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1.
J Microbiol ; 57(4): 252-262, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30929228

RESUMO

Phytoplankton and bacterioplankton play a key role in carbon cycling of aquatic ecosystems. In this study, we found that co-occurrence patterns between different types of phytoplankton, bacterioplankton, and environmental parameters in Lake Baikal during spring were different over the course of three consecutive years. The composition of phytoplankton and bacterial communities was investigated using microscopy and 16S rRNA gene pyrosequencing, respectively. Non-metric multidimensional scaling (NMDS) revealed a relationship between the structure of phytoplankton and bacterial communities and temperature, location, and sampling year. Associations of bacteria with diatoms, green microalgae, chrysophyte, and cryptophyte were identified using microscopy. Cluster analysis revealed similar correlation patterns between phytoplankton abundance, number of attached bacteria, ratio of bacteria per phytoplankton cell and environmental parameters. Positive and negative correlations between different species of phytoplankton, heterotrophic bacteria and environmental parameters may indicate mutualistic or competitive relationships between microorganisms and their preferences to the environment.


Assuntos
Organismos Aquáticos/isolamento & purificação , Bactérias/isolamento & purificação , Lagos/microbiologia , Lagos/parasitologia , Fitoplâncton/isolamento & purificação , Organismos Aquáticos/classificação , Organismos Aquáticos/genética , Bactérias/classificação , Bactérias/genética , Ecossistema , Lagos/química , Filogenia , Fitoplâncton/classificação , Fitoplâncton/genética , Estações do Ano , Temperatura Ambiente
2.
Environ Monit Assess ; 191(4): 201, 2019 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-30826892

RESUMO

Both environmental and geographic factors interact to structure the metacommunities in river networks, but the importance of these factors is difficult to distinguish. We used six aquatic taxonomic groups to test the relationship between environmental and geographic factors and their effect on species turnover patterns in an agriculturally dominated river (Chaohu Lake Basin, China). The relationships between three dissimilarity indices and geographic distance were assessed using the Mantel test while considering the differences in environmental factors between sites. Then, we employed a variation partitioning method to distinguish the isolated and combined effects of environmental and geographic distance on species turnover. There were significant relationships between environmental distance and species turnover in all groups. All organisms except periphytic diatoms were significantly correlated with two geographic (Euclidean and network) distances when the Chao dissimilarity index was considered. The results suggest that the strength of the correlations changed with environmental and geographic distances and with the aquatic community. The communities displayed more complex relationships with the distance measures when different dissimilarity (Jaccard, Chao, and Bray-Curtis dissimilarity) indices were considered. Nevertheless, aquatic communities are strongly influenced by both environmental and geographic distance, and the former has a stronger effect than the latter.


Assuntos
Biodiversidade , Diatomáceas/classificação , Monitoramento Ambiental , Peixes/classificação , Fitoplâncton/classificação , Rotíferos/classificação , Zooplâncton/classificação , Agricultura , Animais , China , Diatomáceas/isolamento & purificação , Geografia , Lagos , Fitoplâncton/isolamento & purificação , Rios , Rotíferos/isolamento & purificação , Zooplâncton/isolamento & purificação
3.
Mar Pollut Bull ; 139: 197-204, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30686419

RESUMO

A bloom of putatively non-indigenous species (NIS) Prorocentrum shikokuense was detected for the first time in the Mediterranean Sea at the Brindisi harbor (Southern Adriatic Sea) on September 2016, in the context of EU Marine Strategy Framework Directive monitoring in the ports. This species is usually observed in the East China Sea and Japanese and Korean waters. In the Brindisi harbor this dinoflagellate reached the concentration 105 cell/L and represented from 30 to 50% of the total phytoplankton population. Besides this event, Prorocentrum shikokuense has not been found blooming until today in Mediterranean waters. This study suggests the necessity to improve the monitoring surveys in areas that are known vulnerable systems to alien and invasive species, such as ports.


