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1.
Nat Commun ; 12(1): 1150, 2021 02 19.
Artigo em Inglês | MEDLINE | ID: mdl-33608542

RESUMO

The formation of sinking particles in the ocean, which promote carbon sequestration into deeper water and sediments, involves algal polysaccharides acting as an adhesive, binding together molecules, cells and minerals. These as yet unidentified adhesive polysaccharides must resist degradation by bacterial enzymes or else they dissolve and particles disassemble before exporting carbon. Here, using monoclonal antibodies as analytical tools, we trace the abundance of 27 polysaccharide epitopes in dissolved and particulate organic matter during a series of diatom blooms in the North Sea, and discover a fucose-containing sulphated polysaccharide (FCSP) that resists enzymatic degradation, accumulates and aggregates. Previously only known as a macroalgal polysaccharide, we find FCSP to be secreted by several globally abundant diatom species including the genera Chaetoceros and Thalassiosira. These findings provide evidence for a novel polysaccharide candidate to contribute to carbon sequestration in the ocean.


Assuntos
Carbono/metabolismo , Diatomáceas/metabolismo , Eutrofização/fisiologia , Polissacarídeos/metabolismo , Anticorpos , Ciclo do Carbono , Sequestro de Carbono , Epitopos , Glicômica , Mar do Norte , Polissacarídeos/imunologia , Água do Mar/química
2.
Nat Commun ; 12(1): 1211, 2021 02 22.
Artigo em Inglês | MEDLINE | ID: mdl-33619262

RESUMO

Primary production in the Southern Ocean (SO) is limited by iron availability. Hydrothermal vents have been identified as a potentially important source of iron to SO surface waters. Here we identify a recurring phytoplankton bloom in the high-nutrient, low-chlorophyll waters of the Antarctic Circumpolar Current in the Pacific sector of the SO, that we argue is fed by iron of hydrothermal origin. In January 2014 the bloom covered an area of ~266,000 km2 with depth-integrated chlorophyll a > 300 mg m-2, primary production rates >1 g C m-2 d-1, and a mean CO2 flux of -0.38 g C m-2 d-1. The elevated iron supporting this bloom is likely of hydrothermal origin based on the recurrent position of the bloom relative to two active hydrothermal vent fields along the Australian Antarctic Ridge and the association of the elevated iron with a distinct water mass characteristic of a nonbuoyant hydrothermal vent plume.


Assuntos
Eutrofização/fisiologia , Fontes Hidrotermais/química , Ferro/farmacologia , Oceanos e Mares , Fitoplâncton/crescimento & desenvolvimento , Regiões Antárticas , Biomassa , Carbono/análise , Clorofila/análise , Eutrofização/efeitos dos fármacos , Cinética , Nitrogênio/análise , Fósforo/análise , Fitoplâncton/efeitos dos fármacos , Água/química
3.
Nat Commun ; 12(1): 570, 2021 01 25.
Artigo em Inglês | MEDLINE | ID: mdl-33495440

RESUMO

Melting of the Greenland Ice Sheet is a leading cause of land-ice mass loss and cryosphere-attributed sea level rise. Blooms of pigmented glacier ice algae lower ice albedo and accelerate surface melting in the ice sheet's southwest sector. Although glacier ice algae cause up to 13% of the surface melting in this region, the controls on bloom development remain poorly understood. Here we show a direct link between mineral phosphorus in surface ice and glacier ice algae biomass through the quantification of solid and fluid phase phosphorus reservoirs in surface habitats across the southwest ablation zone of the ice sheet. We demonstrate that nutrients from mineral dust likely drive glacier ice algal growth, and thereby identify mineral dust as a secondary control on ice sheet melting.


