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1.
J Environ Manage ; 301: 113898, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34626943

RESUMO

In shallow eutrophic lakes, submersed macrophytes are essential for maintaining a clear water state, and they are affected markedly by fishes directly through herbivory and indirectly by fish-invertebrate-periphyton complexity, a pathway that presently is not well understood in subtropical lakes but probably vital to lake managements. We conducted a mesocosm study involving benthic fish (Misgurnus anguillicaudatus), snails (Radix swinhoei) and submersed macrophyte (Vallisneria natans), aiming to examine whether benthic fish is detrimental to reestablishment of clear-water macrophyte-dominated state in eutrophic degraded lakes. In addition, we aimed to investigate the cascading effect that benthic fish might have on periphyton and phytoplankton and to what extent snails can alleviate this effect. Our results showed that benthic fish promoted nutrient release from the sediment and thereby facilitated the growth of phytoplankton and periphyton, leading to reduced growth of submerged macrophytes due to shading. Snails consumed the periphyton attached on the leaves of macrophytes, thereby being beneficial to the plant growth, albeit it could not fully counteract the adverse effects from benthic fish. The water quality indicators in terms of nutrients concentrations, phytoplankton biomass and light extinction coefficient along the water column was affected primarily by benthic fish, followed by macrophytes and snails. To target a clear-water condition, the water quality was best at the presence of macrophytes alone or in combination with snails, and worst at the presence of benthic fish. Our results implied that the removal of benthic fish should be a useful ecological restoration method for rehabilitation of submersed macrophytes and water quality improvement in subtropic, eutrophic, shallow lakes following external nutrient loading reduction.


Assuntos
Hydrocharitaceae , Lagos , Animais , Biomassa , Peixes , Fósforo , Fitoplâncton
2.
Chemosphere ; 286(Pt 1): 131648, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34315079

RESUMO

Aquatic macrophytes have been widely employed for in-situ phytoremediation of cadmium (Cd) polluted sediments. But, little is known about the responses of rhizosphere bacteria and their interspecific interactions to phytoremediation. In this study, the α-diversity, community composition, co-occurrence network and keystone species of sediment bacteria in rhizosphere zones of two typical macrophytes, Hydrilla verticillata and Elodea canadensis, were investigated using 16S rRNA gene high-throughput sequencing. The results showed that after fifty days of phytoremediation, a group of specialized sediment bacteria were assembled in the rhizosphere zones closely associated with different host macrophytes. Rhizosphere micro-environments, i.e., the increases of redox potential and organic matter and the decreases of pH, nitrogen and phosphorus, reduced bacterial α-diversity through niche-based species-sorting process, which in turn reduced interspecific mutualistic relationships. But meanwhile, benefiting from the nutrients supplied from macrophyte roots, more bacterial species survived in the highly Cd-contaminated sediments (50 mg kg-1). In addition, the co-occurrence network revealed that both macrophytes harbored two same keystone bacteria with the high betweenness centrality values, including the family Pedosphaeraceae (genus_unclassified) and genus Parasegetibacter. Their relative abundances were up to 28-fold and 25-fold higher than other keystone species, respectively. Furthermore, these two keystone bacteria were metabolic generalists with vital ecological functions, which posed significant potentials for promoting plant growth and tolerating Cd bio-toxicity. Therefore, the identified keystone rhizobacteria, Pedosphaeraceae and Parasegetibacter, would be potential microbial modulations applied for the future optimization of phytoremediation in Cd-contaminated sediment.


Assuntos
Hydrocharitaceae , Biodegradação Ambiental , Cádmio/análise , RNA Ribossômico 16S/genética , Rizosfera
3.
Sci Total Environ ; 806(Pt 3): 150735, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34606867

RESUMO

Mobilization of trace metals in the rhizosphere of macrophytes is controlled by root-driven chemical changes, especially the steep gradients of O2 and pH from the rhizosphere to bulk sediments. Here, the O2 and pH dynamics, and the distribution of trace metal, in the rhizosphere of Vallisneria spiralis were obtained using planar optodes and diffusive gradients in thin films, respectively. Radial O2 loss (ROL) and acidification occurred on all visible roots of V. spiralis and exhibited highly spatiotemporal dynamics depending on the root growth and various environmental conditions. Trace metals showed different mobilization mechanisms in the rhizosphere. ROL and produced Fe(III) (oxyhydr)oxides decreased the mobility of Fe, As, Co, V and W in the rhizosphere. However, Mn, Ni and Cu exhibited greater mobility in the rhizosphere than bulk sediments as a result of the oxidation of metal sulfide and proton-induced dissolution of minerals. In particular, Co and Ni presented increased activity at the interface between rhizosphere and bulk sediment, which was attributed to the redox dissolution processes of Fe and Mn as a result of ROL and rhizosphere acidification. These results provide new insights into the roles of macrophyte root-induced O2 and pH changes in controlling trace metal mobility in sediments.


