Environmental effects on the reproduction and fecundity of the introduced calcareous sponge Paraleucilla magna in Rio de Janeiro,Brazil          下载免费PDF全文

Emilio Lanna  Rodolfo Paranhos  Paulo C. Paiva  Michelle Klautau 《Marine Ecology》2015,36(4):1075-1087

The calcareous sponge Paraleucilla magna (Porifera, Calcarea) has been the subject of several studies in the last decade. It was first described along the Brazilian coast, where it is considered cryptogenic, and was subsequently found in the Mediterranean, where it is considered invasive. The wide artificial distribution of this species allows us to compare different aspects of the biology of an introduced species in different locations. Here, we analysed the effects of selected environmental parameters on the reproductive dynamics of P. magna in Rio de Janeiro (Brazil) over 18 months and compared our results with those obtained for the same species in the Mediterranean Sea. Specimens were collected monthly and analysed through histological methods. The density of reproductive elements in each month was calculated, and the effects of environmental parameters (photoperiod, precipitation, temperature, phytoplankton and bacterioplankton) were analysed using a regression tree analysis. Paraleucilla magna was reproductive throughout the study period. The densities of the reproductive elements (oocytes, embryos and larvae) showed no seasonality, and this species presented one of the highest reproductive efforts documented to date in the phylum Porifera (99.0 oocytes · mm^?3; 89.0 embryos · mm^?3; 319.0 larvae · mm^?3). The main environmental parameters related to the reproduction of P. magna were temperature, photoperiod and bacterioplankton. Temperature was the main driver associated with the densities of oocytes and embryos, while bacterioplankton was the main driver of larvae (positive relationships). In Rio de Janeiro, larvae were present and continuously released. This strategy is different from that observed in the Mediterranean, where a larger larval output was observed but only during the summer months. Our results show that P. magna is a species with a strong invasive potential, considering its high and continuous reproductive effort. This high fecundity stimulated by high temperatures may be a key factor contributing to the growth of P. magna populations and its invasion of new areas.  相似文献   

西沙群岛生物碳酸盐的成因和沉积:来自活体仙掌藻的证据   总被引：1，自引：0，他引：1  

许红  赵新伟  Gregor P. Eberli  LIU Xinyu  朱玉瑞  蔡瑛  LUO Wei  闫桂京  张柏林  魏凯  施剑 《海洋学报(英文版)》2015,34(4):62-73

A recent island survey reveals that the Xuande Atoll and the Yongle Atoll in the Xisha Islands can be classified into one of two systems: the depleted atoll system and growth atoll system; the survey also indicates that the decreased area of several shoals is an unbearable burden for the Xisha Islands, of which the largest island area is 2.13 km2 and the minimum elevation is 1.4 m. According to a survey on the ecological characteristics of Halimeda in the Laolongtou breaker zone of Shidao Island in the Xisha Islands, the green and white living Halimeda are collected,the isotopic ages of 14 C contained in the Halimeda are shown to be 27 years and 55 years, respectively, and carbonate mainly occurs in five types, i.e., luster, segment, sand, sand grain, and marl in the formation. The Halimeda segments mainly provide the carbonate sediments of long-term biogenic deposits in the reef environment and the annual productivity per area is 60–100 g/m2; the characteristics of the microstructure of the Halimeda are analyzed, the aragonite raphide carbonate is deposited and enriched in the cortexes, medullas and cysts, and the Halimeda generally contain major elements such as C, O, Ca, Cl, Mg, K, Na, S and Al, and are rich in trace elements such as tellurium(Te), rhodium(Rh) and strontium. It is believed that the Halimeda grow slowly,including the biotic community of reef corals in the reef areas, thus they possess an environmental remediation capacity, but it takes much time to remedy the environment, and it is necessary to make the law to protect the diversity and vulnerability of the Xisha marine ecology, the ecology of the reef community and the island environment in a scientific way. As indicated in the survey, under the background of global warming and sea-level rise, the discovery of large amounts of Halimeda in the Laolongtou sea area is significant for the natural increase of the depleted atoll system of the Xuande Atoll, while the Halimeda segments represent the primary form of the fossil Halimeda, of which the species can be identified and preserved in great numbers under geological conditions. The Miocene was discovered in large amounts in the Xichen-1 well, therefore the study on the characteristics and mechanism of Halimeda carbonate sediments plays a pivotal role in the formation and construction of organic reefs in the South China Sea as well as oil and gas exploration.  相似文献   