Assuntos
Eutrofização/fisiologia , Camada de Gelo , Microalgas/crescimento & desenvolvimento , Minerais/metabolismo , Fósforo/metabolismo , Biomassa , Ecossistema , Congelamento , Geografia , Aquecimento Global , Groenlândia , Gelo , Microalgas/citologia , Microalgas/ultraestrutura , Microscopia Eletrônica de Varredura , Estações do Ano
4.
Environ Monit Assess ; 192(2): 94, 2020 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-31907685

RESUMO

A multimetric water quality standards (WQS) attainment indicator (MMI) was created to assess the habitat quality of the Chesapeake Bay and its tidal tributaries. The indicator uses metrics of dissolved oxygen concentrations, water clarity assessments, underwater bay grass acreages, and season-specific chlorophyll a distributions. This suite of metrics is recognized as symptomatic of eutrophication and responsive to nutrient and sediment management actions. Habitat criteria for these metrics were established by the US Environmental Protection Agency (USEPA) to protect the survival, growth, and reproduction of tidal bay living resources. The criteria were adopted into state WQS used to define outcome targets of the regulatory 2010 Chesapeake Bay Total Maximum Daily Load (TMDL). Direct accounting of monitoring results compared with state standards would be the most direct measure of water quality status related to achieving habitat health goal conditions under the TMDL. However, the Chesapeake Bay Program long-term water quality monitoring program that supports Clean Water Act 303d water quality impairment assessments does not provide sufficient measurement resolution across all temporal scales represented in these TMDL-related WQS. Recognizing data and analysis gaps, we developed the indicator to provide estimates of WQS attainment for the Chesapeake Bay. The structure of the indicator uses metrics that have been measured consistently with the historical Chesapeake Bay tidal water quality data collections since 1985. The ability to compute scores on contemporary and historical data will provide for bay-wide and spatially explicit long-term trend evaluations of habitat quality.


Assuntos
Baías/química , Monitoramento Ambiental/métodos , Qualidade da Água/normas , Clorofila A/análise , Ecossistema , Eutrofização/fisiologia , Oxigênio/análise , Estados Unidos , United States Environmental Protection Agency
5.
Environ Sci Pollut Res Int ; 26(35): 35779-35786, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31705409

RESUMO

The effects of eutrophication on the growth and phenotypic performance of macrophytes have been widely studied. Experimental evidence suggests that an increase in the water nutrient level would promote the performance of several invasive free-floating macrophytes. However, few studies have focused on how a shift in water nutrient (nitrogen and phosphorus) stoichiometric regimes may influence the performance of invasive free-floating macrophytes. In the present study, two exotic invasive plant species, free-floating Eichhornia crassipes and Pistia stratiotes, were subjected to different water nutrient stoichiometric regimes, and their phenotypic performance was studied. We found that the two species converged in several resource use traits and diverged in lateral root length. This implied that their similarities in fitness-correlated traits and their underwater niche differentiation probably contribute to their stable coexistence in the field. Additionally, the eutrophic conditions in the different N:P regimes scarcely altered the performance of both species compared to their performance in the oligotrophic condition. Based on previous studies, we predicted that moderate eutrophication with slight overloading of nitrogen and phosphorus would not improve the performance of several invasive free-floating plants and thus would scarcely alter the invasive status of these species. However, moderate eutrophication may cause other problems, such as the growth of phytoplankton and algae and increased pollution in the water.


Assuntos
Araceae/química , Eichhornia/crescimento & desenvolvimento , Eutrofização/fisiologia , Nitrogênio/análise , Fósforo/análise , Fitoplâncton/química , Poluentes Químicos da Água/análise , China , Eichhornia/química , Espécies Introduzidas , Nitrogênio/química , Nutrientes , Fósforo/química , Água
6.
Environ Monit Assess ; 191(9): 586, 2019 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-31440835

