Spatiotemporal variability in archaeal communities of tropical coastal waters

Spatiotemporal variations in the archaeal community structure from four locations along the central west coast of India were analyzed by denaturing gradient gel electrophoresis (DGGE) profiling and sequencing of prominent bands on the DGGE gels. A total of 36 water samples were collected during pre-monsoon, post-monsoon and monsoon seasons from three depths (surface, mid-depth , and close to bottom ～20 m). The community DNA extracts from these samples were subjected to DGGE analysis. The results of this study clearly indicate a significant difference in the community structure between sampling locations and seasons. Location-wise variation was more pronounced during pre-monsoon and post-monsoon seasons. During monsoon, however, the depth-wise variation was pronounced, suggesting monsoon influence on archaeal community structure. Sequencing of DGGE bands suggested the presence of marine group I and II archaea. Canonical correspondence analysis indicated that nitrate, nitrite and chlorophyll a were the significant explanatory variables responsible for > 60 % variation in archaeal community in these coastal waters.     

Temporal variability of attached and free-living bacteria in coastal waters

The temporal variability of the abundance and the incorporation of ³H-thymidine and ¹⁴C-glucose by attached and free-living bacteria, as well as their relation with environmental factors, were analyzed in a coastal marine ecosystem during a year. Both communities were quantitatively very different. Attached bacteria represented only 6.8% of the total bacterial abundance, whereas free-living bacteria represented 93.2%. The environmental factors most closely linked to the abundance and activity of free-living bacteria were temperature and the concentration of dissolved nutrients. Moreover, the free-living community showed similar temporal variations in abundance and in activity, with lower values in the cold months (from October to May). The attached community did not present the same pattern of variation as the free-living one. The abundance of the attached bacteria was mainly correlated to the concentration of particulate material, whereas their activity was correlated to temperature. We did not find a significant correlation between the abundance and the activity of the attached community. On the other hand, the activity per cell of the two communities did not present a clear temporal variation. Attached bacteria were more active than free-living ones in the incorporation of radiolabeled substrates on a per cell basis (five times more in the case of glucose incorporation and twice as active in thymidine incorporation). However, both communities showed similar specific growth rates. The results suggest that the two aquatic bacterial communities must not be considered as being independent of each other. There appears to be a dynamic equilibrium between the two communities, regulated by the concentrations of particulate matter and nutrients and by other environmental factors.Offprint requests to: M. Unanue.     

New Data on Dinosaurs of the Crimean Peninsula

Reexamination of the holotype of Riabininohadros weberae from the Upper Cretaceous (upper Maastrichtian) of the Crimean Peninsula (Besh-Kosh) allowed determination of previously unknown elements of the femur, astragalus, and calcaneus. This taxon shows a set of primitive characters observed in iguanodontids and basal ornithischians and is referred to as Styracosterna indet. The second dinosaur specimen from Crimea (Aleshino) is a fragmentary skeleton, including cervical and dorsal vertebrae. It possibly belongs to advanced iguanodontids or primitive hadrosauroids. Thus, in the Maastrichtian of the Crimean Peninsula, at least two dinosaur species coexisted.     

青岛近岸水域春、秋季鱼类群落结构

根据2004年春、秋季渔业资源底拖网调查数据,应用单元和多元统计方法分析了青岛近岸水域春、秋季鱼类群落结构。春、秋季调查分别渔获31、32种鱼类,平均每网渔获量分别为7.36kg/h和2.99kg/h,优势种类主要包括赤鼻棱鳀Thrissa chefuensis、大泷六线鱼Hexagrammo sotakii、方氏云鳚Enedrias fangi、黄鳍刺鰕虎鱼Acanthogobius flavimanus、细纹狮子鱼Liparis tanakai和长条蛇鲻Saurida elongata等。聚类分析表明,春、秋季青岛近岸水域鱼类群落都可划分为3个站位组,分别对应于北部、中部和南部调查水域。不同站位组的优势种组成变化较大,不同站位组间种类组成差异显著。分析了造成站位组内种类组成相似的特征种和造成不同站位组间相异的分歧种。不同站位组的特征种不同。赤鼻棱鳀、大泷六线鱼、黄鳍刺鰕虎鱼、方氏云鳚、星康吉鳗Conger myriaster、角木叶鲽Pleuronichthys cornutus和细纹狮子鱼是春季所有站位组间的分歧种;赤鼻棱鳀、白姑鱼Argyrosomus argentatus、大泷六线鱼、带鱼Trichiurus lepturus、短吻红舌鳎Cynoglossus joyneri、方氏云鳚、细条天竺鱼Apogonichthys lineatus、小黄鱼Pseudosciaena polyactis和矛尾鰕虎鱼Chaeturichthys stigmatias是秋季所有站位组间的分歧种。大多数特征种也是不同站位组间的分歧种,主要是由于这些种类的数量分布的空间变化造成的。青岛沿海鱼类群落结构存在明显的时空异质性。     