Assuntos
Dinoflagelados/isolamento & purificação , Monitoramento Ambiental/métodos , Espécies Introduzidas/tendências , Fitoplâncton/isolamento & purificação , Água do Mar/química , Eutrofização , Itália , Mar Mediterrâneo
4.
Toxins (Basel) ; 11(1)2019 01 14.
Artigo em Inglês | MEDLINE | ID: mdl-30646509

RESUMO

Blooms of Dinophysis acuminata occur every year in Galicia (northwest Spain), between spring and autumn. These blooms contaminate shellfish with lipophilic toxins and cause lengthy harvesting bans. They are often followed by short-lived blooms of Dinophysis acuta, associated with northward longshore transport, at the end of the upwelling season. During the summers of 1989 and 1990, dense blooms of D. acuta developed in situ, initially co-occurring with D. acuminata and later with the paralytic shellfish toxin-producer Gymnodinium catenatum. Unexplored data from three cruises carried out before, during, and following autumn blooms (13⁻14, 27⁻28 September and 11⁻12 October) in 1990 showed D. acuta distribution in shelf waters within the 50 m and 130 m isobaths, delimited by the upwelling front. A joint review of monitoring data from Galicia and Portugal provided a mesoscale view of anomalies in SST and other hydroclimatic factors associated with a northward displacement of the center of gravity of D. acuta populations. At the microscale, re-examination of the vertical segregation of cell maxima in the light of current knowledge, improved our understanding of niche differentiation between the two species of Dinophysis. Results here improve local transport models and forecast of Dinophysis events, the main cause of shellfish harvesting bans in the most important mussel production area in Europe.


Assuntos
Bivalves , Dinoflagelados/isolamento & purificação , Ácido Okadáico/análise , Frutos do Mar/análise , Animais , Contagem de Células , Monitoramento Ambiental , Fitoplâncton/isolamento & purificação , Portugal , Estações do Ano , Água do Mar/microbiologia
5.
Microb Ecol ; 77(2): 288-303, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30019110

RESUMO

Two annual Baltic Sea phytoplankton blooms occur in spring and summer. The bloom intensity is determined by nutrient concentrations in the water, while the period depends on weather conditions. During the course of the bloom, dead cells sink to the sediment where their degradation consumes oxygen to create hypoxic zones (< 2 mg/L dissolved oxygen). These zones prevent the establishment of benthic communities and may result in fish mortality. The aim of the study was to determine how the spring and autumn sediment chemistry and microbial community composition changed due to degradation of diatom or cyanobacterial biomass, respectively. Results from incubation of sediment cores showed some typical anaerobic microbial processes after biomass addition such as a decrease in NO2- + NO3- in the sediment surface (0-1 cm) and iron in the underlying layer (1-2 cm). In addition, an increase in NO2- + NO3- was observed in the overlying benthic water in all amended and control incubations. The combination of NO2- + NO3- diffusion plus nitrification could not account for this increase. Based on 16S rRNA gene sequences, the addition of cyanobacterial biomass during autumn caused a large increase in ferrous iron-oxidizing archaea while diatom biomass amendment during spring caused minor changes in the microbial community. Considering that OTUs sharing lineages with acidophilic microorganisms had a high relative abundance during autumn, it was suggested that specific niches developed in sediment microenvironments. These findings highlight the importance of nitrogen cycling and early microbial community changes in the sediment due to sinking phytoplankton before potential hypoxia occurs.


Assuntos
Bactérias/isolamento & purificação , Cianobactérias/crescimento & desenvolvimento , Diatomáceas/crescimento & desenvolvimento , Sedimentos Geológicos/microbiologia , Fitoplâncton/crescimento & desenvolvimento , Bactérias/classificação , Bactérias/genética , Biomassa , Cianobactérias/classificação , Cianobactérias/genética , Cianobactérias/isolamento & purificação , Diatomáceas/classificação , Diatomáceas/genética , Diatomáceas/isolamento & purificação , Eutrofização , Sedimentos Geológicos/química , Nitratos/análise , Nitratos/metabolismo , Nitritos/análise , Nitritos/metabolismo , Filogenia , Fitoplâncton/classificação , Fitoplâncton/genética , Fitoplâncton/isolamento & purificação , Estações do Ano , Água do Mar/química , Água do Mar/microbiologia
6.
PLoS One ; 13(11): e0206821, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30462664