RESUMO

Lakes and reservoirs around the world are facing a substantial water quality degradation problem that poses significant environmental, social, and economic impacts. Reservoir productivity is influenced primarily by the climatic, morphometric, and hydro-edaphic features. High nutrient loadings in the reservoir from agriculture runoff often provide ideal conditions for algal blooms, leading to eutrophication. Reservoir and lake management to prevent or reduce eutrophication, therefore, has become the need of the hour. The traditional approach of trophic state monitoring by rigorous field surveys and eutrophication modeling has been revised in the present study by developing a new trophic state index (TSI)-based model for tropical shallow freshwater reservoirs. The new model has been constructed based on Carlson's Limnology and Oceanography, 22, 361-369, (1977) guidelines by establishing an empirical relationship between trophic parameters including total phosphorus (TP), Secchi disk depth (SDD), and chlorophyll (Chl-a). After comparing the new model with various earlier models for its applicability and validation with actual field conditions, it was found to be most precise over previous TSI models. Temporal and spatial fluctuations in the water quality of the Tiru reservoir were primarily attributed to the changing climatic conditions during the study period. Seasonal monsoon with less frequency, heavy nutrient loading from agriculture runoff, and increased turbidity due to a high level of sediment inflow during monsoon raised the TSI (SDD) values of the Tiru reservoir to place it in the hyper-eutrophic class. Average TSI values during winter for SDD, Chl-a, and TP were indicative of the meso-eutrophic to eutrophic state. Saturation of nutrients due to low water level during summer season caused the poly-eutrophic condition for TSI (SDD)- and TSI (TP)-based estimates and eutrophic condition as per TSI (Chl-a) estimates. However, seasonal deviations of the TSI values based on the relationship between TSI (Chl-a) and TSI (SD) indicated a predominance of smaller particles (non-algal turbidity) during all seasons. Even though TP present in the Tiru reservoir is controlling the algal production, it is also affected by low-light conditions due to non-algal turbidity. The recommendation from this study is that the TSI method for estimating the health of the water bodies is the efficient, cost-effective, and time-saving approach. The model developed during the study would help managers and policy makers to take necessary steps to reduce eutrophication levels in the reservoir and would be helpful for researchers in developing new concepts and protocols, mainly focusing on shallow freshwater reservoirs.


Assuntos
Clorofila/análise , Monitoramento Ambiental/métodos , Eutrofização/fisiologia , Fósforo/análise , Poluentes Químicos da Água/análise , Agricultura , Clima , Lagos/química , Modelos Teóricos , Estações do Ano , Qualidade da Água , Abastecimento de Água
7.
Artigo em Inglês | MEDLINE | ID: mdl-31450850

RESUMO

Nutrients released from sediments have a significant influence on the water quality in eutrophic lakes and reservoirs. To clarify the internal nutrient load and provide reference for eutrophication control in Yuqiao Reservoir, a drinking water source reservoir in China, pore water profiles and sediment core incubation experiments were conducted. The nutrients in the water (soluble reactive P (SRP), nitrate-N (NO3--N), nitrite-N (NO2--N), and ammonium-N (NH4+-N)) and in the sediments (total N (TN), total P (TP) and total organic carbon (TOC)) were quantified. The results show that NH4+-N was the main component of inorganic N in the pore water. NH4+-N and SRP were higher in the pore water than in the overlying water, and the concentration gradient indicated a diffusion potential from the sediment to the overlying water. The NH4+-N, NO3--N, and SRP fluxes showed significant differences amongst the seasons. The NH4+-N and SRP fluxes were significantly higher in the summer than in other seasons, while NO3--N was higher in the autumn. The sediment generally acted as a source of NH4+-N and SRP and as a sink for NO3--N and NO2--N. The sediments release 1133.15 and 92.46 tons of N and P, respectively, to the overlying water each year.


Assuntos
Monitoramento Ambiental , Sedimentos Geológicos/química , Lagos/química , Poluentes Químicos da Água/análise , China , Monitoramento Ambiental/métodos , Eutrofização/fisiologia , Humanos , Nutrientes , Análise Espaço-Temporal , Qualidade da Água/normas
8.
Sci Rep ; 9(1): 11144, 2019 07 31.
Artigo em Inglês | MEDLINE | ID: mdl-31366993

RESUMO

We present the results of an analysis of the 16S rRNA-based taxonomical structure of bacteria together with an analysis of carbon source utilization ability using EcoPlate (Biolog, USA) metabolic fingerprinting assessment against the backdrop of physicochemical parameters in fifteen interconnected lakes. The lakes exhibit a wide spectrum of trophic gradients and undergo different intensities of anthropopressure. Sequences of V3-V4 16S rRNA genes binned by taxonomic assignment to family indicated that bacterial communities in the highly eutrophicated lakes were distinctly different from the bacterial communities in the meso-eutrophic lakes (ANOSIM r = 0.99, p = 0.0002) and were characterized by higher richness and more diverse taxonomical structure. Representatives of the Actinobacteria, Proteobacteria, Cyanobacteria, Planctomycetes, Verrucomicrobia, Bacteroides phyla predominated. In most cases their relative abundance was significantly correlated with lake trophic state. We found no similar clear relationship of community-level physiological profiling with lake trophic state. However, we found some significant links between the taxonomic and metabolic structure of the microbes in the studied lakes (Mantel's correlation r = 0.22, p = 0.006). The carbon source utilization ability of the studied microorganisms was affected not only by the taxonomic groups present in the lakes but also by various characteristics like a high PO43- concentration inhibiting the utilization of phosphorylated carbon.