Temporal variability in copepod fecundity during two different spring bloom periods in coastal waters off Plymouth (SW England)

The temporal variation in egg production of the planktonic copepodsCalanus helgolandicus, Temora longicornis and Pseudocalanuselongatus was studied during two different spring bloom periodsin 1989 and 1990 by weekly sampling at two permanent stationsin coastal waters off Plymouth (SW England). Copepod egg productionwas estimated in situ by incubating individual adult femalesin filtered seawater for 24 h (72 h until hatching for P.elongatus)at the field surface temperature. The relationship between copepodegg production rates and: (i) chlorophyll a concentration (totaland >10 µm size fraction), (ii) temperature and (iii)initial copepod gut pigment content was investigated. The springbloom periods were very different in both years, with the occurrenceof a Phaeocystis sp. bloom in 1990, which negatively affectedthe feeding and fecundity of copepods. Egg production ratesin spring 1989 were significantly correlated with chlorophylla concentration (particularly with the >10 µm fraction),field temperature and copepod gut pigment contents. In spring1990, egg production rates were also correlated with copepodgut pigment contents, but no significant correlations were obtainedwith temperature or with chlorophyll a concentration, as a consequenceof the lower egg production rates obtained during the Phaeocystissp. dominance period. These results show that food availabilityis the factor which mainly affects the fecundity of neriticcopepods in short time periods.     

Phytoplankton spring bloom in the Tagus coastal waters: hydrological and chemical conditions

Spatial variability of phytoplankton as well as hydrological and chemical conditions in the Tagus coastal waters were studied during the spring of 1994. The highly patchy distribution of phytoplankton and the community structure were related to the specific abiotic conditions prevailing in the area. Two main water masses were distinguished: a tidally mixed one alongshore Lisbon-cape Espichel and a stratified region strongly related to the Tagus plume river. The latter seems to control, to some extent, the spatial phytoplankton variability and the timing and size of the spring bloom. The highest surficial levels of nutrients, specifically PO₄ ^3–=1.00 M, NO₃ ^–=16.0 M and Si(OH)₄=14.6 M, were clearly associated with Tagus river discharges, while the lowest levels were attained offshore in the zone of maximum chlorophyll a concentrations (30 mg m^–3) reflecting the occurrence of high nutrient consumption. Furthermore, the near depletion of PO₄ ^3– indicates P limitation for phytoplankton growth. The diatom Detonula pumila (0.1×10⁶ cells l^–1) was the dominant species of phytoplankton communities in the mixed zone, alongshore Lisbon-cape Espichel, whereas, the small diatom Thalassiosira sp. (3×10⁶ cells l^–1) was blooming offshore, associated with the stratified region.     

春季海南岛近岸海域尿素与浮游生物的脲酶活性

2011年春季(4-5月),对海南岛的海口湾、澄迈湾、文昌八门湾、陵水新村湾和大东海5个海湾的尿素浓度及浮游生物的脲酶活性开展调查研究,结合其它理化环境因子,分析海南岛近岸海域尿素的可利用性及其对该海区浮游植物生长可能产生的影响.结果表明,海南岛近岸水体中尿素平均浓度为2.07-3.30 μmol/L,占总溶解态氮TDN含量的14％-38％,尿素占TDN比例由北向东、南方向递增.浮游生物脲酶活性为0.30-0.84 μmolN· L-1· h-1,海口湾最高,从北部向东、南部逐渐减少.各海湾较高水平的尿素和脲酶活性主要分布在排污口、养殖区或旅游区的近岸海域.硅藻为优势种,甲藻种类少且密度低,部分甲藻密度达到104-105个/L的水体,尿素和脲酶活性也处于较高水平.海区浮游植物细胞密度与脲酶活性或尿素占TDN比例等因子存在相关性,表明尿素是海南海域浮游植物生长不可忽略的重要氮源.尿素在一定程度上促进春季海南岛近岸海域甲藻等浮游植物的生长,可能对浮游植物群落结构的改变产生重要影响.     