RESUMO

This study assessed the distribution, abundance, and viability of pre- and post-overwintering Microcystis sediment seed stocks in Western Lake Erie and how these variables are potentially related to past and subsequent bloom formation. We conducted a two-year spatiotemporal survey of vegetative seed stocks in Western Lake Erie, the region where annual algal blooms generally develop. Sediment was collected from 16 sites covering an area of 375 km2 and water column depths ranging from 3-9 meters. Sample collection occurred in November 2014, April 2015, November 2015, and April 2016. The abundance of total and potentially-toxic Microcystis cell equivalents were determined using quantitative polymerase chain reaction. A series of laboratory experiments using lake sediment were conducted to assess the viability of Microcystis vegetative seed stocks. Across all sampling periods, the abundance of total Microcystis in the sediment ranged from 6.6 x 10(4) to 1.7 x 10(9) cell equivalents g-1, and potentially-toxic Microcystis ranged from 1.4 x 10(3) to 4.7 x 10(6) cell equivalents g-1. The percent potentially-toxic Microcystis in the sediment ranged from <1% to 68% across all samples. Total Microcystis abundance diminished significantly over winter with densities in spring nearly 10 times less than the previous fall. However, despite cell loss from fall to spring, lab experiments demonstrated that remaining non-toxic and potentially-toxic cells were viable after the overwintering period. Further, lab grow-out experiments indicate that potentially-toxic strains recruited at a slightly higher rate than non-toxic strains, and may in part, contribute to the pattern of higher relative toxicity during early stages of the blooms. The abundance and distribution of overwintering cells did not correlate strongly to areas in the lake where subsequent summer blooms were most persistent. However, numerical analysis suggests that recruitment of benthic overwintering populations could help explain a portion of the initial rapid increase in bloom biomass and the spatial extent of this bloom initiation, particularly when recruitment is paired with subsequent growth in appropriate water column conditions.


Assuntos
Sedimentos Geológicos/microbiologia , Proliferação Nociva de Algas , Lagos/microbiologia , Microcystis/fisiologia , Fitoplâncton/fisiologia , Biomassa , Microcystis/isolamento & purificação , Fitoplâncton/isolamento & purificação , Reação em Cadeia da Polimerase em Tempo Real , Estações do Ano , Análise Espaço-Temporal
7.
Protist ; 169(5): 615-631, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30096708

RESUMO

To understand the diversity of the diatom genus Chaetoceros Ehrenberg, the C. lorenzianus complex was previously chosen as a model and three new species were described. In the present study, yet another new species, Chaetoceros pauciramosus sp. nov., was discovered from Chinese tropical waters and the temperate south-eastern Baltic Sea. In the latter locality it has been known since 2003 and identified as C. cf lorenzianus, and now found to comprise a dominating component of the autumn phytoplankton community. Vegetative cells and resting spores were examined by light and electron microscopy. The LSU and SSU of the nuclear rDNA were sequenced. The characters suggesting that C. pauciramosus belongs to C. lorenzianus complex are: 1) the vegetative cells contain four or more chloroplasts, 2) the cells have stiff setae and form regular straight chains, 3) the terminal setae differ in the direction from the intercalary setae. The relationship was well-supported by molecular phylogenetic analyses inferred from both LSU and SSU markers. The primary valve of the resting spore has two conical elevations, each with dichotomously branching processes, similar to other species in the C. lorenzianus complex. Each process forms a tree-like structure with the pointed distal tips which possess one or two thin spikes, that distinguishes C. pauciramosus from allied taxa. In the phylogenetic trees, Chaetoceros pauciramosus clustered with C. elegans, in agreement with their morphologically similar resting spores.


