992 resultados para 11.77%
Resumo:
保护生物地理学(Conservation biogeography)就是运用生物地理学的原理、理论和分析方法,特别是那些有关物种分布格局的信息,去解决生物多样性保护的相关问题,是当前生物多样性及其保护生物学研究领域的热点。通过构建中国蕨类植物物种及分布数据库得知,中国现有蕨类植物63科,221属,2456种,其中有1218种属于中国特有(中国蕨类总数约50%),3种蕨类植物为外来种。科的统计表明:最大的科为鳞毛蕨科、蹄盖蕨科、金星蕨科和水龙骨科4个科所包含的种类占全国总种数的51.5%。鳞毛蕨科、蹄盖蕨科、金星蕨科、水龙骨科、铁角蕨科、凤尾蕨科、碗蕨科、中国蕨科、叉蕨科、观音座莲科等十个大科所含种数占了中国特有种总数的80%。云南、四川、贵州、广西、台湾、湖南、西藏等省区是中国蕨类植物种类数量及中国特有种数量较多的地区;全国有22个省区拥有地方特有种,地方特有蕨类植物数量由西向东、由南向北逐渐递减,云南、台湾、西藏、海南等四省区的地方特有蕨类植物种数占各省区蕨类植物总数10%以上,反映了青藏高原隆起及岛屿现象对中国特有蕨类植物分化的影响。 中国蕨类植物与各地理、环境及气候因子的相关性分析结果表明:(1)随着经度、纬度的增加, 蕨类植物物种总数及中国特有蕨类植物总数具有减少的趋势;(2)蕨类植物在海拔1000-1600米之间、特有蕨类植物在海拔700-2100米之间具有最大的多样性,此区间外随着海拔的降低及升高,物种丰富度依次降低;(3)气候因子特别是一月均温、年均温、相对湿度、年降雨量等因素对蕨类植物及中国特有蕨类植物均具有较大的影响,与最热月均温成低度线性相关或相关不显著;(4)地形因子是影响蕨类植物多样性的一个独立因素,地形条件越复杂,蕨类植物种类及中国特有蕨类植物种类越丰富。 运用SPSS统计分析软件分析了中国蕨类植物在各省之间种的相似性,以省区为单元对中国各省区蕨类植物物种组成进行了聚类分析,最后结果划分成:①南方蕨类植物区(包括横断山—青藏高原亚区、华中亚区、华东亚区、华南亚区)和北方蕨类植物区(包括东北—华北—西北亚区、秦岭亚区、江淮亚区)。 中国蕨类植物区系地理成分分析结果表明:(1)中国—喜马拉雅分布(40.86%)、热带亚洲分布(30.95%)、东亚分布(12.77%)和中国—日本分布(8.24%)构成中国蕨类植物区系成分的主体;在洲际关系方面,中国蕨类植物与大洋洲的蕨类植物关系最为紧密,共有种最多,达94种;与南美洲共有的蕨类植物种类最少,仅32种。(2)基于地理成分的聚类分析结果表明,可将我国蕨类植物区系地理区划为代表温带亚洲成分的(特别是中亚、西亚地中海分布成分)西北温带亚洲植物区、代表古热带成分的华南古热带植物区和代表广义东亚成分的东亚植物区,东亚植物区可继续下分为中国东北—俄罗斯远东亚区(该区分布有大量的东亚-北美间断分布类型)、中国—日本植物亚区、中国—喜马拉雅植物亚区。 运用IUCN濒危物种等级对中国蕨类植物及其国家重点保护蕨类植物进行了现状评估,结果表明:可能灭绝(EX)的2种,极危(CR)的蕨类植物有33种,属于濒危(EN)的蕨类植物51种,属于易危(VU)的蕨类植物有109种,接近受危(NT)的蕨类植物158种,需予关注(LC)的845种,数据不足(DD)的1255种。对国家重点保护蕨类植物的保护级别提出部分变更的建议,对部分没有列入保护名录珍稀蕨类提出保护的建议,并就建议保护级别变更和增加保护的种类进行了必要的说明。
Resumo:
Based on the data collected from the year 1987-1991 the growth, mortality and recruitment pattern of eighteen species of fish, two species of cephalopods and four species of penaeid prawns have been presented in the present communication. The total mortality coefficient, (Z) varied from lowest of 1.20 for O. cuvieri to a highest of 10.78 for P. stylifera. The natural mortality coefficient, (M) varied from 0.52 for T. thalassinus to 3.44 for S. crassicornis. The average annual yield of eighteen species of fish, four species of prawns and two species of cephalopods are 65.083, 38.404 and 11.373 tons as against the MSY of 83.023, 72.460 and 10.475 tons respectively. The MSY estimated for the total fish stock is 1.77.753 tons whereas the present yield is 1.14.859 tons. This indicates that higher yield can be obtained by increasing the effort.
