Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 2.190
Filtrar
1.
J Environ Sci (China) ; 151: 174-186, 2025 May.
Artigo em Inglês | MEDLINE | ID: mdl-39481931

RESUMO

Diel investigations of water environments are one means to holistically understand the dynamics and functional roles of phytoplankton, bacteria and viruses in these ecosystems. They have the potential to substantially impact carbon (C), nitrogen (N) and phosphorus (P) biogeochemistry through their respective roles. This study characterizes the phytoplankton, bacteria and virus communities and the elemental composition of various C, N and P nutrients flow over three diel cycles in tropical urban lake. Our results show that ratios of C:N:P fluctuated strongly from the lack of dissolved organic phosphorus (DOP) and PO4. Specifically, green algae peaked during day time and exudate dissolved organic matter (DOM) that strongly modulate dissolved organic carbon (DOC):DOP ratio to diel DOP limitation. Multiple linear regression and Stella modelling emphasize the roles of viruses together with Synechococcus as important nutrient recyclers of NH4 and PO4 in nutrients-limited waters. Respective normalised surface PO4 and combined surface and bottom NH4 concentration selected both viruses and Synechococcus as important drivers. Process model of N and P biogeochemical cycles can achieve 69% and 57% similar to observed concentration of NH4 and PO4, respectively. A short latent period of 9 hr was calculated, in addition to the calibrated high infectivity of viruses to Synechococcus. Taken together, the rapid turn-over between Synechococcus and viruses has biogeochemical significance, where the rapid recycling of essential nutrients allows for shortcuts in the N and P cycle, supporting a wide range of microbes.


Assuntos
Bactérias , Nitrogênio , Fósforo , Fitoplâncton , Vírus , Fósforo/análise , Nitrogênio/análise , Bactérias/metabolismo , Nutrientes/análise , Carbono/análise , Lagos/química , Lagos/microbiologia , Lagos/virologia , Clima Tropical , Monitoramento Ambiental , Ecossistema
2.
J Environ Sci (China) ; 148: 375-386, 2025 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-39095172

RESUMO

Tuojiang River Basin is a first-class tributary of the upper reaches of the Yangtze River-which is the longest river in China. As phytoplankton are sensitive indicators of trophic changes in water bodies, characterizing phytoplankton communities and their growth influencing factors in polluted urban rivers can provide new ideas for pollution control. Here, we used direct microscopic count and environmental DNA (eDNA) metabarcoding methods to investigate phytoplankton community structure in Tuojiang River Basin (Chengdu, Sichuan Province, China). The association between phytoplankton community structure and water environmental factors was evaluated by Mantel analysis. Additional environmental monitoring data were used to pinpoint major factors that influenced phytoplankton growth based on structural equation modeling. At the phylum level, the dominant phytoplankton taxa identified by the conventional microscopic method mainly belonged to Bacillariophyta, Chlorophyta, and Cyanophyta, in contrast with Chlorophyta, Dinophyceae, and Bacillariophyta identified by eDNA metabarcoding. In α-diversity analysis, eDNA metabarcoding detected greater species diversity and achieved higher precision than the microscopic method. Phytoplankton growth was largely limited by phosphorus based on the nitrogen-to-phosphorus ratios > 16:1 in all water samples. Redundancy analysis and structural equation modeling also confirmed that the nitrogen-to-phosphorus ratio was the principal factor influencing phytoplankton growth. The results could be useful for implementing comprehensive management of the river basin environment. It is recommended to control the discharge of point- and surface-source pollutants and the concentration of dissolved oxygen in areas with excessive nutrients (e.g., Jianyang-Ziyang). Algae monitoring techniques and removal strategies should be improved in 201 Hospital, Hongrihe Bridge and Colmar Town areas.


Assuntos
Monitoramento Ambiental , Fitoplâncton , Rios , Rios/química , China , Poluentes Químicos da Água/análise , Fósforo/análise
3.
Environ Res ; : 120286, 2024 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-39491607