Assuntos
Diatomáceas/isolamento & purificação , Fitoplâncton/isolamento & purificação , Águas Salinas/análise , Água do Mar/parasitologia , China , DNA Ribossômico/genética , Diatomáceas/classificação , Diatomáceas/genética , Diatomáceas/crescimento & desenvolvimento , Filogenia , Fitoplâncton/classificação , Fitoplâncton/genética , Fitoplâncton/crescimento & desenvolvimento , Água do Mar/análise
8.
ISME J ; 12(11): 2807-2810, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30013161

RESUMO

Metabarcoding has offered unprecedented insights into microbial diversity. In many studies, short DNA sequences are binned into consecutively lower Linnaean ranks, and ranked groups (e.g., genera) are the units of biodiversity analyses. These analyses assume that Linnaean ranks are biologically meaningful and that identically ranked groups are comparable. We used a metabarcode dataset for marine planktonic diatoms to illustrate the limits of this approach. We found that the 20 most abundant marine planktonic diatom genera ranged in age from 4 to 134 million years, indicating the non-equivalence of genera because some have had more time to diversify than others. However, species richness was largely independent of genus age, suggesting that disparities in species richness among genera were better explained by variation in rates of speciation and extinction. Taxonomic classifications often do not reflect phylogeny, so genus-level analyses can include phylogenetically nested genera, further confounding rank-based analyses. These results underscore the indispensable role of phylogeny in understanding patterns of microbial diversity.


Assuntos
Diatomáceas/classificação , Biodiversidade , Código de Barras de DNA Taxonômico , Diatomáceas/genética , Diatomáceas/isolamento & purificação , Filogenia , Fitoplâncton/classificação , Fitoplâncton/genética , Fitoplâncton/isolamento & purificação
9.
Sci Rep ; 8(1): 9405, 2018 06 20.
Artigo em Inglês | MEDLINE | ID: mdl-29925879

RESUMO

Oceanic gateways are sensitive to climate driven processes. By connecting oceans, they have a global influence on marine biological production and biogeochemical cycles. The furthest north of these gateways is Nares Strait at the top of the North Water between Greenland and Ellesmere Island (Canada). This gateway is globally beneficial, first by supporting high local mammal and bird populations and second with the outflow of phosphate-rich Arctic waters fueling the North Atlantic spring bloom. Both sides of the North Water are hydrologically distinct with counter currents that make this Arctic portal a Janus gateway, after Janus, the Roman god of duality. We examined oceanographic properties and differences in phytoplankton and other protist communities from the eastern and western sides of the North Water (latitude 76.5°N) and found that species differed markedly due to salinity stratification regimes and local hydrography. Typical Arctic communities were associated with south flowing currents along the Canadian side, while potentially noxious Pseudo-nitzschia spp. were dominant on the Greenland side and associated with greater surface freshening from ice melt. This susceptibility of the Greenland side to Pseudo-nitzschia spp. blooms suggest that monitoring species responses to climate mediated changes is needed.


Assuntos
Água Doce/microbiologia , Água do Mar/microbiologia , Regiões Árticas , Mudança Climática , Groenlândia , Fitoplâncton/genética , Fitoplâncton/isolamento & purificação
10.
Harmful Algae ; 75: 94-104, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29778229

RESUMO

This paper presents a novel portable sample filtration/concentration system, designed for use on samples of microorganisms with very low cell concentrations and large volumes, such as water-borne parasites, pathogens associated with faecal matter, or toxic phytoplankton. The example application used for demonstration was the in-field collection and concentration of microalgae from seawater samples. This type of organism is responsible for Harmful Algal Blooms (HABs), an example of which is commonly referred to as "red tides", which are typically the result of rapid proliferation and high biomass accumulation of harmful microalgal species in the water column or at the sea surface. For instance, Karenia brevis red tides are the cause of aquatic organism mortality and persistent blooms may cause widespread die-offs of populations of other organisms including vertebrates. In order to respond to, and adequately manage HABs, monitoring of toxic microalgae is required and large-volume sample concentrators would be a useful tool for in situ monitoring of HABs. The filtering system presented in this work enables consistent sample collection and concentration from 1 L to 1 mL in five minutes, allowing for subsequent benchtop sample extraction and analysis using molecular methods such as NASBA and IC-NASBA. The microalga Tetraselmis suecica was successfully detected at concentrations ranging from 2 × 105 cells/L to 20 cells/L. Karenia brevis was also detected and quantified at concentrations between 10 cells/L and 106 cells/L. Further analysis showed that the filter system, which concentrates cells from very large volumes with consequently more reliable sampling, produced samples that were more consistent than the independent non-filtered samples (benchtop controls), with a logarithmic dependency on increasing cell numbers. This filtering system provides simple, rapid, and consistent sample collection and concentration for further analysis, and could be applied to a wide range of different samples and target organisms in situations lacking laboratories.