Assuntos
Hydrocharitaceae , Oligoelementos , Compostos Férricos , Sedimentos Geológicos , Oxirredução , Rizosfera
4.
Sheng Wu Gong Cheng Xue Bao ; 37(10): 3663-3674, 2021 Oct 25.
Artigo em Chinês | MEDLINE | ID: mdl-34708618

RESUMO

Aquatic plants and the epiphytic microorganisms are important contributors to the purification of constructed wetlands. Taking the dragon-shaped water system of Beijing Olympic Park as a model, this study analyzed the structure and function of the microbial communities reside the sediment, the water body and the rhizosphere and phyllosphere of three submerged plants-Vallisneria natans, Myriophyllum verticillatum, and Potamogeton pectinatus using high-throughput sequencing technology. The results showed that the microbial diversity from the highest to the lowest were samples from sediment, plant rhizosphere, plant phyllosphere and water. The microbial diversity of plant phyllosphere samples were significantly higher than those of the water body. LEfSe analysis showed that different habitats enriched different microbial groups. The sediments mainly enriched anaerobic microbes, while the water body and the phyllosphere of plants mainly enriched aerobic microbes, and the rhizosphere of plants had the both. Functional prediction analysis showed that the abundance of denitrification marker genes in phyllosphere samples was higher than that in samples from rhizosphere, sediment and water body, and the abundance of denitrification marker genes in phyllosphere samples of M. verticillatum and P. pectinatus was higher than that of V. natans. This study could serve as a guidance for the selection of submerged plants and functional microorganisms for constructed wetlands.


Assuntos
Hydrocharitaceae , Microbiota , Pequim , Rizosfera , Água
5.
Sci Total Environ ; 800: 149579, 2021 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-34399336

RESUMO

The high biomass and sediment features of seagrass beds can make their belowground portions critical sources of blue carbon sinks. However, seagrass belowground production and decomposition have rarely been quantified in the field. To assess the significance of seagrass belowground production to carbon sequestration, belowground carbon budgets were constructed in intertidal seagrass beds of the late-successional species Thalassia hemprichii and the early-successional species Haloduleuninervis in southern Taiwan. For both species, the turnover rates of the belowground portions were much longer than that of the aboveground portion, so the belowground biomass was much higher than the aboveground biomass. The leaf productivity of both species was significantly higher than the belowground productivity, but most of the leaf production decomposed within a year. The lower turnover and slower decomposition rates of the belowground portions allowed the late-successional seagrass T. hemprichii to store more carbon in the sediments than the early-successional seagrass H. uninervis. Long-term changes for the past 20 years in the sediment depth showed that the sediments of seagrass beds were increasing in the habitats at low elevation but were decreasing or had no clear trends in the habitats at high elevation or on the windward side. The carbon storage rates according to the belowground production of T. hemprichii and H. uninervis were 0.3-4.7 and 1.5-2.3 g C m-2 yr-1, respectively, which can potentially contribute 53% of the long-term organic carbon storage in the low-elevation sediments.


Assuntos
Sequestro de Carbono , Hydrocharitaceae , Biomassa , Carbono , Ecossistema
6.
Huan Jing Ke Xue ; 42(9): 4311-4318, 2021 Sep 08.
Artigo em Chinês | MEDLINE | ID: mdl-34414729

