene of the two common species Baetis alpinus and Baetis rhodani. We found a gradual replacement of the dominant species along the altitudinal gradient. Baetis alpinus inhabited sites at high-altitudes, and this species was replaced by B. rhodani when the altitude decreased. Baetis melanonyx and Alainites muticus attained low abundance at all river sections, and no clear altitudinal trend appeared. Our hypothesis at the population level was that genetic structuring is associated with geographic distance and limited by drainage boundaries among the three studied catchments because of the short-time dispersion of adults. Unexpectedly, analyses of molecular variance (AMOVA) and isolation-bydistance (IBD) showed genetic diversity was unstructured by distance for both species, which may be explained by the relatively short spatial scale studied and small topographic barriers among the three catchments. The Generalized Mixed Yule-Coalescent (GMYC) model showed that B. rhodani had two differentiated genetic lineages that co-occurred in all sites. Overall, diversity of baetids was structured at the community level along the altitudinal gradient, whereas it was unstructured at the population level within the Montseny Mountain range.
Resumo:
This study aimed to describe patterns of diversity of Baetidae (Ephemeroptera) at the ommunity and population levels within the Montseny Mountain range (North-East Iberian Peninsula). We studied both the distribution of 4 species of baetids in 20 sites among three catchments along the altitudinal gradient (350-1700 masl); and the genetic diversity of the mtDNA cytochrome c oxidase subunit I (cox1) gene of the two common species Baetis alpinus and Baetis rhodani. We found a gradual replacement of the dominant species along the altitudinal gradient. Baetis alpinus inhabited sites at high-altitudes, and this species was replaced by B. rhodani when the altitude decreased. Baetis melanonyx and Alainites muticus attained low abundance at all river sections, and no clear altitudinal trend appeared. Our hypothesis at the population level was that genetic structuring is associated with geographic distance and limited by drainage boundaries among the three studied catchments because of the short-time dispersion of adults. Unexpectedly, analyses of molecular variance (AMOVA) and isolation-bydistance (IBD) showed genetic diversity was unstructured by distance for both species, which may be explained by the relatively short spatial scale studied and small topographic barriers among the three catchments. The Generalized Mixed Yule-Coalescent (GMYC) model showed that B. rhodani had two differentiated genetic lineages that co-occurred in all sites. Overall, diversity of baetids was structured at the community level along the altitudinal gradient, whereas it was unstructured at the population level within the Montseny Mountain range.
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The publication of the fourth IPCC report, as well as the number of research results reported in recent years about the regionalization of climate projections, were the driving forces to justify the update of the report on climate change in Catalonia. Specifically, the new IPCC report contains new climate projections at global and continental scales, while several international projects (especially European projects PRUDENCE and ENSEMBLES) have produced continental-scale climate projections, which allow for distinguishing between European regions. For Spain, some of these results have been included in a document commissioned by the“State Agency of Meteorology”. In addition, initiatives are being developed within Catalonia (in particular, by the Meteorological Service of Catalonia) to downscale climate projections in this area. The present paper synthesizes results of these and other previously published studies, as well as our own analysis of results of the ENSEMBLES project. The aim is to propose scenarios of variation in temperature and rainfall in Catalonia during the 21st Century. Thus, by the middle of this century temperatures could rise up to 2 C compared with that of the late 20th Century. These increases would probably be higher in summer than in winter, generalized across the territory but less pronounced in coastal areas. Rainfall, however, would not change much, but it could slightly decrease. Towards the end of the 21st Century, temperatures could rise to about 5 C above that of the last century, while the average rainfall could decrease by more than 10%. Increases in temperature would be higher in summer and in areas further from the coast. Rainfall would decrease especially during the summer, while it could even increase in winter in mountainous areas such as the Pyrenees.
Homogenization Dynamics and Introduction Routes of Invasive Freshwater Fish in the Iberian Peninsula
Resumo:
Nonnative invasive species are one of the main global threats to biodiversity. The understanding of the traits characterizing successful invaders and invasion-prone ecosystems is increasing, but our predictive ability is still limited. Quantitative information on biotic homogenization and particularly its temporal dynamics is even scarcer. We used freshwater fish distribution data in the Iberian Peninsula in four periods (before human intervention, 1991, 1995, and 2001) to assess the temporal dynamics of biotic homogenization among river basins. The percentage of introduced species among fish faunas has increased in recent times (from 41.8% in 1991 to 52.5% in 2001), leading to a clear increase in the similarity of community composition among basins. The mean Jaccard's index increase (a measure of biotic homogenization) from the pristine situation to the present (17.1%) was similar to that for Californian fish but higher than for other studies. However, biotic homogenization was found to be a temporally dynamic process, with finer temporal grain analyses detecting transient stages of biotic differentiation. Introduced species assemblages were spatially structured along a latitudinal gradient in the Iberian Peninsula, with species related to sport fishing being characteristic of northern basins. Although the comparison of fish distributions in the Iberian Peninsula and France showed significant and generalized biotic homogenization, nonnative assemblages of northeastern Iberian basins were more similar to those of France than to those of the rest of the Iberian Peninsula, indicating a main introduction route. Species introduced to the Iberian Peninsula tended to be mainly piscivores or widely introduced species that previously had been introduced to France. Our results indicate that the simultaneous analysis of the spatial distribution of introduced assemblages (excluding native species that reflect other biogeographical patterns) and their specific traits can be an effective tool to detect introduction and invasion routes and to predict future invaders from donor regions