Stratified Communities of Methanogens in the Jiulong River Estuarine Sediments, Southern China

Methane is a potent greenhouse gas and produced mainly by methanogens. Few studies have specifically dealt so far with methanogens in estuarine environments. In this study, diversity and distribution of methanogens were investigated by clone library and T-RFLP analysis in a Jiulong River estuarine sediment core which contained clear sulfate–methane-transition zone. The majority of obtained sequences in clone libraries and T-RF peaks from T-RFLP analysis were assigned mainly to Methanosaeta, Methanomicrobiales and Methanosarcinales/ANME. The fragments of Methanosarcinales/ANME were most dominant group (mean 51 %) and composed largely of ANME-2a. In addition, Methanosaeta and Methanomicrobiales accounted for 21 and 28 % of all fragments. Therefore, the presence of Methanomicrobiales, Methanosaeta and ANME-2a was indicative of acetoclastic methanogenesis, hydrogenotrophic methanogenesis, and anaerobic methane oxidation in Jiulong River estuarine sediments. This study provided the important knowledge towards understanding methane cycling association of representative of methanogens involved in estuarine environments.     

上海淀山湖2种硅藻植物中国新记录

该文报道了采自上海淀山湖的硅藻门中国新记录植物2种,分别为粗肋小环藻(Cyclotella costei Druart&Straub)和假凸腹鞍形藻[Sellaphora pseudoventralis(Hustedt)Chudaev&Gololobova]。对2个中国新记录种的形态特征、生境和地理分布进行了详细描述,丰富了中国硅藻植物的生物多样性。     

Occurrence and Implications of SEM-AVS for Surface Sediments from Baihua Lake,China

The concentrations of acid volatile sulfide (AVS) and simultaneous extracted metals (SEMs, including SEM_Cu, SEM_Cd, SEM_Pb, SEM_Zn, SEM_Ni, SEM_Hg, SEM_As and SEM_Cr) in 17 superficial sediment samples were determined to better understand their spatial distribution in Baihua Lake, Guizhou Province, in southwest China. The SEMs/AVS ratio was employed to assess the bioavailability of the eight cationic metals. The SEMs/AVS ratio was significantly lower than 1.0, indicating that AVS in the sediments was sufficient to shield the eight selected heavy metals; thus the eight heavy metals showed no significant bioavailability to the benthic organisms. In addition, a preliminary study on the crystal composition in the sediments from Baihua Lake before and after SEMs’ extraction by X-ray diffraction analysis partly confirmed the efficiency of the cold-acid purge-and-trap technique.     

Full-Sibs in Cohorts of Newly Settled Coral Reef Fishes

Reef fishes exhibit a bipartite life cycle where a benthic adult stage is preceded by a pelagic dispersal phase during which larvae are presumed to be mixed and transported by oceanic currents. Genetic analyses based on twelve microsatellite loci of 181 three-spot dascyllus (Dascyllus trimaculatus) that settled concurrently on a small reef in French Polynesia revealed 11 groups of siblings (1 full sibs and 10 half-sibs). This is the first evidence that fish siblings can journey together throughout their entire planktonic dispersal phase (nearly a month long for three-spot dascyllus). Our findings have critical implications for the dynamics and genetic structure of fish populations, as well as for the design of marine protected areas and management of fisheries.     

南京玄武湖底泥微生物群落结构研究

采用变性梯度凝胶电泳(DGGE)的方法研究了南京玄武湖底泥中的微生物群落结构分布。此外,我们还采用了典范对应分析(CCA)的方法研究了底泥中一些环境因子对微生物群落结构的影响。在玄武湖三个不同湖区共选取八个采样点采集底泥样品,测定不同底泥样品中的总氮(TN)、总磷(TP)、有机质(OM)、pH和氧化还原电位(Eh),发现不同采样点的环境参数存在差异。其中,采样点S2底泥样品的总氮和有机质含量最高,氧化还原电位水平最低。对DGGE分离的DNA条带进行测序,测序结果利用BLAST与GenBank数据库中的菌种进行对比,运用MEGA 3.0软件构建了系统进化树。结果表明:玄武湖底泥中分离出的微生物属于Proteobacteria, Actinobacteria, Verrucomicrobia 和 Nitrospira,它们都属于富营养化湖泊中常见的微生物类群。典范对应分析(CCA)的结果表明: 底泥样品的pH值和氧化还原电位水平对底泥当中的微生物群落结构有显著影响。     

