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91.
To examine the suitability of benthic foraminifera and their test deformations as bioindicators of pollution in coastal marine environments, we studied foraminifera and metal concentrations in 72 marine sediment samples, collected from the inner shelf along the Sicilian coast (Gulfs of Palermo and Termini) and on the south-eastern coast of Lampedusa Island. These areas are characterised by different environmental conditions. On the basis of pollution sources and foraminiferal assemblages, we recognised different zones in the Gulf of Palermo. The most polluted zones showed high metal concentrations, and low diversity of benthic foraminifera with species typical of stressed environments. By contrast, the lowest polluted zones showed a high population density and the highest percentages of epiphytes. Epiphytes were abundant where a Posidonia oceanica meadow was present and decreased in the most polluted zones. Sediments of the Gulf of Termini and Lampedusa exhibited high percentages of benthic foraminifera typical of well-oxygenated waters and low concentrations of metals, with the exception of sites located near sewage outfalls and harbour areas. Furthermore, even though deformed tests are commonly known in natural stressed environmental conditions, this study shows that in the most polluted zones, benthic foraminifera were characterised by the highest percentages of deformed individuals. 相似文献
92.
The allelopathic potential of fescue (Festuca arundinacea Shreb.) was investigated under field and laboratory conditions. In the field, incorporation of fescue aboveground biomass
into the soil provided an effective weed control as it significantly reduced both the number and the dry weight of all weed
species. The effect on weeds was species specific. The reduction of the most abundant species, Picris echioides, with respect to the number of individuals and their dry weight was 67 and 45%. Fescue aboveground biomass, harvested immediately
before soil incorporation, was utilized in a bioassay-oriented fractionation, aimed at identifying the compounds in the toxic
extracts of the plant. While phytotoxic activity was detected for the n-butanol fraction, no activity was found for the aqueous one. Germination of an indicator species, lettuce (Lactuca sativa L.), was reduced by 33% at the higher extract concentration of 20 mg/mL, owing to the increase of the number of abnormal
seedlings. The LC/MS profile of the extract revealed the presence of two alkaloids, seven flavonol glycosides, and two flavonol
aglyca. Quercetin 3-O-rutinoside, isorhamnetin 3-O-rutinoside, and kaempferol 3-O-rutinoside were reported in fescue for the first time. 相似文献
93.
Bruno G. Lages Beatriz G. Fleury Ana M. C. Hovell Claudia M. Rezende Angelo C. Pinto Joel C. Creed 《Marine Biology》2012,159(7):1551-1559
Competition for space changes species’ distributions and community organization on tropical rocky shores, and the presence of secondary metabolites in the tissues of non-indigenous species may aid them in establishing and expanding their range through negative competitive interactions. The aim of this study was to describe the range of chemical substances produced by the non-indigenous cup corals Tubastraea coccinea and T. tagusensis and to test whether they varied in the field when the corals were placed in proximity to two local competitors. Cholest-5-en-3β-ol and 9-octadecanoic acid were two common secondary metabolites found in the tissues of Tubastraea. In the competition interaction experiment, necrosis was detected on the tissues of the coral Mussismilia hispida, and this species induced variation in sterol, alkaloid, and fatty acid production in Tubastraea tissues. In contrast, a sponge overgrew Tubastraea colonies. These results indicate that chemical defense may contribute to the ability of these non-indigenous corals to invade native communities. 相似文献
94.
Giuseppe Esposito Riccardo Salvini Fabio Matano Marco Sacchi Claudia Troise 《Journal of Coastal Conservation》2018,22(5):957-972
Geomorphic evolution of sea cliffs has significant impact on coastal settlements worldwide, so that evaluation of cliff instability processes, failure factors, and retreat rates involves a growing number of scientists for coastal risk and management purposes. Aerial photogrammetry and lidar are among the most used techniques for topographic characterization and geomorphic monitoring of coastal environments. A crucial role in the combined use of such techniques is the evaluation of different spatial accuracy and co-registration between derived terrain models, so that a robust error analysis is required. In this study, we present a change detection analysis of the Torrefumo coastal cliff, in the Campi Flegrei volcanic area (Southern Italy). Aerial images taken in 1956 and 1974, processed through digital photogrammetry, and an airborne lidar point cloud acquired in 2008 were used to produce Digital Elevation Models of the cliff. The analysis was based on the multi-temporal comparison of these models and included the calculation of volumetric changes and average retreat rates of the cliff face with reference to the 1956–1974 and 1974–2008 time intervals. The spatially variable elevation uncertainty of each Digital Elevation Model was evaluated with a probabilistic approach based on the fuzzy set theory. The results of this study showed significant eroded volumes during the period 1956–1974 and relatively smaller volumes in the 1974–2008 time span, with mean annual retreat rates of 1.2 m/year and 0.17 m/year, respectively. We infer that the significant decrease of erosion characterizing the second period was induced by the sheltering effect at the base of the cliff produced by the construction of a seawall in the early 80’s. 相似文献
95.
