Quanzhou Bay Research Articles

Genome sequence of Sulfurimonas sp. C5, a potential chemolithoautotrophic, sulfur-oxidizing bacterium isolated from a mangrove sediment.

Sulfurimonas sp. strain C5 (MCCC 1A19556) is a strain with potential chemolithoautotrophic sulfur-oxidizing function, which is isolated from a mangrove sediment sample collected from Quanzhou Bay, Fujian Province, China. This report describes the genome sequence of strain C5, which possesses the gene sets for the sulfur-oxidizing pathway.

Identification of key anthropogenic and land use factors and ecological risk assessment of dissolved polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) in an urbanized estuary in China

This study investigated dissolved PAHs and OCPs in Quanzhou Bay estuaries, assessed their ecological risk, and examined anthropogenic impacts on contaminant distribution. Results showed that dissolved ∑24PAH concentrations ranged from 117 to 709 ng/L (mean: 358 ng/L), with dominance of 2-ring PAHs (Naphthalene, 1-Methylnaphthalene, and 2-Methylnaphthalene). Dissolved DDT levels ranged from 0.06 to 0.49 ng/L (mean: 0.28 ng/L), while HCBz concentrations varied from 0.02 to 0.44 ng/L (mean: 0.20 ng/L). PAHs were higher in the north due to urbanization and transport, while OCPs showed higher levels in the south due to historical agricultural use. Rural areas, water bodies, and wetlands significantly influenced the behavior of PAHs according to Spearman correlation and lasso regression analyses. Quanzhou Bay was categorized as a low to medium risk area based on dispersion simulation and ecological risk assessment, highlighting implications for future sustainable development and policy planning. CapsuleThe coupled relationship between human activities and the distribution of dissolved PAHs and OCPs in urbanized estuaries was explored using statistical methods and GIS technology, providing valuable insights into environmental processes and pollutant control policies.

Occurrence, accumulation, ecological risk, and source identification of potentially toxic elements in multimedia in a subtropical bay, Southeast China

Potentially toxic elements (PTEs) in seawater and sediments may be amplified along the aquatic food chain, posing a health threat to humans. This study comprehensively analyzed the concentrations, distribution, potential sources, and health risk of 7 PTEs in multimedia (seawater, sediment and organism) in typical subtropical bays in southern China. The results indicated that Zn was the most abundant element in seawater, and the average concentration of Cd in sediment was 3.93 times higher than the background value. Except for As, the seasonal differences in surface seawater were not significant. The content of Zn in fishes, crustacea, and shellfish was the highest, while the contents of Hg and Cd were relatively low. Bioaccumulation factor indicated that Zn was a strongly bioaccumulated element in seawater, while Cd was more highly enriched by aquatic organisms in sediment. According to principal component analysis (PCA), and positive matrix factorization (PMF), the main sources of PTEs in Quanzhou Bay were of natural derivation, industrial sewage discharge, and agricultural inputs, each contributing 40.4 %, 24.2 %, and 35.4 %, respectively. This study provides fundamental and significant information for the prevention of PTEs contamination in subtropical bays, the promotion of ecological safety, and the assessment of human health risk from PTEs in seafood.

Empirical Analysis of a Super-SBM-Based Framework for Wetland Carbon Stock Safety Assessment

With climate change and urbanization expansion, wetlands, which are some of the largest carbon stocks in the world, are facing threats such as shrinking areas and declining carbon sequestration capacities. Wetland carbon stocks are at risk of being transformed into carbon sources, especially those of wetlands with strong land use–natural resource conservation conflict. Moreover, there is a lack of well-established indicators for evaluating the health of wetland carbon stocks. To address this issue, we proposed a novel framework for the safety assessment of wetland carbon stocks using the Super Slack-Based Measure (Super-SBM), and we then conducted an empirical study on the Quanzhou Bay Estuary Wetland (QBEW). This framework integrates the unexpected output indicator (i.e., carbon emissions), the expected output indicators, including the GDP per capita and carbon stock estimates calculated via machine learning (ML)-based remote sensing inversion, and the input indicators, such as environmental governance investigations, climate conditions, socio-economic activities, and resource utilization. The results show that the annual average safety assessment for carbon pools in the QBEW was a meager 0.29 in 2015, signaling a very poor state, likely due to inadequate inputs or excessive unexpected outputs. However, there has been a substantial improvement since then, as evidenced by the fact that all the safety assessments have exceeded the threshold of 1 from 2018 onwards, reflecting a transition to a “weakly effective” status within a safe and acceptable range. Moreover, our investigation employing the Super-SBM model to calculate the “slack variables” yielded valuable insights into optimization strategies. This research advances the field by establishing a safety measurement framework for wetland carbon pools that leverages efficiency assessment methods, thereby offering a quantitative safeguard mechanism that supports the achievement of the “3060” dual-carbon target.