桥弯藻科和异极藻科（硅藻门）植物中国7种新记录

对采自黑龙江省东南部兴凯湖湿地的100余号硅藻标本进行分类研究,共发现桥弯藻科、异极藻科（硅藻门）中国新记录植物5种2变种,分别为亚粗糙桥弯藻（Cymbella peraspera Krammer）、尖头弯肋藻［Cymbopleura cuspidata (Kützing) Krammer］、不显内丝藻高山变种（Encyonema obscurum var.alpina Krammer）、西里西亚内丝藻翼形变种（Encyonema silesiacum var.lata Krammer）、耳状异极藻（Gomphonema auritum Braun & Kützing）、棍棒异极藻（Gomphonema clava Reichardt）、极细异极藻［Gomphonema exilissimum (Grunow) Lange-Bertalot & Reichardt］。对其分类学特征进行了详细的描述,与同属中相似的种类进行了比较与讨论,为今后该区域的藻类研究提供了基础的资料。     

Recruitment of Total Phytoplankton,Chlorophytes and Cyanobacteria from Lake Sediments Recorded by Photosynthetic Pigments in a Large,Shallow Lake (Lake Taihu,China)

Recruitment of total phytoplankton, chlorophytes and cyanobacteria from lake sediments to the water column was studied using photosynthetic pigments at one site (1.5 m) in Lake Taihu, a large shallow lake in China. Samples were taken weekly from the migration traps installed on the bottom from March to May 2004. Abundance of total phytoplankton, chlorophytes and cyanobacteria were represented by Chlorophyll (Chl) a, b, and phycocyanin (PC), respectively. Over the three months, total phytoplankton, chlorophytes, and cyanobacteria corresponding to 48.9%, 68.9% and 316.2% of their initial concentrations in surface sediments were recruited in Lake Taihu. However, compared with their increase in pelagic abundance over the same period, the recruitment accounted for a rather small inoculum. Accompanying the recruitment, total phytoplankton and chlorophytes declined and cyanobacteria increased in the upper 0–2 cm sediments; colonies of Microcystis aeruginosa in the water column enlarged from small size with several cells to large colonies with hundreds of cells. Thus, overwintering and subsequent growth renewal of pelagic phytoplankton merits further study and comparison with benthic survival and recruitment. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

大兴安岭达尔滨湖菱形藻科（硅藻门）中国新记录植物

报道了采自大兴安岭达尔滨湖及其周围沼泽水体的硅藻门管壳缝目菱形藻科中国新记录植物3种、1变种,分别为Hantzschia rhaetica Meister、Hantzschia robusta Ostrup、Nitzschia dissipatavat．media（Hantzsch）Grun．、Nitzschia perminuta（Grun．）M．Peragallo。使用光学显微镜对这些种类进行了观察,对其分类学特征进行了详细的描述,并记录了它们的生境特征。     

广州蕨类植物增补

报道了广州蕨类植物新记录种38种,隶属于18科25属。其中莲座蕨科（Angiopteridaceae),膜蕨科,裸子蕨科（Gymnogrammaceae)等3科为广州新记录科,莲座蕨属（Angiopteris)。团扇蕨属（Gonocormus)。粉叶蕨属（Pityrogramme),假蹄盖蕨属（Athyriopsis)。针毛蕨属（Macrothelypteris)。狗脊属（Woodwardia),黑桫椤属（Gymnosphaera)。沙皮蕨属（Hemigramma)。线蕨属（Colysis)等9属为新记录属。     

Response of Methanogens in Arctic Sediments to Temperature and Methanogenic Substrate Availability