Assuntos
Monitoramento Ambiental/métodos , Filtração/métodos , Proliferação Nociva de Algas , Microalgas/isolamento & purificação , Replicação de Sequência Autossustentável/métodos , Filtração/instrumentação , Fitoplâncton/isolamento & purificação , Água do Mar/análise , Replicação de Sequência Autossustentável/instrumentação
11.
Can J Microbiol ; 64(11): 786-797, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-29791806

RESUMO

The spatiotemporal shifts of the bacterioplankton community can mirror their transition of functional traits in an aquatic ecosystem. However, the spatiotemporal variation of the bacterioplankton community composition structure (BCCS) within a large, shallow, highly dynamic freshwater lake is still poorly understood. Here, we examined the seasonal and spatial variability of the BCCs within Poyang Lake by sequencing the 16S rRNA gene amplicon to explore how hydrological changes affect the BCCs. Principal coordinate analysis showed that the BCCs varied significantly among four sampling seasons, but not spatially. The seasonal changes of the BCCs were mainly attributed to the differences between autumn and spring-winter. Higher α diversity indices were observed in autumn. Redundancy analysis indicated that the BCCs co-variated with water level, pH, temperature, total phosphorus, ammoniacal nitrogen, electrical conductivity, total nitrogen, and turbidity. Among them, water level was the key determinant separating autumn BCCs from the BCCs in other seasons. A significantly lower relative abundance of Burkholderiales (betI and betVII) and a higher relative abundance of Actinomycetales (acI, acTH1, and acTH2) were found in autumn than in other seasons. Overall, our results suggest that water level changes associated with pH, temperature, and nutrient status shaped the seasonal patterns of the BCCs within Poyang Lake.


Assuntos
Actinomycetales/isolamento & purificação , Burkholderia/isolamento & purificação , Água Doce/microbiologia , Lagos/microbiologia , Fitoplâncton/isolamento & purificação , Estações do Ano , Microbiologia da Água , Actinomycetales/genética , Organismos Aquáticos , Biodiversidade , Burkholderia/genética , Ecossistema , Nitrogênio/análise , Fósforo/análise , Fitoplâncton/genética , RNA Bacteriano/genética , RNA Ribossômico 16S/genética
12.
FEMS Microbiol Ecol ; 94(5)2018 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-29562328

RESUMO

To quantitatively link microbial identity with biogeochemical function, we carried out 14 simultaneous stable isotope probing experiments with organic and inorganic C and N substrates to measure the isotope incorporation by over one hundred co-occurring eukaryotic and prokaryotic populations in a coastal community. We found that nitrate was the most commonly incorporated substrate, and that light-driven carbon fixation was carried out by some bacterial taxa from the Flavobacteriales and OM60 (NOR5) clade, in addition to photoautotrophic phytoplankton. We found that organisms that incorporated starch, maltose, glucose, lactose and bicarbonate were phylogenetically clustered, suggesting that specific bacterial lineages specialized in the incorporation of these substrates. The data further revealed that coastal microorganisms spanned a range of resource utilization strategies from generalists to specialists and demonstrated a high level of substrate partitioning, with two thirds of taxa exhibiting unique substrate incorporation patterns and the remaining third shared by no more than three OTUs each. Specialists exhibited more extreme incorporation levels (high or low), whereas generalists displayed more intermediate activity levels. These results shed valuable insights into the bottom-up ecological strategies enabling the persistence of high microbial diversity in aquatic ecosystems.