RESUMO

In this study, four typical submerged macrophytes, namely Hydrilla verticillata, Elodea canadensis, Potamogeton crispus, and Ceratophyllum demersum, were tested for their chlorophyll content and antioxidant enzyme activity, to analyze their cadmium tolerance. The biota-sediment accumulation factor (BSAF) and plant transport factor (TF) were utilized to understand the accumulation capacity of the plants. Finally, the distribution of cadmium in submerged macrophytes was revealed through phytohistochemical methods, to provide theoretical support for the practical application of submerged macrophytes. The results showed that three of the plants, excluding C. demersum, exhibited varying tolerances to cadmium pollution in sediments, among which the tolerance of H. verticillata and E. canadensis were the strongest. P. crispus had the strongest accumulation capacity (BSAF was 2.32) at relatively low pollution levels (≤20 mg·kg-1). In this study, because of its weak root system, the BSAF of C. demersum was less than 1.0, indicating that macrophyte roots play an important role in phytoremediation of Cd-contaminated sediments. Comparing the TF of different plants, it can be found that the roots of H. verticillata had the strongest above-ground cadmium transport capacity, while P. crispus mainly accumulated cadmium in its roots. At the same time, when the cadmium concentration was 50 mg·kg-1, cadmium was found to be evenly distributed in the stem organelles of P. crispus, in contrast to the other plants. Based on the cadmium tolerance and accumulation mechanism of the plants, and in consideration of real-world factors, H. verticillata and P. crispus were selected as ideal plants for repairing cadmium-containing sediments. Meanwhile, based on the different transport capabilities of plants, it is recommended that only the above-ground part of H. verticillate should be removed, while P. crispus should be uprooted regularly.


Assuntos
Hydrocharitaceae , Potamogetonaceae , Biodegradação Ambiental , Cádmio , Clorofila
7.
Environ Res ; 202: 111635, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34242674

RESUMO

Phosphorus (P) availability is closely related to the distributions of pH, O2 and phosphatase activities in the rhizosphere of plants growing in soils and sediments. In this study, the P uptake processes and mechanisms of Vallisneria natans (V. natans) during two vegetation periods (i.e., week three and six) were revealed using three noninvasive 2D imaging techniques: planar optode (PO), diffusive gradients in thin films (DGT) and zymography. The results showed that increased phosphatase activity, O2 concentration and root-induced acidification were observed together in the rhizosphere of root segments and tips. In week three, when V. natans was young, the flux of DGT-labile P accumulated more in the rhizosphere in comparison with the bulk sediment. This was because increased phosphatase activity (of up to 35%) and root-induced acidification (with pH decreasing by up to 0.25) enhanced P acquisition of V. natans by the third week. However, the flux of DGT-labile P turned to depletion during weeks three to six of V. natans growth, after Fe plaque formed at the matured stage. The constant hydrolysis of phosphatase and acidification could not compensate for the P demand of the roots by the sixth week. At this stage, Fe plaque become the P pool, due to P fixation with solid Fe(III) hydroxides. Subsequently, V. natans roots acquired P from Fe plaque via organic acid complexation of Fe(III).


Assuntos
Hydrocharitaceae , Poluentes Químicos da Água , Compostos Férricos , Sedimentos Geológicos , Fósforo , Rizosfera , Solo , Poluentes Químicos da Água/análise
8.
Mar Pollut Bull ; 170: 112602, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34237606

RESUMO

Seagrass habitats at the Cocos (Keeling) Islands (CKI), a remote atoll in the Indian Ocean, have suffered a catastrophic decline over the last decade. Seagrass monitoring (1996-2020) in relation to dredging and coastal development works (2009 to 2011) provide a historical baseline, and document the decline of mixed tropical seagrass Thalassia hemprichii and macroalgal (predominantly Caulerpa spp.) beds over a decadal scale time series. Attribution of loss to coastal development is confounded by lagoon-wide die-off events in 2007, 2009 and 2012 and high air and water temperatures from 2009 to 2016, with evidence of broad scale changes, visible in satellite imagery between 2006 and 2018. We conclude that up to 80% of seagrass habitats in the CKI lagoon (~1200 ha) have been lost due to multiple stressors including episodic die-off events related to high temperatures and calm conditions, and loss due to sediment disturbance and increased turbidity. Grazing pressure from the resident green sea turtles (Chelonia mydas) may have also exacerbated the loss of seagrass, which in turn poses a dire threat to their ongoing health and survival. This study highlights the fragility of tropical seagrass habitats and the cascading effect of system imbalance as a result of anthropogenic pressures and climate drivers. Although small in comparison to global estimates, the loss of seagrass habitats at CKI could change the entire ecosystem of a remote atoll. Due to the significance of the Thalassia beds for coastal stability, as food for an isolated population of green sea turtles and as a fish nursery, rehabilitation efforts are warranted.