RESUMO

Increasing frequency, intensity and duration of marine heatwaves (MHWs) are supposed to affect coastal biological production in different regions to different extents. To understand how MHWs impact coastal primary productivity and community succession of phytoplankton and assess the changes in resilience of phytoplankton communities, we conducted a mesoscale enclosure experiment simulating a marine MHW in the coastal water of southern China. After 8 days of the MHW (+3 oC) treatment, community biomass was significantly lower than the control's, and primary productivity per volume of water was reduced by about 56%. Nevertheless, the phytoplankton community retrieved its biomass and primary productivity after the temperature was subsequently reset to that of the control. Although the MHW treatment decreased the abundance of diatom and increased the percentages of Synechococcus and Prasinophytes, the main phytoplankton functional types showed positive resilience that allowed the recovery of the phytoplankton community after the MHW. Our results indicate that key phytoplankton functional types in the southern coastal waters of China exhibited significant resilience, recovery, and temporal stability under the influence of the marine MHW by 3 oC rise. However, reduced primary productivity during the MHW period, along with decreased biomass density, might significantly influence secondary producers. In addition, the altered phytoplankton community structure may affect coastal food web processes at least during the MHW period.

5.
Math Biosci Eng ; 21(8): 6870-6897, 2024 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-39483097

RESUMO

Chemical heterogeneity significantly influences the dynamics of phytoplankton and zooplankton interactions through its effects on phytoplankton carrying capacity and zooplankton ingestion rates. Our central objective of this study was to develop and examine a nonautonomous model of phytoplankton-zooplankton growth, which incorporates season-driven variations in light intensity and chemical heterogeneity. The dynamics of the system is characterized by positive invariance, dissipativity, boundary dynamics, and internal dynamics. Subsequently, numerical simulations were conducted to validate the theoretical findings and to elucidate the effects of seasonal light intensity, nutrient availability, and zooplankton loss rates on phytoplankton dynamics. The outcomes of our model and analysis offer a potential explanation for seasonal phytoplankton blooms.


Assuntos
Simulação por Computador , Luz , Modelos Biológicos , Fitoplâncton , Estações do Ano , Zooplâncton , Fitoplâncton/crescimento & desenvolvimento , Fitoplâncton/fisiologia , Fitoplâncton/efeitos da radiação , Zooplâncton/fisiologia , Animais , Eutrofização , Ecossistema , Biomassa , Dinâmica Populacional , Cadeia Alimentar
6.
Plant Cell Environ ; 2024 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-39494748

RESUMO

The marine microalga Emiliania huxleyi is widely distributed in the surface oceans and is prone to infection by coccolithoviruses that can terminate its blooms. However, little is known about how global change factors like solar UV radiation (UVR) and ocean warming affect the host-virus interaction. We grew the microalga at 2 temperature levels with or without the virus in the presence or absence of UVR and investigated the physiological and transcriptional responses. We showed that viral infection noticeably reduced photosynthesis and growth of the alga but was less harmful to its physiology under conditions where UVR influenced viral DNA expression. In the virus-infected cells, the combination of UVR and warming (+4°C) led to a 13-fold increase in photosynthetic carbon fixation rate, with warming alone contributing a change of about 5-7-fold. This was attributed to upregulated expression of genes related to carboxylation and light-harvesting proteins under the influence of UVR, and to warming-reduced infectivity. In the absence of UVR, viral infection downregulated the metabolic pathways of photosynthesis and fatty acid degradation. Our results suggest that solar UV exposure in a warming ocean can reduce the severity of viral attack on this ecologically important microalga, potentially prolonging its blooms.

7.
BMC Ecol Evol ; 24(1): 129, 2024 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-39438801

RESUMO

BACKGROUND: Sanniang Bay (SNB) and Dafeng River (DFR), located in the northern Beibu Gulf, is well-known as one of the eight habitats for humpback dolphins in China. This region is representative of typical estuarine and bay ecosystems and produce complex hydrodynamic seawater conditions. Moreover, anthropogenic pressure, such as eutrophication and large-scale infrastructure projects, have caused ongoing habitat deterioration and loss. It is urgent to know the phytoplankton community and their relationships with environmental factors in this region. RESULTS: In this study, we assessed the diversity and assembly mechanisms of phytoplankton communities, as well as their relationship with the physicochemical characteristics of seawater in SNB and DFR region using 18 S rDNA metabarcoding analysis. The results showed that seasonal changes markedly impacted the alpha diversity of the phytoplankton community. From March to July, with the average temperature increasing from 25.2℃ to 28.1℃,the Shannon or Species Richness were negatively correlated with temperature. During hot season (in Sep, average temperature 32.1℃), phytoplankton diversity was negatively correlated with nutrients (NH4 +, NO3-, PO43-, TN). Additionally, during the rainy season, the Bray-Curtis similarity of the phytoplankton community was significantly lower than during the dry season. In March, the distance among the sampling sites was most strongly and positively correlated with the Bray-Curtis dissimilarity. Stochastic processes, specifically dispersal limitation and ecological drift, are the primary drivers of community assembly, while deterministic assembly processes (mainly heterogeneous selection) contribute a relatively minor portion (< 17%). CONCLUSIONS: Rising temperature diminished the diversity of phytoplankton in SNB and DFR, and nutrient inputs and eutrophication in estuarine areas will aggravate the loss of phytoplankton diversity.