Resumo:
Water beetle larvae and pupae were collected from the lotic biotopes in localities of the southern part of Ceylon. The species are described and findings are related to previous investigations. The following families were represented: Dytiscidae, Gyrinidae, Hydrophilidae, Helodidae, Dascillidae (Eubrianacinae), Dryopidae and Lampyridae.
Resumo:
This report on the “Sub-regional Dialogue on Labour, Migration and Fisheries Management”, held at Chulalongkorn University, Bangkok, Thailand, from 11 to 13 December 2013, highlights the issue of migrant labour on board fishing vessels and the problems migrant workers face in their workaday lives. This report will be useful for students, researchers, activists and anyone else interested in matters related to fisheries and small-scale fishing communities.
Resumo:
Biological data on Metapenaeus monoceros has been regularly collected in Maputo Bay since 1968. The main objective of this report is to study growth as a function of the size, since this is one of the basic parameters for population dynamics. As the possibility of studying shrimp growth by modal progression analysis depends very much on the space-time configuration of sampling, the years 1968 and 1969 were chosen to study growth of the population available to the bottom trawl used by the fishing industry. In those years sampling was very frequent (twice a week) and the samples were collected from a rather small fishing area. Complementary data on the spawning, juvenile phase and recruitment to the fishery was used to establish the relationship between the different stages of the life cycle and to obtain an age/length key. Data on juveniles in estuaries was only available for 1969 and 1973.
Resumo:
An experiment was conducted to assess the performance of mola (Amblyphmyngodon mola) in rice fish culture system with freshwater prawn Macrobrachium rosenbergii), Thai silver barb (Bm·bades ganianotus) and common carp (Cyprinus cmpia) for a period of 4 months at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh, Bangladesh. Four treatments viz., treatment-I (T1) with A. mala and M. rosenbergii; treatmen t-II (T2) with A. mala, M. rosenbergii and B. gonianatus ; treatmentIII (T3) with A. mala, 1Vf. rosenbergii and C. cmpia, and treatment- IV (T4) as control (without fish) were used in triplicate. All treatments were equally fertilized with urea (200 kg/ha), TSP (150 kg/ha) and MP (75 kg/ha). The mean values of water quality parameters viz., temperature, dissolved oxygen, pH, nitrate-nitrogen showed a very small variations among different treatments, but phosphate-phosphorus and chlorophyll-a were relatively higher in T4 without fish (i.e., control). The fish production of 480.5 kg/ha in T3 was significantly higher than that of 355.6 kg/ha T2 and 223.8 kg/ha in T 1• The values of soil organic matter, total-nitrogen, phosphorus and potassium at harvest were significantly (P<0.05) higher in the treatments with fish than without fish, but pH did not show any significant differences. The yield of rice grain and straw was also obtained significantly (P<0.05) higher in the treatments with fish. The increase in grain was higher over the control by 11.81%, 9.41% and 14.76% and that in straw was by 9.83%, 4.77% and 13.29% in Tl> T2, and T3 respectively.
