Microbial Distribution in a Hydrothermal Plume of the Southwest Indian Ridge

Hydrothermal plumes are widely distributed throughout the global spreading ridges, yet few of them are microbiologically explored. The ultraslow-spreading ridges, recently recognized as a unique, new class of mid-ocean-ridge system, have provided surprises and new insights in hydrothermal system research. A suite of water column samples including both hydrothermal plume samples and ambient seawater were collected at different depths from the ultraslow-spreading Southwest Indian Ridge (SWIR) in 2010. We use molecular approaches such as clone libraries, denaturing gradient gel electrophoresis (DGGE) and quantitative PCR to determine microbial community compositions and their spatial variability within the hydrothermal plume and seawater. Phylogenetic analysis showed that plume samples were mainly dominated by members of α-Proteobacteria and γ-Proteobacteria and members of marine group I group within the Crenarchaeota. Within the hydrothermal plume, archaeal populations were spatially homogeneous, while bacterial compositions were heterogeneous and remarkably distinct at different depths. Moreover, several lineages, closely related to known Mn(II) oxidizers were found to be abundant and even predominant within the plume bacterial communities. DGGE band patterns showed that there was no significant difference in microbial compositions between the samples of hydrothermal plume and ambient seawater. Taken together, we inferred that microbial communities in the SWIR hydrothermal plumes were sourced from ambient seawater rather than from seafloor vent-derived niches. This is the first report on the characteristics of microbial community structures in hydrothermal plume and ambient seawater in the Southwest Indian Ridge.     

Comparison of a New Thiomicrospira Strain from the Mid-Atlantic Ridge with Known Hydrothermal Vent Isolates

A new autotrophic Thiomicrospira strain, MA-3, was isolated from the surface of a polymetal sulfide deposit collected at a Mid-Atlantic Ridge hydrothermal vent site. The DNA homology among three vent isolates, Thiomicrospira crunogena, Thiomicrospira sp. strain L-12, and Thiomicrospira sp. strain MA-3, was 99.3% or higher, grouping them as the same species, T. crunogena (type strain, ATCC 35932). The fact that T. crunogena and Thiomicrospira sp. strain L-12 were isolated from Pacific vent sites demonstrates a cosmopolitan distribution of this species.     

Bacteria of the gamma-subclass Proteobacteria associated with zooplankton in Chesapeake Bay

The seasonal abundance of gamma-subclass Proteobacteria, Vibrio-Photobacterium, Vibrio cholerae-Vibrio mimicus, Vibrio cincinnatiensis, and Vibrio vulnificus in the Choptank River of Chesapeake Bay associated with zooplankton was monitored from April to December 1996. Large (>202- microm) and small (64- to 202- microm) size classes of zooplankton were collected, and the bacteria associated with each of the zooplankton size classes were enumerated by fluorescent oligonucleotide direct count. Large populations of bacteria were found to be associated with both the large and small size classes of zooplankton. Also, the species of bacteria associated with the zooplankton showed seasonal abundance, with the largest numbers occurring in the early spring and again in the summer, when zooplankton total numbers were correspondingly large. Approximately 0.01 to 40.0% of the total water column bacteria were associated with zooplankton, with the percentage of the total water column bacteria population associated with zooplankton varying by season. A taxonomically diverse group of bacteria was associated with zooplankton, and a larger proportion was found in and on zooplankton during the cooler months of the year, with selected taxa comprising a larger percent of the Bacteria in the summer. V. cholerae-V. mimicus and V. vulnificus comprised the bulk of the large and small zooplankton-associated Vibrio-Photobacterium species. In contrast, V. cincinnatiensis accounted for less than 0.1 to 3%. It is concluded that water column and zooplankton bacterial populations vary independently with respect to species composition since no correlation was observed between taxa occurring with highest frequency in the water column and those in association with zooplankton.     