环梅山岛海域春季浮游古菌群落空间分布特征研究

[目的]海洋浮游古菌是生物地球化学循环的关键驱动者,但其在近岸海域的水平空间分布特征还未被充分了解.本研究以与陆地紧密相连的环梅山岛海域为例研究浮游古菌在海陆过渡带的水平分布模式.[方法]利用16S rRNA基因扩增子测序,以期从优势类群分布、群落组成变化和物种共现模式3个层面揭示梅山湾潟湖区和临近海域春季浮游古菌的空...     

Potential phytoplankton indicator species for monitoring Baltic coastal waters in the summer period

There are very few time series documenting clear trends of change in the biomass of total phytoplankton or single taxa that coincide with trends of increasing nutrient concentrations. Weekly or biweekly monitoring since 1997 on a cross section of the central Gulf of Finland (NE Baltic Sea) with similar climatic and hydrographic conditions, but different nutrient levels, provided a uniform dataset. In order to evaluate seasonal (June–September) patterns of phytoplankton succession, more than 1,200 samples were statistically analyzed by selecting 12 dominant taxa using wet weight biomass values. In addition, the continuously measured hydrographic parameters on board the ships of opportunity, and simultaneous nutrient analyses gave high frequency information on the water masses. The objective of this study was to identify the taxa that may prove indicative in the assessment of eutrophication in the appropriate monitoring time periods. None of the most common bloom-forming species (Aphanizomenon sp., Nodularia spumigena, and Heterocapsa triquetra) showed reliable correlations with enhanced nutrient concentrations. The species we suggest as reliable eutrophication indicators—oscillatorialean cyanobacteria and the diatoms Cyclotella choctawhatcheeana and Cylindrotheca closterium—showed the best relationships with total phosphorus concentrations. Their maxima appear toward the end of July or in August–September when phytoplankton community structure is more stable, and less frequent observations may give adequate results. Another diatom, Skeletonema costatum, exhibited stronger correlations with dissolved inorganic and total nitrogen in June, during the period of the summer phytoplankton minimum. Guest editors: J. H. Andersen & D. J. Conley Eutrophication in Coastal Ecosystems: Selected papers from the Second International Symposium on Research and Management of Eutrophication in Coastal Ecosystems, 20–23 June 2006, Nyborg, Denmark     

Spatio-temporal structure of tidally mixed coastal waters: variability and heterogeneity

In the tidally mixed coastal waters of the eastern English Channel,the vertical properties of temperature, salinity, in vivo fluorescence,turbidity and light were investigated along an inshore-offshoretransect, sampled in different tidal conditions. The verticaldistribution of these parameters was then characterized in termsof mean value, variability (i.e. standard deviation) and heterogeneity(i.e. fractal dimension), regarded as a quantitative characterizationof the structure of the vertical variability of both physicaland biological parameters. These different estimates were thensubjected to multivariate spatio-temporal analysis and showeda very specific spatio-temporal structure suggesting a differentialcontrol of the vertical properties of water masses associatedwith both inshore-offshore gradient and tidal advection. Inparticular, the fractal dimension (i.e. heterogeneity) of invivo fluorescence is higher during ebb for offshore waters,suggesting a density dependence of the phytoplankton biomassstructure. In contrast, the vertical variability of fluorescenceis higher during flood for inshore waters, leading to an inverserelationship between variability and heterogeneity of the verticaldistribution of phytoplankton biomass.     

Identification of Aerobic Methane-Oxidizing Bacteria in Coastal Sediments of the Crimean Peninsula

Microbiology - Methane oxidation rates and diversity of methane-oxidizing microorganisms in the upper sediment layers of the Crimean Peninsula coastal regions (Black Sea) were investigated....     

State of the Ichthyoplankton Community along the Crimean Peninsula in August 2011

Data on species composition, spatial distribution of ichthyoplankton, and feeding of fish larvae in August 2011 are presented for the shelf and the open waters along the Crimean Peninsula from Kerch Strait to Karkinit Bay. In the ichthyoplankton, fish eggs and larvae represented 19 species from 16 families. The average egg abundance was 111 egg/m² and larvae abundance was 22 ind./m². The elimination ratio of the European anchovy Engraulis encrasicolus, which dominates in the plankton from the final stages of development to the prelarvae in 2011, was similar to that observed in 1957. The high number of larvae of the older age group in the western halistatic zone is explained by the peculiarities of the hydrological regime. Decrease in the pressure of predatory jelly macroplankton and an fodder zooplankton (zooplankton abundance) contribute to the survival of the fish larvae.     