Genome-based analysis of the family Paracoccaceae and description of Ostreiculturibacter nitratireducens gen. nov., sp. nov., isolated from an oyster farm on a tidal flat.

Two bacterial strains, designated FR2A1T and MT2-5-38, were isolated from the surface sediments of an oyster farm on a tidal flat in Quanzhou Bay, China. Both strains were Gram-stain-negative, rod-shaped, aerobic, catalase-positive, and oxidase-positive. The 16S rRNA gene sequences of the two strains were 100% identical and had the highest similarity (97.1%) with Phaeovulum vinaykumarii JA123T. The average nucleotide identity (ANI) value and digital DNA-DNA hybridization (DDH) value indicated that the two strains belonged to a single species. Gene annotation revealed that the two strains contained a gene cluster for nitrate reduction and a gene cluster for sulfur oxidation, indicating a possible role in N and S cycling in the tidal flat sediment. The phylogeny inferred from the 16S rRNA gene and 120 conserved proteins indicated that the two strains formed a distinct monophyletic clade within the family Paracoccaceae. The respiratory quinone was Q-10. The major fatty acids consisted of summed feature 8 (C18:1ω7c and/or C18:1ω6c) and C18:0. The polar lipids consisted of phosphatidylethanolamine, phosphatidylglycerol, and several unidentified phospholipids. Based on the above characteristics, strains FR2A1T and MT2-5-38 represent a novel genus and a novel species, for which we propose the name Ostreiculturibacter nitratireducens gen. nov., sp. nov. The type strain is FR2A1T (=MCCC 1K08809T = KCTC 8317T). Phylogenomic analysis of 1,606 high-quality genomes of the family Paracoccaceae, including type strains, non-type strains, and uncultivated bacteria, was performed using the Genome Taxonomic Database Toolkit (GTDB-Tk), and the average amino acid identity (AAI) value of the phylogenetic clade was estimated. We found that 35 species of the family Paracoccaceae needed re-classification, and an AAI value of 70% was chosen as the genus boundary within the family Paracoccaceae.

Coupling use of stable isotopes and functional genes as indicators for the impacts of artificial restoration on the carbon storage of a coastal wetland invaded by Spartina alterniflora, southeastern China

Coastal wetlands are characterized by high production and thus play an important role in global climate change. In past decades, the invasion of Spartina alterniflora has caused many problems of coastal wetlands in southeastern China, and the restoration of such areas was mainly conducted by replacing Spartina alterniflora with mangrove plants. This may impact the carbon storage dynamics in such areas. In this study, stable isotopes (δ13C and δ15N) and molecular analysis were used to reveal the impact of artificial restoration on the carbon storage of Quanzhou Bay Estuary Wetland Natural Reserve. The major results are as follows: (1) the change in dominant plants results in a changing major source of soil organic matter, from external sources to mangrove plants; (2) the decrease in soil organic matter following the removal of Spartina alterniflora may be primarily caused by the loss of external organic matter, while the production of mangroves may offset such loss and enhance the content and stability of carbon storage over the long term; (3) microbial CO2 assimilation may serve as an alternative source of bioavailable carbon and thus support the activity of benthic community. Our results revealed the long-term benefits of such restoration on the carbon storage function of wetlands invaded by Spartina alterniflora. Furthermore, the integrating of isotopic tracers and molecular technology may provide new insights in understanding the response of the carbon storage in coastal areas to human activity.

Environmental microbial diversity and water pollution characteristics resulted from 150 km coastline in Quanzhou Bay offshore area.

