Short-term temporal dynamics of algal species in a subtidal kelp bed in relation to changes in environmental conditions and canopy biomass

Understanding temporal variation at the scale of weeks to months is critical to understanding broad temporal patterns in diversity in the same way as understanding diversity across landscapes relies on understanding variation at the scale of meters. However, whereas small-scale spatial variation in temperate reef algal assemblages has been extensively studied, fine-scale temporal changes have not been well addressed. By sampling the macroalgae of a subtidal reef near Perth (Australia), dominated by the small kelp Ecklonia radiata, every ∼40 days over a 2-year period, we were able to test whether temporal changes in species richness, assemblage structure and species turn-over were related to seasonal changes in surface temperature, solar radiation and wave height. A total of 93 macroalgal taxa were identified, and species richness per sampling time ranged from 25 to 64 taxa 1.25 m⁻². Biomass of E. radiata was positively correlated with changes in sea surface temperature and light, and negatively correlated with wave height. Species richness, assemblage structure and turn-over of other macroalgae were more associated with seasonal changes in kelp biomass than environmental variables per se. We conclude that seasonal changes in environmental conditions drive changes in the kelp canopy, which in turn drive changes in species richness and assemblage structure. This suggests that habitat-formers such as kelps can exert a strong temporal influence on associated communities, analogous to well-described spatial influences. Thus, as kelp canopy biomass expands and retracts over time-scales of weeks to months, so does available space for colonization and growth, resulting in a high species turn-over. Species richness is therefore increased and maintained through time, in the same way as canopy-gap mosaics increase and maintain species richness across spatial landscapes.     

澥浦大弹涂鱼群体生化遗传分析

于2004年4月,在浙江省宁波市镇海区澥浦滩涂采集野生大弹涂鱼(Boleophthalmus pectinirostris)30尾,采用聚丙烯酰胺凝胶(PAGE)电泳方法,分析了乳酸脱氢酶(LDH)、甲酸脱氢酶(FDH)、谷氨酸脱氢酶(GDH)、D-葡糖脱氢酶(GCDH)、葡萄糖-6-磷酸脱氢酶(G6PDH)、苹果酸脱氢酶(MDH)、苹果酸酶(ME)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和酯酶(EST)等10种酶在大弹涂鱼肝脏组织中的表达,并对同工酶表型进行了生化遗传分析。实验结果表明,大弹涂鱼10种同工酶中除CAT外的另9种酶都得到了清晰的酶谱。该9种酶共记录了23个基因座位,筛选出LDH-1,FDH-1,G6PDH-1,ME-1,SOD-1,EST-1,EST-2,EST-3等8个多态基因座位。澥浦大弹涂鱼多态座位比例(P)为34.78%,平均杂合度(H)为0.0594,与其他海水鱼类相比,遗传多样性水平相对较低。     

Microbial dynamics in cyclonic and anticyclonic mode-water eddies in the northwestern Sargasso Sea

The EDdy Dynamics, mixing, Export, and Species composition (EDDIES) project provided a unique opportunity to evaluate the response of the microbial community and further understand the biological and biogeochemical consequences of mesoscale perturbation events in an oligotrophic system. In order to characterize microbial dynamics, we performed measurements of bacterial biomass (BB) and production (BP) and phytoplankton pigment analyses in two upwelling eddies in the Sargasso Sea sampled in 2004 and 2005. We also observed a 3-fold increase in BP at the Bermuda Atlantic Time-series Study (BATS) site during the passage of a cyclonic eddy in 2003. Although the integrated BB and BP over 140 m in 2004 and 2005 eddies remained within the climatological range measured at the BATS site, there was systematic variability in bacterioplankton dynamics across both eddies. Cyclonic eddy C1 demonstrated decreased BP at the feature's center relative to its periphery, and BP was not correlated with total chlorophyll a (TChl a) variability. However, BP correlated with prymnesiophyte pigments throughout the feature. In contrast, mode-water eddy A4 showed an enhancement in BP at the eddy center (EC) relative to its edges and was coincident with elevated TChl a, high primary production measurements, and a high concentration of diatoms. In eddy A4, the tight relationship between enhanced BP, TChl a and specific phytoplankton taxa implies that the phytoplankton community structure was an important factor influencing BP variability. While the heterotrophic bacterial response in C1 and A4 was not enhanced relative to BATS summer climatology, these data and the presence of similar nutrient fields across both eddies suggest that BP and BB were influenced by the eddy perturbations and responded to changes in the phytoplankton community.     