Assuntos
Hydrocharitaceae , Tartarugas , Animais , Cocos , Ecossistema , Ilhas do Oceano Índico
9.
Mar Drugs ; 19(5)2021 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-34069768

RESUMO

The Red Sea is one of the most biodiverse aquatic ecosystems. Notably, seagrasses possess a crucial ecological significance. Among them are the two taxa Halophila stipulacea (Forsk.) Aschers., and Thalassia hemprichii (Ehrenb. ex Solms) Asch., which were formally ranked together with the genus Enhalus in three separate families. Nevertheless, they have been recently classified as three subfamilies within Hydrocharitaceae. The interest of this study is to explore their metabolic profiles through ultra-high-performance liquid chromatography-high-resolution mass spectrometry (UPLC-HRMS/MS) analysis in synergism with molecular networking and to assess their chemosystematics relationship. A total of 144 metabolites were annotated, encompassing phenolic acids, flavonoids, terpenoids, and lipids. Furthermore, three new phenolic acids; methoxy benzoic acid-O-sulphate (16), O-caffeoyl-O-hydroxyl dimethoxy benzoyl tartaric acid (26), dimethoxy benzoic acid-O-sulphate (30), a new flavanone glycoside; hexahydroxy-monomethoxy flavanone-O-glucoside (28), and a new steviol glycoside; rebaudioside-O-acetate (96) were tentatively described. Additionally, the evaluation of the antidiabetic potential of both taxa displayed an inherited higher activity of H. stipulaceae in alleviating the oxidative stress and dyslipidemia associated with diabetes. Hence, the current research significantly suggested Halophila, Thalassia, and Enhalus categorization in three different taxonomic ranks based on their intergeneric and interspecific relationship among them and supported the consideration of seagrasses in natural antidiabetic studies.


Assuntos
Diabetes Mellitus Experimental/tratamento farmacológico , Hydrocharitaceae/química , Hipoglicemiantes/farmacologia , Metaboloma , Animais , Glicemia/efeitos dos fármacos , Cromatografia Líquida de Alta Pressão , Ensaios Enzimáticos , Transportador de Glucose Tipo 2/metabolismo , Hydrocharitaceae/genética , Hidrólise , Hipoglicemiantes/uso terapêutico , Oceano Índico , Insulina/sangue , Masculino , Malondialdeído/metabolismo , Espectrometria de Massas , Óxido Nítrico/sangue , Filogenia , Compostos Fitoquímicos/análise , Ratos Wistar
10.
Water Environ Res ; 93(10): 2237-2249, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34091983

RESUMO

The degeneration of submerged macrophytes and the invasion of Eichhornia crassipes (E. crassipes) destroyed the balance of aquatic ecosystems environments. In this study, responses of Vallisneria natans (V. natans) and the leaf-epiphytic biofilms to E. crassipes were analyzed to provide a technical scheme for V. natans restoration and E. crassipes control in eutrophic water. The results showed that a significant improvement of water quality achieved in 1100 ind·m-2 E. crassipes density group and TN removal rate reached 63.53%. The presence of E. crassipes changed the morphological characteristics of V. natans, which stimulated the adaptive mechanisms via promotion of shoot height and root length. Concentrations of the antioxidant enzymes, peroxidase, superoxide dismutase, and catalase in the V. natans leaves remained stable. But E. crassipes greatly increased the microbial diversity on V. natans leave biofilms. Furthermore, the greatest richness in bacterial community diversity was observed at 700, 1100, and 1200 ind·m-2 E. crassipes densities in heatmap, which was beneficial to the stability of the water ecological environment. These results showed that the combination of V. natans with E. crassipes of 1100 ind m-2 providing more favorable conditions for the growth and restoration of submerged macrophytes and improve the water quality. PRACTITIONER POINTS: The responses of submerged macrophytes to floating plants were studied. The optimal density of Eichhornia crassipes was 1100 ind m-2 . The biofilm microbial community changed in response to Eichhornia crassipes.


