High-sediment tolerance in the reef coral Turbinaria mesenterina from the inner Great Barrier Reef lagoon (Australia)     

Jeremy J. Sofonia  Kenneth R.N. Anthony   《Estuarine, Coastal and Shelf Science》2008,78(4):748-752

Sedimentation is an important stressor on coral reefs subjected to run-off, dredging and resuspension events. Reefs with a history of high-sediment loads tend to be dominated by a few tolerant coral species. A key question is whether such species live close to their tolerance thresholds or near their niche optima. Here, we analyse experimentally the sediment tolerance of a spatially dominant coral, Turbinaria mesenterina (Dendrophylliidae), at nearshore reefs in the central Great Barrier Reef lagoon. Testing was conducted in a 5-week tank experiment under manipulated sediment loading and flow conditions. Physiological stress was assessed based on the behaviour of three key response variables: skeletal growth rate, energy reserves (lipid content) and photosynthetic performance. Because sediment effects are likely to vary between flow regimes, sediment and flow responses were tested using a full factorial design. Sediment loads greater than 110 mg cm⁻² had no effect on any of the physiological variables, regardless of flow (0.7–24 cm s⁻¹). Turbinaria mesenterina is thus tolerant to sediment loads an order of magnitude higher than most severe sediment conditions in situ. Likely mechanisms for such tolerance are that: (1) colonies covered in sediment (60–120 μm) in low-flow were able to clear themselves rapidly (within 4–5 h); and (2) sediment provides a source of food. These results suggest that intensified sediment regimes on coastal reefs may shift coral communities towards dominance by a few well-adapted species.  相似文献   

南极沿海伯尔顿盐湖两种越冬浮游动物温度耐性的初步研究          下载免费PDF全文

王自磐 《极地研究》1988,1(2):28-36

本文报导了南极大陆沿海伯尔顿湖两种越冬浮游动物:双刺镰状水蚤和球栉水母的耐热和耐过冷能力的实验.结果表明,两种动物具有较强的温度耐性,其12小时LD_(50)的上、下限温度,雌性双刺镰状水蚤可在14.8℃和—10℃偏下,球栉水母可在13.1℃和—8℃偏下.它们忍受的温度范围大于其他一些南极沿岸海洋无脊椎动物的.这两种动物的耐温能力有明显的季节差异,表明动物具有较强的适应环境温度变化和生理调节能力,这可能是受环境温度自然驯化的结果.  相似文献   

胁迫浓度和胁迫时间对印度芥菜中镉形态分布的影响     

杨红霞  刘崴  李冰  魏巍  张惠娟 《岩矿测试》2013,32(2):306-310

螯合作用是植物对细胞内重金属耐受的主要方式之一,植物中螯合肽(PCs)在植物耐重金属毒害中的作用已有许多报道,但作用程度并未得出一致的结论,关于PCs是在镉刺激下直接合成还是以谷胱甘肽为底物合成同样存在争议.本文研究了胁迫浓度和胁迫时间对超积累植物印度芥菜(Brassica juncea)中镉形态分布的影响.印度芥菜幼苗分别用0.5、1.0、3.0、5.0、10.0 mg/L镉标准溶液胁迫24 h、48 h、72 h、96 h后收获,用体积排阻高效液相色谱-电感耦合等离子体质谱技术测定植物体根部和叶部中镉形态的含量.结果表明,在低胁迫浓度下(≤3.0 mg/L),植物叶中PCs-Cd的含量与胁迫浓度成正比;在高胁迫浓度下,PCs-Cd含量反而降低,根中PCs-Cd的含量持续增加,但叶中PCs-Cd总量高于根部,说明PCs在植物体内会由根部向叶部转移,从而提高了镉耐受性.在持续长时间胁迫下,PCs-Cd含量也降低,表明PCs在镉解毒机制中仅有短暂的作用;持续高浓度胁迫下,植物会引发其他机制来抵制Cd的毒性.研究认为PCs在镉解毒机制中的作用需要考虑胁迫时间和胁迫浓度这两个重要参数.  相似文献   

Screening Indian Mustard Genotypes for Phytoremediating Arsenic‐Contaminated Soils     

Mohd Kafeel Ahmad Ansari  Hong‐Bo Shao  Shahid Umar  Altaf Ahmad  Shahid Hussain Ansari  Muhammad Iqbal  Gary Owens 《洁净——土壤、空气、水》2013,41(2):195-201