A metaproteomic assessment of winter and summer bacterioplankton from Antarctic Peninsula coastal surface waters

A metaproteomic survey of surface coastal waters near Palmer Station on the Antarctic Peninsula, West Antarctica, was performed, revealing marked differences in the functional capacity of summer and winter communities of bacterioplankton. Proteins from Flavobacteria were more abundant in the summer metaproteome, whereas winter was characterized by proteins from ammonia-oxidizing Marine Group I Crenarchaeota. Proteins prevalent in both seasons were from SAR11 and Rhodobacterales clades of Alphaproteobacteria, as well as many lineages of Gammaproteobacteria. The metaproteome data were used to elucidate the main metabolic and energy generation pathways and transport processes occurring at the microbial level in each season. In summer, autotrophic carbon assimilation appears to be driven by oxygenic photoautotrophy, consistent with high light availability and intensity. In contrast, during the dark polar winter, the metaproteome supported the occurrence of chemolithoautotrophy via the 3-hydroxypropionate/4-hydroxybutyrate cycle and the reverse tricarboxylic acid cycle of ammonia-oxidizing archaea and nitrite-oxidizing bacteria, respectively. Proteins involved in nitrification were also detected in the metaproteome. Taurine appears to be an important source of carbon and nitrogen for heterotrophs (especially SAR11), with transporters and enzymes for taurine uptake and degradation abundant in the metaproteome. Divergent heterotrophic strategies for Alphaproteobacteria and Flavobacteria were indicated by the metaproteome data, with Alphaproteobacteria capturing (by high-affinity transport) and processing labile solutes, and Flavobacteria expressing outer membrane receptors for particle adhesion to facilitate the exploitation of non-labile substrates. TonB-dependent receptors from Gammaproteobacteria and Flavobacteria (particularly in summer) were abundant, indicating that scavenging of substrates was likely an important strategy for these clades of Southern Ocean bacteria. This study provides the first insight into differences in functional processes occurring between summer and winter microbial communities in coastal Antarctic waters, and particularly highlights the important role that ‘dark'' carbon fixation has in winter.     

A metagenomic assessment of winter and summer bacterioplankton from Antarctica Peninsula coastal surface waters

Antarctic surface oceans are well-studied during summer when irradiance levels are high, sea ice is melting and primary productivity is at a maximum. Coincident with this timing, the bacterioplankton respond with significant increases in secondary productivity. Little is known about bacterioplankton in winter when darkness and sea-ice cover inhibit photoautotrophic primary production. We report here an environmental genomic and small subunit ribosomal RNA (SSU rRNA) analysis of winter and summer Antarctic Peninsula coastal seawater bacterioplankton. Intense inter-seasonal differences were reflected through shifts in community composition and functional capacities encoded in winter and summer environmental genomes with significantly higher phylogenetic and functional diversity in winter. In general, inferred metabolisms of summer bacterioplankton were characterized by chemoheterotrophy, photoheterotrophy and aerobic anoxygenic photosynthesis while the winter community included the capacity for bacterial and archaeal chemolithoautotrophy. Chemolithoautotrophic pathways were dominant in winter and were similar to those recently reported in global ‘dark ocean'' mesopelagic waters. If chemolithoautotrophy is widespread in the Southern Ocean in winter, this process may be a previously unaccounted carbon sink and may help account for the unexplained anomalies in surface inorganic nitrogen content.     

Microzooplankton herbivory and bacterivory in Newfoundland coastal waters during spring, summer and winter

Grazing by microzooplankton on autotrophic and heterotrophicpicoplankton as well as >0.7 µm phytoplankton (as measuredby chlorophyll a) was quantified during July, August, October,January and April in the surface layer of Logy Bay, Newfoundland(47°38'14'N, 52°39'36'W). Rates of growth and grazingmortality of bacteria, Synechococcus and >0.7 µm phytoplanktonwere measured using the sea water dilution technique. Microzooplanktoningested 83–184, 96–366 and 64–118% of bacterial,Synechococcus and >0.7 µm phytoplankton daily potentialproduction, respectively and 34–111, 25–30 and 16–131%of bacterial, Synechococcus and >0.7 µm phytoplanktonstanding stocks, respectively. The trends in prey net growthrates followed the seasonal cycles of prey biomass, suggestingthat microzooplankton are important grazers in Newfoundlandcoastal waters. Ingestion was lowest during January and October(~2 µg C l^–1 day^–1) and highest in August(~20 µg C l^–1 day^–1). Aside from April when>0.7 µm phytoplankton represented the majority (~80%)of carbon ingested, bacterioplankton and <1 µm phytoplanktonrepresented most of the carbon ingested (~40–100%). Althoughmicrozooplankton have here-to-fore been unrecognized as an importantgrazer population in Newfoundland coastal waters, these resultssuggest that they play an important role in carbon flow withinthe pelagic food web, even at low temperatures in Logy Bay.     