Assuntos
Eichhornia , Hydrocharitaceae , Microbiota , Biofilmes , Água
11.
Ecotoxicol Environ Saf ; 221: 112415, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34171691

RESUMO

In order to understand the mechanisms of arsenic (As) accumulation and detoxification in aquatic plants exposed to different As species, a hydroponic experiment was conducted and the three aquatic plants (Hydrilla verticillata, Pistia stratiotes and Eichhornia crassipes) were exposed to different concentrations of As(III), As(V) and dimethylarsinate (DMA) for 10 days. The biomass, the surface As adsorption and total As adsorption of three plants were determined. Furthermore, As speciation in the culture solution and plant body, as well as the arsenate reductase (AR) activities of roots and shoots, were also analyzed. The results showed that the surface As adsorption of plants was far less than total As absorption. Compared to As(V), the plants showed a lower DMA accumulation. P. stratiotes showed the highest accumulation of inorganic arsenic but E. crassipes showed the lowest at the same As treatment. E. crassipes showed a strong ability to accumulate DMA. Results from As speciation analysis in culture solution showed that As(III) was transformed to As(V) in all As(III) treatments, and the oxidation rates followed as the sequence of H. verticillata>P. stratiotes>E. crassipes>no plant. As(III) was the predominant species in both roots (39.4-88.3%) and shoots (39-86%) of As(III)-exposed plants. As(V) and As(III) were the predominant species in roots (37-94%) and shoots (31.1-85.6%) in As(V)-exposed plants, respectively. DMA was the predominant species in both roots (23.46-100%) and shoots (72.6-100%) in DMA-exposed plants. The As(III) contents and AR activities in the roots of P. stratiotes and in the shoots of H. verticillata were significantly increased when exposed to 1 mg·L-1 or 3 mg·L-1 As(V). Therefore, As accumulation mainly occurred via biological uptake rather than physicochemical adsorption, and AR played an important role in As detoxification in aquatic plants. In the case of As(V)-exposed plants, their As tolerance was attributed to the increase of AR activities.


Assuntos
Araceae , Arseniato Redutases/metabolismo , Arsênio , Ácido Cacodílico , Eichhornia , Hydrocharitaceae , Proteínas de Plantas/metabolismo , Poluentes Químicos da Água , Adsorção , Araceae/química , Araceae/metabolismo , Arsênio/química , Arsênio/metabolismo , Ácido Cacodílico/química , Ácido Cacodílico/metabolismo , Eichhornia/química , Eichhornia/metabolismo , Hydrocharitaceae/química , Hydrocharitaceae/metabolismo , Hidroponia , Raízes de Plantas/química , Raízes de Plantas/metabolismo , Brotos de Planta/química , Brotos de Planta/metabolismo , Poluentes Químicos da Água/química , Poluentes Químicos da Água/metabolismo
12.
Ecotoxicology ; 30(9): 1781-1788, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34115256

RESUMO

Seagrass meadows have seriously deteriorated in recent years. Seagrass associated phytate-mineralizing rhizobacteria potentially have functions related to seagrass nutrition, health and sustainable growth. The ß-propeller phytases (BPPs) are the only phytase family in aquatic environments, but there are few studies on the BPP community structure of seagrass. In this study, clone libraries and quantitative PCR (qPCR) assays were used to compare the diversity and abundances of the BPP communities of Halodule endl, Halophila ovalis and Thalassia hemprichii in Xisha and Sanya, and to investigate the distribution characteristics of BPP genes in the rhizosphere sediment, which provedes insight into species specialty from phytic mineralization in subtropical and tropical seagrass ecosystems. The highest diversity of BPP genes was found for Thalassia hemprichii in Sanya Bay. Thalassia hemprichii in Sanya had higher abundances of BPPs, which were linked to Gammaproteobacteria. The BPP community diversity and OTUs of Thalassia hemprichii in Sanya were much higher than those of Thalassia hemprichii on Yongxing Island and Stone Island. The seagrass BPP communities had higher diversity and evenness from sampling sites with more human activity. The qPCR results showed that the abundance of phytate acid-degradating bacteria was approximately three times larger in Thalassia hemprichii rhizosphere sediment samples than in Halodule endl and Halophila ovalis rhizosphere sediment samples. This study highlighted that the diversity and abundances of bacteria genetically encoding BPP in the rhizosphere of Thalassia hemprichii were clearly higher than those of Halodule endl and Halophila ovalis. Further study of microbial phosphorus cycling will provide new insights into seagrass meadow ecosystems.