Assuntos
Bactérias/genética , Eutrofização/fisiologia , Lagos/microbiologia , Biodiversidade , Carbono/metabolismo , Sedimentos Geológicos/microbiologia , RNA Ribossômico 16S/genética
9.
Sci Rep ; 9(1): 8395, 2019 06 10.
Artigo em Inglês | MEDLINE | ID: mdl-31182791

RESUMO

Lake Winnipeg was coined "Canada's sickest lake" and "the most threatened lake in the World" due to its recurrent algal blooms caused by nutrient-rich water inputs. While conceptual frameworks link bloom occurrence to hydrologic connectivity, data-based validation is lacking. We analyzed 355 multi-year satellite-derived images to quantify phytoplankton biomass in Lake Winnipeg and the timing of runoff activation and hydrologic connectivity in the Lake Winnipeg Watershed. Our analyses reveal that the majority of watershed runoff-producing areas exhibit a strong coupling between runoff activation and hydrologic connectivity: they are proximal to rivers and become hydrologically connected to them multiple times a year. Conversely, a smaller number of runoff-producing areas are located further upslope and connect to rivers much less frequently. The latter act as water gatekeepers by selectively enabling the downstream transfer of runoff from headwater regions. Major blooms in Lake Winnipeg only occur when 50% of the water gatekeepers enable headwater-downstream connectivity during 31.5% (or more) of the spring-fall period. We conclude that an explicit assessment of the timing of runoff activation and hydrologic connectivity serves as a predictor of bloom occurrence and provides new information about the influence of a small number of locations on Lake Winnipeg.


Assuntos
Eutrofização/fisiologia , Lagos , Fitoplâncton/fisiologia , Água , Biomassa , Geografia , Hidrologia , Estações do Ano , Fatores de Tempo
10.
Artigo em Inglês | MEDLINE | ID: mdl-31159184

RESUMO

To study the microbial community structure in sediments and its relation to eutrophication environment factors, the sediments and the overlying water of Sancha Lake were collected in the four seasons. MiSeq high-throughput sequencing was conducted for the V3-V4 hypervariable regions of the 16S rRNA gene and was used to analyze the microbial community structure in sediments. Pearson correlation and redundancy analysis (RDA) were conducted to determine the relation between microbial populations and eutrophic factors. The results demonstrated four main patterns: (1) in the 36 samples that were collected, the classification annotation suggested 64 phyla, 259 classes, 476 orders, 759 families, and 9325 OTUs; (2) The diversity indices were ordered according to their values as with summer > winter > autumn > spring; (3) The microbial populations in the four seasons belonged to two distinct characteristic groups; (4) pH, dissolved oxygen (DO), total phosphorus (TP), and total nitrogen (TN) had significant effects on the community composition and structure, which further affected the dissolved total phosphorus (DTP) significantly. The present study demonstrates that the microbial communities in Sancha Lake sediments are highly diverse, their compositions and distributions are significantly different between spring and non-spring, and Actinobacteria and Cyanobacteria may be the key populations or indicator organisms for eutrophication.


Assuntos
Eutrofização/fisiologia , Sedimentos Geológicos/química , Lagos/microbiologia , Microbiota , Actinobacteria/crescimento & desenvolvimento , China , Cianobactérias/crescimento & desenvolvimento , Concentração de Íons de Hidrogênio , Nitrogênio/análise , Oxigênio/análise , Fósforo/análise , RNA Ribossômico 16S , Estações do Ano
11.
Environ Pollut ; 252(Pt B): 1325-1334, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31252130