Assuntos
Código de Barras de DNA Taxonômico , Fitoplâncton , Rios , Temperatura , Fitoplâncton/genética , China , Código de Barras de DNA Taxonômico/métodos , RNA Ribossômico 18S/genética , RNA Ribossômico 18S/análise , Biodiversidade , Estações do Ano , DNA Ribossômico/genética , Água do Mar
8.
Mar Pollut Bull ; 209(Pt A): 117147, 2024 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-39418872

RESUMO

Mining of sea sand in the water area of Tunda Island can result in changes in the quality of the aquatic environment. Phytoplankton may indicate changes due to their rapid reaction to external influences in water. This study aims to determine the water quality condition in Tunda Island waters using phytoplankton communities. The sample collection included 20 observation stations in Tunda Island waters, Banten province. The analyzed water samples had parameters of depth, temperature, pH, dissolved oxygen, total dissolved solids, salinity, nitrates, and phytoplankton communities. The results obtained by several quality water parameters still meet the quality standards except for nitrates. The composition of phytoplankton consists of 3 classes: Cyanophyceae, Bacillariophyceae, and Dinophyceae. Eight phytoplankton genera of the Bacillariophyceae class dominated during observation: Bacteriastrum sp., Chaetoceros sp., Hemiaulus sp., Lauderia sp., Nitzschia sp., Rhizosolenia sp., Skeletonema sp., Thalassiosira sp., and Thalassiotrix sp. The phytoplankton biological index describes the phytoplankton diversity index as moderate diversity, phytoplankton evenness is classified as unstable communities, and phytoplankton dominance is at a moderate condition. Variations within a phytoplankton group can reflect seasonal dynamics and the impact of changes in the aquatic environment.

9.
Bull Math Biol ; 86(11): 136, 2024 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-39397103

RESUMO

The two main components of the planktonic ecosystem are phytoplankton and zooplankton. Fungal parasites can infect zooplankton and spread between them. In this paper, we construct a dynamic model to describe the spread of fungal parasites among zooplankton. Basic reproduction number for fungal parasite transmission among zooplankton are rigorously derived. The dynamics of this system are analyzed including dissipativity and equilibria. We further explore the effects of ecological factors on population dynamics and the relationship between fungal parasite transmission and phytoplankton blooms. Interestingly, our theoretical and numerical results indicate that a low-light or oligotrophic aquatic environment is helpful in mitigating the transmission of fungal parasites. We also show that fungal parasites on zooplankton can increase phytoplankton biomass and induce blooms.


Assuntos
Número Básico de Reprodução , Ecossistema , Conceitos Matemáticos , Modelos Biológicos , Fitoplâncton , Zooplâncton , Animais , Zooplâncton/fisiologia , Zooplâncton/microbiologia , Fitoplâncton/microbiologia , Fitoplâncton/crescimento & desenvolvimento , Número Básico de Reprodução/estatística & dados numéricos , Fungos/fisiologia , Fungos/patogenicidade , Dinâmica Populacional/estatística & dados numéricos , Luz , Biomassa , Eutrofização , Nutrientes/metabolismo , Simulação por Computador , Plâncton/microbiologia
10.
J Phycol ; 2024 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-39413213

RESUMO

Unveiling the interactions among phytoplankton and bacteria at the level of species requires axenic isolates to experimentally demonstrate their mutual effects. In this study, we describe the interactions among the diatoms Pseudo-nitzschia granii and Chaetoceros tenuissimus and their associated bacterial species, isolated from surface water of a coastal upwelling system using coculture experiments. Microalgae growth was assessed in axenic monocultures or in coculture with each of their co-isolated bacteria in the presence or absence of B vitamins. Pseudo-nitzschia granii growth was limited by B-vitamin supply, except when cultured with the bacteria Jannaschia cystaugens, which seemed to provide adequate levels of B vitamins to the diatom. Chaetoceros tenuissimus growth was reduced in the absence of B vitamins. Moreover, the growth of C. tenuissimus was stimulated by Alteromonas sp. and Celeribacter baekdonensis during the exponential growth. These results show a diversity of specific interactions between the diatoms and co-isolated bacteria, ranging from allelopathy to commensalism. Understanding how interactions between phytoplankton and bacteria modulate the structure and function of marine microbial plankton communities will contribute to a greater knowledge of plankton ecology and improve our ability to predict nutrient fluxes in marine ecosystems or the formation of blooms in a context of global change.