Assuntos
6-Fitase , Bactérias/enzimologia , Hydrocharitaceae , 6-Fitase/genética , Bactérias/genética , Ecossistema , Rizosfera
13.
Sci Total Environ ; 792: 148410, 2021 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-34146816

RESUMO

In natural ecosystems, large amounts of epiphytic bacteria live on the surfaces of submerged plants or non-biological substrates. Although it contributes greatly to host plant health or ecological functions in waters, little is known about the temporal dynamics and assembly mechanisms of epiphytic bacteria. To test whether host plant chemistry leads to divergent community dynamics, we investigated the fine scale temporal community successions of both epiphytic bacteria and the bacterioplankton of the surrounding water in two submerged plants and one non-biological artificial substance. We first observed differentiated epiphytic or surrounding water bacterial communities for different substrates in small spaces (approximately 1 m × 1 m). Selection played dominant roles in affecting the assembly of epiphytic bacteria in the high-phenolic plant Hydrilla verticillata, while for the artificial substance and the low-phenolic plant Vallisneria natans, drift and dispersal drove the assembly of both epiphytic bacteria and bacterioplankton. The higher selection may also contribute to higher turnover rates in both bacterioplankton and epiphytic communities of H. verticillata, with the latter changing drastically in approximately one week. Epiphytic bacteria in H. verticillata developed more complex networks with a higher proportion of positive links, suggesting that more intense interactions such as mutualism or facilitation may exist within epiphytic bacterial communities of the high-phenolic plant. Our results also implied that for the submerged macrophytes used in biological purification, the dynamics of epiphytic biofilm in the purification-related functional capacities might also be considered.


Assuntos
Ecossistema , Hydrocharitaceae , Organismos Aquáticos , Bactérias , Biofilmes
14.
Sci Total Environ ; 792: 148413, 2021 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-34153748

RESUMO

Macrophytes have often been considered as a prospective tool for the elimination of cyanobacterial bloom, because they may produce chemical compounds that outcompete bloom-forming cyanobacteria. However, a comprehensive, unbiased overview of evidence to support this is missing. Moreover, studies into the effects of individual macrophyte species have often used different methodologies and, thus, cannot be compared. Herein, we firstly carried out a systematic review of studies into the effects of macrophytes on the growth of bloom-forming cyanobacteria. Secondly, we carried out an experiment into the effects of aqueous and ethanol extracts from 19 macrophyte species on the growth of two of the most common cyanobacteria, Aphanizomenon gracile and Microcystis aeruginosa, using a uniform methodological approach. The systematic review revealed that most of the 69 macrophyte species previously studied have shown a combination of inhibitory, stimulatory, and neutral effects. In our own experiment, an inhibitory effect was exhibited only 15 times out of 532 experimental variants, specifically by Chara globularis, Ceratophyllum submersum, Elodea nuttallii, Hydrilla verticillata, Myriophyllum heterophyllum, M. spicatum, and Vallisneria americana. Put together, these results indicate that the practical application of chemical compounds produced by macrophytes to eliminate cyanobacterial bloom may have lower prospects than previously anticipated.


Assuntos
Aphanizomenon , Cianobactérias , Hydrocharitaceae , Microcystis
15.
Mar Pollut Bull ; 167: 112326, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33940432

RESUMO

Apart from direct light effects, we tested whether the takeover of the seagrass Thalassia testudinum by the seaweed Anadyomene sp. in high nutrient areas of Biscayne Bay, Florida, USA, is related to a faster nutrient surge uptake capacity of the seaweed and/or a negative effect on the seagrass uptake rates. Anadyomene sp. and T. testudinum showed a similar ammonium surge uptake capacity, but the seagrass performed better than the seaweed in mixed incubations at high ammonium concentrations. T. testudinum was faster than Anadyomene sp. at taking up pulses of phosphate, but the uptake rates of the seagrass were significantly decreased in the presence of the seaweed. The takeover of T. testudinum by Anadyomene sp. at Biscayne Bay is likely dominated by light and cannot be simply explained by their single or mixed nutrient surge uptake rates, but the phosphate availability and the seagrass uptake inhibition by the seaweed may also play a key role in the process.


