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991.
Abstract The European Union, Water Framework Directive (WFD) requires monitoring of riverine fish fauna. When the WFD came into force in 2000, most of the EU member states did not have fish-based assessment methods compliant to WFD requirements. Therefore, the objectives of FAME ( http://fame.boku.ac.at ), a project under the fifth R&D Framework Programme of the European Commission were to develop, evaluate and implement a standardised fish-based method for assessing the ecological status of European running waters. This paper synthesises the outputs of FAME and defines future research needs. Two different methodologies were used: the so-called spatially based modelling and the site-specific modelling, the latter leading to the European Fish Index (EFI). The advantage of the EFI is that, despite being a single index, it is applicable to a wide range of environmental conditions across Europe precluding the need for inter-calibration. The EFI will support the WFD towards harmonised/standardised assessment and management of running waters in Europe, thus enabling comparative analyses of the ecological status of running waters across Europe. 相似文献
992.
应用底栖动物完整性指数评价水源地水库溪流健康状态 总被引:2,自引:0,他引:2
及时了解水源地水库入库溪流的水生态健康状态对保障供水安全十分重要。依据2010-2011年对浙江省水源地汤浦水库的环境和底栖动物观测资料建立了底栖动物完整性指数(B-IBI)。根据Shannon-Wiener指数、百分比模式相似性指数(PMA)和多元统计分析结果对参照条件进行量化并确立参照点群。从60个候选参数中筛选出6个核心参数参与构建B-IBI指标体系,采用四分法进行量纲的统一,以参照点群25%分位值作为水生态系统健康与否的阈值,并对小于25%的分位值分布范围进行2等分,确立了水源地汤浦水库入库溪流健康评价标准:B-IBI>25.50,健康;B-IBI 12.75~25.50,亚健康;B-IBI<12.75,差。B-IBI分值与溶氧水平和pH显著正相关(P<0.05)。 相似文献
993.
994.
ABSTRACT: This study assessed the stock-recruitment relationship (SRR) for the Japanese sardine Sardinops melanostictus in the North-western Pacific. Of the 20 SRR models investigated, the Akaike information criterion (AIC) was the minimum (AIC = 551.2) when the data were separated into two groups (A and B) and the log-normal distribution was applied as the error term. Group A was constructed with SRR data from 1976–1987 and 1992–2004. Group B consisted of data from 1988–1991. The AIC minimum model was R = 22.8 S × e ε for Group A, where R , S , and ε denote the recruitment of sardine (individual number of 0-year old fish), spawning stock biomass (SSB), and error term, respectively. This model indicated that recruitment was proportional to the SSB and that no density-dependent effect operated over the range of SSB investigated (51 000–11.3 million t). Recruitment was markedly higher (lower) when the sea surface temperature (SST) of the Kuroshio Extension area in February was low (high). The essential SRR can simply be expressed as R = 22.8 S × e ε with the level of recruitment deviating from the model to a greater or lesser degree depending on the environmental conditions. 相似文献
995.
In the coastal zone of the Sea of Okhotsk off Hokkaido, Japan, the giant ezo scallop ( Patinopecten yessoensis ) is widely cultivated on the sea bed, making its fishery a major industry. However, the area experiences intense cyclones, including typhoons, about once a decade and the scallop resources appear to have received severe damage from the storms. Such an event occurred on 29 October 1988. The storm caused 12-m-high wind waves, which appeared to be fully developed sea waves. The water above the sea bed repeatedly moved back and forth at speeds of 1∼2 m s-1 causing damage to the scallops due to collisions and rubbing with gravel and other scallops. From a comparison of wind data with the annual catch of scallops, intense cyclones seem to play an important role on the year-to-year fluctuations in the scallop fishery. 相似文献
996.
997.
通过现场测定养殖日龄为16~18d的斑节对虾的体长、体重和全长,并应用石蜡切片技术对被测虾的中肠腺中部进行细胞计数,研究了斑节对虾体长与中肠腺细胞数的相关性。结果表明,对虾体长与中肠腺中部每个高倍视野的平均细胞数呈密切负相关(r=-0.947),公式为:C=330.362323e-0.087384L。对虾体长与体重密切相关(r=0.948),可用对数回归方程描述:lgW=-1.923578+3.082832lgL。对虾体长与全长密切相关(r=0.995),其线性回归方程为:Y=-0.187137+1.316705X。通过这些公式,中肠腺中部每个高倍视野的平均细胞数可由体长直接推算出或由体重和全长间接算出,使斑节对虾杆状病毒感染度的计算更加简单和准确。 相似文献
998.
Flavobacterium psychrophilum is the causative agent of bacterial cold-water disease and rainbow trout fry syndrome of salmonids. The pathogen has been reported from all regions in the world involved in salmonid aquaculture, but also from natural fresh-water environments. We established a quantitative loop-mediated isothermal amplification of DNA (LAMP) method to estimate quantities of F. psychrophilum . LAMP primers were designed based on the sequence of the DNA topoisomerase IV subunit B gene, parE , of F. psychrophilum. parE LAMP exhibited a high specificity for the parE gene of F. psychrophilum but not for other related species. parE LAMP detected the gene in a wide range of concentrations from 2.0 × 101 to 2.0 × 109 copies/reaction within 70 min and revealed a good correlation between threshold times and gene copy number. 相似文献
999.
1000.
尼罗罗非鱼出肉率与可量性状的相关性 总被引:4,自引:1,他引:4
运用统计分析方法研究了吉富品系和埃及品系尼罗罗非鱼(Oreochro misniloticus)2龄成鱼雌、雄个体的出肉率和可量性状之间的相关性。结果显示,尼罗罗非鱼的平均出肉率为38.68%,雄性个体出肉率比雌性个体略高,吉富品系出肉率比埃及品系略高。尼罗罗非鱼出肉率与可量性状间存在较强的线性关系,拟合方程相关系数为0.985。在有显著意义的可量性状相关系数中(P0.01),与肉片质量和出肉率的相关性均最高的可量性状为体质量,相关系数分别为0.964和0.575;其次为体高、体长和体厚。而头长与肉片质量、出肉率均呈负相关关系。雄性个体的相关系数均高于雌性个体,在雄性个体中,出肉率与体质量的相关系数为0.630,与体高的相关系数为0.617,均为中等程度相关。对可量性状之间的比值与出肉率进行相关性分析,相关系数普遍比单个性状高,特别在雄性个体中表现明显。其中相关系数较高的比例组合有身长/头长比值(0.765)、体长/头长比值(0.732)、身长/体厚比值(0.703),均达到较强程度的相关,比单个性状的相关性有明显提高。结果表明,利用可量性状预测罗非鱼的出肉率是可行的。 相似文献