Assuntos
Bactérias/metabolismo , Isótopos/metabolismo , Microbiota , Água do Mar/microbiologia , Bactérias/classificação , Bactérias/genética , Bactérias/isolamento & purificação , Isótopos de Carbono/metabolismo , Isótopos de Nitrogênio/metabolismo , Filogenia , Fitoplâncton/classificação , Fitoplâncton/genética , Fitoplâncton/isolamento & purificação , Fitoplâncton/metabolismo
13.
FEMS Microbiol Ecol ; 94(4)2018 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-29360960

RESUMO

Photosynthetic picoeukaryotes (PPEs) play an important role in aquatic ecosystem functioning. There is still a relative lack of information on freshwater PPEs, especially in eutrophic lakes. We used a combination of flow cytometric sorting and pyrosequencing to investigate the PPEs community structure in more than 20 mesotrophic and eutrophic lakes along the middle-lower reaches of the Yangtze River in China. The abundance of PPEs ranged between 2.04 × 103 and 5.92 × 103 cells mL-1. The contribution of PPEs to total picophytoplankton abundance was generally higher in eutrophic lakes than in mesotrophic lakes. The sequencing results indicated that the Shannon diversity of PPEs was significantly higher in mesotrophic lakes than in eutrophic lakes. At the class level, PPEs were mainly dominated by three taxonomic groups, including Cryptophyceae, Coscinodiscophyceae and Chlorophyceae, and 15 additional known phytoplankton classes, including Synurophyceae, Dinophyceae, Chrysophyceae, Trebouxiophyceae and Prymnesiophyceae, were identified. Coscinodiscophyceae dominated in the most eutrophic lakes, while Chrysophyceae, Dinophyceae and other classes of PPEs were more abundant in the mesotrophic lakes. We also observed several PPEs operational taxonomic units, and those affiliated with Cyclotella atomus, Chlamydomonas sp. and Poterioochromonas malhamensis tended to be more prevalent in the eutrophic lakes. The canonical correspondence analysis and Mantel analysis highlighted the importance of environmental parameters as key drivers of PPEs community composition.


Assuntos
Chrysophyta/isolamento & purificação , Criptófitas/isolamento & purificação , Diatomáceas/isolamento & purificação , Dinoflagelados/isolamento & purificação , Haptófitas/isolamento & purificação , Lagos/parasitologia , Fitoplâncton/isolamento & purificação , Rios/parasitologia , Estramenópilas/isolamento & purificação , China , Clorófitas/classificação , Clorófitas/genética , Chrysophyta/classificação , Chrysophyta/genética , Criptófitas/classificação , Criptófitas/genética , Diatomáceas/classificação , Diatomáceas/genética , Dinoflagelados/classificação , Dinoflagelados/genética , Ecossistema , Citometria de Fluxo , Haptófitas/classificação , Haptófitas/genética , Fotossíntese , Fitoplâncton/classificação , Fitoplâncton/genética , Estramenópilas/classificação , Estramenópilas/genética
14.
ISME J ; 12(1): 237-252, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-29064479

RESUMO

Temperate coastal marine environments are replete with complex biotic and abiotic interactions that are amplified during spring and summer phytoplankton blooms. During these events, heterotrophic bacterioplankton respond to successional releases of dissolved organic matter as algal cells are lysed. Annual seasonal shifts in the community composition of free-living bacterioplankton follow broadly predictable patterns, but whether similar communities respond each year to bloom disturbance events remains unknown owing to a lack of data sets, employing high-frequency sampling over multiple years. We capture the fine-scale microdiversity of these events with weekly sampling using a high-resolution method to discriminate 16S ribosomal RNA gene amplicons that are >99% identical. Furthermore, we used 2 complete years of data to facilitate identification of recurrent sub-networks of co-varying microbes. We demonstrate that despite inter-annual variation in phytoplankton blooms and despite the dynamism of a coastal-oceanic transition zone, patterns of microdiversity are recurrent during both bloom and non-bloom conditions. Sub-networks of co-occurring microbes identified reveal that correlation structures between community members appear quite stable in a seasonally driven response to oligotrophic and eutrophic conditions.