Although cold environments are major contributors to global biogeochemical cycles, comparatively little is known about their microbial community function, structure, and limits of activity. In this study a microcosm based approach was used to investigate the effects of temperature, and methanogenic substrate amendment, (acetate, methanol and H₂/CO₂) on methanogen activity and methanogen community structure in high Arctic wetlands (Solvatnet and Stuphallet, Svalbard). Methane production was not detected in Stuphallet sediment microcosms (over a 150 day period) and occurred within Solvatnet sediments microcosms (within 24 hours) at temperatures from 5 to 40°C, the maximum temperature being at far higher than in situ maximum temperatures (which range from air temperatures of -1.4 to 14.1°C during summer months). Distinct responses were observed in the Solvatnet methanogen community under different short term incubation conditions. Specifically, different communities were selected at higher and lower temperatures. At lower temperatures (5°C) addition of exogenous substrates (acetate, methanol or H₂/CO₂) had no stimulatory effect on the rate of methanogenesis or on methanogen community structure. The community in these incubations was dominated by members of the Methanoregulaceae/WCHA2-08 family-level group, which were most similar to the psychrotolerant hydrogenotrophic methanogen Methanosphaerula palustris strain E1-9c. In contrast, at higher temperatures, substrate amendment enhanced methane production in H₂/CO₂ amended microcosms, and played a clear role in structuring methanogen communities. Specifically, at 30°C members of the Methanoregulaceae/WCHA2-08 predominated following incubation with H₂/CO₂, and Methanosarcinaceaeand Methanosaetaceae were enriched in response to acetate addition. These results may indicate that in transiently cold environments, methanogen communities can rapidly respond to moderate short term increases in temperature, but not necessarily to the seasonal release of previously frozen organic carbon from thawing permafrost soils. However, as temperatures increase such inputs of carbon will likely have a greater influence on methane production and methanogen community structure. Understanding the action and limitations of anaerobic microorganisms within cold environments may provide information which can be used in defining region-specific differences in the microbial processes; which ultimately control methane flux to the atmosphere.     

Simultaneous Monitoring of Phosphine and of Phosphorus Species in Taihu Lake Sediments and Phosphine Emission from Lake Sediments

Phosphine (PH₃) was monitored in the Taihu Lake in China by a GC/NPD method, coupled with cryo-trapping enrichment technology. Results showed that PH₃ was universally detected in sediments, lake water and atmosphere of the Taihu Lake area. Total phosphorus (TP_s) and fractions of different phosphorus species in lake sediments were separately measured as dissolved phosphate (DP), phosphorus bound to aluminum (Al-P), iron (Fe-P) and calcium (Ca-P), occluded phosphorus (OP), and organic phosphorus (Org-P) by sequential chemical extraction. High PH₃ levels were correlated with high TP_s values in sediments and with eutrophication at different sites. In addition, a positive linear correlation equation was obtained between the concentrations of PH₃ in lake sediments and of the phosphorus fractions. The resulting multiple linear regression equation is PH₃ = −165 + 63.3 DP + 0.736 Al-P + 2.33 Ca-P + 2.29 Org-P. The flux of PH₃ across the sediment–water interface was estimated from sediment core incubation in May and October 2002. The annual average sediment–water flux of PH₃ was estimated at ca. 0.0138±0.005 pg dm⁻² h⁻¹, the average yearly emission value of PH₃ from Taihu Lake sediments to water was calculated to be 28.3±10.2 g year⁻¹, which causes a water PH₃ concentration of up to 0.178±0.064 pmol dm⁻³. The real importance of PH₃ could be higher, because PH₃ could be consumed in the oxic sediment–water boundary layer and in the water column. Spatial and temporal distributions of total phosphorus (TP_w) and chlorophyll a (Chl-a) in the water column of Taihu Lake were measured over the study period. Higher water PH₃ has also been found where the TP_w content was high. Similarly, high Chl-a was consistent with higher water PH₃. Positive relationships between PH₃ and TP_w (average R² = 0.47±0.26) and Chl-a (average R² = 0.23±0.31) were observed in Taihu Lake water.     

宁夏4种新记录植物

报道了宁夏4个新记录种(变种)——对叶兰[Neottia puberula(Maximowicz)Szlachetko]、花叶对叶兰[N.puberulavar.maculata(T.Tang et F.T.Wang)S.C.Chen et al.]、岐山金丝桃(Hypericum elatoides R.Kel-ler)和小卫矛(Euonymus nanoides Loes.et Rehd.)。     

Methyl Coenzyme M Reductase A (mcrA) Gene-Based Investigation of Methanogens in the Mudflat Sediments of Yangtze River Estuary, China