As a typical transitional area between the land and sea, the offshore area is subjected to the triple synergistic pressure from the ocean, land, and atmosphere at the same time, and has obvious characteristics such as complex and diverse chemical, physical, and biological processes, coupled and changeable environmental factors, and sensitive and fragile ecological environment. With the deepening of the urbanization process, the offshore area has gradually become the final receptions of pollutants produced by industry, agriculture, and service industries, and plays a key role in the global environmental geochemical cycle of pollutants. In this study, the Quanzhou Bay offshore area was selected as the research object. Sediment and water samples were collected from 8 sampling points within about 150 km of coastline in the Quanzhou Bay offshore area. 16s rDNA high-throughput sequencing method was used to investigate the variation rule of microbial diversity in the offshore area, and multi-parameter water quality analysis was carried out at the same time. The results showed that the distribution characteristics of microbial communities and water quality in the Quanzhou Bay offshore area showed significant differences in different latitudes and longitudes. This difference is closely related to the complexity of offshore area. This study can provide scientific support for protecting and improving the ecological environment of offshore areas.

Rapid Discovery of Substances with Anticancer Potential from Marine Fungi Based on a One Strain-Many Compounds Strategy and UPLC-QTOF-MS.

The secondary metabolites of marine fungi with rich chemical diversity and biological activity are an important and exciting target for natural product research. This study aimed to investigate the fungal community in Quanzhou Bay, Fujian, and identified 28 strains of marine fungi. A total of 28 strains of marine fungi were screened for small-scale fermentation by the OSMAC (One Strain-Many Compounds) strategy, and 77 EtOAc crude extracts were obtained and assayed for cancer cell inhibition rate. A total of six strains of marine fungi (P-WZ-2, P-WZ-3-2, P-WZ-4, P-WZ-5, P56, and P341) with significant changes in cancer cell inhibition induced by the OSMAC strategy were analysed by UPLC-QTOF-MS. The ACD/MS Structure ID Suite software was used to predict the possible structures with inhibitory effects on cancer cells. A total of 23 compounds were identified, of which 10 compounds have been reported to have potential anticancer activity or cytotoxicity. In this study, the OSMAC strategy was combined with an untargeted metabolomics approach based on UPLC-QTOF-MS to efficiently analyse the effect of changes in culture conditions on anticancer potentials and to rapidly find active substances that inhibit cancer cell growth.

Mangrovimonas aestuarii sp. nov., isolated from tidal flat sediment.

A Gram-stain-negative, rod-shaped and light yellow-pigmented strain designated MBT5T was isolated from tidal flat sediment of an oyster farming area in Quanzhou Bay, PR China. Catalase activity and oxidase activity were positive. Flexirubin-type pigment was absent. Growth was observed at 10-40 °C (optimum, 35 °C), pH 6-9 (optimum, pH 7), and with 1-7 % NaCl (optimum, 2 %, w/v). The 16S rRNA gene of strain MBT5T had maximum sequence similarity values with Meridianimaribacter flavus NH57NT, Mangrovimonas yunxiaonensis LYYY01T and Mangrovimonas futianensis AS18T of 95.6, 95.4 and 94.9 %, respectively. Phylogenetic analysis based on 16S rRNA gene sequences and 120 conserved concatenated proteins indicated that strain MBT5T was affiliated to the genus Mangrovimonas and formed a distinct monophyletic branch. The digital DNA-DNA hybridization, average nucleotide identity and average amino acid identity values between strain MBT5T and the type strains of Mangrovimonas were estimated to be 17.3-18.7 %, 70.9-71.5 % and 66.4-68.2 %, respectively. The respiratory quinone was menaquinone-6. The major fatty acids were iso-C15 : 0 and iso-C15 : 1 G. The draft genome size was 2 952 053 bp with a DNA G+C content of 36.5 %. Based on phenotypic, physiological, phylogenetic and genomic data, together with chemotaxonomic characteristics, strain MBT5T represents a novel species, for which the name Mangrovimonas aestuarii sp. nov. is proposed. The type strain is MBT5T (=MCCC 1K06186T=KCTC 92888T=GDMCC 1.3851T).

