枸杞岛铜藻种群分布的季节变化

为了查清铜藻(Sargassum horneri)的时空分布,并探明大型海藻场生态保护及修复的方法,采用水下样方法,对枸杞岛铜藻种群藻苗和成藻两个时期的分布变化情况进行了跟踪调查.结果表明:铜藻幼苗到成藻阶段密度平均损失率达61％,除了波浪作用对附着牢度差的铜藻造成移除作用外,密度制约机制可能也起了一定作用;铜藻幼苗时期水深分布范围为121 ～547 cm,而成藻时期为132～461 cm,铜藻垂直分布的宽幅缩小,而且不同站点间的水深分布宽幅变化较大,这与站点间环境因子影响程度不同有关;尤其是对分布在水深上限的铜藻来说,暴波强度的影响可能占主要作用;铜藻的生长速度与海水透明度相关,波浪的作用可能导致了沉积物再悬浮影响光照强度,抑制铜藻生长;光照强度降低是否会导致铜藻死亡还需做进一步研究,以便查清铜藻垂直分布上移的现象.     

沉积物对潮下带岩礁上铜藻早期定居阶段的影响

采用沉积物捕获器和抽吸泵测量不同站点和不同水深的沉积物相对数量,通过现场测量铜藻的分布密度,评估了枸杞岛潮下带铜藻分布与沉积水平和暴波强度的关系,并通过试验研究了不同沉积水平对铜藻幼孢子体附着和附着后藻苗存活的影响.结果表明:沉积物少且暴波强度小的站位铜藻分布密度最高,沉积物数量多、暴波强度高的站位铜藻分布稀少;在不同水深处,铜藻分布密度与沉积物数量呈负相关关系;附着基上沉积物数量干质量达到10.47 mg·cm-2(0.543 mm厚)时,仅4.4％的铜藻幼孢子体能够附着,当沉积数量为13.96 mg·cm-2(0.724 mm厚)时,则完全阻止幼孢子体附着;幼孢子体附着1周后,沉积物覆盖数量达到13.96 mg·cm-2时,铜藻幼苗仍有24.0％存活,当沉积物覆盖数量达到34.9 mg·cm-2(1.81 mm厚)时,铜藻幼苗全部死亡.总的来说,铜藻分布密度不但与沉积数量有关,在一定程度上还受暴波强度制约,沉积物对铜藻早期定居阶段的影响在铜藻种群分布上起到决定性作用.     

江苏如东海岸互花米草盐沼沉积物叶绿素a分布特征

潮间带沉积物叶绿素a(Chl-a))是潮间带生态系统底栖微藻初级生产力的表征因子.为了解互花米草盐沼沉积物Chl-a的分布,于2010年夏季及秋季对江苏如东海岸11个站位的表层底质(0～8 cm)内Chl-a含量进行了分析.结果表明:垂直方向上,除10月1～5站位垂直分层不明显外,整体变化趋势为,在0 ～2 cm,随深度的增加而锐减,2～8 cm,变化较小,光照的垂直递减是造成这一趋势的原因;在水平方向上,夏季,沉积物Chl-a含量在互花米草盐沼高于光滩,秋季则相反;光照和沉积物组成的季节变化是造成沉积物Chl-a水平方向分布格局的直接原因;互花米草枝叶对光照的遮挡及对细颗粒物质的圈闭作用随植株生长阶段而变化;互花米草一方面通过促进细颗粒沉积物堆积影响底质的粒度组成,另一方面通过其枝叶生长影响滩面接受的光照,直接影响潮间带微藻的生长,继而影响底栖生态系统的初级生产力.     

附着基材质对鼠尾藻幼苗附着及生长的影响

附着基是影响幼苗人工繁育的重要因素。为了选择有利于鼠尾藻幼苗附着和生长的附着基, 该研究利用六种不同材质的附着基(水泥块、砖块、岩块、扇贝壳、化纤布、尼龙绳)分别进行了人工采苗、车间培育及野外增殖等实验并测定了附苗效率、附苗密度、出苗率及相对生长率等生物学参数。结果显示, 静水采苗条件下, 各种附着基上受精卵附着效率为60.3% ―73.6%, 采苗期附着基材质影响不显著; 流水暂养20 d 后, 扇贝壳附着基的附苗密度明显下降(32±10 ind·cm^–2, p<0.05), 其它附 着基的附苗密度变化不明显; 野外移植30 d 后, 不同附着基上出苗率和幼苗长度变化显著(p<0.05), 其中化纤布附着基上出苗率和幼苗长度值最高(60.6±19.7 %, 7.3 ± 2.6 mm), 扇贝壳附着基上出苗率和幼苗长度值最低(6.5±11.3 %, 2.8 ± 1.6 mm)。因此,附着基材质对鼠尾藻受精卵附着影响不显著, 但附着基表面的特殊结构很可能会影响幼苗固着和生长。实验表明, 使用化纤布、水泥块、砖块附着基培育幼苗效果较好。     