冰激直立腿海洋平台疲劳寿命分析   总被引：1，自引：1，他引：0  

张大勇  刘笛  许宁  岳前进  郭龙玮 《海洋工程》2015,33(4):35-44

由于渤海特殊环境条件与油藏分布决定了该海域导管架油气平台属于典型的柔性抗冰结构。多年现场观测发现,该类结构存在显著的冰激振动现象。冰振不仅能激起较大的甲板加速度响应,还会引起明显的导管架管节点交变应力。在结构设计与安全保障中进行疲劳分析及寿命估计是必要的。对于直立腿抗冰结构,精确的冰激疲劳寿命计算方法还不成熟。基于多年的现场监测,首先分析了冰与直立腿抗冰结构相互作用过程;其次,提出了冰激直立腿平台的疲劳寿命分析流程;最后,选取渤海某典型直立腿平台,利用ANSYS数值模拟,对比了稳态冰力和随机冰力下结构的疲劳损伤,进而计算出疲劳寿命。本研究为寒区柔性结构抗冰设计与安全保障提供了理论基础。  相似文献   

大视场面阵数字航摄仪检测关键技术探讨     

肖海红  王成龙  韩菲 《测绘科学》2015,(9):129-133

针对常规室内检校场无法满足大视场面阵数字航摄仪检测的问题,文章提出了一种适合此类航摄仪检校的野外检校场的建立方法,通过对检校场控制点布设方案设计、适合影像识别的地标形状设计和地标点三维坐标的精确测定方案研究,实现了检测场内控制点的高精度测量:建立适合大面阵数字航空摄影仪几何误差改正的数学模型,并通过多摄站拍摄足够数量的检校场影像,自动识别并测定每幅影像上全部地标点的影像坐标,用最小二乘平差计算间接求出相机的内方位元素和各项畸变参数,最后通过多组检测参数对比,验证了数学模型及其参数的可靠性与稳定性。  相似文献   

天地图·福建数据融合技术与方法     

翟梦 《测绘与空间地理信息》2015,(10):184-186

通过对福建省1∶10 000核心要素与天地图国家主节点数据研究,分析天地图国家主节点与福建省基础地理信息数据现状,结合天地图数据融合的技术要求,充分考虑融合与共享,设计了福建省1∶10 000核心要素与国家天地图数据融合的总体流程,并分要素阐述处理要求,有效解决了多源多尺度异构数据的融合问题,该技术已经在天地图·福建数据融合项目中得到了应用,为省级基础地理信息数据参与国家天地图数据融合提供了参考。  相似文献   

辽东山地老秃顶子冰缘地貌植物群落类型及基本特征   总被引：3，自引：0，他引：3  

张华  刘剑刚  伏捷  孙明扬  罗璇  何红  祝业平  兰玉波  王颖 《冰川冻土》2015,37(2):500-510

基于48个样地的群落调查数据,运用TWINSPAN分类方法,对辽东山地老秃顶子冰缘地貌植物群落类型进行了划分,并对群落结构、种类组成和生活型谱进行了系统研究.结果表明:老秃顶子冰缘地貌植被可划分为16个森林群系、6个灌丛群系,归并为落叶阔叶林、针阔混交林、暗针叶林、矮曲林、灌丛、灌草丛6个植被型.其中,石海地貌主要发育灌丛和灌草丛,也有针阔混交林和矮曲林分布;石河地貌主要发育针阔混交林和落叶阔叶林,也有暗针叶林分布;石流坡地貌主要发育针阔混交林、落叶阔叶林和灌丛,也有矮曲林分布.老秃顶子冰缘地貌植被由68科138属193种维管束植物组成;石海与石河间植物群落物种组成属中等不相似,而石河与石流坡间属中等相似.老秃顶子冰缘地貌植物群落中高位芽植物占38.0%,隐芽植物占36.3%,地面芽植物占21.8%,地上芽植物和一年生植物均很少,反映出辽东山地冰缘地貌区具有夏季温暖多雨、冬季寒冷漫长的气候特点.相对而言,石海、石流坡地貌中隐芽植物较多,石河地貌中高位芽植物较多,表明石海、石流坡地貌具有更为冷湿的小气候环境.  相似文献   