Distribution of zooplankton community in Mediterranean-climate lakes

The sometimes sharp thermal variations and irregular precipitations and force concentrated over short periods characterize the Mediterranean climate. The structure of the zooplanktonic settlement was analyzed during one year in three Algerian reservoirs (lakes) with different geographical and climatic situation, in relation to abiotic factors (temperature, dissolved oxygen, pH, suspended matter, carbonates, nitrogenized and phosphorated nutritive salts). A canonical correspondence analysis was used to estimate the influence of the abiotic factors on the temporal distribution.The studied lakes are located, on the one hand, in northern Algeria, in a sub-humid area (Lake Boukourdane) and, on the other hand, in the South of the country, in the arid region (Foum El Ghorza and Djorf Torba). Analysis of the environmental parameters indicates that there is a seasonal variation in the three reservoirs. In Lake Foum El Ghorza, the temperature and hydrology variations, linked with the arid climate, affects the concentration of dissolved oxygen, which strongly decreases (1.5 mg/l), involving a pH reduction; suspended matters are sometimes high, coming from the stripped catchment area, causing a turbidity in this not very deep lake. The study of the distribution of the species allowed us to highlight a seasonal temporal variation. Lake Boukourdane, in the sub-humid zone, has an increased specific richness (SR=13). The various species evolve in alternation during the annual cycle. The representative species of this lake is Copidodiaptomus numidicus, characteristic of the rainy and endemic zone of the western Mediterranean; it is dominant (67%) in the spring. The Stenothermal species Diaphanosoma brachyurum, endemic of hot waters, is common to the two lakes; it evolves particularly in the summer (51.3%) at Boukourdane, whereas it is perennial and dominant (55%) in the spring at Djorf Torba. The specific richness is lower in Djorf Torba (SR=7) and in Foum El Ghorza (SR=6). The species collected in these two lakes are common and cosmopolitan, but they are adapted to the extreme conditions of the arid climate. Nevertheless, the species evolving in Lake Foum El Ghorza have undergone a significant decline, which has reduced the number of species and their density in the summer-autumn period. Thus, we can say that in the studied lakes, the hydrological factors and the temperature related to the Mediterranean climate would be two of the principal causes of the temporal distribution of the species. To cite this article: M. Cherbi et al., C. R. Biologies 331 (2008).     

Higher zooplankton species richness associated with an invertebrate top predator

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Distribution of surface zooplankton and seabirds across the Southern Ocean

Surface zooplankton and seabird densities and community composition in the Atlantic (between Cape Town and Sanae) and Pacific (between New Zealand and the Ross Sea) sectors of the Southern Ocean are described and related to oceanographic features. Samples were collected during two return voyages aboard the MV Benjamin Bowring as part of the Transglobe Expedition (1979–1981). High abundances of surface zooplankton and seabirds were consistently observed within the main frontal systems of the Southern Ocean. Generally, on a mesoscale significant correlations between surface temperature and the distribution of zooplankton or seabirds were observed. On a macroscale, the geographical positions of the zooplankton and seabird communities coincided with specific water masses. The results of this study suggest that appropriate food availability rather than water temperature is important for the determination of seabird distribution. The ecological importance of the recently described frontal zone associated with the northern boundary of the maximum winter expansion of sea ice is confirmed by biological data obtained in this study.     

Occurrence and Diversity of Yeasts in the Mid-Atlantic Ridge Hydrothermal Fields Near the Azores Archipelago

The yeast community associated with deep-sea hydrothermal systems of the Mid-Atlantic Rift was surveyed for the first time. This study relied on a culture-based approach using two different growth media: a conventional culture medium for yeasts supplemented with sea salts (MYPss) and the same medium additionally supplemented with sulfur (MYPssS). For the evaluation of species diversity, a molecular approach involving minisatellite-primed polymerase chain reaction (MSP-PCR) strain typing and sequence analysis of the D1/D2 domains of the 26S rDNA was followed. In the seven water samples that were studied, the number of colony-forming units per liter (cfu/L) ranged from 0 to 5940. The nonpigmented yeasts were much more abundant than the pink-pigmented ones. This disproportion was not observed in studies of other marine systems and may be due to the unique conditions of hydrothermal vents, characterized by a rich animal and microbial diversity and therefore by the availability of organic compounds utilizable by yeasts. Higher counts of nonpigmented yeast were obtained using MYPss, whereas for pink yeasts, higher counts were obtained using MYPssS. Moreover, among pink yeasts, some of the MSP-PCR classes obtained were composed of isolates obtained only on MYPssS, which might be an indication that these isolates are adapted to the ecosystems of the hydrothermal vents. Twelve phylotypes belonged to the Ascomycota and seven phylotypes belonged to the Basidiomycota. The nonpigmented yeasts were identified as Candida atlantica, C. atmosphaerica, C. lodderae, C. parapsilosis, Exophiala dermatitidis, Pichia guilliermondii, and Trichosporon dermatis, whereas the pigmented yeasts were identified as Rhodosporidium diobovatum, R. sphaerocarpum, R. toruloides, and Rhodotorula mucilaginosa. Some of the yeasts that were found belong to phylogenetic groups that include species reported from other marine environments, and eight phylotypes represent undescribed species. The new phylotypes found at Mid-Atlantic Ridge hydrothermal fields represent 33% of the total number of yeast taxa that were found.     