Assuntos
Hydrocharitaceae , Baías , Florida , Nitrogênio , Fósforo
16.
Environ Sci Pollut Res Int ; 28(38): 53224-53238, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34023990

RESUMO

With the increasing eutrophication of the aquatic environments, cyanobacteria blooms caused certain damage to the animals and plants in the aquatic environments. In this experiment, two species were selected from six species of submerged macrophytes, the experimental conditions were changed to achieve the best inhibitory effect on Microcystis aeruginosa, and oxidative damage analysis was carried out. The experiment results demonstrated that the inhibition rate of Vallisneria natans and Ceratophyllum demersum was nearly 100% at the concentration of 3 g/L after 15 days of anaerobic soaking extract. In addition, the longer the soaking time of the two submerged macrophytes, the weaker the photosynthesis effect, and the lower the chlorophyll fluorescence parameters, the more obvious the inhibition effect on M. aeruginosa. Lipid peroxidation injury of M. aeruginosa could be reflected by malondialdehyde (MDA) concentration. The MDA concentration in the experimental group was significantly higher than the control group. Results showed that V. natans and C. demersum could induce oxidative damage in M. aeruginosa. It was also observed that the secondary metabolites produced by V. natans were mainly fatty acids (e.g., the oxidative acid was 6.92 w/%, and the successful acid was 9.85 w/%) which inhibited M. aeruginosa in gas chromatography-mass spectrometry (GC-MS). The main secondary metabolites in C. demersum were hydroxyl acids (e.g., the 4-hydroxy-3-methoxyphenylacetic acid was 24.33 w/%), which could inhibit the algae through allelopathy. This study provided reference for submerged macrophytes to inhibit M. aeruginosa under different conditions.


Assuntos
Hydrocharitaceae , Microcystis , Peroxidação de Lipídeos , Malondialdeído , Estresse Oxidativo
17.
Ecotoxicology ; 30(5): 919-928, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33830383

RESUMO

Seagrasses constitute a significant part of coral reef ecosystems, representing high primary productivity and one of the most important coastal habitats in marine ecosystems. Though seagrasses possess irreplaceable ecological services to the marine environment, taxonomical ambiguity still exists due to similar morphological characters and phenotypic plasticity. As an emerging technology, DNA barcoding can effectively identify cryptic species using a short orthologous DNA region. In this study, we collected samples from five different locations (Daya Bay, Xincun Bay, Sanya Bay, Xisha Islands, and Nansha Islands), and three seagrass species Cymodocea rotundata, Thalassia hemprichii and Halophila ovalis was evaluated. Moreover, ITS, matK and rbcL genes were used as DNA barcodes. The results indicated that single ITS and concatenated ITS/matK/rbcL both conducted better species resolution than single matK and rbcL. Nevertheless, single ITS was more convenient. Furthermore, in all the four topology trees, three species resolved as 3 clusters as well H. ovalis and T. hemprichii grouped as sister clade. In the meantime, differentiation lay in intra-species based on the result of single ITS and three-locus analysis. Within H. ovalis and T. hemprichii separately, individuals from Xisha Islands first group together, then grouped with individuals from Nansha Islands and/or Xincun Bay and/or Sanya Bay and/or Daya Bay, which indicated that geographical distribution influenced population evolution. However, intra-species differentiation did not emerge in the tree of matK or rbcL.


Assuntos
Recifes de Corais , Hydrocharitaceae , DNA , Código de Barras de DNA Taxonômico , Ecossistema , Humanos
18.
Glob Chang Biol ; 27(11): 2592-2607, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33843114

RESUMO

The introduction and establishment of exotic species often result in significant changes in recipient communities and their associated ecosystem services. However, usually the magnitude and direction of the changes are difficult to quantify because there is no pre-introduction data. Specifically, little is known about the effect of marine exotic macrophytes on organic carbon sequestration and storage. Here, we combine dating sediment cores (210 Pb) with sediment eDNA fingerprinting to reconstruct the chronology of pre- and post-arrival of the Red Sea seagrass Halophila stipulacea spreading into the Eastern Mediterranean native seagrass meadows. We then compare sediment organic carbon storage and burial rates before and after the arrival of H. stipulacea and between exotic (H. stipulacea) and native (C. nodosa and P. oceanica) meadows since the time of arrival following a Before-After-Control-Impact (BACI) approach. This analysis revealed that H. stipulacea arrived at the areas of study in Limassol (Cyprus) and West Crete (Greece) in the 1930s and 1970s, respectively. Average sediment organic carbon after the arrival of H. stipulacea to the sites increased in the exotic meadows twofold, from 8.4 ± 2.5 g Corg  m-2  year-1 to 14.7 ± 3.6 g Corg  m-2  year-1 , and, since then, burial rates in the exotic seagrass meadows were higher than in native ones of Cymodocea nodosa and Posidonia oceanica. Carbon isotopic data indicated a 50% increase of the seagrass contribution to the total sediment Corg pool since the arrival of H. stipulacea. Our results demonstrate that the invasion of H. stipulacea may play an important role in maintaining the blue carbon sink capacity in the future warmer Mediterranean Sea, by developing new carbon sinks in bare sediments and colonizing areas previously occupied by the colder thermal affinity P. oceanica.