Preliminary investigations on fossil diversity variation of Mesozoic Marattialean ferns in China

The Marattiales is one of the oldest lineages of vascular plants with extensive fossil records dated back to the Carboniferous. Understanding the fossil diversity variation and distribution pattern is helpful for exploring the evolutionary history of this fern group. In this work, the preliminary analysis of diversity change and distribution of the Mesozoic Marattialean fossil records in China are reported covering the Triassic and Jurassic periods based on available published data. In addition, a brief discussion is made regarding to the potential causes for these variation and distribution of this fern group.     

Influence of livestock soil eutrophication on floral composition in the Pyrenees mountains

Livestock behaviour in the Pyrenees includes free grazing and a long resting period that provokes the accumulation of dung and urine in some places,so-called camping areas. The aims of this study were （i） to analyze any change in floral composition,and in nutritional and chemical contents of plants in a livestock camping area; and （ii） to relate the floral composition with soil chemical properties. In a linear transect,five sampling zones were established,from the centre of the camping area to the surrounding Nardus stricta-dominant pasture. The above ground plant biomass and the topsoil were sampled in each zone with 6 replicates per zone. Plant species were classified and weighed to calculate above ground biomass,nutritional and chemical contents,and Shannon diversity and evenness indices. Additionally,soils were sampled in two periods,at the beginning and at the end of grazing period. Soil available nutrients （nitrate,ammonium,phosphorus,potassium,calcium and magnesium）,total nitrogen,organic carbon and pH were measured.
Plant chemical contents （protein,lignin and others） were significantly related to the proportions of grasses,legumes and other plants; so,the protein content is positively correlated with legumes plant biomass while lignin content is negatively correlated with grasses. Both plant and soil nutrients increased linearly towards the centre of the camping area. However,the relationship among plant species richness,diversity and evenness relative to its position along the studied transect was bell-shaped. From the outskirts to the centre of the camping area,plants with low nutrient demand were progressively replaced by those with medium and high nutrients demand and by pioneers.
Nardus stricta-dominant pasture has low plant diversity and plant nutrient content as well as a poor soil nutrient availability. The presence of the camping area introduced patches with more soil nutrients and new species in the large spatial scale. However at a small spatial scale,the strong soil nutrien     

虾池浮游微藻的种类组成、数量和多样性变动

报道了在集约化养虾中应用有益微生物制剂对虾池浮游微藻的影响,分析了整个养虾周期浮游微藻的种类组成、生物量、优势种及多样性指数的周期变化情况。结果表明,早期虾池浮游微藻细胞数量维持在1×103~3×103mL-1的水平,养殖中期开始呈指数增长状态,后期达到顶峰,并维持在70×103~160×103mL-1的水平,生物量比自然海区高。优势种类明显,前期为中肋骨条藻和伏氏海毛藻等硅藻类,后期则为绿球藻和栅列藻等绿藻类,水色及藻相呈良好状态,而不施加芽孢杆菌制剂的对照池则在后期出现较大比例的有害的蓝藻。虾池藻类多样性指数、均匀度指数和种类丰度均呈现前期高后期低的趋势,而优势度指数则相反,呈现前期低后期高的趋势。浮游植物的多样性指数为0.60~3.80,平均为1.88,均匀度指数为0.14~0.83,平均为0.45;种类丰度为0.80~2.46,平均为1.38;优势度指数在0.17~0.85,平均为0.41。多样性指数和均匀度均比粤东海域低,但优势度则甚高。     