11.
Microbiome ; 12(1): 205, 2024 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-39420440

RESUMO

BACKGROUND: Reciprocal exchanges of metabolites between phytoplankton and bacteria influence the fitness of these microorganisms which ultimately shapes the productivity of marine ecosystems. Recent evidence suggests that plant growth-promoting hormones may be key metabolites within mutualistic phytoplankton-bacteria partnerships, but very little is known about the diversity of plant growth-promoting hormones produced by marine bacteria and their specific effects on phytoplankton growth. Here, we aimed to investigate the capacity of marine bacteria to produce 7 plant growth-promoting hormones and the effects of these hormones on Actinocyclus sp. growth. RESULTS: We examined the plant growth-promoting hormone synthesis capabilities of 14 bacterial strains that enhance the growth of the common diatom Actinocyclus. Plant growth-promoting hormone biosynthesis was ubiquitous among the bacteria tested. Indeed all 14 strains displayed the genomic potential to synthesise multiple hormones, and mass-spectrometry confirmed that each strain produced at least 6 out of the 7 tested plant growth-promoting hormones. Some of the plant growth-promoting hormones identified here, such as brassinolide and trans-zeatin, have never been reported in marine microorganisms. Importantly, all strains produced the hormone indole-3 acetic acid (IAA) in high concentrations and released it into their surroundings. Furthermore, indole-3 acetic acid extracellular concentrations were positively correlated with the ability of each strain to promote Actinocyclus growth. When inoculated with axenic Actinocyclus cultures, only indole-3 acetic acid and gibberellic acid enhanced the growth of the diatom, with cultures exposed to indole-3 acetic acid exhibiting a two-fold increase in cell numbers. CONCLUSION: Our results reveal that marine bacteria produce a much broader range of plant growth-promoting hormones than previously suspected and that some of these compounds enhance the growth of a marine diatom. These findings suggest plant growth-promoting hormones play a large role in microbial communication and broaden our knowledge of their fuctions in the marine environment. Video Abstract.


Assuntos
Bactérias , Diatomáceas , Reguladores de Crescimento de Plantas , Reguladores de Crescimento de Plantas/metabolismo , Diatomáceas/crescimento & desenvolvimento , Diatomáceas/metabolismo , Bactérias/metabolismo , Bactérias/classificação , Bactérias/genética , Ácidos Indolacéticos/metabolismo , Água do Mar/microbiologia , Fitoplâncton/crescimento & desenvolvimento , Fitoplâncton/metabolismo , Organismos Aquáticos/metabolismo , Organismos Aquáticos/crescimento & desenvolvimento , Simbiose
12.
J Environ Manage ; 370: 122793, 2024 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-39423617

RESUMO

Human activities, intensified urbanization and climate changes altered source and quantity of dissolved organic matter (DOM), complicating its interaction with phytoplankton in aquatic ecosystems. However, relationship between DOM and phytoplankton in urban lakes strongly disturbed by human activities was still unclear. Thus, a whole-year sampling campaign was conducted in the Tangxun Lake, China's largest urban lake, to reveal the interaction between DOM and phytoplankton. Results indicated that trophic state in the Tangxun Lake varied from mesotrophic to moderately eutrophic. Parallel factor analysis method combined with excitation-emission matrix fluorescence spectroscopy revealed that DOM in the Tangxun Lake consisted of three components, two protein-like components (C1, C3), and one humic-like component (C2). Protein-like components occupied 80% ± 11% of total CDOM pool, mainly due to urbanization driving DOM to be more protein-like, less humic-like. Besides, DOM in the Tangxun Lake was mainly autochthonous input and more recently formed. Furthermore, a total of 129 phytoplankton species were identified, belonging to 78 genera and 7 phyla. Tangxun Lake's phytoplankton community structure was dominated by the Chlorophyta-Bacillariophyta-Cyanophyta type. The temporal succession of phytoplankton varied significantly. It was found that the abundance of Cryptophyta and Cyanophyta were predominant in the mesotrophic state, while Cyanophyta and Bacillariophyta were prevailing in the eutrophic and middle-eutrophic states. As for the interaction between DOM and phytoplankton, results demonstrated that phytoplankton biomass was significantly positively correlated with a (254), a proxy of DOM abundance. Moreover, phytoplankton abundance and biomass significantly positively correlated with autochthonous and freshly released DOM, indicating that the more autochthonous and freshly released DOM, the higher phytoplankton abundance and biomass. Overall, this study provides profound environmental implications for aquatic ecosystem management, especially those strongly affected by human activities.