Atmospheric nitrogen deposition is associated with elevated phosphorus limitation of lake zooplankton

Here, we present data that for the first time suggests that the effects of atmospheric nitrogen (N) deposition on nutrient limitation extend into the food web. We used a novel and sensitive assay for an enzyme that is over‐expressed in animals growing under dietary phosphorus (P) deficiency (alkaline phosphatase activity, APA) to assess the nutritional status of major crustacean zooplankton taxa in lakes across a gradient of atmospheric N deposition in Norway. Lakes receiving high N deposition had suspended organic matter (seston) with significantly elevated carbon:P and N:P ratios, indicative of amplified phytoplankton P limitation. This P limitation appeared to be transferred up the food chain, as the cosmopolitan seston‐feeding zooplankton taxa Daphnia and Holopedium had significantly increased APA. These results indicate that N deposition can impair the efficiency of trophic interactions by accentuating stoichiometric food quality constraints in lake food webs.     

Distribution patterns of zooplankton in Tjeukemeer, The Netherlands

The vertical and horizontal distribution of Copepoda and Cladocerain Tjeukemeer were studied. Indices of dispersion are discussed,the sample variance of log-transformed data proved to be anappropriate way to quantify patchiness. Indices of dispersionwere calculated to express species specific differences. Onlyduring short periods of the year the population densities appearedto be influenced by canals and pumping stations that bring waterto the lake. Dispersion values were influenced by windspeed,inhomogenities in the chlorophyll-a concentrations and by thepopulation densities of the populations studied. Sample variancesare relatively low, compared with those of other lakes.     

Diversity and Abundance of Ammonia-Oxidizing Archaea in Hydrothermal Vent Chimneys of the Juan de Fuca Ridge