Methanogen populations of an intertidal mudflat in the Yangtze River estuary of China were investigated based on the methyl coenzyme M reductase A (mcrA) gene using 454-pyrosequencing and quantitative real-time polymerase chain reaction (qPCR). Samples were collected at six depths from three locations. In the qPCR analyses, a mean depth-wise change of mcrA gene abundance was observed from (1.23?±?0.13)×10⁷ to (1.16?±?0.29)×10⁸ per g dried soil, which was inversely correlated with the depletion of sulfate (R ²?=0.74; α?=?0.05) and salinity (R ²?=?0.66; α?=?0.05). The copy numbers of mcrA was at least 1 order of magnitude higher than dissimilatory sulfate reductase B (dsrB) genes, likely indicating the importance of methanogenesis at the mudflat. Sequences related to the orders Methanomicrobiales, Methanosarcinales, Methanobacteriales, Methanococcales and the uncultured methanogens; Rice Cluster I (RC-I), Zoige cluster I (ZC-I) and anaerobic methane oxidizing archaeal lineage-1 (ANME-1) were detected. Methanomicrobiales and Methanosarcinales dominated the entire sediment layers, but detectable changes of proportions were observed with depth. The hydrogenotrophic methanogens Methanomicrobiales slightly increased with depth while Methanosarcinales showed the reverse. Chao1 and ACE richness estimators revealed higher diversity of methanogens near the surface (0–10 cm) when compared with the bottom sediments. The near-surface sediments were mainly dominated by the family Methanosarcinaceae (45 %), which has members that can utilize substrates that cannot be used by sulfate-reducing bacteria. Overall, current data indicate that Methanosarcinales and Methanomicrobiales are the most dominant methanogens within the entire depth profile down to 100 cm, with higher abundance and diversity of methanogens in the deeper and upper sediment layers, respectively.     

Kinetic Analysis of Competition Between Sulfate Reducers and Methanogens for Hydrogen in Sediments

The competition between sulfate-reducing and methanogenic bacteria for hydrogen was investigated in eutrophic lake sediments that contained low in situ sulfate concentrations and in sulfate-amended sediments. Sulfate reduction and methane production coexisted in situ in lake surface sediments (0 to 2 cm), but methane production was the dominant terminal process. Addition of 10 to 20 mM sulfate to sediments resulted in a decrease in the hydrogen partial pressure and a concomitant inhibition of methane production over time. Molybdate inhibition of sulfate reduction in sulfate-amended sediments was followed by an increase in the hydrogen partial pressure and the methane production rate to values comparable to those in sediments not amended with sulfate. The sulfate reducer population had a half-saturation constant for hydrogen uptake of 141 pascals versus 597 pascals for the methanogen population. Thus, when sulfate was not limiting, the lower half-saturation constant of sulfate reducers enabled them to inhibit methane production by lowering the hydrogen partial pressure below levels that methanogens could effectively utilize. However, methanogens coexisted with sulfate reducers in the presence of sulfate, and the outcome of competition at any time was a function of the rate of hydrogen production, the relative population sizes, and sulfate availability.     

大兴安岭达尔滨湖桥弯藻科（硅藻门）中国新记录植物

报道了采自大兴安岭达尔滨湖及其周围沼泽水体的硅藻门桥弯藻科中国新记录植物9种1变种,分别为新箱形桥弯藻新月变种Cymbella neocistulavar.lunataKrammer、近箱形桥弯藻Cymbella subcistulaKrammer、疏纹内丝藻Encyonema paucistriatum(Cleve-Euler)Mann、普通内丝藻Encyonema vulgareKrammer、尖锐弯肋藻Cymbopleuraacuta(Schmidt)Krammer、英吉利弯肋藻Cymbopleura anglica(Lagerstedt)Krammer、线形弯肋藻Cymbopleura linearis(Foged)Krammer、十字形弯肋藻Cymbopleura stauroneiformis(Lagerstedt)Krammer、泰尼弯肋藻Cymbopleura tynnii(Krammer)Krammer、两尖拟内丝藻Encyonopsis amphioxys(K櫣tzing)Liu et Shi。其中两尖拟内丝藻Encyonopsis am-phioxys(K櫣tzing)Liu et Shi为新组合。对这些种类进行了光镜观察,部分种类进行了扫描电镜观察,对其分类学特征进行了详细的描述,并记录了它们的生境特征。     

Biomass Measurement of Methanogens in the Sediments of Tokyo Bay Using Archaeol Lipids

An archaeal ether-linked lipid, archaeol, was determined to be a biomass indicator for methanogens both in the laboratory enriched culture and in marine sediments. The archaeol measurement method described by Ohtsubo et al. in 1993 was modified and applied to marine sediments. We compared the amount of archaeol with the cell number of methanogens or methane concentration in laboratory enriched culture of methanogens from marine sediment. Good correlations were obtained as follows: (Methane, mmol) = 11.2 × (Archaeol, mg): r= .996 or (Cell number) = 1.13 × 10¹¹× (Archaeol, mg): r= .995, respectively. In the sediments of Tokyo Bay, archaeol was measured from approximately 46 to 561 ng/dry g sediment at the entrance to 267 to 4160 ng/dry g sediment at the innermost area. Using the coefficient from the laboratory experiment, these data corresponded to cell numbers of 5.2 × 10⁶ to 4.7 × 10⁸/dry g sediment. These values were 1 or 2 orders of magnitude higher than those obtained by culture methods in previous studies. Although dead or decomposed cells might be detected, archaeol measurement is useful for estimating the biomass of methanogens because of the good correlation between methane concentration and archaeol content in marine environments. In this study, we found a correlation of (Methane, mmol) = 0.012 × (Archaeol, mg): r= .932, n= 17 in marine sediments. Received December 21, 1998; accepted June 16, 1999     