RESUMO

The ammonium (NH4+) pool in the water column of eutrophic lakes is dynamic and undergoes tightly coupled production and consumption processes because of the metabolism of bacterial and algal communities, particularly in summer. However, NH4+ recycling rates along nutrient gradients at river-lake transitional zones and the extent to which NH4+ regeneration can compensate for consumption have been poorly studied. In August (flood period) and November (normal period), 2016, NH4+ regeneration rates (REGs) and potential uptake rates (Upots) were measured in northwestern Lake Taihu and adjacent rivers. Results showed that the REGs ranged from 0.09 to 3.30 µmol N L-1 h-1 and the Upots ranged from 0.20 to 4.88 µmol N L-1 h-1, with higher recycling rates occurring at the river sites. Yet, the lake sites showed significantly higher water column NH4+ demand (WCAD) than that of the adjacent river sites during both seasons (p < 0.05), probably as a result of the low REGs and the lack of exogenous nitrogen (N) inputs. The flood period showed significantly higher REG and Upot values than those of the normal period (p < 0.05), probably controlled by higher water temperature and algal biomass. This study confirms that regenerated NH4+ was more important than the ambient NH4+ for sustaining cyanobacterial blooms in northwestern Lake Taihu and indicates that the river-lake transitional zones are key areas for N control in this hypereutrophic system.


Assuntos
Compostos de Amônio/metabolismo , Cianobactérias/metabolismo , Lagos/química , Rios/química , China , Eutrofização/fisiologia , Lagos/microbiologia , Nitrogênio/análise , Nutrientes , Rios/microbiologia , Estações do Ano
12.
Bioinspir Biomim ; 14(5): 056008, 2019 07 29.
Artigo em Inglês | MEDLINE | ID: mdl-31242471

RESUMO

A new filter was developed to collect harmful algae colonies by adapting the cross-step filtration structures and mechanisms discovered recently in filter-feeding fish. Extending beyond previously published models that closely emulated the basic morphology of the fish, the new cross-step filter's major innovations are helical slots, radial symmetry, and rotation as an active anti-clogging mechanism. These innovations enable the transport of concentrated particles to the downstream end of the filter. This advance was made possible by recognizing that biologically imposed constraints such as bilateral symmetry do not apply to human-made filters. The use of helical slots was developed in a series of iterative tests that used water-tracing dye and algae-sized microspheres. The major products of the iterative tests were refinements in the helical design and an understanding of how varying the major structural parameters qualitatively influenced fluid flow and filter performance. Following the iterative tests, the clogging behavior of select filters was quantified at high particle concentrations. Vortices in the helical filter were effective at reducing clogging in the center of the slots. By considering the design space that is free of the biological constraints on the system and exploring the effects of variations in major structural parameters, our work has identified promising new directions for cross-step filtration and provided key insights into the biological system.


Assuntos
Materiais Biomiméticos/química , Eutrofização/fisiologia , Peixes/anatomia & histologia , Animais , Rotação
13.
Sci Rep ; 9(1): 7366, 2019 05 14.
Artigo em Inglês | MEDLINE | ID: mdl-31089175

RESUMO

Disentangling the relative importance of deterministic and stochastic processes in shaping natural communities is central to ecology. Studies about community assembly over broad temporal and spatial scales in aquatic microorganisms are scarce. Here, we used 16S rDNA sequence data from lake sediments to test for community assembly patterns in cyanobacterial phylogenies across ten European peri-Alpine lakes and over a century of eutrophication and climate warming. We studied phylogenetic similarity in cyanobacterial assemblages over spatial and temporal distance, and over environmental gradients, comparing detected patterns with theoretical expectations from deterministic and stochastic processes. We found limited evidence for deviation of lake communities from a random assembly model and no significant effects of geographic distance on phylogenetic similarity, suggesting no dispersal limitation and high levels of stochastic assembly. We detected a weak influence of phosphorus, but no significant effect of nitrogen levels on deviation of community phylogenies from random. We found however a significant decay of phylogenetic similarity for non-random communities over a gradient of air temperature and water column stability. We show how phylogenetic data from sedimentary archives can improve our understanding of microbial community assembly processes, and support previous evidence that climate warming has been the strongest environmental driver of cyanobacterial community assembly over the past century.