The abundance and diversity of archaeal ammonia monooxygenase subunit A (amoA) genes from hydrothermal vent chimneys at the Juan de Fuca Ridge were investigated. The majority of the retrieved archaeal amoA sequences exhibited identities of less than 95% to those in the GenBank database. Novel ammonia-oxidizing archaea may exist in the hydrothermal vent environments.Ammonia-oxidizing archaea (AOA) may play important roles in carbon and nitrogen cycles in various temperate environments (5, 7, 10, 12, 16). The frequent detection (23, 24) and successful enrichment (2, 6) of thermophilic AOA from terrestrial hot springs suggested a wide distribution of thermophilic AOA in geothermal environments. High concentrations of NH₄⁺ (1, 9, 11) and high rates of ammonia oxidation (9, 22) have been observed at the Juan de Fuca Ridge. However, the presence of AOA in this deep-sea hydrothermal system has not been reported. Here, the abundance and diversity of AOA in three hydrothermal vent chimneys in the Endeavor segment of the Juan de Fuca Ridge were investigated by targeting the conserved amoA genes. This is also the first report on AOA from deep-sea hydrothermal vent chimneys.These vent chimneys were sulfide structures obtained in the fall of 2005 using the submersible Alvin on board the research vessel Atlantis (dive numbers 4143, 4136, and 4148). Chimney 4148 was an active black smoker venting at around 310°C in the Main Endeavor field (47°56.876′N, 129°5.915′W; depth, 2,192 m). Chimney 4143-1 was an active black smoker venting at 316°C in the Mothra field (47°55.424′N, 129°6.533′W; depth, 2,267 m). The outer layers (samples 4148-1A and 4143-1A) of these chimneys were used in this study. The sample from chimney 4136-1 was from a diffusive field (Clambed field) (47°57.909′N, 129°5.443′W; depth, 2,200 m), where the in situ temperature was measured as 29.2°C. The chimney samples were stored at −20°C on board, transported to the home laboratory on dry ice, and stored at −80°C until analyses were performed.Chimney samples were frozen in liquid nitrogen and milled upon thawing. This procedure was repeated three times to break down the solid sample into small particles, which were then mixed with DNA extraction buffer for DNA isolation as described before (25). The obtained crude DNA was purified by an E-Z N.A. Cycle-Pure kit (Omega Bio-Tek Inc., Norcross, GA). PCR amplifications for the archaeal 16S rRNA gene, the crenarchaeal marine group I (MGI) 16S rRNA gene, the archaeal amoA gene, and the bacterial amoA gene followed procedures previously described (Table ​(Table1)1) (3, 5, 10, 14). Quantitative PCR (Q-PCR) was performed using a model 7500 real-time system (Applied Biosystems, United Kingdom) and a 20-μl reaction mixture that consisted of 1 μl (1 to 10 ng) of DNA as the template, a 0.15 μM concentration of each primer, and 10 μl of Power SYBR green PCR master mix (Applied Biosystems, United Kingdom) with ROX and SYBR green I. The inserted PCR fragments of clones 4143-1A-71 (from the amoA gene library) and 4136-1-4 (from the archaeal 16S rRNA gene library) were amplified and purified to generate standard DNAs for amoA or archaeal 16S rRNA gene quantification. A serial dilution of standard DNAs was performed to generate calibration curves for sample quantification. A melting curve analysis was performed after amplification, and the cycle threshold was set automatically using system 7500 software, version 1.3.

TABLE 1.

PCR primers and procedures used in this study

Isolation of Aerobic Anoxygenic Photosynthetic Bacteria from Black Smoker Plume Waters of the Juan de Fuca Ridge in the Pacific Ocean

A strain of the aerobic anoxygenic photosynthetic bacteria was isolated from a deep-ocean hydrothermal vent plume environment. The in vivo absorption spectra of cells indicate the presence of bacteriochlorophyll a incorporated into light-harvesting complex I and a reaction center. The general morphological and physiological characteristics of this new isolate are described.     

Distribution and abundance of zooplankton in the Waikato River,New Zealand

Potamoplankton is often a well developed component in large lowland rivers, yet little is known about its structure in New Zealand's longest river, the Waikato River. To redress this gap we sampled bimonthly at seven sites along the length of the river over 12 months. Rotifers were the dominant zooplankton in the Waikato River making up 85% of the total densities. Cladocerans represented 9% and copepods only 6%. Rotifers were also the most taxonomically rich group with 41 species in 20 genera identified throughout the study. Thirty rotifer species and nine genera represent new records for the river – two cladoceran species were also recorded for the first time. The highest densities of crustaceans and rotifers were found in the hydro lakes. Densities of crustaceans decreased with increasing distance downstream and densities of rotifers were on average 15 times greater than crustaceans in the lower river. The seasonality of Crustacea was similar to that in New Zealand lakes and rivers with high densities in summer and minimum densities over the winter period. Total rotifer densities showed a similar trend although there were marked seasonal differences between individual species.     

Distribution of zooplankton in the estuary of Keretskaya Guba (White Sea)

The horizontal heterogeneity of common zooplankton species in the Keretskaya Guba tidal estuary in the White Sea was studied. Based on an analysis of a series of simultaneously taken samples and the dispersion index, I _w = σ²/[`(m)]bar{m} (where σ<sup>2</sup> is dispersion and [`(m)]bar{m} is average population number), the existence of two and more levels of aggregation in most of the studied zooplankton species was found. The formation of patches of 1–20 m was most likely determined by biological causes, while patches some hundreds of meters long were formed due to the hydrodynamic conditions of the area.     