Comparison of the Meiofauna and Marine Nematode Communities before and after Removal of Spartina alterniflora in the Mangrove Wetland of Quanzhou Bay, Fujian Province

The invasion of Spartina alterniflora is one of the main threats faced by mangrove wetlands in Quanzhou Bay, Fujian. To effectively manage S. alterniflora, mangrove plants (Kandelia obovata, Aegiceras corniculatum, Bruguiera gymnorhiza, Rhizophora stylosa, and Avicennia marina) were used to replace it in 2022 to restore the wetland ecosystem. Samples of meiofauna and marine nematodes were collected four times, including in September 2022 (before the removal of S. alterniflora), October 2022 (after removal), and December 2022 and March 2023 (after planting mangrove plants). This paper investigates changes in the composition, abundance, and biomass of meiofauna in different time periods, with a specific focus on comparing the community structure and biodiversity indices of marine nematodes in S. alterniflora and mangrove habitats. The results indicate that among the five meiofauna groups identified, marine nematodes account for 92.91%, 91.91%, 92.03%, and 85.92% of the total meiofauna abundance in the respective study periods. In the S. alterniflora habitat in September, marine nematodes were identified belonging to 12 families and 20 genera, of which 6 genera were dominant (percentage ≥ 5%). They were Ptycholaimellus, Parodontophora, Terschellingia, Halichoanolaimus, Metachromadora, and Parasphaerolaimus. In the mangrove habitat in December, marine nematodes were identified belonging to 15 families and 23 genera, with 6 genera being dominant, namely Daptonema, Admirandus, Parodontophora, Ptycholaimellus, Terschellingia, and Anoplostoma. Comparing the marine nematode communities in the two habitats, the mangrove habitat exhibits higher diversity than the S. alterniflora habitat. There was a change in the dominant genera, and their dominance has decreased. The dominant genera of marine nematodes found in both habitats are common and widely distributed groups. The changes in the abundance of meiofauna and the community structure of marine nematodes following the restoration of the S. alterniflora habitat by planting mangroves provide valuable insights for ecological monitoring after restoration measures in estuarine wetland conservation areas.

Antibiotics and their associations with antibiotic resistance genes and microbial communities in estuarine and coastal sediment of Quanzhou Bay, Southeast China

The antibiotic concentrations spanned from 11.2 to 173.8 ng/g, with quinolones and tetracyclines being observed to be prevalent. The amount of microbial biomass as determined by Phospholipid fatty acid (PLFA) ranged from 2.92 to 10.99 mg kg−1, with G- bacteria dominating. A total of 254 distinct ARGs and 10 MEGs were identified, with multidrug ARGs having the highest relative abundance (1.18 × 10−2 to 3.00 × 10−1 copies/16S rRNA gene copies), while vancomycin and sulfonamide resistance genes were the least abundant. Results from canonical-correlation analyses combined with redundancy analysis indicated that macrolides were significantly related to the shifts of microbial community structure in sediments, particularly in G+ bacteria that were more sensitive to antibiotic residues. It was observed that sulfonamide ARGs had a greater correlation with residual antibiotics than other ARGs. This study provided a field evidence that multiple residual antibiotics from coastal sites could cause fundamental shifts in microbial community and their associated ARGs.

Occurrence and Distribution of Tetrabromobisphenol A and Diversity of Microbial Community Structure in the Sediments of Mangrove.

The occurrence and distribution characteristics of tetrabromobisphenol A (TBBPA) and its relationship with microbial community diversity in different mangrove sediments need further investigation. The results of this study indicated levels of TBBPA in mangrove sediments from the Zhangjiang Estuary (ZJ), Jiulongjiang Estuary (JLJ), and Quanzhou Bay (QZ) in Southeast China ranging from 1.80 to 20.46, 3.47 to 40.77, and 2.37 to 19.83 ng/g dry weight (dw), respectively. Mangrove sediments from JLJ contained higher levels of TBBPA, possibly due to agricultural pollution. A correlation analysis revealed a significant correlation between total organic carbon (TOC), total nitrogen (TN), and TBBPA distribution in ZJ and JLJ mangrove sediments, but not in QZ mangrove sediments. TOC significantly affected the distribution of TBBPA in mangrove sediments, but pH had no effect. High-throughput 16S rRNA gene sequencing showed that Pseudomonadota dominated the sediment bacteria followed by Chloroflexota, Actinobacteota, Bacillota, Acidobacteriota, Bacteroidota, and Aminicenantes in mangrove sediments. Although the microbial community structure of the ZJ, JLJ, and QZ mangrove sediments was similar, the taxonomic profile of their sensitive responders differed markedly. The genus Anaerolinea was dominant in the mangrove sediments and was responsible for the in situ dissipation of TBBPA. Based on redundancy analysis, there was a correlation between TBBPA, TOC, TN, C/N, pH, and microbial community structure at the genus level. Combining TBBPA, TN, and TOC may induce variations in the microbial community of mangrove sediments.

