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51.
There has been a lengthy debate on whether the abundance of adult reef fishes depends on prerecruitment or postrecruitment processes; however, we still do not have the ability to predict the magnitude of local fish recruitment. Here we show that the success of the leopard grouper (Mycteroperca rosacea) recruitment in the Gulf of California, Mexico, is determined by the availability of nursery habitat, which in turn is strongly correlated to climate conditions. Observational and experimental studies showed that leopard grouper larvae recruit preferentially on shallow rocky bottoms with brown algal (Sargassum spp.) beds, and that abundance of recruits is determined by the availability of Sargassum. The biomass of Sargassum decreases linearly with an increase in the Multivariate El Ni?o Southern Oscillation (ENSO) Index (MEI; an index positively correlated with water temperature and negatively correlated with nutrient availability). We analyzed the relationship between the interannual variation of MEI and the recruitment of the leopard grouper using field estimates of abundance of juvenile groupers. Our results show that there is a nonlinear relationship between recruitment and the oceanographic climate, in that the density of recruits decreases exponentially with increasing MEI. The predictability of leopard grouper recruitment has important implications for fisheries management, since it could allow adaptive management without expensive stock assessment programs. 相似文献
52.
Martín M. Dávila-Jiménez Esmeralda García-Díaz Miguel González M. E. Mendoza M. J. Robles-Águila 《Journal of environmental science and health. Part. B》2017,52(8):538-546
Carbofuran is a toxic carbamate pesticide, and its use has increased in recent years. While marketing information indicates stability in different chemical media, carbofuran exhibits relative photolability. The aim of this research was to decompose carbofuran and to identify the photoproducts achieved when two different doped titania photocatalysts were employed under UV irradiation. The iron-doped TiO2 materials were obtained (a) via a hydrothermal method and (b) by an ultrasound-assisted sol–gel method. The precursors were TiOSO4?xH2O and Fe3(NO3)·9H2O. X-ray studies confirmed that the anatase phase of the iron-doped TiO2 resulted from the two preparation methods. The photocatalytic performance of the prepared materials was monitored by LC/ESI-QTOF-MS, enabling the identification of photoproducts: oxo-carbamates, hydroxylated benzofuranes, a carboxamide, and one amine. By using the iron-doped TiO2 materials, 2,2-dimethyl-2,3-dihydrobenzofuran-3,7-diol was the most abundant photoproduct, and N,2,2-trimethyl-2,3-dihydrobenzofuran-7-amine was the only compound that had not been previously reported in the photolysis and photocatalysis of carbofuran. The product 3-hydroxy carbofuran, a cholinesterase inhibitor, was quantified and was found to be transformed into compounds that lack this inhibitive property. 相似文献
53.
固相萃取和气相色谱-质谱分析酚类化合物应用简报 总被引:2,自引:0,他引:2
固相萃取为分析水中痕量化合物提供了简便的分析方法 .高分子树脂如聚苯乙烯 二乙烯基苯比常用的十八烷基和类似的硅胶基体的固相萃取吸附剂好 ,特别是对极性较大的化合物 .最近 ,安捷伦科技扩展了所提供的固相萃取产品 ,包括了聚苯乙烯 二乙烯基苯固相萃取材料AccuBondⅡ ENV小柱 ,专门用于环境应用 .本文用以前介绍的保留时间锁定气相色谱 /质谱分析方法[1 ] ,使用这种聚苯乙烯 二乙烯基苯固相萃取材料对水中浓度为1 0 μg·l- 1 的选定酚类分析能达到的准确度和精密度进行了初步论证 .固相萃取过程快速 ,缩短干燥时间 ,且只需要两种回收率指示物 (Surrogates) .小柱经优化设计 ,提高了酚类化合物的回收率 ,而其它小柱的回收率通常很低且不重复 .苯酚的回收率超过 70 % ,其它酚类化合物的回收率超过 90 % .精密度大于 5 % ,以平均绝对偏差表示的准确度 (以百分数表示 )除了 2 环己基 2 4 二硝基酚之外 ,都大于 8% .样品萃取速率高 (2 0— 2 5ml·min- 1 ) ,萃取 1L样品不到 1h即可完成 相似文献
54.
We report 20 infants with severe bilateral renal disease examined by prenatal ultrasound and by autopsy. In 17, the prenatal and pathologic diagnoses correlated well. Although the prenatal and autopsy findings differed in the three remaining cases, the autopsy confirmed the presence of severe bilateral renal abnormalities. All 20 pregnancies were complicated by oligohydramnios, which was severe in 60 per cent. Most of these fetuses had malformation of other organ systems. This series supports the utility of prenatal ultrasound examinations, but emphasizes the need for postnatal evaluation of congenital renal disease including pathologic examination of tissue when possible for correct classification and genetic counselling. 相似文献
55.
Biological sampling of Spanish sardine (Sardinella aurita Valenciennes, 1847) off the coast of Venezuela from 1956 to 1989 was used to study the reproductive strategy and migration
pattern of the population. Whereas in many pelagic fishes the energy re-allocation necessary for reproduction usually occurs
optimally at the end of the upwelling season when planktonic production reaches a maximum, in the present study a 5 mo delay
was observed. This suggests that energy was stored as lipids early in the season and released later via metabolism for gamete
production. Major reproduction did not occur in an area and at a time when offshore transport and turbulence were low, which
is also unusual for a pelagic fish species. These results are discussed in terms of the life cycle of the Spanish sardine
and its possible migratory patterns. The reproductive strategy of this population apparently gives priority to optimising
food availability for the offspring and not to preventing eggs and larvae being transported offshore. The presence of “retention”
areas could explain this unexpected strategy.