13.
Cell ; 187(21): 5935-5950.e18, 2024 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-39368476

RESUMO

Diatoms are central to the global carbon cycle. At the heart of diatom carbon fixation is an overlooked organelle called the pyrenoid, where concentrated CO2 is delivered to densely packed Rubisco. Diatom pyrenoids fix approximately one-fifth of global CO2, but the protein composition of this organelle is largely unknown. Using fluorescence protein tagging and affinity purification-mass spectrometry, we generate a high-confidence spatially defined protein-protein interaction network for the diatom pyrenoid. Within our pyrenoid interaction network are 10 proteins with previously unknown functions. We show that six of these form a shell that encapsulates the Rubisco matrix and is critical for pyrenoid structural integrity, shape, and function. Although not conserved at a sequence or structural level, the diatom pyrenoid shares some architectural similarities to prokaryotic carboxysomes. Collectively, our results support the convergent evolution of pyrenoids across the two main plastid lineages and uncover a major structural and functional component of global CO2 fixation.


Assuntos
Ciclo do Carbono , Dióxido de Carbono , Diatomáceas , Organelas , Ribulose-Bifosfato Carboxilase , Diatomáceas/metabolismo , Dióxido de Carbono/metabolismo , Organelas/metabolismo , Ribulose-Bifosfato Carboxilase/metabolismo , Mapas de Interação de Proteínas , Fotossíntese
14.
Mar Pollut Bull ; 208: 116952, 2024 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-39353371

RESUMO

The micro-phytoplankton (>20 µm) adaptations and resilience were assessed using morphological traits (shape, surface-to-volume ratio; S:V, and greatest-axial-linear-dimension; GALD) from sea-surface and different SCML-depths (shallow:20-50 m, intermediate:50-100 m, and deep:100-140 m) across different bioregions of Indian Ocean. The dominant simple elongated phytoplankton-geometric-shapes (PGSs) and morphological traits showed distinct north-south distribution and varied with light and nutrient availability. Further, SCML and corresponding sea-surface PGS will be similar or dissimilar if the former is located within or deeper than mixed-layer depth. Also, simple and complex PGS contribution gradually decreases and increases with increasing depth. Additionally, shallow SCML-PGS showed low-S:V and high-GALD while vice-versa for intermediate/deep SCML-PGS due to phenotypic plasticity behavior. Overall, only simple-PGS (cylinder, elliptic-prism, and prism-on-parallelogram) showed strong adaptive behavior through phenotypic plasticity and were highlighted as potential ecological tracers to address ecological impact of oceanographic processes (including coastal eutrophication, and aerosol deposition) linked to nutrient and light availability in predicted ocean change scenarios.


Assuntos
Fitoplâncton , Oceano Índico , Monitoramento Ambiental , Eutrofização
15.
Mar Pollut Bull ; 208: 117021, 2024 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-39368148

RESUMO

Ocean alkalinity enhancement (OAE) has been proposed as a mitigation method for negative carbon emission. Its effects on marine phytoplankton communities would depend on species differences in tolerance to high pH, which results from phytoplankton photosynthetic drawdown of dissolved inorganic carbon (DIC). In this study, 20 marine phytoplankton species were grown in sealed batch cultures and DIC, pH and chlorophyll a (Chl-a) were measured at the peaks of biomass. These results revealed a wide range of species differences. The drawdown DIC (ΔDIC) vs. increases in pH (ΔpH) graph resembled a Michaelis-Menten curve: significantly linear for ΔDIC < ~1000 µM and starting to plateau at ΔDIC > 1000 µM. This indicated that two mechanisms were operating: CO2 limitation at ΔpH < 1.41 and biologically-mediated precipitation-CO2 released carbon uptake at ΔpH > 1.41. These findings suggest that the potential effects of OAE on the phytoplankton communities would depend on the species differences in oceans.