Assessment of Heavy Metal Enrichment,Bioavailability, and Controlling Factors in Sediments of Taihu Lake,China

Heavy metal distribution, bioavailability, and ecological risk in the surface sediment of Taihu Lake were evaluated. Samples were collected from eight representative sites in September 2011 and February 2012. In the surface sediment, average metal contents were in the order of Cr > Zn > Ni > Pb > Cu. Spatially, Zhushan Bay maintained higher Cu, Ni, and Zn contents and Xiaomeikou maintained higher Cr and Pb contents than other sites. Spatial and temporal variation were observed in the bioavailable metals determined by acid-soluble fraction of BCR extraction. The labile metals in Zhushan Bay and Xiaomeikou were quantified by diffusive gradients in thin films (DGT) and DGT-labile concentrations of Zn, Ni, Cu, Pb, and Cd were in descending order, indicating the inconsistence of labile concentrations of different heavy metals with the total metal contents and that the toxic effect of Cd in sediment should be given attention. The ecological risk assessed by Hakanson potential ecological risk index showed that Zhushan Bay suffered the most serious pollution and should be given special attention. Bioavailability of metals should be taken into account during risk assessment for more accurate estimation.     

西藏被子植物分布新记录

首次报道了西藏被子植物8个新记录种：虎耳草科(Saxifragaceae)虎耳草属(Saxifraga Linn.)的阿墩子虎耳草(Saxifraga atuntsiensis W. W. Smith)、橙黄虎耳草(Saxifraga aurantiaca Franchet),罂粟科(Papaveraceae)紫堇属(Corydalis DC.)的雅曲距紫堇(Corydalis dolichocentra Z. Y. Su & Lidén),龙胆科(Gentianaceae)龙胆属(Gentiana Linn.)的圆萼龙胆(Gentiana suborbisepala C. Marquand),报春花科(Primulaceae)点地梅属(Androsace Linn.)的小点地梅［Androsace gmelinii (Linn.) Roemer & Schultes］,忍冬科(Caprifoliaceae)忍冬属(Lonicera Linn.)的垫状忍冬(Lonicera oreodoxa H. Smith ex Rehder J.),毛茛科(Ranunculaceae)毛茛属(Ranunculus Linn.)的川青毛茛(Ranunculus chuanchingensis L. Liou),玄参科(Scrophulariaceae)马先蒿属(Pedicularis Linn.)鹬形马先蒿(Pedicularis scolopax Maximowicz)。并提供其形态描述和照片,凭证标本保存于西藏高原生态研究所标本室(XZE)。     

中国爵床科一新记录种——翅柄裸柱草

报道中国爵床科一新记录种——翅柄裸柱草[Gymnostachyum sigantum (Benoist) J. B. Imlay],并提供了该种的描述。为名称Gymnostachyum sigantum指定了后选模式。     

Phosphorus Fractionation in Core Sediments from Haihe River Mainstream,China

Sediments from Haihe River mainstream, located in Xingjiaquan, Zhangjiazui, Tianjin, were collected and examined on the basis of P fractionation. SMT (standards, measurements and testing) procedure was adopted to investigate the changes in P concentration with depth in the core sediments collected from the different sampling sites of Haihe River mainstream. The relationships among different P fractions, such as exchangeable P (Ex-P), metal oxide bounded P (NaOH-P), organic matter and grain size, were also discussed. The results indicate that in both sites the rank order of P fractions was HCl-P > Organic P (OP) > NaOH-P > Ex-P in terms of their concentration. The Ex-P represented < 4% of the sediment total P, while the NaOH-P ranged 5–21%. The calcium bound phosphorus (HCl-P) showed considerable contribution (53–80%) to the sediment total P loads. Silt/clay sized sediments exhibited significantly higher concentrations of HCl-P and Ex-P in both sites. However, coarse-sand-sized sediments exhibited significantly higher concentrations of OP in both sites and NaOH-P in Xingjiaquan. Multivariate statistics were performed to identify the factors that influenced the sediment P.