铜藻苗种繁育研究

2011—2013年, 以浙江省南麂岛马祖岙的野生铜藻作为亲本, 详细观察了铜藻繁殖特性、胚胎发育和幼孢子体的早期发育过程, 开展了铜藻幼孢子体早期发育条件(温度、盐度、光照强度、光照周期等)的优化研究。结果发现, 南麂岛铜藻的自然繁殖盛期为每年3月下旬至5月上旬, 室内海水温度为13—18℃, 较适宜于雌雄生殖托的形成。在试验条件下, 铜藻受精卵发育的适宜温度为10—20℃, 盐度是20—30, 在该培育条件下, 经过48h的孵化, 受精卵可以大批量同步化发育成具有假根的幼孢子体。人工育苗结果表明, 适宜的环境因子(温度20℃, 盐度20—30, 光照强度4500 lx, 光照时间12—18h/d)较利于幼孢子体的生长发育。铜藻幼孢子体的前期培育连续流水和充气为宜, 经18—20d的室内培育, 幼孢子体可发育成具有2—3叶片的幼苗。质地坚硬、表面粗糙的水泥砖较适合铜藻幼孢子体的附着和生长, 可满足后期藻场修复的要求。     

风浪对枸杞岛铜藻(Sargassum horneri)分布格局的影响

通过潜水调查枸杞岛铜藻的分布特征,并统计西北太平洋近65年台风生成的波浪对枸杞岛产生的影响以及近3年枸杞岛日常风力和风向的变化规律,分析了枸杞岛铜藻分布格局与风浪影响之间的关系。结果表明:铜藻主要分布在枸杞岛西北侧沿岸,且集中分布在平均海平面以下1~4 m较浅的水深范围内,而枸杞岛东到南侧则无铜藻分布,这与85.1%台风生成的波浪影响枸杞岛的东到南侧有关;近年来枸杞岛铜藻数量减少,但近年来台风生成的波浪对枸杞岛产生的影响并没有显著增强,说明铜藻数量的减少并不是由于近年来台风的显著增强而引起;虽然枸杞岛日常风力以西北-北向最强,西北-北向风向的发生频次也较多,但铜藻却集中分布在枸杞岛西北侧沿岸,说明枸杞岛西北侧大面积贻贝养殖筏可能对风浪的影响起到一定缓解作用,保护了近岸岩礁区铜藻的分布与生长。因此,在铜藻垂直分布上移的趋势下,风浪的影响加剧了对铜藻的破坏作用,风浪对枸杞岛铜藻的分布格局起到重要作用。     

瓦氏马尾藻规模化繁育技术研究

研究了瓦氏马尾藻(Sargassum vachellianum)规模化育苗及海区养殖技术。采集海区成熟藻体, 室内催熟放散受精卵, 收集并喷洒于水泥板、棕绳、木板3种附着基, 进行受精卵附着、萌发及苗体生长等实验, 发现棕绳育苗效果最佳。受精卵喷洒10d后, 3种附着基的出苗率分别为 85.5%、80.2%和91.3%, 平均株高约1.3 mm。前20天木板幼苗密度最高, 达8.2株/cm2, 但幼苗均生长缓慢。第30天, 幼苗出现明显分枝, 生长率增大到前20天的1.6倍, 其中棕绳幼苗株高最大, 幼苗存活率分别为83.6%、79.7%和75.6%。第60天棕绳幼苗密度及平均株高均最大。将附有幼苗的水泥板(藻礁)、棕绳放入海区进行养殖, 发现幼苗在浪大流急海区生长较快, 4周后平均株高分别达98.7和103.1 mm, 是对照组的1.5倍, 但棕绳脱苗严重。藻礁较适合海区规模化投放养殖, 是藻场修复和重建的理想材料。     