Assuntos
Carbono , Clorofila A , Fitoplâncton , Fitoplâncton/crescimento & desenvolvimento , Carbono/metabolismo , Água do Mar/química , Concentração de Íons de Hidrogênio , Clorofila , Dióxido de Carbono/análise , Biomassa , Fotossíntese , Oceanos e Mares , Especificidade da Espécie
16.
Microbiol Resour Announc ; : e0065924, 2024 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-39365054

RESUMO

Here, we report on the raw and coassembled metatranscriptomes of 39 Lake Erie surface (1.0 m) water samples collected over a 2-day diel period encompassing episodic weather and bloom events. Preliminary taxonomic annotations and read mappings revealed that Microcystis spp. accounted for up to ~47% of the transcriptionally active community.

17.
Environ Res ; 263(Pt 2): 120142, 2024 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-39401604

RESUMO

Phytoplankton are crucial primary producers in freshwater ecosystems, driving matter and energy flow across trophic levels, essential for biodiversity and ecological balance. Most research emphasizes environmental factors shaping their diversity, while the role of hydrological connectivity remains poorly understood. This study collected 81 phytoplankton samples from the Hetao Irrigation District along a gradient from upstream to downstream and utilized high-throughput sequencing to evaluate the spatial distribution patterns of phytoplankton diversity. The study analyzed the impacts of environmental factors, hydrological connectivity (water surface ratio, Wp), and human activities (land-use intensity, LUI) on phytoplankton diversity. The results revealed that the phytoplankton community comprised 9 phyla, 158 families, 378 genera, and 1189 species. There were significant differences in phytoplankton diversity among different water bodies, with a gradual increase in phytoplankton diversity from west to east across the five major irrigation areas. Lake Ulansuhai had relatively low phytoplankton diversity. The ASV number, Chao1 index, and ACE index showed significant positive correlations with dissolved oxygen (DO), pH, and water temperature (WT). The Shannon index and Pielou'e evenness (Pielou_e) index showed significant positive correlations with the water surface ratio (Wp). The partial least squares model indicated that environmental factors directly influenced phytoplankton diversity. Hydrological connectivity indirectly affected phytoplankton diversity by altering environmental factors. We emphasize that hydrological connectivity is as important as environmental factors in driving phytoplankton diversity in the Hetao Irrigation District. This study provides key insights for water quality assessment and biodiversity conservation in the region.

18.
Mar Pollut Bull ; 209(Pt A): 117016, 2024 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-39393245

RESUMO

Submarine groundwater discharge is a pivotal factor in modifying the structure of phytoplankton communities in coastal waters. The objective of the study was to investigate how variations in nutrient concentrations and ratios influence the composition of phytoplankton communities along the coastal waters of Bay of Bengal. The experiment involved mixing groundwater with coastal water at 5 % and 10 % proportions. Phytoplankton growth was more pronounced in 10 % groundwater than those with 5 % and control samples. In control samples, Chl-a and other pigments, experienced decrease from 20 % to 80 %, except in Odisha-Paradeep and Visakhapatnam-Andhra Pradesh, where peridinin concentrations increased by 60 % to 65 % owing to low Si:N ratios below 0.2. A shift was observed from diatoms to dinoflagellates due to low Si: N ratios. The results reaffirm the hypothesis that variations in nutrient concentrations and ratios play a substantial role in shaping the composition of phytoplankton in the adjacent coastal waters.