Ten Indian mustard (Brassica juncea L.) genotypes were screened for their phytoremediation potential for arsenic (As) contaminated water under laboratory‐controlled conditions. The genotypes were grown in a hydroponic chamber for 20 days in 250‐mL beakers containing As‐contaminated water. During plant development, changes in plant growth, biomass, and total As were evaluated. Of the 10 genotypes (Pusa Agrani, BTO, Pusa Kranti, Pusa Bahar, Pusa Bold, Pusa Basant, Pusa Jai Kisan, Arka Vardhan, Varuna, and Vaibhav) Pusa Jai Kisan was the most effective in phytoremediating As‐contaminated water under hydroponic conditions. This will provide new information for Indian mustard genotypes for phytoremediating As‐contaminated soils.  相似文献   

一种基于阵列结构的4容错数据布局     

万武南  杨威 《成都信息工程学院学报》2014,29(3):238-243

保证数据可靠性是存储系统设计的一个关键问题。EEOD码是一类3容错的数据布局,不允许任意4个磁盘同时故障。但随着存储系统中存储介质增大,数据损失概率也越来越大,为了提高系统可靠性,需要高效易于实现的存储容错技术。因此,对EEOD码进行扩展,增加了2列冗余校验列,提出一种新4容错HD-EEOD(Horizontal Diagonal EEOD)码,能容许任意4个磁盘同时故障,并保留EEOD具有简单几何结构编译码特性。基于码的几何结构,给出快速纠4错译码算法,算法易于软硬件实现。并对码的空间利用率、编译码效率进行分析,趋近于容4错编码的最优值,具有很好的性能和应用前景。  相似文献   

Salinity tolerance and growth response of juvenile <Emphasis Type="Italic">Oreochromis mossambicus</Emphasis> at different salinity levels     

Khalid?JamilEmail author  Muhammad?Shoaib  Faisal?Ameer  Lin?Hong 《中国海洋大学学报(英文版)》2004,3(1):53-55

1　Introduction　Theuseofnaturalresources ,includingthosebeingofseeminglymarginalvalue ,isanimportanthumanactivitydesignedtoincreasefoodproductionandin come .Inagriculture ,soilsmaybetoosalinetosup portprofitablecrophusbandry ,yetsuchsoilmaybeusedalternat…  相似文献   

GIS结点捕捉的广义算法及误差传播模型   总被引：5，自引：0，他引：5  

刘文宝  夏宗国  崔先国 《测绘学报》2001,30(2):140-147

根据最小二乘原理，本文提出了结点捕捉的一种广义算法，并建立了伴随的误差传播模型，针对位于模糊公差范围内待捕捉点组中各点坐标误差统计我的各种可能的特殊情况，进一步导出了相应的简化算法以及其误差传播模型，并从理论和数值模拟两方面系统地分析了结点坐标的相准确性一对捕捉结果的影响，理论推导表明，现有的GIS结点捕捉算法属广义算法的一种特殊情况，最后通过算例说明了广义算法和误差传播模型的实际应用前景。  相似文献   

无人机遥感组网冗余容错的研究     

李国  姜凯文  王勇  孙山林  杨明  李云  赵海盟  晏磊 《地理科学进展》2021,40(9):1480-1487

针对无人机在遥感遥测领域组网过程中存在的随机故障,进而导致无人机在任务执行过程中任一约束的及时响应缺失,将会影响任务总体结果或导致整个任务部分及完全失败的问题,论文提出无人机遥感组网冗余容错方法。该方法采用领航—跟随的无人机编队飞行模式,多台组网无人机稳定可靠完成指定的飞行任务,验证了冗余容错方法,解决了无人机遥感组网冗余容错技术中的有和无的问题。  相似文献   

建筑工程施工平面控制测量精度的确定和实现     

李觉明 《四川测绘》1998,21(2):84-90

本文论述了建筑工程施工控制测量的特点,并根据工程施工要求,运用平差理论,分析并确定测量中误差,最后探讨了经纬仪标称精度和测量技术标准。本文的论述可以使建筑工程测量更趋于合理,易于实现。  相似文献   

Multi-Objective Fuzzy Optimum Design Based on Reliability for Offshore Jacket Platforms     

KANG  Haigui 《中国海洋工程》2001,(4):467-478

In consideration of the fuzzy constraint boundary and through analysis of structural reliability, a model of structural fuzzy optimum design is established based on reliability for offshore jacket platforms. According to the characteristics of offshore jacket platforms, the tolerance coefficient of the constraint boundary is determined with the fuzzy optimization method. The optimum level cut set which is the intersection of the fuzzy constraint set and fuzzy objective set, is determined with the bound search method, and then the fuzzy optimum solution to the fuzzy optimization problem is obtained. The central offshore platform SZ36-1 is designed with the fuzzy optimum model based on reliability; the results are compared with those from deterministic optimum design and fuzzy optimum design. The tendency of design variables in the above three methods and its reasons are analyzed. The results of an example show that the fuzzy optimum design based on reliability is stable and reliable.  相似文献