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21.
The threat imposed by increased sediment loading rates ranks among the most important stressors affecting coral reef ecosystems worldwide. This study represents an effort to quantify the effects of unpaved roads on erosion rates in a dry sub-tropical area of Puerto Rico and is intended to aid in developing scientifically-based erosion mitigation strategies. Hence, the specific objectives of this study were to: (1) measure sediment production rates from unpaved roads; (2) evaluate the effect of precipitation, rainfall erosivity, slope, plot length, and vegetation cover on sediment production rates; and (3) compare measured sediment production rates to published surface erosion data from roaded and natural sites in the Eastern Caribbean. Sediment production from nine abandoned road segments with varying slopes and plot lengths were measured with sediment traps in southwestern Puerto Rico from August 2003 to September 2005.  相似文献   
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  • 1. Drifting longlines are considered a major threat to endangered sea turtle populations worldwide. However, for a number of reasons, the mortality rate of captured turtles is not known with any certainty.
  • 2. Information on 409 loggerhead turtles (Caretta caretta), collected during the day‐to‐day activities of a turtle rescue centre in Lampedusa island, central Mediterranean, in the period 2001–2005 has been analysed.
  • 3. Observations indicate that: (i) drifting longlines are a major cause of mortality for sea turtles in the area; (ii) in addition to the hook, the piece of line attached to it (branchline) can easily cause death if it is long enough and well‐anchored; (iii) hooks and branchlines cause death in the short and long term, respectively; (iv) a turtle with a hook in the lower oesophagus/stomach has a very low chance of surviving the combined effect of hook and branchline; (v) the mortality of turtles with a hook in the mouth or higher oesophagus is probably important, though less than that of turtles with a hook in the lower oesophagus/stomach; (vi) in the study fishery, the average mortality of a turtle caught by a drifting longline is probably much higher than 30%.
  • 4. Without specific investigations on the mortality of turtles with hooks in the mouth or higher oeasophagus, which are usually removed, the mortality induced by drifting longlines will remain unknown, preventing a full understanding of the effect on population growth and the real effectiveness of conservation measures such as use of different hooks and fishing depths, and proposals for adequate fishery management measures.
  • 5. The number of turtles captured by drifting longlines should be drastically reduced, and because of the above uncertainty and the socio‐economic importance of the fishery sector, an ecosystem‐based management scheme should be promoted that is not limited to addressing only the turtle issue.
Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   
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  • 1. The coastline is very sensitive to both climatic and human influences but also provides essential goods and services upon which human welfare depends. Species inhabiting these coastal areas provide valuable resources and enhance ecosystem functioning: it is therefore essential to understand the main factors influencing species abundance patterns. The aim of this study is to estimate the amount of variation in nekton coastal assemblages explained by spatial, temporal and environmental variables.
  • 2. Nekton sampling was carried out over 17 months in the Terminos Lagoon, a reserve area situated in the Gulf of Mexico, using a shrimp trawl. At each station, 11 environmental variables were recorded. The influence of seasonal, spatial and environmental variables on nekton species abundance was analysed using Partial Canonical Correspondence Analysis (PCCA).
  • 3. The explanatory variables explained only 19.7% of the total observed variation in the nekton community for the Terminos Lagoon. The major part of the explained variation was due to the spatial effect (9.2%), while environmental variables and seasonality explained only 3.6% and 0.8%, respectively, suggesting the necessity to consider experimental fishing design in such artisanal fisheries.
  • 4. Results also suggest focusing on more integrative indicators of community structure such as measures of taxonomic diversity based on presence/absence or on measures related to functional attributes of communities rather than using species abundance patterns to predict changes in coastal ecosystems.
Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   
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We estimate a spatial econometric interaction model for bilateral aggregate FDI stock data between 25 European Union member countries in 2010. We find evidence for spatial spillovers of foreign direct investment for three different types of spatial dependence. Our results document FDI spillovers between neighboring countries of FDI origin countries, neighboring countries of FDI destination countries as well as between neighboring countries of both FDI origin and destination countries. Relying on recently developed methods, we provide the first model‐consistent interpretation of marginal effects of market size (measured by GDP) as well as GDP per capita on bilateral FDI activity. Our research highlights the importance of taking into account spatial lags when estimating bilateral FDI gravity models.  相似文献   
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Jaagsiekte sheep retrovirus (JSRV) causes ovine pulmonary adenocarcinoma. JSRV can be transmitted via infected colostrum or milk, which contain somatic cells (SCs) harboring JSRV provirus. Nevertheless, the cell types involved in this form of transmission and the involvement of the mammary gland remain unknown. We separated adherent cells (macrophages and monocytes) by plastic adherence, and lymphocytes (CD4+ and CD8+ T cells, and B cells) by flow cytometry, from SCs in milk samples from 12 naturally infected, PCR blood test JSRV–positive, subclinical ewes. These cell populations were tested by PCR to detect JSRV provirus. The ewes were euthanized, and mammary gland samples were analyzed immunohistochemically to detect JSRV surface protein. We did not detect JSRV provirus in any milk lymphocyte population, but milk adherent cells were positive in 3 of 12 sheep, suggesting a potential major role of this population in the lactogenic transmission of JSRV. Immunohistochemistry did not reveal positive results in mammary epithelial cells, pointing to a lack of participation of the mammary gland in the biological cycle of JSRV and reducing the probability of excretion of free viral particles in colostrum or milk.  相似文献   
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Microalgae are known as a producer of proteins and lipids, but also of valuable compounds for human health benefits (e.g., polyunsaturated fatty acids (PUFAs); minerals, vitamins, or other compounds). The overall objective of this research was to prospect novel products, such as nutraceuticals from microalgae, for application in human health, particularly for metabolic diseases. Chlorella vulgaris and Chlorococcum amblystomatis were grown autotrophically, and C. vulgaris was additionally grown heterotrophically. Microalgae biomass was extracted using organic solvents (dichloromethane, ethanol, ethanol with ultrasound-assisted extraction). Those extracts were evaluated for their bioactivities, toxicity, and metabolite profile. Some of the extracts reduced the neutral lipid content using the zebrafish larvae fat metabolism assay, reduced lipid accumulation in fatty-acid-overloaded HepG2 liver cells, or decreased the LPS-induced inflammation reaction in RAW264.7 macrophages. Toxicity was not observed in the MTT assay in vitro or by the appearance of lethality or malformations in zebrafish larvae in vivo. Differences in metabolite profiles of microalgae extracts obtained by UPLC-LC-MS/MS and GNPS analyses revealed unique compounds in the active extracts, whose majority did not have a match in mass spectrometry databases and could be potentially novel compounds. In conclusion, microalgae extracts demonstrated anti-obesity, anti-steatosis, and anti-inflammatory activities and could be valuable resources for developing future nutraceuticals. In particular, the ultrasound-assisted ethanolic extract of the heterotrophic C. vulgaris significantly enhanced the anti-obesity activity and demonstrated that the alteration of culture conditions is a valuable approach to increase the production of high-value compounds.  相似文献   
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