Assuntos
Cianobactérias/crescimento & desenvolvimento , Eutrofização/fisiologia , Aquecimento Global , Lagos/microbiologia , Microbiota/fisiologia , Cianobactérias/genética , Cianobactérias/isolamento & purificação , DNA Bacteriano/genética , DNA Bacteriano/isolamento & purificação , Monitorização de Parâmetros Ecológicos , Sedimentos Geológicos/microbiologia , Filogenia , RNA Ribossômico 16S/genética , Análise Espaço-Temporal
14.
PLoS One ; 14(4): e0215463, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30990831

RESUMO

Harmful Algal Blooms (HABs) are of global concern, as their presence is often associated with socio-economic and environmental issues including impacts on public health, aquaculture and fisheries. Therefore, monitoring the occurrence and succession of HABs is fundamental for managing coastal regions around the world. Yet, due to the lack of adequate in situ measurements, the detection of HABs in coastal marine ecosystems remains challenging. Sensors on-board satellite platforms have sampled the Earth synoptically for decades, offering an alternative, cost-effective approach to routinely detect and monitor phytoplankton. The Red Sea, a large marine ecosystem characterised by extensive coral reefs, high levels of biodiversity and endemism, and a growing aquaculture industry, is one such region where knowledge of HABs is limited. Here, using high-resolution satellite remote sensing observations (1km, MODIS-Aqua) and a second-order derivative approach, in conjunction with available in situ datasets, we investigate for the first time the capability of a remote sensing model to detect and monitor HABs in the Red Sea. The model is able to successfully detect and generate maps of HABs associated with different phytoplankton functional types, matching concurrent in situ data remarkably well. We also acknowledge the limitations of using a remote-sensing based approach and show that regardless of a HAB's spatial coverage, the model is only capable of detecting the presence of a HAB when the Chl-a concentrations exceed a minimum value of ~ 1 mg m-3. Despite the difficulties in detecting HABs at lower concentrations, and identifying species toxicity levels (only possible through in situ measurements), the proposed method has the potential to map the reported spatial distribution of several HAB species over the last two decades. Such information is essential for the regional economy (i.e., aquaculture, fisheries & tourism), and will support the management and sustainability of the Red Sea's coastal economic zone.


Assuntos
Biodiversidade , Recifes de Corais , Eutrofização/fisiologia , Modelos Biológicos , Fitoplâncton/crescimento & desenvolvimento , Aquicultura , Oceano Índico
15.
Sci Rep ; 9(1): 5579, 2019 04 03.
Artigo em Inglês | MEDLINE | ID: mdl-30944391

RESUMO

Excess nutrient loading to nearshore environments has been linked to declining water quality and ecosystem health. Macro-algal blooms, eutrophication, and reduction in coral cover have been observed in West Maui, Hawaii, and linked to nutrient inputs from coastal submarine groundwater seeps. Here, we present a forty-year record of nitrogen isotopes (δ15N) of intra-crystalline coral skeletal organic matter in three coral cores collected at this site and evaluate the record in terms of changes in nitrogen sources. Our results show a dramatic increase in coral δ15N values after 1995, corresponding with the implementation of biological nutrient removal at the nearby Lahaina Wastewater Reclamation Facility (LWRF). High δ15N values are known to be strongly indicative of denitrification and sewage effluent, corroborating a previously suggested link between local wastewater injection and degradation of the reef environment. This record demonstrates the power of coral skeletal δ15N as a tool for evaluating nutrient dynamics within coral reef environments.


Assuntos
Antozoários/metabolismo , Isótopos de Nitrogênio/metabolismo , Nutrientes/metabolismo , Animais , Recifes de Corais , Ecossistema , Monitoramento Ambiental/métodos , Eutrofização/fisiologia , Água Subterrânea , Hawaii , Nitrogênio/metabolismo , Esgotos , Poluentes Químicos da Água/metabolismo , Qualidade da Água
16.
PLoS One ; 14(4): e0214933, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30951553

