Quanzhou Bay Research Articles

Description of Aestuariivivens marinum sp. nov., Aestuariivivens sediminis sp. nov. and Aestuariivivens sediminicola sp. nov., three new species isolated from the upper layer of tidal flat sediment

Nine bacterial strains designated MT3-5-12T, MT3-5-27, MTV1-9, S-DT1-15T, S-DT1-34, MTV5-3T, MTV4-17, MTV5-12 and MTV5-13 were isolated from the upper layer (1–5 cm in depth) of tidal flat sediment in Quanzhou Bay, China. The 16S rRNA gene of these strains shared maximum sequence similarities with Aestuariivivens insulae KCTC 42350T of 94.9–97.1%. Phylogenetic analyses based on 16S rRNA gene sequences and 120 conserved concatenated proteins placed these strains in three novel phylogenetic clades affiliated to the genus Aestuariivivens of the family Flavobacteriaceae. Strains MT3-5-12T, MT3-5-27 and MTV1-9 were phylogenetically close to A. insulae KCTC 42350T. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strains MT3-5-12Tand MTV1-9 and A. insulae KCTC 42350T were estimated to be 78.5-78.7% and 22.5%, respectively. Strains S-DT1-15T and S-DT1-34 formed a distinctly separated clade from A. insulae KCTC 42350T. The ANI and dDDH values between strains S-DT1-15T and S-DT1-34 and A. insulae KCTC 42350T were 76.3–76.4% and 20.4–20.5%, respectively. The other four strains MTV5-3T, MTV4-17, MTV5-12 and MTV5-13, formed a third novel clade, distinctly separated from A. insulae KCTC 42350T. The ANI and dDDH values between strains MTV5-3T and MTV4-17 and A. insulae KCTC 42350T were 74.7% and 19.1–19.2%, respectively. The phylogenetic analyses and whole genomic comparisons, combined with phenotypic and chemotaxonomic features, strongly supported the nine strains could be classified as three novel species within the genus Aestuariivivens, for which the names Aestuariivivens marinum sp. nov. MT3-5-12T, Aestuariivivens sediminis sp. nov. S-DT1-15T, and Aestuariivivens sediminicola sp. nov. MTV5-3T are proposed.

Multivariate statistical analysis of potentially toxic elements in the sediments of Quanzhou Bay, China: Spatial relationships, ecological toxicity and sources identification

In this paper, the spatial distribution, pollution degree, ecological toxicity and possible sources of seven potentially toxic elements (PTEs) collected from the surface sediments of Quanzhou Bay (QZB) were analyzed by obtaining concentration measurements. The results indicated that the areas with high Cu, Pb, Zn and Hg concentrations were mainly located in the Luoyang River estuary, while the areas with high contents of Cd and As appeared in the Luoyang River estuary area and in the southern part of QZB, respectively. The contamination indices showed that the Cd pollution degree was slight to serious, while other elements were slightly enriched. The calculation results of the potential ecological risk index (RI) and toxic risk index (TRI) indicated that Cd was the main element posing ecological risk among the PTEs of sediments in QZB, followed by Hg. Moreover, in approximately 30% of the surveyed sites, PTEs exhibited low toxicity to aquatic ecosystems. Finally, the self-organizing map (SOM) and positive matrix factorization (PMF) model were used to determine the PTEs sources. Natural sources, industrial emissions, and the combustion of fossil fuels were three main sources for PTEs in the surface sediments of QZB. This study provides a reference for assessing sediment pollution and managing marine pollution in QZB.