Evolution of sedimentary dynamic process/pattern in the Quanzhou Bay under impact of Typhoon Matmo (2014)

Typhoons are one of the most dramatic weather events affecting the nearshore environment, which significantly affect the processes of sediment erosion, transport, and redeposition in a short period of time. In this study, the hydrodynamic evolution and sedimentary source and sink processes in the Quanzhou Bay after the typhoon’s passing were systematically studied by using the water column observation data (flow field and turbidity) and the surface sediment grain-size analysis results obtained in two surveys: 3–4 days and 1 month after Typhoon Matmo (2014), respectively. The results show that the typhoon process significantly increased the sediment flux input from the Jinjiang River and expanded the sediment “sink” in the Jinjiang River estuary. After the typhoon’s passing, the sediments in the bay were redistributed under the stable tidal transport, and the estuarine sediments were transformed from a sink of riverine material into a source of sediment transport and diffusion. Typhoon processes play an important role in the evolution of estuarine sediments and sedimentary environment.

Mechanical Analysis of Junction Pier of Fuzhou-Xiamen High-Speed Railway Rigid-Frame Bridge

The continuous rigid structure bridge on both sides of the Quanzhou Bay Crossing Bridge uses double-limbed thin-walled flexible piers for the junction piers between the links, and the whole bridge has no bearings. In China, the monolithic bearing-free prestressed concrete continuous rigid-frame bridge is used in railway bridges. The junction pier between the two adjacent couplets is a double-leg thin-walled flexible pier. The single leg thin-walled pier is connected with half of the pier-top segment. During the construction process, the block with numbered zero on the top of the pier is temporarily anchored and connected. Symmetrical cantilevered baskets are used on both sides for construction, and after the mid-pier cantilevered construction is completed, the temporary anchoring device for the block with numbered zero is removed. Because the structural system conversion is required in the construction, the mechanical properties of the junction pier will change greatly before and after the conversion, so it is very necessary to calculate and analyze it to master. In this paper, the finite element model of the connecting pier is established accurately, the stress and deformation of each part of the connecting pier under unfavorable working conditions is analyzed in detail, the seismic spectrum analysis under the action of common earthquake and rare earthquake is carried out, and the stress and deformation law of the structure is expounded, which can provide some reference for the construction of similar projects in the future.

Two-Stream Translating LSTM Network for Mangroves Mapping Using Sentinel-2 Multivariate Time Series

Monitoring mangroves is critical to protect the coastal ecosystems, and deep learning has gained great popularity in mapping mangroves using remote sensing. However, mangroves are usually submerged by cyclical tide since they are grown in land-sea interface places, resulting in some drawbacks of existing mangroves mapping models. For one side, the correlations between vegetation index (VI) and water index (WI) time series of mangroves are not fully considered. For another side, existing models rarely explored the local differences between mangroves and other land covers. Considering the above two aspects, we propose a novel two-stream translating long short-term memory network (TSTLN) for mangroves mapping. Firstly, we construct multivariate time series (MTS) by compositing VI and WI based on Sentinel-2 time series data. Secondly, we build a two-stream architecture and design a siamese translating (ST) module in both streams. In global stream, MTS are embedded into ST module directly to get global features. Whereas in local stream, a depthwise convolutional self-attention (DCA) module is conceived to capture local information firstly, and then local features are further learnt by ST module. Finally, a fully connected layer and softmax are used to classify the representations extracted from the two streams. Experiments conducted over Maowei Sea, Dongzhai Port, and Quanzhou Bay in 2019 demonstrate that: 1) TSTLN outperforms other methods, with improved OA of 0.49%-3.89%, 1.35%-6.85%, and 0.73%-3.65% in the three areas, respectively; 2) Two-stream architecture, ST module, and DCA module all contribute to the good performance of TSTLN; 3) TSTLN maintains higher accuracy with few parameters and less running time compared to other counterparts.