Resumo:
The study aimed to investigate the productivity and profitability of rice-fish farming. It also determined the factors affecting rice-fish and fingerling production in Bangladesh. Among the total respondents about 55% were involved in rice-fish farming, 37% in pond fish culture and rest 9% in fish nursery. Integrated rice-fish farming contributed about 83% of the annual farm income in Comilla while it was about 20% in both Kishoregonj and Chandpur districts. Among the different farming systems integrated rice-fish culture and rearing fingerlings in the nursery pond were more profitable at the farm level. Farmers earned a net return of Tk. 49,714/ha from integrated fish culture with boro rice while the net return of boro rice-alone was only Tk. 11,179/ha. This indicated that farmer could earn 218% higher net return from integrated rice-fish farming than that of boro rice only farming. Moreover, integrated rice-fish culture also reduced pesticides cost to about 77% and weeding cost to about 51% in boro season. Fingerling nursing earned highest net returns among the three technologies.
Resumo:
Preliminary midwater fishing trials were conducted off Cochin with an 11m dual purpose trawl during the monsoon months when the prawns were available in the column layers. Further, with a view to assess its suitability as bottom trawl, the gear with suitable modifications in the rigging was towed in comparison with a 15m bottom trawl along the depth ranges of 5-10m and 10-20m and the fishing operations were found satisfactory.
Resumo:
通过比较一段357bp的细胞色素b的序列,分析了熊蜂属5亚属11种熊蜂系统发育关系。5亚属包括Bombus(5种)、Thoracobombus(3种)、Mendacibombus(1种)、Fervidobombus(1种)和Pyrobombus(1种)。该序列有65个单变异多态位点和71个简约信息多态位点,翻译成119个氨基酸序列后有45个氨基酸变异位点。根据P-距离构建的邻接树(NJ tree)和最大简约树(MP tree)都显示同样的结果:Mendacibombus(B. avinovielllus)分化最早;Fervidobombus(B. pensylvanicus)次之;Pyrobombus(B. impatiens)和Bombus形成姊妹群;Bombus亚属是单系群,其中B. ignitus在所研究的5个种中分化最早。
Resumo:
Cost-benefit analysis of a 9.82 m and 11 m fishing trawlers based on the number of fishing trips is presented. The number of fishing trips per year determines the profit and loss of the trawler. With the increase in the number of fishing trips, the profit also increase for both the sizes of trawlers. The minimum quantity of prawn and fish to be landed for 0-20% profit for varying number of fishing trips are worked out. The break-even for 9.82 and 11m trawlers was observed to be 185 and 210 fishing trips respectively during 1980-81.
Resumo:
Five species of flat fishes, namely Cynoglossus semifaciatus, C. lida, C. bilineatus, C. macrolepidotus and Psettodes erumei caught in trawlers off Mangalore were analysed for proximate composition of different body parts. These data are discussed in terms of their variability and applications. In whole body of C. lida and C. semifaciatus mean values for moisture, protein, fat and ash content on dry basis respectively were 75.9%, 75.3%, 7.1%, 16.1% and 78.9%, 75.6%. 7.9% and 16.6%. Mean values of these constituents of edible parts in the same order for C. semifaciatus and Psettodes erumei were 77.3%, 80.7%, 7.8%, 10.8% and 77.4%, 86.2%, 3.5% and 11.1% respectively.
Resumo:
A simple laser refractometer based on the detection of the critical angle for liquids is presented. The calibrated refractometer presents up to 0.000 11 of uncertainty when the refractive index is in the range between 1.300 00 and 1.340 00. The experimental setup is easy to construct and the material needed is available at most optics laboratories. The calibration method is simple and can be used in other devices. The refractive index measurements in aqueous solutions of sodium chloride were carried out to test the device and a linear dependence between the refractive index and the salt concentration was found. © 2006 American Institute of Physics.