RESUMO

Phytoplankton blooms are an important, widespread phenomenon in open oceans, coastal waters and freshwaters, supporting food webs and essential ecosystem services. Blooms are even more important in exploited coastal waters for maintaining high resource production. However, the environmental factors driving blooms in shallow productive coastal waters are still unclear, making it difficult to assess how environmental fluctuations influence bloom phenology and productivity. To gain insights into bloom phenology, Chl a fluorescence and meteorological and hydrological parameters were monitored at high-frequency (15 min) and nutrient concentrations and phytoplankton abundance and diversity, were monitored weekly in a typical Mediterranean shallow coastal system (Thau Lagoon). This study was carried out from winter to late spring in two successive years with different climatic conditions: 2014/2015 was typical, but the winter of 2015/2016 was the warmest on record. Rising water temperature was the main driver of phytoplankton blooms. However, blooms were sometimes correlated with winds and sometimes correlated with salinity, suggesting nutrients were supplied by water transport via winds, saltier seawater intake, rain and water flow events. This finding indicates the joint role of these factors in determining the success of phytoplankton blooms. Furthermore, interannual variability showed that winter water temperature was higher in 2016 than in 2015, resulting in lower phytoplankton biomass accumulation in the following spring. Moreover, the phytoplankton abundances and diversity also changed: cyanobacteria (< 1 µm), picoeukaryotes (< 1 µm) and nanoeukaryotes (3-6 µm) increased to the detriment of larger phytoplankton such as diatoms. Water temperature is a key factor affecting phytoplankton bloom dynamics in shallow productive coastal waters and could become crucial with future global warming by modifying bloom phenology and changing phytoplankton community structure, in turn affecting the entire food web and ecosystem services.


Assuntos
Eutrofização/fisiologia , Modelos Biológicos , Fitoplâncton/crescimento & desenvolvimento , Estações do Ano , Temperatura , Mar Mediterrâneo
17.
Sci Total Environ ; 676: 62-71, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31029901

RESUMO

Dinoflagellate blooms are the results of rapid cell proliferation governed by cell cycle, a highly-ordered series of events that culminates in cell division. However, little is known about cell cycle progression of the in situ bloom cells. Here, we compared proteomes of the in situ blooming cells of a dinoflagellate Prorocentrum donghaiense collected at different cell cycle phases. The blooming P. donghaiense cells completed a cell cycle within 24 h with a high synchronization rate of 82.7%. Proteins associated with photosynthesis, porphyrin and chlorophyll synthesis, carbon, nitrogen and amino acid metabolisms exhibited high expressions at the G1 phase; DNA replication and mismatch repair related proteins were more abundant at the S phase; while protein synthesis and oxidative phosphorylation were highly enriched at the G2/M phase. Cell cycle proteins presented similar periodic diel patterns to other eukaryotic cells, and higher expressions of proliferating cell nuclear antigen and cyclin dependent kinase 2 at the S phase ensured the smooth S-G2/M transition. Strikingly, four histones were first identified in P. donghaiense and highly expressed at the G2/M phase, indicating their potential roles in regulating cell cycle. This study presents the first quantitative survey, to our knowledge, of proteome changes at different cell cycle phases of the in situ blooming cells in natural environment and provides insights into cell cycle regulation of the blooming dinoflagellate cells.


Assuntos
Dinoflagelados/fisiologia , Eutrofização/fisiologia , Proteoma/metabolismo , Proteômica , Carbono , Ciclo Celular , Nitrogênio , Fotossíntese
18.
Environ Microbiol ; 21(7): 2320-2332, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-30924222

RESUMO

Ammonia-oxidizing archaea (AOA) are ubiquitous in natural ecosystems, and they are responsible for a significant fraction of ammonia oxidation globally. Since the first AOA isolate was established a decade ago, molecular surveys of their environmental distribution [based primarily on amplicon sequencing of the amoA, which codes for the alpha subunit of ammonia monooxygenase (AMO)], show that their habitats are believed to range from marine to terrestrial environments. However, the mechanisms of adaptation underpinning to their habitat expansion remain poorly understood. Here, we report that AOA accounts for almost all of the ammonia oxidizers in the shelf water adjacent to the Pearl River estuary (PRE), with the Nitrosopumilus maritimus SCM1-like (SCM1-like) being the main amoA genotype. Using a metagenomic approach, seven high-quality AOA genomes were reconstructed from the PRE. Phylogenetic analysis indicated that four of these genomes with high completeness were closely affiliated with the Nitrosomatrinus catalina strain SPOT01, which was originally isolated off the coast of California. Genomic comparison revealed that the PRE AOA genomes encoded genes functioning in amino acid synthesis, xenobiotic biodegradation metabolism and transportation of inorganic phosphate and heavy metals. This illustrates the different adaptations of AOA in one of the largest estuaries in China, which is strongly influenced by anthropogenic input. Overall, this study provides additional genomic information about estuarine AOA and highlights the importance of their contribution to nitrification in eutrophic coastal environments.