香溪河库湾春季水华期间硝酸盐、磷酸盐的时空分布

在三峡水库香溪河库湾春季水华连续暴发期间(2005年2月26日—4月28日)对香溪河与长江汇合处(河口)至香溪河库湾上游库尾处总计14个采样点进行连续监测,结果表明硝酸盐和磷酸盐在库湾中存在明显的时空分布规律。在空间上,河口的硝酸盐浓度高,库尾浓度低,其变化趋势是随着与河口距离的增加而降低;磷酸盐的分布规律是库尾的浓度高,河口的浓度低,其变化趋势与硝酸盐恰好相反。各采样点硝酸盐和磷酸盐浓度在时间上也呈现出明显的规律。河口硝酸盐的浓度在不同时间变化幅度较小,库尾采样点的硝酸盐浓度的变化幅度较大,随着与河口距离的增加硝酸盐浓度在不同时间的变化幅度逐渐增大。各样点磷酸盐在时间上的变化趋势是样点S04-S08的变化幅度较大,位于香溪河库湾河口和库尾的变化幅度较小。     

Grazing impact of micro- and mesozooplankton during a spring situation in coastal waters off the Gironde estuary

The aim of this study was to characterize the grazing link betweenphytoplankton and zooplankton. Quantifying rates of phytoplanktonutilization by micro- and mesozooplankton is an attempt to understandthe control of phytoplankton populations in marine ecosystemsand the export flux of organic matter to the depths. Sampleswere taken in the plume of dilution of the Gironde estuary duringspring (May 1995). The mesozooplankton community was dominatedby the heterotrophic dinoflagellate Noctiluca scintillans andby copepods. Our estimates showed that on average, 26% of thetotal primary production was grazed daily by mesozooplankton.However, the pressure exerted by microzooplankton on the primaryproduction was estimated to be approximately four times higher.As a consequence, during this spring situation in the plumeof dilution of the Gironde estuary when small cells dominated,microzooplankton represented the most important grazing communityand could potentially control the growth of phytoplankton.     

Feeding and diel vertical migration cycles of Metridia gerlachei (Giesbrecht) in coastal waters of the Antarctic Peninsula

Diel vertical migration and feeding cycles of adult female Metridia gerlachei in the upper 290 m of a 335-m water column were measured during a total of 65 h in two periods of early summer (Dec 20–21 and Dec 25–26, 1991). Samples collected in eight depth strata by 35 MOCNESS tows (333-m mesh) were analyzed for abundance and mean individual gut pigment content. Most of the copepod population was concentrated in a 50-m depth interval at all times. Feeding began simultaneously with nocturnal ascent from a depth of 200–250 m at 18:00 h (local time), when the relative change in ambient light intensity was greatest. Ingestion rate increased exponentially (k_i = 0.988 h^–1) at double the gut evacuation rate (k_e = 0.488 h^–1) as the population moved upward at 22.3–26.5 m h^–1 through increasing concentrations of particulate chlorophyll-a. Although the bulk of the population did not move to depths shallower than 50 m, and began its downward migration at a rate of 20.8–31.7 mh^–1 in complete darkness, individual females continued to make brief excursions into chlorophyll-rich surface waters (4–8 g l^–1) during the first few hours of population descent. Ingestion rate diminished abruptly by one order of magnitude (k_i = 0.068 h^–1) at dawn ( 0330 h). Within four more hours, the population had reached its daytime depth and gut pigment content remained constant at a minimum value until the next migration cycle. No feeding appeared to take place at depth during the day. Ingestion by M. gerlachei females removed < 4% of daily primary production, with only 20% of this amount being removed from surface waters by active vertical transport.     

A bacteriological study of geothermal spring waters dating from the dogger and trias period in the Paris Basin

An enumeration of different physiological microbial types detected in the groundwaters of four geothermic sites dating from the Dogger and Trias periods that make up the Paris Basin reveals a predominance of anaerobes over aerobes and thermophiles over mesophiles. The main biological activity is performed via chemolithotrophic metabolism. The anaerobic chemolithotrophic thermophiles are well adapted to an aquifer environment and are capable of a metabolic activity in the aquifer. More important, such microflora can cause biocorro‐sion.