This study extends research on creativity by exploring the boundary conditions of the creativity–job effectiveness relationship. Building on social exchange theory, we argue that the extent to which employee creativity is related to sales—an objective work effectiveness measure—depends on the quality of leader–member exchange (LMX). We hypothesize that the relationship between creativity and sales is significant and positive when LMX is high, but not when LMX is low. Hierarchical linear modelling analysis provided support for the interaction hypothesis in a sample of 151 sales agents and 26 supervisors drawn from both pharmaceutical and insurance companies. Results showed that sales agents who were more creative generated higher sales only when they had high‐quality LMX. An ad hoc qualitative study provided a more detailed understanding of the moderator role played by LMX. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
96.
The photovoice research project, “At the water's edge”, which gives voice to communities exploring the threats and impact of climate change and rising sea levels on coastal communities, was conducted during an environmental art symposium in the Noosa Biosphere Reserve, Australia in June 2009. Photos by participants illustrated both local and global threats and reflected psychological tension between global and local action. This research partnership with the local people demonstrated an innovative visualisation technique which can be used to collaboratively build capacity and consensus about adaptation to climate change. It also contributed to the Biosphere Reserve's educational and cultural aims in relation to climate change. 相似文献
97.
Optimization of the recovery of plastics for recycling by density media separation cyclones 总被引:1,自引:0,他引:1
Gent Malcolm Richard Menendez MarioToraño Javier Torno Susana 《Resources, Conservation and Recycling》2011,55(4):472-482
Material recovery processes are presented as the optimum option for recycling plastic wastes as a means of recovering hydrocarbon resources. There exist a large variety of automated material recovery processes for recycling of such wastes but each with significant limitations. Of these, the separation based on differences in densities is advocated as the optimum process either for producing recycled products or preparing wastes for subsequent recovery processing.Density separation processes based on cyclone type density media separation (DMS) is presented as an important, potential method for increasing plastics recycling process capacities. It is demonstrated to have the capacity to separate a significantly larger range of particle sizes than those presently processed industrially. The mathematical relationship for the prediction of quality of typical LARCODEMS type density media separations by particle size and density as expressed by the Ecart Probable is presented.A proposed device configuration is presented for density media separation to optimize the recovery and purity of both density fractions produced. It is also suggested that to be economically viable, a large scale of operation is required for industrial plastics recycling operations recovering and producing a number of different plastics with a purity to be used as a substitute for virgin material. 相似文献
98.
Claudia Hollatz Leonardo Flach C. Scott Baker Fabrício R. Santos 《Marine Biology》2011,158(4):927-933
A large macrogeographic differentiation has been observed among Sotalia guianensis populations along the South American coast. However, no genetic structure has been detected so far in closely distributed
populations of this species, even though it has been observed in other cetaceans. Here, we examined the fine scale population
structure for the largest populations of S. guianensis inhabiting Sepetiba and Paraty embayments at the south-eastern coast of Rio de Janeiro, Brazil. Analysis of mitochondrial
DNA (mtDNA) control region sequences failed to detect variability among sequences. Conversely, evidence of significant male
population structure was found on the basis of ten nuclear microsatellite loci. Surprisingly, the microsatellite markers were
able to distinguish between individuals from the two embayments located 60 km apart. The results suggest that differences
in habitat type and behavioral specializations are likely to explain the patterns of genetic structure. These findings should
provide baselines for the management of communities exposed to increasing human-driven habitat loss. 相似文献
99.
Galante-Oliveira S Oliveira I Ferreira N Santos JA Pacheco M Barroso C 《Journal of environmental monitoring : JEM》2011,13(2):304-312
Nucella lapillus (dog whelk) imposex levels were assessed along the mainland Portuguese coast in 2006 and 2008 and were compared with available data from 2003 for the same area. Given that specimen size has been described as a factor inducing variation in some of the imposex assessment indices, and thus resulting in less reliable results, new monitoring and data analysis procedures are described and applied to study change of imposex levels from 2003 to 2008. A significant decline in imposex intensity was observed in the study area during the study period, and the Portuguese coast ecological status (under the terms defined by the OSPAR Commission) notably improved after 2003, confirming the effectiveness of the Regulation (EC) No. 782/2003 in reducing TBT pollution. Nevertheless, N. lapillus populations are still extensively affected by imposex, and fresh TBT inputs were detected in seawater throughout the coast in 2006. These recent inputs are attributed to vessels still carrying TBT antifoulants applied before 2003, as their presence in vessels was only forbidden in 2008. Considering that Regulation (EC) No. 782/2003 is an anticipation of the IMO global ban entered into force in September 2008, a worldwide-scale decrease in TBT pollution can be expected in the near future. 相似文献