舟山海域夏、秋季浮游动物的分布特征及其与环境因子的关系

为更好地了解舟山海域浮游动物的群落结构、生物量和丰度的时空分布特征及其与主要环境因子的关系,分别于2014年7月和10月进行了夏季、秋季两次生态综合调查,并用多维尺度分析法、典范对应分析法对浮游动物群落结构进行了研究。结果表明:夏季舟山海域调查的浮游动物有13类,64种,优势种为背针胸刺水蚤(Centropages dorsispinatus)、圆唇角水蚤(Labidocera rotunda)、中华哲水蚤(Calanus sinicus)、精致真刺水蚤(Euchaeta concinna)、百陶带箭虫(Zonosagitta bedoti)和真刺唇角水蚤(Labidocera euchaeta);秋季鉴定到浮游动物12类,45种,优势种为背针胸刺水蚤(Centropages dorsispinatus)、百陶带箭虫(Zonosagitta bedoti)、双生水母(Diphyes chamissonis)、瓜水母(Beroёcucumis)和中华哲水蚤。夏季浮游动物平均丰度及平均生物量(144.0 ind/m3和176.3 mg/m~3)都分别高于秋季(21.4个/m3和86.3 mg/m3);Shannon-Wiener多样性指数夏季(3.03)高于秋季(2.82),Pielou均匀度指数则是秋季(0.83)高于夏季(0.64);夏季不同区域浮游动物群落之间具有明显的差异,而秋季大部分站位群落之间差异不显著;温度、盐度、叶绿素a浓度和营养盐含量是影响舟山海域浮游动物分布的主要环境因子;与历史资料相比,舟山海域浮游动物丰度及生物量呈下降趋势,其优势种保持较稳定。     

Distribution and abundance of zooplankton populations in Crater Lake,Oregon

The zooplankton assemblages in Crater Lake exhibited consistency in species richness and general taxonomic composition, but varied in density and biomass during the period between 1988 and 2000. Collectively, the assemblages included 2 cladoceran taxa and 10 rotifer taxa (excluding rare taxa). Vertical habitat partitioning of the water column to a depth of 200 m was observed for most species with similar food habits and/or feeding mechanisms. No congeneric replacement was observed. The dominant species in the assemblages were variable, switching primarily between periods of dominance of Polyarthra-Keratella cochlearis and Daphnia. The unexpected occurrence and dominance of Asplanchna in 1991 and 1992 resulted in a major change in this typical temporal shift between Polyarthra-K. cochlearis and Daphnia. Following a collapse of the zooplankton biomass in 1993 that was probably caused by predation from Asplanchna, Kellicottia dominated the zooplankton assemblage biomass between 1994 and 1997. The decline in biomass of Kellicottia by 1998 coincided with a dramatic increase in Daphnia biomass. When Daphnia biomass declined by 2000, Keratella biomass increased again. Thus, by 1998 the assemblage returned to the typical shift between Keratella-Polyarthra and Daphnia. Although these observations provided considerable insight about the interannual variability of the zooplankton assemblages in Crater Lake, little was discovered about mechanisms behind the variability. When abundant, kokanee salmon may have played an important role in the disappearance of Daphnia in 1990 and 2000 either through predation, inducing diapause, or both. Electronic supplementary material Electronic supplementary material is available for this article at and accessible for authorised users.     

Low archaeal diversity linked to subseafloor geochemical processes at the Lost City Hydrothermal Field, Mid-Atlantic Ridge

The recently discovered Lost City Hydrothermal Field (LCHF) represents a new type of submarine hydrothermal system driven primarily by exothermic serpentinization reactions in ultramafic oceanic crust. Highly reducing, alkaline hydrothermal environments at the LCHF produce considerable quantities of hydrogen, methane and organic molecules through chemo- and biosynthetic reactions. Here, we report the first analyses of microbial communities inhabiting carbonate chimneys awash in warm, high pH fluids at the LCHF and the predominance of a single group of methane-metabolizing Archaea. The predominant phylotype, related to the Methanosarcinales, formed tens of micrometre-thick biofilms in regions adjacent to hydrothermal flow. Exterior portions of active structures harboured a diverse microbial community composed primarily of filamentous Eubacteria that resembled sulphide-oxidizing species. Inactive samples, away from regions of hydrothermal flow, contained phylotypes related to pelagic microorganisms. The abundance of organisms linked to the volatile chemistry at the LCHF hints that similar metabolic processes may operate in the subseafloor. These results expand the range of known geological settings that support biological activity to include submarine hydrothermal systems that are not dependent upon magmatic heat sources.     