Assuntos
Alismatales , Hydrocharitaceae , Carbono/análise , Sequestro de Carbono , Ecossistema , Sedimentos Geológicos , Oceano Índico , Mar Mediterrâneo
19.
J Environ Manage ; 289: 112461, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-33831758

RESUMO

The application of compost has been recognized as one of the most promising approaches for preserving soil quality and crop production. The present study exhaustively investigates the impact of Water Hyacinth Compost (WHC), Hydrilla verticillata Compost (HVC) and Vegetable Waste Compost (VWC) on soil nutrient quality and engineering properties [Bulk Density (BD), water retention and specific gravity]. For the study, six different proportions constituting 5, 10, 15, 25, 35 and 45% of the composts by weight of the soil were taken. The soil compost mixtures were evaluated at different periods (0, 15, 30, 45, 60 and 120 days) for various nutrients [Na, Mg, P, K, Ca, Total Organic Carbon (TOC), Total Kjeldahl Nitrogen (TKN)], BD, water retention capacity, change in specific gravity and Cation Exchange Capacity (CEC) values. It was observed that when the percentage of compost was increased to 15-45%, it resulted in enhanced nutrient value of the soil. Also, for WHC, HVC and VWC 60 days was sufficient to improve the soil quality to its maximum extend. Based on the optimized physico-chemical properties generated from the Response Surface Methodology (RSM) model, it was found that compared to WHC and HVC, the VWC performed better results viz., generating low BD (0.87 g/cm3), high water retention capacity (45.63%) and degree of saturation (77.49%) of the soil. While WHC, HVC and VWC can be used to improve soil nutrient content and overall physico-chemical parameters in long terms, VWC could be more efficient and beneficial to degraded soil for restoring soil health.


Assuntos
Compostagem , Hydrocharitaceae , Nitrogênio/análise , Nutrientes , Solo
20.
Arch Microbiol ; 203(6): 3443-3456, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33893827

RESUMO

Seagrass meadows are vital ecosystems with high productivity and biodiversity and often in the oligotrophic area. Nitrogen usually limits productivity in this ecosystem as the main nutrient factor. Biological nitrogen fixation by diazotrophs in the rhizosphere sediment can introduce "new" nitrogen into the ecosystem. Previous studies revealed that most sulfate-reducing bacteria (SRB) can also fix nitrogen like the nitrogen-fixing bacteria (NFB). Moreover, both sulfate reduction and nitrogen fixation were affected by the organic pollutant. However, rare information is available regarding the NFB and SRB community composition and their temporal response to the pollutant. The quantitative real-time polymerase chain reaction and polymerase chain reaction denaturing gradient gel electrophoresis have been used to analyze NFB and SRB communities' shifts under different PAHs concentrations. They both experienced a dramatic shift under PAHs stress but exhibited different patterns. SRB could use the low and high concentration PAHs at the early stage of the incubation, while only the low concentration of PAHs could stimulate the growth of NFB through the whole incubation period. The predominant species of NFB communities were Alphaproteobacteria, Gammaproteobacteria, and Deltaproteobacteria; while for SRB communities were class Epsilonproteobacteria. Redundancy analysis indicated the significant environmental factors for the two communities were both ammonium and pH (P < 0.05). There existed nifH sequences related to known nitrogen fixing SRB Desulfatibacillum alkenivorans, which confirmed that microbial N2 fixation and sulfate reduction were coupled in the seagrass ecosystem by molecular technique. Our investigation provides new insight into the NFB and SRB community in the seagrass meadow.


Assuntos
Bactérias , Sedimentos Geológicos , Microbiota , Hidrocarbonetos Policíclicos Aromáticos , Bactérias/classificação , Bactérias/efeitos dos fármacos , Bactérias/genética , Deltaproteobacteria/genética , Sedimentos Geológicos/microbiologia , Hydrocharitaceae/microbiologia , Microbiota/efeitos dos fármacos , Microbiota/genética , Fixação de Nitrogênio , Oxirredutases/genética , Hidrocarbonetos Policíclicos Aromáticos/farmacologia , Sulfatos/metabolismo , Poluentes Químicos da Água/farmacologia
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