Multi-Scenario Simulation to Predict Ecological Risk Posed by Urban Sprawl with Spontaneous Growth: A Case Study of Quanzhou.

The rapid expansion of different types of urban land continues to erode natural and semi-natural ecological space and causes irreversible ecological damage to rapidly industrialized and urbanized areas. This work considers Quanzhou, a typical industrial and trade city in southeastern China as the research area and uses a Markov chain integrated into the patch-generating land use simulation (PLUS) model to simulate the urban expansion of Quanzhou from 2005 to 2018. The PLUS model uses the random forest algorithm to determine the contribution of driving factors and simulate the organic and spontaneous growth process based on the seed generation mechanism of multi-class random patches. Next, leveraging the importance of ecosystem services and ecological sensitivity as indicators of evaluation endpoints, we explore the temporal and spatial evolution of ecological risks from 2018 to 2031 under the scenarios of business as usual (BAU), industrial priority, and urban transformation scenarios. The evaluation endpoints cover water conservation service, soil conservation service, biodiversity maintenance service, soil erosion sensitivity, riverside sensitivity, and soil fertility. The ecological risk studied in this work involves the way in which different types of construction land expansion can possibly affect the ecosystem. The ecological risk index is divided into five levels. The results show that during the calibration simulation period from 2005 to 2018 the overall accuracy and Kappa coefficient reached 91.77% and 0.878, respectively. When the percent-of-seeds (PoS) parameter of random patch seeds equals 0.0001, the figure of merit of the simulated urban construction land improves by 3.9% compared with the logistic-based cellular automata model (Logistic-CA) considering organic growth. When PoS = 0.02, the figure of merit of the simulated industrial and mining land is 6.5% higher than that of the Logistic-CA model. The spatial reconstruction of multiple types of construction land under different urban development goals shows significant spatial differentiation on the district and county scale. In the industrial-priority scenario, the area of industrial and mining land is increased by 20% compared with the BAU scenario, but the high-level risk area is 42.5% larger than in the BAU scenario. Comparing the spatial distribution of risks under the BAU scenario, the urban transition scenario is mainly manifested as the expansion of medium-level risk areas around Quanzhou Bay and the southern region. In the future, the study area should appropriately reduce the agglomeration scale of urban development and increase the policy efforts to guide the development of industrial land to the southeast.

Coupling Relationship of Geomorphic Evolution and Marine Hydrodynamics in the Stage-Specific Development of Urban Bays: A Modelling Case Study in Quanzhou Bay (1954–2017), China

With the development of social economy and human activities, the geomorphology and hydrodynamic conditions of coasts have been dramatically changed, causing serious environmental pollution and resource depletion. Taking Quanzhou Bay as an example, this study combined geomorphologic change with a hydrodynamic model to simulate the change in tidal currents in different periods. The results show a change in the coastline was the main cause of hydrodynamic change during the industrialization reform. During the past 70 years, the tidal prism decreased year by year, and the average velocity of the tidal current in the channel decreased by 33.7% and 30.8% at flood and ebb tide, respectively. In the early stages of industrialization, reclamation land was used in a single way. The tidal prism decreased by 22.2% and 29.8% in the spring and neap tide, respectively. In the middle and later stages, the tidal current velocity increased, and reclamation land was used in a variety of ways. In modern society, the reclamation land-use type was unitary. Based on this research, we show the influence of human activities on the evolution of the bay’s geomorphology and provide suggestions for the management of the bay.

Portibacter marinus sp. nov., isolated from the sediment on the surface of plastics and proposal of a novel genus Neolewinella gen. nov. based on the genome-based phylogeny of the family Lewinellaceae.