水(冰):宇宙矿物     

陈丰  李雄耀  唐红  王世杰 《矿物学报》2015,35(2):255-266

水(冰)是最简单的化合物,也是宇宙中丰度最大的矿物。通常认为,水无嗅、无味,无处不在。然而,液态水或固态水却是异乎寻常的物质。水具有某些其它物质没有的,特别是赋予生命所要求的特殊性质,如氢键、水簇和kosmotrope离子等。本文综述水(冰)的结构、化学性质、物理性质、分布以及与生命的关系。  相似文献   

基于地球化学组合求异的津巴布韦奇马尼马尼地区成矿预测          下载免费PDF全文

张素荣  赵更新  杨俊泉  贺福清  张燕  俞礽安 《地质找矿论丛》2015,30(S1):172-180

如何有效地解释评价异常是化探找矿取得成功的关键,传统的地球化学异常处理方法一般是以单一元素的含量值与背景值的差异来圈定异常,因子-泛克立格求异模型则建立在矿床主成矿期元素共生组合与地球化学异常之间的对应关系。采用因子-泛克立格模型对津巴布韦东部奇马尼马尼地区进行成矿预测,结果表明:奇马尼马尼地区存在7种元素组合,分别对应于不同的岩性组合,F4和F6元素组合异常可作为区内热液成矿指示标志,与东部塔卡金矿套合程度高。利用该模型圈定了5处找矿远景区,Ⅰ号远景区为铜镍金钛铁矿成矿有利区,Ⅱ号远景区具有与塔卡金矿相似的地球化学组合背景,Ⅲ号、Ⅳ号和Ⅴ号远景区则具寻找热液型金铜矿及多金属矿的潜力。  相似文献   

Characterization of Galena and Vein Paragenesis in the Penjom Gold Mine, Malaysia: Trace Elements, Lead Isotope Study and Relationship to Gold Mineralization Episodes     

Zakaria ENDUT  NG Tham Fatt  Jasmi Hafiz ABDUL AZIZ  Sebastien MEFFRE  Charles MAKOUNDI 《《地质学报》英文版》2015,89(6):1914-1925

The Penjom Gold Mine is located 30 km from the Bentong-Raub Suture at the western boundary of the Central Belt in Peninsular Malaysia. Gold mineralization hosted within the vein system is associated with pyrite, arsenopyrite, and minor base metals including galena. Trace element and lead isotope analysis was undertaken on nine samples that represent two stages of galena formed during two tectonic events. Both the Pb isotopes and the trace elements show that the first stage galena within the mineralized areas at the footwall has different geochemical characteristics compared with galena in non mineralized areas in the hanging wall, suggesting that galena crystallized from two different ore fluids and probably at two different times. Higher Te, Se and Bi in the galena from the mineralized area may indicate hydrothermal fluids that migrate through the structural conduit and leached out the metal along the pathway that consist of dominant carbonaceous unit. The Pb isotopic ratio composition are transitional between the bulk crustal growth and an upper crustal growth curve, indicating that derivation was from arc rocks associated with continental crust or a crustal source that includes arc volcanic and old continental sedimentary rocks.  相似文献   

南海北部沉积物常量元素变化、碳酸盐旋回及其古环境意义   总被引：1，自引：0，他引：1  

李小洁  梁莲姬  吴枫  孙有斌 《第四纪研究》2015,35(2)

通过对南海北部ODP1145站沉积物的常量元素和碳酸盐分析,探讨了早更新世南海北部沉积物常量元素和碳酸盐含量变化特征及其古环境意义.结果表明,南海北部沉积物中主量元素CaO、Fe2O3、K2O、Na2O、MnO和P2O5受碳酸盐含量影响相对较小,而SiO2、MgO、Al2O3和TiO2受到碳酸盐含量影响相对较大.碳酸盐校正后的常量元素变化可以划分为3种类型,即PC1、PC2和PC3,它们的主要特点有:PC1元素组合包括了SiO2、CaO、Na2O、P2O5、Fe2O3和K2O,主要反映了与季风强度有关的生源物质产率变化,指示了距今2.5～1.5Ma时段生产力的逐渐降低;PC2元素组合(Al2O3、TiO2)代表了陆源物质的输入,指示了在约2Ma开始陆源物质输入的明显增加;PC3元素组合(MgO、MnO)可能与海洋自生作用有关,反映了海底氧化/还原环境的相对变化.早更新世南海北部CaCO3含量呈阶段性降低,一方面受陆源物质稀释作用的影响,另一方面可能更与生物生产力逐渐降低有关.主量元素组合及碳酸盐含量在约2Ma和1.7Ma左右均发生显著变化,可能指示了早更新世时期东亚冬季风的两次增强.  相似文献