Assuntos
Amônia/metabolismo , Archaea/genética , Archaea/fisiologia , Eutrofização/fisiologia , Oxirredutases/genética , California , China , Ecossistema , Estuários , Genoma Arqueal/genética , Genômica , Sedimentos Geológicos/microbiologia , Metais Pesados/metabolismo , Nitrificação , Oxirredução , Proteínas de Transporte de Fosfato/genética , Filogenia , Rios/microbiologia
19.
Mar Pollut Bull ; 140: 301-307, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30803648

RESUMO

Large-scale green tides caused by Ulva prolifera, occurred for 12 consecutive years in the Yellow Sea of China. To resolve the abrupt shift in species composition between attached and floating macroalgal assemblages, field experiments were conducted from May to July 2017 to quantify the net buoyancy force and compare the floating potential of the common green macroalgae from the red algal seaweed Pyropia yezoensis rafts. At the same time, U. prolifera from different sampling locations were tested to study variable buoyancy of this species and the associated influencing factors. Our results illustrated a stronger positive buoyant force and a proportionally greater buoyancy capacity of U. prolifera, compared to the other co-occurring species. Buoyancy is a dynamic trait and is closely correlated with light intensity, morphology and physiological status. The positive buoyancy of U. prolifera is an important factor that helps explain its predominance in the Yellow Sea's large-scale green tides.


Assuntos
Monitoramento Ambiental/métodos , Eutrofização/fisiologia , Ulva/fisiologia , China , Oceanos e Mares , Estações do Ano , Água do Mar/química , Alga Marinha/fisiologia , Ulva/crescimento & desenvolvimento
20.
Environ Pollut ; 248: 36-47, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30771746

RESUMO

Applications of aluminium (Al) salt or lanthanum (La) modified bentonite (LMB) have become popular methodologies for immobilizing phosphorus (P) in eutrophic lakes. The presence of humic substances, has been shown to inhibit this form of treatment due to the complexation with La/Al. However, the effects of other dissolved organic matter (DOM), especially that derived from phytoplankton (the dominant source in eutrophic lakes) are unknown. In this study, the interaction with La/Al of Suwannee River Standard Humic Acid Standard II (SRHA) and algae-derived DOM (ADOM) were investigated and compared. Differed to SRHA which was dominated by polyphenol-like component (76.8%, C1-SRHA), majority in ADOM were protein-like substance, including 41.9% tryptophan-like component (C2-ADOM) and 21.0% tyrosine-like component (C3-ADOM). Two reactions of complexation and coprecipitation were observed between SRHA/ADOM and La/Al. Complexation dominated at low metal inputs less than 10 µM and coprecipitation was the main reaction at higher metal inputs. For ADOM, the tryptophan-like component (C2-ADOM) was the important component to react with metal. The reaction rate for C2-ADOM with La were about two-third of that for C1-SRHA, indicating that the influence of C2-ADOM was significant during the P immobilization by La/Al-based treatment in eutrophic lakes. The P removal data in the presence of ADOM confirmed the significant inhibition of ADOM. In addition, based on the composition of coprecipitates and relatively biodegradable character of tryptophan-like substances (C2-ADOM), the coprecipitation of ADOM was assumed to reduce the stability of precipitated P in eutrophic lakes. The release of P from the potential biodegradation of the coprecipitates and thus the possible decline of the performance of P immobilization by La/Al-based treatments is an important work in the future.


Assuntos
Alumínio/química , Bentonita/química , Eutrofização/fisiologia , Lagos/química , Lantânio/química , Fósforo/química , Rios/química , Sedimentos Geológicos/química , Substâncias Húmicas/análise , Íons , Fitoplâncton , Espectrometria de Fluorescência/métodos
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