濒危植物香果树幼苗空间格局及数量动态研究

采用相邻格子样方法采集数据,应用理论分布模型、分布系数法、Morisita格局指数法、聚集强度指数以及Greig-Smith区组均方方法研究了香果树幼苗种群空间格局,结果表明:(1)濒危植物香果树幼苗呈聚集分布,聚集强度受区组尺度的影响较大,随尺度的增加而减小;不同幼苗种群格局强度随着纬度增加,也呈现下降的趋势。(2)Greig-Smith区组均方法研究显示,香果树种群在8~16m2和50~64m2处聚集;香果树幼苗大小结构呈现出高度在0~40cm范围内幼苗较多现象,但经过强烈的环境筛选,大部分生长未达到120cm而死亡。(3)主成分分析表明,香果树幼苗受乔木盖度、灌木盖度、光照强度以及大气的温湿度影响较大。因此,建议加强香果树原生生境的保护,严禁对香果树幼苗进行滥砍、滥伐、放牧等破坏;通过降低乔木层和灌木层盖度,清理林下枯落物、苔藓等,增加林下光照强度,建立小面积林窗,促进香果树幼苗发育。     

潮滩底栖微藻生物量垂直变化对其遥感反演模式的影响

遥感信号与潮滩表层沉积物底栖微藻生物量的定量关系, 与定义生物量对应的沉积物深度相关。以叶绿素浓度表征沉积物底栖微藻生物量, 对烟台四十里湾潮滩表层沉积物柱样分别以3 mm 和1 mm 间隔分层, 分析研究其叶绿素垂直分布特征; 模拟、分析以指数衰减曲线斜率表征的叶绿素垂直分布变化对叶绿素浓度遥感反演模式的影响。结果显示, 潮滩表层1 cm 和3 cm 内, 叶绿素浓度均随着深度增加呈指数式衰减; 垂直衰减曲线斜率逐渐变大时, 沉积物表层1 cm 内的叶绿素浓度逐渐降低, 基于叶绿素浓度与光谱指数NDI-MPB 间回归方程的遥感反演模式亦发生变化。     

浙北近岸典型岛礁瓦氏马尾藻空间分布格局分析

为探明浙北近岸典型岛礁瓦氏马尾藻(Sargassum vachellianum)的空间分布格局, 于2016年5月底至6月初, 分别采用走航观察和水下样方法, 对按离岸距离远近的3条岛礁带上12个岛礁瓦氏马尾藻成藻时期的分布特征进行了调查, 并从不同空间尺度比较分析了3条岛礁带上瓦氏马尾藻在水平和垂直分布上的差异。结果表明: (1)在地区尺度上, 高浊度和高波浪能的水域环境限制了瓦氏马尾藻的分布与生长, 导致浙北近岸的瓦氏马尾藻仅分布在第二条岛礁带这一狭窄的分布带上。依据瓦氏马尾藻最低适宜生长水温要高于10 ℃的特性, 我们可以推断出舟山群岛的绿华岛可能是我国特有种瓦氏马尾藻分布的最北部端线。(2)在站点尺度上, 岛礁东南向瓦氏马尾藻定生密度明显低于西北向, 这与调查站位所受风浪影响的方位和强度相一致。在第二岛礁带上的4个岛礁北向瓦氏马尾藻的平均株高仅为26.3 cm, 说明瓦氏马尾藻不适宜在高波浪能生境中生存。(3)在站点尺度内, 第二岛礁带上浊度最低的北渔山岛瓦氏马尾藻有较大的垂直分布范围, 且定生深度达到了6.4 m, 而浊度高的近岸岛礁瓦氏马尾藻垂直分布范围较小。瓦氏马尾藻株高随着水深的增加而逐渐降低, 由此推测, 瓦氏马尾藻虽不能耐受强光, 但光照对瓦氏马尾藻的分布生长起重要作用。与同海区铜藻的垂直分布格局相比, 瓦氏马尾藻具有一定适应高浊度、高沉积物环境的能力。因此, 在浙北近岸海域瓦氏马尾藻是较适合进行生态移植修复的种类。     

Plant-Parasitic Nematodes of South Viet Nam

Between 1974 and 1978, 2,842 identifications of plant-parasitic nematodes were made from more than 1,700 soil and plant samples collected in eight provinces of South Viet Nam. Species in nine genera—Helicotylenchus, Criconemoides, Meloidogyne, Pratylenchus, Tylenchorhynchus, Hoplolaimus, Hirschmanniella, Xiphinema, and Rotylenchulus—comprised 96.1% of the identifications; the remaining 3.9% were species of 11 genera. Fourteen genera were associated with rice which was grown on about 2,500,000 ha in 1970. Of these, Ditylenchus, Hirschmanniella, and Meloidogyne were most important. Ditylenchus angustus caused severe damage to about 50,000 ha of flooded rice in the Mekong Delta in 1976. Hirschmanniella spp. were found in all samples examined from flooded rice fields. Meloidogyne spp. were common in rice seedbeds, upland rice, and rice not kept flooded continuously. Meloidogyne and Pratylenchus spp. were found in roots of 22 of the 32 crop plants sampled. Little or no attempt was made in South Viet Nam to control nematodes.     