Assuntos
Bactérias/isolamento & purificação , Biodiversidade , Fitoplâncton/isolamento & purificação , Bactérias/genética , Eutrofização , Fitoplâncton/genética , RNA Ribossômico 16S/genética , Estações do Ano , Água do Mar/microbiologia
15.
Environ Microbiol ; 20(2): 506-520, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-28984410

RESUMO

We compared the composition of eukaryotic communities using two genetic markers (18S rRNA V4 and V9 regions) at 27 sites sampled during Ocean Sampling Day 2014, with a focus on photosynthetic groups and, more specifically green algae (Chlorophyta). Globally, the V4 and V9 regions of the 18S rRNA gene provided similar images of alpha diversity and ecological patterns. However, V9 provided 20% more OTUs built at 97% identity than V4. 34% of the genera were found with both markers and, of the remnant, 22% were found only with V4 and 44% only with V9. For photosynthetic groups, V4 and V9 performed equally well to describe global communities at different taxonomic levels from the division to the genus and provided similar Chlorophyta distribution patterns. However, at lower taxonomic level, the V9 dataset failed for example to describe the diversity of Dolichomastigales (Chlorophyta, Mamiellophyceae) emphasizing the lack of V9 sequences for this group and the importance of the reference database for metabarcode analysis. We conclude that in order to address questions regarding specific groups (e.g., a given genus), it is necessary to choose the marker based not only on the genetic divergence within this group but also on the existence of reference sequences in databases.


Assuntos
Clorófitas/classificação , Fitoplâncton/classificação , RNA Ribossômico 18S/genética , Clorófitas/genética , Eucariotos/classificação , Eucariotos/genética , Eucariotos/isolamento & purificação , Fotossíntese , Filogenia , Fitoplâncton/genética , Fitoplâncton/isolamento & purificação
16.
ISME J ; 12(2): 463-472, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29160864

RESUMO

Genetic diversity is what selection acts on, thus shaping the adaptive potential of populations. We studied micro-evolutionary patterns of the key planktonic diatom Pseudo-nitzschia multistriata at a long-term sampling site over 2 consecutive years by genotyping isolates with 22 microsatellite markers. We show that both sex and vegetative growth interplay in shaping intraspecific diversity. We document a brief but massive demographic and clonal expansion driven by strains of the same mating type. The analysis of an extended data set (6 years) indicates that the genetic fingerprint of P. multistriata changed over time with a nonlinear pattern, with intermittent periods of weak and strong diversification related to the temporary predominance of clonal expansions over sexual recombination. These dynamics, rarely documented for phytoplankton, contribute to the understanding of bloom formation and of the mechanisms that drive microevolution in diatoms.


Assuntos
Diatomáceas/crescimento & desenvolvimento , Diatomáceas/genética , Evolução Biológica , Diatomáceas/isolamento & purificação , Variação Genética , Repetições de Microssatélites , Fitoplâncton/genética , Fitoplâncton/crescimento & desenvolvimento , Fitoplâncton/isolamento & purificação
17.
Sci Total Environ ; 625: 185-193, 2018 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-29289004

RESUMO

Autotrophic picoplankton (0.2-2µm) can be a significant contributor to primary production and hence play an important role in carbon flow. The phytoplankton community structure in the Baltic Sea is very region specific and the understanding of the composition and dynamics of pico-size phytoplankton is generally poor. The main objective of this study was to determine the contribution of picoeukaryotic algae and their taxonomic composition in late summer phytoplankton community of the West-Estonian Archipelago Sea. We found that about 20% of total chlorophyll a (Chl a) in this area belongs to autotrophic picoplankton. With increasing total Chl a, the Chl a of autotrophic picoplankton increased while its contribution in total Chl a decreased. Picoeukaryotes play an important role in the coastal area of the Baltic Sea where they constituted around 50% of the total autotrophic picoplankton biomass. The most abundant groups of picoeukaryotic algae were cryptophytes (16%), chlorophytes (13%) and diatoms (9%). Picocyanobacteria were clearly dominated by phycoerythrin containing Synechococcus. The parallel use of different assessment methods (CHEMTAX and flow cytometry) revealed the share of eukaryotic and prokaryotic part of autotrophic picoplankton.