Received: 4 November 1996 / Accepted: 20 December 1996 相似文献
56.
Afolabi Adisa Angelica Jimenez Cara Woodham Kevin Anthony Thao Nguyen 《Journal of environmental science and health. Part. B》2013,48(8):552-559
Twenty-eight different tea samples sold in the United States were evaluated using high-performance liquid chromatography (HPLC) with fluorescence detection (FLD) for their contamination with polycyclic aromatic hydrocarbons (PAHs). Many PAHs exhibit carcinogenic, mutagenic, and teratogenic properties and have been related to several kinds of cancer in man and experimental animals. The presence of PAHs in environmental samples such as water, sediments, and particulate air has been extensively studied, but food samples have received little attention. Eighteen PAHs congeners were analyzed, with percentage recovery higher than 85%. Contamination expressed as the sum of the 18 analyzed PAHs was between 101 and 1337 μg/kg on dry mass and the average contents in all of the 28 examined samples was 300 μg/kg on dry mass. Seven of the congeners were found in all samples with wide ranges of concentrations as follows: fluorene (7–48 μg/kg), anthracene (1–31 μg/kg), pyrene (1–970 μg/kg), benzo(a)anthracene (1–18 μg/kg) chrysene (17–365 μg/kg), benzo(a)pyrene (1–29 μg/kg), and indeno(1,2,3-cd)pyrene (4–119 μg/kg). The two most toxic congeners benzo(a)pyrene and dibenzo(a,h)anthracene were found at high concentrations only in Earl Grey Twinnings, Earl Grey Harney& Sons Fine Teas, and Chai Ultra Spice Black Tea Twinnings. Six PAH congeners are considered as suspected carcinogens (U.S.EPA), formed the basis of the estimation of the toxic equivalent (TEQ), Chai Ultra-Spice Black Tea Twinnings had the highest TEQ (110.9) followed by two grey tea samples, Earl Grey Harney & Sons Fine Tea (57.7) and Earl Grey Twinnings (54.5). Decaffeinated grey teas had the lowest TEQs, decaffeinated Earl Grey Bigelow (9.4) and Green Tea Honey Lemon Decaffeinated Lipton (9.6). 相似文献
57.
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59.
Francesco Paladini de Mendoza Simone Bonamano Giuseppe Stella Monica Giovacchini Dario Capizzi Fulvio Fraticelli Sergio Muratore Calogero Burgio Sergio Scanu Maximo A. Peviani Marco Marcelli 《Journal of Coastal Conservation》2016,20(1):13-29
The present work proposes a siting process for the detection of a suitable site for wave energy exploitation. The choice of a suitable site is based on the good agreement between energy availability, environmental sustainability, and equipped facilities to exploit wave energy. The case study in the northern Latium coast is explicative because in this area there are several activities that affect marine ecosystems, and the introduction of renewable energies promote the reduction of anthropic pressures. The nearshore wave power is studied through the numerical wave model (CMS-Wave), and available wave buoys along the coast were used to compare numerical results. In correspondence with Civitavecchia harbour, the largest nearshore wave energy was found; the large depth in front of the breakwater allows to conserve a great part of offshore wave power, with an average dissipation rate of 10 % less than offshore, with mean annual available wave energy of 25.4 MWh/m and seasonal fluctuation of 5.4 MWh/m. This area appears to be an optimal site for nearshore and shoreline wave energy device tests and installations, for energy availability (intermediate level respect Mediterreanean Sea), low potential environmental impact, easier accessibility, and policy oriented towards a larger sustainability of harbour activities. 相似文献
60.
Despite widespread acceptance of sustainability as the ultimate goal of forest management, perspectives about its meaning, significance, and relevant indicators may still differ. This paper examines local perspectives on sustainability, and evaluates their similarities and differences. A systematic procedure based on criteria of proximity, pre-existing rights, dependency, knowledge of forest management, forestry spirit, daily activity, and legal rights was used to identify a small group of relevant stakeholders representing different groups, institutions, and organizations. Using participatory action research (PAR), stakeholders were asked to identify relevant indicators of sustainable forest management. The indicators identified by each stakeholder were then compared to a consolidated list assembled by field facilitators with respect to whether relevant indicators are present or not. Based on the resulting presence/absence matrix, a statistical tool called the simple matching coefficient was used to estimate the similarity measures among the stakeholders' perspectives. In addition, cluster analysis was used to classify groups of stakeholders depending on their similarities to each other. Finally, hypotheses related to the 'closeness' of perspectives among local communities, non-governmental organizations, a timber company, and government organizations, as revealed by their selection of indicators, were tested. Results show that: (a) local communities have different perceptions in terms of what they consider to be important indicators compared to the NGOs, (b) there are significantly different perceptions between the government and the timber companies, and (c) there are also different perceptions between urban and field-based personnel of the same organization. 相似文献