长江中华鲟遗传多样性变化

采用随机扩增多态性DNA(RAPD)技术对2000年共30尾长江中华鲟(Acipenser sinensis)幼鲟遗传多样性进行了分析。共用40个10bp长的随机引物,在25个可分析的引物中,只有OPK01,OPK02,OPK03,OPK09和OPK14RAPD-PCR产物有多态现象,多态引物占20%。25个引物共扩增出101条稳定的DNA带。其中12条为多态带,多态座位比例为9.9%。香农遗传多样性指数(H0)为2.6332,遗传多样性指数(H)为0.0261,遗传相似性指数平均为0.9824,遗传距离平均为0.0176。其遗传多样性明显低于葛洲坝截流以前。     

长兴岛刀鲚群体的遗传多样性分析

用随机扩增多态DNA(RAPD)技术对长兴岛刀鲚(Coilia ectenes)38个个体的遗传多样性进行了检测,从40个随机引物中筛选出13个对刀鲚的DNA进行扩增,结果为:13个引物共检测到112条清晰且重复性好的条带,分子质量在200~2000 bp之间,其中多态位点为74个,占66.07%;群体的Shannon多样性指数为0.3164,Nei基因多样性指数为0.2075,结果表明中国刀鲚遗传多样性处于较高水平。刀鲚成熟年龄早,对产卵条件要求不甚严格,产卵率和孵化率都比较高,具有较强的种群恢复能力;另外,由于长江中下游和湖泊刀鲚的捕食者和饵料竞争者的减少,客观上为刀鲚提供了良好的繁殖和幼鱼索饵条件,因此,结合刀鲚自身的生物学特征及生活环境特点,采取合理的保护和管理措施,中国刀鲚资源有望得到恢复。     

Phylogenetic diversity and phenotypic characterization of cultivable bacterioplankton isolated from polar oceans

A set of 27 marine planktonic bacteria isolated from the polar regions was characterized by 16S rDNA sequencing and physiological and biochemical testing. More than half of these bacteria were positive for caseinase, gelatinase and 13-glucosidase, and could utilize glucose, maltose or malic acid as carbon source for cell growth. Twelve isolates expressed nitrate reduction activities. Except for one antarctic isolate BSwlO175 belonging to Actinobacteria phylum, these isolates were classified as γ-Proteobacteria, suggesting that γ-Proteobacteria dominated in cultivable marine bacterioplankton at both poles. Genus Pseudoalteromonas was the predominant group in the Chukchi Sea and the Bering Sea, and genus ShewaneUa dominated in cultivable bacterioplankton in the Prydz Bay. With sequence similarities above 97%, genus Psychrobacter was found at both poles. These 27 isolates were psychrotolerant, and significant 16S rDNA sequence similarities were found not only between arctic and antarctic marine bacteria （ 〉 99% ）, but also between polar marine bacteria and bacteria from other aquatic environments （ ≥ 98.8% ）, including temperate ocean, deep sea, pond and lake, suggesting that in the polar oceans less temperature-sensitive bacteria may be cosmopolitan and have a bipolar, even global, distribution at the species level.     

天文望远镜子镜超磁致伸缩驱动器驱动模型及参数识别

采用超磁致伸缩驱动器(GMA,Giant Magnetostrictive Actuator)驱动拼接镜面天文望远镜子镜,并建立GMA精密位移驱动准确模型。针对传统遗传算法在辨识GMA位移模型参数时容易过早收敛到次优解的问题,提出了基于分层遗传算法(HGA,HierarchicalGenetic Algorithm)的参数识别方法,其结果在改善驱动位移模拟准确性和提高求解初期种群多样性,相对于其他算法都有较大程度的提高。研究通过与实验结果对比验证了所提出参数辨识方法和建立模型的有效性,位移预测值和实验值的平均偏离值不超过满行程的1.3%。研究还就驱动磁场强度幅值和预应力等因素对滞回、损耗、饱和磁化强度、饱和磁致伸缩量等模型参数的影响进行了分析。