A Gram-stain-negative, rod-shaped and orange-pigmented bacterial strain designated 10MBP4-2-1T was isolated from the sediment on the surface of a plastic straw collected from oyster-farming areas in Quanzhou Bay, PR China. Catalase activity and oxidase activity were positive. Flexirubin-type pigment was absent. The 16S rRNA gene of strain 10MBP4-2-1T showed highest sequence similarity to Portibacter lacus YM8-076T of 98.3 %. Phylogenetic analysis based on 16S rRNA gene sequences and 120 conserved concatenated proteins indicated that strain 10MBP4-2-1T was affiliated to the genus Portibacter and formed a monophyletic clade with P. lacus YM8-076T. The digital DNA-DNA hybridization, average nucleotide identity and average amino acid identity values between strain 10MBP4-2-1T and P. lacus YM8-076T were estimated to be 17.7, 70.4 and 70.3 %, respectively. The respiratory quinone was menaquinone 7. The major fatty acid composition was iso-C15 : 0, iso-C17 : 0 3-OH and summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c). The draft genome size was 5 191 941 bp with DNA G+C content of 39.2 %. Based on phylogenetic analyses and whole genomic comparisons, strain 10MBP4-2-1T represents a novel species, for which the name Portibacter marinus sp. nov. is proposed. The type strain is 10MBP4-2-1T (=MCCC 1K07073T=KCTC 92101T). Additionally, phylogeny and whole genomic comparison of the family Lewinellaceae placed Lewinella cohaerens and the remaining Lewinella (currently comprising 11 species) in two clearly distinguishable clades recognized at the genus level. Thus, a novel genus named Neolewinella gen. nov. is proposed to accommodate the 11 species. Our study provides a taxonomic framework for the family Lewinellaceae based on genomic data.

Extreme response analysis of train-track-bridge-wind interaction system based on in-situ monitoring wind data

Deterministic safety curves of safe train running speeds versus mean wind speeds (MWSs) have been studied in the time domain, considering the train-bridge interaction (TBI) dynamics. However, the randomness of track irregularity and wind turbulence makes the extreme response of the TBI system indeterministic; and so does the safety curve. Therefore, an extreme evaluation theory based on the probability density evolution method (PDEM) is adopted in this study to investigate the extreme response distributions of TBI system under crosswinds with the consideration of the field measured turbulence characteristics. The applicability of the theory on train-bridge wind interaction system is verified first, followed by the discussion on the variations of extreme responses of train and bridge versus MWSs and running speeds of trains running on a high-speed railway cable-stayed bridge. A probabilistic safety curve is finally determined based on 40 cases with the wind speeds ranging from 10 m/s to 45 m/s and the train speeds ranging from 200 km/h to 400 km/h. The study analyses demonstrate the computational accuracy and efficiency of the PDEM-based extreme theory applied to the TBI system; and indicate that the extreme responses of high-speed trains and Quanzhou Bay Bridge increase with increasing MWSs and train speeds. In addition, most of performance indicators do not exceed the code-stipulated failure criteria except the train unloading factor and the lateral displacement at the mid-main span. The probabilistic safety curve for the studied bridge is thus deduced according to these two controlling indexes.

Hyperspectral prediction of mangrove leaf stoichiometries in different restoration areas based on machine learning models

Mangroves play an extremely important role in purifying the atmosphere and responding to global temperature changes. The analysis of chemical elements (carbon, nitrogen, phosphorus, etc.) in mangroves is an effective way to investigate physiological activities, such as vegetation growth, development, and material metabolism. Therefore, the monitoring of mangrove stoichiometry is extremely important for mangrove restoration. Here, two mangrove species, Kandelia candel (KC) and Aegiceras corniculatum (AC), were studied in the Quanzhou Bay Estuary Wetland Nature Reserve. Two machine learning models [random forest (RF) and back propagation neural network (BPNN)] and partial least squares (PLS) were established with the original spectral data as independent variables, and the optimal model was selected by comparing the simple cross-validation VEcv, the ratio of performance to deviation, and the root mean square error (RMSE). The results showed that: (1) the contents of total phosphorous and total nitrogen decreased gradually and the content of total carbon of mangroves increased gradually with an increase in age at restoration; (2) hyperspectral modeling can invert the ecological stoichiometries of KC and AC, and it can be used to effectively monitor the growth status of the species studied; and (3) model performance ranking, PLS > RF > BPNN, where PLS (VEcv ≥ 0.60 and RMSE < 40) was significantly better than the other two models, and BPNN was the least effective and not suitable for hyperspectral inversion modeling of KC and AC ecological stoichiometries. This study provides a methodological basis for long-term and large-scale dynamic monitoring of mangrove ecological stoichiometries and mangrove restoration quality based on hyperspectral data.