19.
Huan Jing Ke Xue ; 45(10): 5822-5832, 2024 Oct 08.
Artigo em Chinês | MEDLINE | ID: mdl-39455128

RESUMO

To explore the characteristics of phytoplankton communities and their relationship with environmental factors in different habitats of Hedi Reservoir, the inflow rivers, estuaries, and reservoir area of Hedi Reservoir were investigated in February (recession period), April (flood period), July (flood period), and December (recession period) of 2022. During the investigation, 231 species of phytoplankton that belong to seven phyla were identified, and the cell density of phytoplankton ranged from 2.94 × 106 - 8.04 × 108 cells·L-1. Phytoplankton cell density in flood periods were higher than that in recession periods, and that was higher in estuaries and the reservoir area than that in inflow rivers. Meanwhile, the cell density of phytoplankton in the estuarine and reservoir area was dominated by Cyanobacteria throughout the year, especially Raphidiopsis raciborskii, whereas the cell density of phytoplankton in inflow rivers was dominated by Cyanophyta, Chlorophyta, and Bacillariophyta. In the inflow river area, the dominant species of cyanobacteria were Microcystis aeruginosa, Limnothrix redekei, Pseudanabaena circinalis, and Merismopedia punctata; the dominant species of Chlorophyta were Chlorella vulgaris and Crucigenia tetrapedia; and the dominant species of Bacillariophyta were Chlorella vulgaris and Melosira granulate. The highest biodiversity (Shannon-Wiener Index, Pielou index, and Margalef index) were observed in the inflow river area of Hedi Reservoir. The correlation analysis (Pearson) indicated that the environmental factors that were significantly correlated to phytoplankton communities included water temperature, dissolved oxygen, pH, conductivity, nitrogen, and phosphorus concentration. The RDA analysis indicated that phytoplankton communities in the inflow river area were mainly affected by pH and total nitrogen concentration, which were majorly affected by water temperature and pH in the estuarine area and chiefly affected by turbidity and pH in the reservoir. The pH affected the changes in phytoplankton communities in all three different habitats, whereas the inflow river area was significantly affected by total nitrogen concentration, and the estuarine and reservoir were significantly affected by water temperature and turbidity, respectively.


Assuntos
Ecossistema , Fitoplâncton , Fitoplâncton/crescimento & desenvolvimento , Fitoplâncton/classificação , China , Cianobactérias/crescimento & desenvolvimento , Rios , Abastecimento de Água , Monitoramento Ambiental , Diatomáceas/crescimento & desenvolvimento , Clorófitas/crescimento & desenvolvimento , Estuários , Eutrofização , Dinâmica Populacional
20.
Huan Jing Ke Xue ; 45(10): 5811-5821, 2024 Oct 08.
Artigo em Chinês | MEDLINE | ID: mdl-39455127

RESUMO

In wetland ecosystems, small shallow lakes are critical transition zones of land and water, which are usually dominated by aquatic plants with different growth forms. However, the differences and key influencing factors of phytoplankton communities in shallow lakes dominated by different aquatic plants are unclear. On this basis, nine surveys were conducted at five sampling sites of three lakes in Zhangye National Wetland Park from June to November in 2022, which were respectively dominated by the emergent Phragmites australis (LL), the submerged Potamogeton perfoliatus (CL), and the floating-leaved Nymphaea tetragona (SL). During the study period, the three lakes showed obvious habitat differences. A total of 237 species of phytoplankton in seven phyla and 93 genera were identified in the three lakes, including 189 species, 151 species, and 147 species in the LL, CL, and SL lakes, respectively. Among them, Ulnaria acus, Scenedesmus quadricauda, Achnanthidium minutissimum, Nitzschia stagnorum, Navicula radiosa, and Gymnodinium aeruginosum were shared dominant species of all three lakes, indicating that they had strong environmental adaptability, whereas Navicula lanceolala, Encyonopsis cesatii, and Eunotia diodon and Cymbella aequalis were only dominant in the CL, LL, and SL lakes, respectively. Simultaneously, these dominant algae appeared with obviously distinct statuses of niche width, niche overlap, and interspecific correlation among the three lakes. Using principal coordinate analysis (PCoA) and permutational multivariate analysis of variance (PERMANOVA), significant differences were found in algal community composition among the three lakes (P<0.001). Multiple regression on (dis)similarity matrices analysis (MRM) showed that the heterogeneity of phytoplankton communities among the three lakes was positively affected by NO3--N and pH and negatively affected by dissolved oxygen (DO) and was closely positively correlated with the abundance of six dominant species, namely, S. quadricauda, U. acus, N. stagnorum, Pseudoanabaena sp., Merismopedia punctata, and A. minutissimum. These results indicate that aquatic plants with different growth types could affect the composition, structure, and stability of phytoplankton communities in the same habitat with them by shaping their habitat heterogeneity. Therefore, selecting specific growth types of aquatic plants for aquatic ecosystem restoration in wetland construction and management will be conducive to regulate the state of water habitat and phytoplankton community structure effectively.


Assuntos
Lagos , Fitoplâncton , Áreas Alagadas , Fitoplâncton/crescimento & desenvolvimento , Fitoplâncton/classificação , China , Poaceae/crescimento & desenvolvimento , Plantas/classificação , Ecossistema , Potamogetonaceae/crescimento & desenvolvimento , Dinâmica Populacional
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA