High-throughput sequencing of 16S r RNA amplicons characterizes gut microbiota shift of juvenile sea cucumber Apostichopus japonicus feeding with three antibiotics

Sea cucumber Apostichopus.japonicus is an important marine economic species in Asian countries due to its profound nutritional and medicinal value.So far,with the rapid development of intensified artificial aquaculture of sea cucumbers,the use of antibiotics is still an inexpensive and dispensable way to treat pathogenic infections,especially during the nursery phase.However,there is little information on the effects of antibiotics on the intestinal microbiota of sea cucumber.Therefore an Illumina based sequencing method was used to examine the intestinal bacterial composition of juvenile A.japonicas following diets with three typical antibiotics(tetracycline,erythromycin.,and norfloxacin)under 15,30,and 45 d.The findings reveal that different antibiotics have distinct effects on the growth performance of juvenile sea cucumbers.However,the richness and diversity of microbiota were barely affected by antibiotics but the community composition alterations indicated that the three antibiotics exhibited their respective patterns of reshaping the intestinal bacteria of juvenile sea cucumbers.In common,the abundance of some sensitive genera with helpful functions,such as Thalassotalea,Shewanella,Sulfitobacter,and Halomonas decreased significantly with exposure to antibiotics and the abundance of multiple potential pathogenic-and suspected antibiotic-resistant microorganisms like Arcobacter,Leucothrix,and Clostridium_sensu_stricto_1 was found increased significantly in the antibiotic groups.These results suggest that low doses of antibiotics could affect the composition of the intestinal microbiota of sea cucumbers and might increase the risk of infection of the hosts.This study could help us to explore how antibacterial compounds modify the gut microbiota of sea cucumbers and provide theoretical guidance in hatchery management by scientific antibiotic use in sea cucumber mariculture.     

Fish Assemblage Responses to a Low-head Dam Removal in the Lancang River

Dam removal is becoming an effective approach for aquatic biodiversity restoration in damming river in order to balance the aquatic ecosystem conservation with large-scale cascade damming. However, the effects of dam removal on fish communities in Asian mountainous rivers, which are dominated by Cypriniformes fishes, are still not well known. To determine whether dam removal on a mountainous river benefit restoration of fish diversity, we investigated the response of fish assemblage to dam removal using a before-after-control-impact design in two tributaries of the Lancang River(dam removal river: the Jidu River, and control river: the Fengdian River). Fish surveys were conducted one year prior to dam removal(2012) and three years(2013–2015) following dam removal. We observed rapidly and notably spatio-temporal changes in fish biodiversity metrics and assemblage structure, occurring in the Jidu River within the first year after dam removal. Overall, fish species richness, density and Shannon-Wiener diversity all increased immediately in above-and below-dam sites, and maintained a stable level in subsequent years, compared to unchanged situation in the control river. All sites in the Jidu River experienced shifts in fish composition after dam removal, with the greatest temporal changes occurred in sites below-and above-the former dam, resulting in a temporal homogenization tendency in the dam removed river. These findings suggest that dam removal can benefit the recovery of habitat conditions and fish community in Asian mountainous rivers, but the results should be further evaluated when apply to other dammed rivers since the dam age, fluvial geomorphology and situation of source populations could all affect the responses of fish assemblages.     

全球大洋潮汐模式在北印度洋潮汐预报准确性的评估

为评估DTU10、TPXO8、GOT00.2和NAO.99b 4个全球大洋潮汐模式对北印度洋潮汐的预报能力,采用英国海洋资料中心提供的海区中部和沿岸站潮汐调和常数资料,检验了这些模式4个主要分潮(M_2、S_2、K_1、O_1)的准确度。它们的各分潮调和常数资料准确度都比较高,振幅绝均差的最大值仅5.61 cm,迟角绝均差的最大值仅9.13°。这些模式的调和常数给出潮波传播特征差别不大。基于这些模式提供的调和常数,分别建立了北印度洋4、8和16分潮潮汐预报模型,将预报结果与中国海事服务网提供的沿岸24个站潮汐表资料进行对比。各模式的8分潮(M_2、S_2、N_2、K_2、K_1、O_1、P_1、Q_1)潮汐预报模型均优于4分潮(M_2、S_2、K_1、O_1)潮汐预报模型,NAO.99b模式可以提供16分潮(M_2、S_2、N_2、K_2、K_1、O_1、P_1、Q_1、MU_2、NU_2、T_2、L_2、2N_2、J_1、M1、OO_1)潮汐预报模型,但是对预报结果改善不明显;在各模式中,GOT00.2模式的8分潮潮汐预报模型对北印度洋沿岸的预报效果最好,平均绝均差为14.97 cm。     

ATS藻板与自然礁石上藻群生物多样性的比较

ATS(algal turf scrubber)系统是一种利用潮间带藻类高效去除富营养化水体中氮(N)、磷(P)元素的水质净化系统, 藻类是支持整个系统最重要的组成部分, 其群落结构与水质净化效果密切相关。该研究基于Illumina MiSeq平台的高通量测序技术对海水水族缸的ATS系统中藻板样品和自然礁石上的藻类进行多样性分析。18S rDNA研究结果表明, ATS系统中经筛选得到藻类优化序列21390条, 其中对丝藻属Antithamnion占主要地位, 占序列总数的22.79%, 其次19.07%序列归入斜纹藻属Psammodictyon; 宋井、展南亭、后宅3个地区的藻类经筛选分别得到88435、87129、106458条优化序列, 主要为分枝色指藻属Chroodactylon、宽果藻属Mastocarpus和日本马泽藻属Mazzaella。ATS系统和自然环境样品共有的优势藻为骨条藻属Skeletonema和仙菜属Ceramium。本实验在研究ATS系统与自然礁石上的藻类群落相似性的同时, 深入探究了其群落结构的差异性, 为进一步优化ATS系统的功能提供了理论依据。     

海底玄武岩中次生组分HCl溶解实验研究

次生组分沉淀是海底岩石中普遍存在的现象,次生组分去除是减少次生组分干扰、获取海底岩石高质量数据的关键。选择西太平洋麦哲伦海山区MK海山相对新鲜的玄武岩作为研究对象,经研磨、均一化后将粉末样品分为49份,其中48份分别以0.25,0.50,1.00,1.50,2.00,2.50 mol/L六种浓度的足量HCl溶解0.5,1,2,4,8,16,32和64 h后,选取溶解残渣测定主要氧化物和特征微量元素质量分数,确定HCl溶解法在去除次生组分的同时不会对海底新鲜玄武岩中原生组分造成影响的HCl浓度-时间组合。结果表明,在HCl浓度为1.00～2.50 mol/L,溶解时间为0.5～2 h的12种HCl浓度-时间组合均可保证海底玄武岩中原生组分的安全,并可有效去除次生组分。综合海底蚀变玄武岩次生组分去除实验研究,推荐使用1.00～2.00 mol/L HCl,溶解时间在0.5～1 h的实验方案。     

Improved Priority‐Flood method for depression filling by redundant calculation optimization in local micro‐relief areas

Depression filling is a critical step in distributed hydrological modeling using digital elevation models (DEMs). The traditional Priority‐Flood (PF) approach is widely used due to its relatively high efficiency when dealing with a small‐sized DEM. However, it seems inadequate and inefficient when dealing with large high‐resolution DEMs. In this work, we examined the relationship between the PF algorithm calculation process and the topographical characteristics of depressions, and found significant redundant calculations in the local micro‐relief areas in the conventional PF algorithm. As such calculations require more time when dealing with large DEMs, we thus propose a new variant of the PF algorithm, wherein redundant points and calculations are recognized and eliminated based on the local micro‐relief water‐flow characteristics of the depression‐filling process. In addition, depressions and flatlands were optimally processed by a quick queue to improve the efficiency of the process. The proposed method was applied and validated in eight case areas using the Shuttle Radar Topography Mission digital elevation model (SRTM‐DEM) with 1 arc‐second resolution. These selected areas have different data sizes. A comparative analysis among the proposed method, the Wang and Liu‐based PF, the improved Barnes‐based PF, the improved Zhou‐based PF, and the Planchon and Darboux (P&D) algorithms was conducted to evaluate the accuracy and efficiency of the proposed algorithm. The results showed that the proposed algorithm is 43.2% (maximum) faster than Wang and Liu's variant of the PF method, with an average of 31.8%. In addition, the proposed algorithm achieved similar performance to the improved Zhou‐based PF algorithm, though our algorithm has the advantage of being simpler. The optimal strategies using the proposed algorithm can be employed in various landforms with high efficiency. The proposed method can also achieve good depression filling, even with large amounts of DEM data.     

页岩储层脆性评价分析及可压裂性定量评价新方法研究

目前绝大部分可压裂性模型以弹性参数脆性指数法为基础评价页岩储层可压裂性,然而通过岩石应力应变特性、岩石力学测试统计结果和矿场压裂实例分析可知,通过弹性参数评价页岩脆性缺乏理论依据,且与实验测试、压裂效果等相悖.针对页岩储层可压裂性定义不统一、不全面的问题,综合分析了影响页岩体积压裂过程中压碎难度、缝网的复杂度、获得较高...     

济南和邹平辉长岩的Pb-Sr-Nd同位素特征和岩浆源区中下地壳物质贡献

对鲁西晚中生代济南和邹平辉长岩的Pb-Sr-Nd同位素和元素组成的研究,给出(87Sr/86Sr)i=0.7041~0.7056,εNd(t )=-6.0~-13.0,( 206Pb/204Pb)i=16.545~16.998,(207Pb/204Pb)i=15.242~15.350,(208Pb/204Pb)i=36.488~36.944（除SD792表现出高放射成因Pb外）。由于辉长岩的堆晶性质,其微量元素组成不能用于指示其物质来源。与EMⅠ型大洋和大陆玄武岩对比,表明济南和邹平辉长岩的源区具有与EMⅠ地幔端元一致的同位素特征,但在Pb同位素图解上有明显的下地壳物质的贡献。下地壳物质的参与可能与拆沉有关。     

基于PS-InSAR技术的深圳北站表面位移监测研究

利用2015-01-2018-08的40景COSMO-SKyMed HIMAGE雷达影像,采用永久散射体合成孔径雷达干涉测量(permanent scatterers interferometric synthetic aperture radar,PS-InSAR)技术获得了深圳北站时序形变信息,并基于GIS空间分析...     

一种基于正交频分复用的高速水声通信技术的研究

OFDM(正交频分复用)是一种适合于在多径衰落和受限带宽信道中进行高速传输的技术。论文把OFDM技术应用于高速水声通信中,设计了一套基于OFDM的高速水声通信系统,阐述了OFDM水声通信系统中同步和信道估计的方法。海上试验证明了系统的有效性。