Identification key for European strand-forming house-rot fungi

An identification key for 20 common strand-forming indoor wood decay fungi is given. The key is based on observations of material from affected buildings and on wood samples that have been incubated in the laboratory. The key is with macro- and microscopic photographs.     

Parasites, emerging disease and wildlife conservation

In this review some emerging issues of parasite infections in wildlife, particularly in Australia, are considered. We discuss the importance of understanding parasite biodiversity in wildlife in terms of conservation, the role of wildlife as reservoirs of parasite infection, and the role of parasites within the broader context of the ecosystem. Using a number of parasite species, the value of undertaking longitudinal surveillance in natural systems using non-invasive sampling and molecular tools to characterise infectious agents is illustrated in terms of wildlife health, parasite biodiversity and ecology.     

Phylogenetic relationships among Southeast Asian climbing bamboos (Poaceae: Bambusoideae) and the Bambusa complex

A phylogenetic analysis of Bambusa and allies based on the plastid DNA non-coding regions rps16-trnQ, trnC-rpoB, trnH-psbA and trnD-T, and a partial nuclear GBSSI gene, was carried out. This included representatives from all four Bambusa subgenera (including type species), a group of segregate Southeast Asian genera distinctive by their climbing–scrambling culms (Dinochloa, Holttumochloa, Kinabaluchloa, Maclurochloa, Soejatmia, Sphaerobambos), and two other Bambusinae genera (Dendrocalamus, Gigantochloa). The results do not support the present subgeneric classification of Bambusa. The climbing Southeast Asian genera, all of which include species previously placed in Bambusa, are distinct from the “core Bambusa group” (type species and alliance) and the Bambusa complex generally.     

The identification of microRNAs in the whitespotted bamboo shark (Chiloscyllium plagiosum) liver by Illumina sequencing

MicroRNAs are indispensable players in the regulation of a broad range of biological processes. Here, we report the first deep sequencing of the whitespotted bamboo shark (Chiloscyllium plagiosum) liver. We mapped 91 miRNAs in the Callorhinchus milii genome that have previously been described in the Danio rerio, Fugu rubripes, Oryzias latipes, Xenopus laevis, Xenopus tropicalis, Homo sapiens, and Mus musculus. In addition, 156 new putative candidate (PC) C. plagiosum miRNAs were identified. From these 247 miRNAs, 39 miRNA clusters were identified, and the expression of these clustered miRNAs was observed to vary significantly. A total of 7 candidate miRNAs were selected for expression confirmation by stem-loop RT-PCR. This study resulted in the addition of a significant number of novel miRNA sequences to GenBank and laid the foundation for further understanding of the function of miRNAs in the regulation of C. plagiosum liver development.     

Multilocus phylogenetic analysis of the genus Aeromonas

A broad multilocus phylogenetic analysis (MLPA) of the representative diversity of a genus offers the opportunity to incorporate concatenated inter-species phylogenies into bacterial systematics. Recent analyses based on single housekeeping genes have provided coherent phylogenies of Aeromonas. However, to date, a multi-gene phylogenetic analysis has never been tackled. In the present study, the intra- and inter-species phylogenetic relationships of 115 strains representing all Aeromonas species described to date were investigated by MLPA. The study included the independent analysis of seven single gene fragments (gyrB, rpoD, recA, dnaJ, gyrA, dnaX, and atpD), and the tree resulting from the concatenated 4705 bp sequence. The phylogenies obtained were consistent with each other, and clustering agreed with the Aeromonas taxonomy recognized to date. The highest clustering robustness was found for the concatenated tree (i.e. all Aeromonas species split into 100% bootstrap clusters). Both possible chronometric distortions and poor resolution encountered when using single-gene analysis were buffered in the concatenated MLPA tree. However, reliable phylogenetic species delineation required an MLPA including several “bona fide” strains representing all described species.