Assuntos
Processos Autotróficos , Clorofila/análise , Fitoplâncton/isolamento & purificação , Clorofila A , Estônia , Citometria de Fluxo , Fitoplâncton/classificação , Água do Mar
18.
Sci Total Environ ; 613-614: 1551-1565, 2018 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-28886916

RESUMO

Chlorophyll and phytoplankton distribution and concentration in the Gulf of Cadiz were studied during 2014 and 2015. In both years the highest chlorophyll concentrations are found at coastal stations during spring. Pico- and nanophytoplankton are the main contributors to total chlorophyll, with highest concentrations at the outer limit of the continental shelf. Microphytoplankton is responsible for most of the inshore chlorophyll. Picophytoplankton was analyzed to determine density, biomass and distribution. Prochlorococcus and Synechococcus show differences in distribution depending on distance from the coast and depth. Our results suggest temperature and consequent water stratification seem to be the main factors determining deep fluorescence maxima (DFM), mainly formed by picophytoplankton, especially Prochlorococcus. Pigment identification assisted by CHEMTAX analysis was carried out to analyze relative concentrations of larger phytoplankton.


Assuntos
Clorofila/análise , Fitoplâncton/isolamento & purificação , Estações do Ano , Oceano Atlântico , Biomassa , Espanha , Temperatura Ambiente
19.
Water Sci Technol ; 76(9-10): 2554-2564, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-29144313

RESUMO

Water pollution has been a significant issue in the Huai River Basin (HRB) of China since the late 1970s. In July and December 2013, two field investigations were carried out at 10 sites along the main streams of the basin. The monitoring indices contained both physicochemical variables and the structure and composition of phytoplankton communities. The correlations between communities and physicochemical variables were analyzed using cluster analysis and redundancy analysis. Moreover, water quality was evaluated using the comprehensive nutrition state index (TLI) and Shannon-Wiener diversity index (H). Results indicated that more phytoplankton species were present in December than in July, but total density was less in December. Phytoplankton communities in the midstream of the Shaying River were affected by the same physicochemical factors throughout the year, but ammonia nitrogen and total phosphorus had the greatest influence on these sites in July and December, respectively. The water pollution status of the sampling sites was much greater in the Shaying River midstream than at other sites. TLI was more suitable than H for assessing water quality in the study area. These results provide valuable information for policy makers and stakeholders in water quality assessment, water ecosystem restoration, and sustainable basin management in the HRB.


Assuntos
Fitoplâncton/classificação , Plantas/classificação , Rios/química , Poluentes Químicos da Água/análise , Biodiversidade , China , Ecossistema , Fósforo/análise , Fósforo/metabolismo , Fitoplâncton/crescimento & desenvolvimento , Fitoplâncton/isolamento & purificação , Fitoplâncton/metabolismo , Desenvolvimento Vegetal , Plantas/metabolismo , Poluentes Químicos da Água/metabolismo , Poluição da Água/análise , Qualidade da Água
20.
Mar Pollut Bull ; 125(1-2): 199-207, 2017 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-28823423

RESUMO

In this study, we used flow cytometry and 16S rRNA gene pyrosequencing to investigate bacterioplankton (heterotrophic bacteria and picocyanobacteria) abundance and community structure in surface waters along the Pearl River Estuary. The results showed significant differences in bacterioplankton dynamics between fresh- and saltwater sites and between wet and dry season. Synechococcus constituted the majority of picocyanobacteria in both seasons. During the wet season, Synechococcus reached extremely high abundance at the mouth of the estuary, and heterotrophic bacteria were highly abundant (>106cellsml-1) throughout the studied region. At the same time, bacterioplankton decreased dramatically during the dry season. Pyrosequencing data indicated that salinity was a key parameter in shaping microbial community structure during both seasons. Phytoplankton was also an important factor; the proportion of Synechococcus and Rhodobacteriales was elevated at the frontal zone with higher chlorophyll a during the wet season, whereas Synechococcus were markedly reduced during the dry season.


Assuntos
Bactérias/isolamento & purificação , Fitoplâncton/isolamento & purificação , Microbiologia da Água , Bactérias/genética , Clorofila/análise , Clorofila A , Estuários , Citometria de Fluxo , Fitoplâncton/genética , RNA Ribossômico 16S/genética , Rios/microbiologia , Salinidade , Estações do Ano , Temperatura Ambiente
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