Distribution, diversity and biomass of summer zooplankton from the coastal Canadian Beaufort Sea

Composition, abundance, biomass and distribution of zooplankton in the coastal Canadian Beaufort Sea were studied in the summer of 2005 and 2006. Data were collected from two cross-shelf transects (11 stations in each). Sampling was conducted with vertical hauls using a conical net of 153-μm mesh size. Our results revealed that there are three ecological zones, Intense Plume, Diffuse Plume and oceanic, which are primarily shaped by the highly variable Mackenzie River plume. The Intense Plume Grouping was located at stations influenced greatly by the Mackenzie River, where Podon leuckarti, Pseudocalanus spp., Copepoda nauplii and Limnocalanus macrurus were most abundant. The Diffuse Plume Grouping, that was located in the transitional zone between the river plume and the ocean, had the highest diversity. This grouping was characterised by high abundance of Copepoda nauplii, Polychaeta larvae, Pseudocalanus and L. macrurus. The Oceanic Grouping, located farthest from shore beyond the 85-m depth contour, was mainly inhabited by marine taxa—Calanus glacialis, C. hyperboreus, Triconia (Oncea) borealis and Microcalanus spp.—and had the greatest overall zooplankton abundance and biomass of all groupings.     

Changes in zooplankton community structure associated with the disappearance of invasive alewife in Saginaw Bay, Lake Huron

We evaluated the response of the zooplankton community Saginaw Bay, Lake Huron to the disappearance of the planktivore alewife Alosa pseudoharengus using data collected in 1991–1996 (pre alewife decline) and 2009–2010 (post alewife decline). Bosmina longirostris, Diaptomidae, Cyclops, and Daphnia galeata contributed greatly to the separation of the two time periods with Diaptomidae and D. galeata increasing and Cyclops and B. longirostris decreasing, although B. longirostris remained the dominant species. Peak densities of zooplankton occurred in early summer (June) in the 1990s and in early fall (October) in 2009–2010. For the analysis of environmental variables on a bay-wide, annual basis, abundance of alewife, age-0 yellow perch Perca flavescens and Bythotrephes captured much of the variation in annual zooplankton community structure. Abundances of Bythotrephes and age-0 yellow perch were both higher in 2009–2010 than in 1991–1996. Some changes such as increasing proportions of calanoid copepods reflect a more oligotrophic community and are potentially indicative of resource-driven changes rather than direct or indirect impacts of the alewife disappearance.     

Evidence for Methylotrophic Symbionts in a Hydrothermal Vent Mussel (Bivalvia: Mytilidae) from the Mid-Atlantic Ridge

Symbioses between chemolithoautotrophic bacteria and the major macrofaunal species found at hydrothermal vents have been reported for numerous sites in the Pacific Ocean. We present microscopical and enzymatic evidence that methylotrophic bacteria occur as intracellular symbionts in a new species of mytilid mussel discovered at the Mid-Atlantic Ridge hydrothermal vents. Two distinct ultrastructural types of gram-negative procaryotic symbionts were observed within gill epithelial cells by transmission electron microscopy: small coccoid or rod-shaped cells and larger coccoid cells with stacked intracytoplasmic membranes typical of methane-utilizing bacteria. Methanol dehydrogenase, an enzyme diagnostic of methylotrophs, was detected in the mytilid gills, while tests for ribulose-1,5-bisphosphate carboxylase, the enzyme diagnostic of autotrophy via the Calvin cycle, were negative. Stable carbon isotope values (δ¹³C) of mytilid tissue (−32.7 and −32.5% for gill and foot tissues, respectively) fall within the range of values reported for Pacific vent symbioses but do not preclude the use of vent-derived methane reported to be isotopically heavy relative to biogenically produced methane.