Enhanced mangrove vegetation index based on hyperspectral images for mapping mangrove

As a specific forest community in tropical and subtropical coastal zones, mangrove has unique ecological functions and great social and economic value. Accurate mangrove mapping is important to the protection and restoration of mangrove ecosystem. Traditional classification methods rely on a large number of samples and complex classifiers, which are unsuitable for the large-scale extraction of mangroves because of low computational efficiency and poor generalization ability. This study proposes an Enhanced Mangrove Vegetation Index (EMVI) based on hyperspectral images. This index enhances the difference in greenness and canopy moisture content between mangroves and other vegetation using a green band and two shortwave-infrared bands in the form (Green-SWIR2)/(SWIR1-Green). Six typical mangrove areas (i.e., Qinglan Harbor in Hainan, Zhenzhu Harbor–Fangcheng Harbor in Guangxi, Lianzhou Bay in Guangxi, Zhangjiang Estuary in Fujian, Quanzhou Bay in Fujian, and Oujiang Estuary in Zhejiang) were selected as the study areas, and sample datasets were produced by field surveys and Google Earth high-resolution images. Compared with other VIs, such as the Normalized Difference Vegetation Index, Enhanced Vegetation Index, Moisture Stress Index, Mangrove Vegetation Index, and Combined Mangrove Recognition Index, EMVI exhibited better ability to distinguish mangroves and other vegetation. EMVI was applied to mangrove extraction in the six study areas based on ZY1-02D images, and the extraction results were compared with existing mangrove maps (GMW_2016 and CAS_Mangrove 2015) and the results of SVM. Results showed that EMVI featured the better overall accuracy and the Kappa coefficient than existing mangrove maps and the performance was similar to SVM. Further tests showed that EMVI was also suitable to other hyperspectral remote sensing images (i.e., GF-5, Hyperion, and PRISMA), but not to Sentinel-2 images. These results indicate that EMVI can be applied to different hyperspectral remote sensing images and different types of mangrove extraction. This index also has excellent application potential in mangrove mapping.

Coupling Relationship of Human Activity and Geographical Environment in Stage-Specific Development of Urban Coastal Zone: A Case Study of Quanzhou Bay, China (1954–2020)

Owing to the development of the social economy, the geographical environment and ocean utilization patterns of urban coastal zones have changed. This change, in turn, has influenced the socio-economic development of urban coastal zones. Based on the Geographic Information System technology, the area, coastline length, and shoreland use function of reclamation areas were obtained from the geographic charts (1954–2020) and remote sensing data (1988–2017) of Quanzhou Bay. In this study, we analyzed the geomorphologic change process and the relationship between land use patterns and economic development in Quanzhou Bay from the perspectives of hydrodynamics, sediments, and human activity. Our results indicated that over the past 70 years, the bay area has reduced by 21.5%. The length of the coastline decreased from 208.36 km in 1959 to 149.11 km in 1988, whereas the shape index of the bay (SIB) decreased from 3.09 to 2.41 during the same period. Between 1988 and 2017, the coastline increased to 162.91 km, causing the SIB to increase to 2.72. The artificial index of the bay increased from 0.28 in 1959 to 0.90 in 2017. The intensity of bay the development (IBD) first increased from 0.27 in 1959 to 0.77 in 2006. During the transition to a more modern society (2006 to present), the IBD slightly decreased to 0.73 in 2017. Affected by human activity, the transformation of the reclaimed land in Quanzhou Bay can be divided into four stages that are closely linked to the economic development in the region. In the early industrialization period, reclaimed land in the region was used for agricultural production, whereas in the mid-industrialization period, it was gradually transformed into a combination of industrial (29.8%) and agricultural (56.1%) lands. In the later period of industrialization, the reclaimed land was gradually converted into urban industrial and port lands. Finally, with further refinement and upgrading of economic and industrial structures, the socio-economic and environmental benefits from coastal reclamation projects have been increasing, whereas the proportion of economic benefits (in the total benefits) has been decreasing. The results of this study can provide decision-making references for the optimization of utilization patterns and the economic development of reclamation lands in coastal areas.

Dynamics of labile soil organic carbon during the development of mangrove and salt marsh ecosystems

Labile fractions of soil carbon pools are sensitive to environmental changes, which would influence the stabilization of soil carbon. However, it is unclear whether the dynamics of labile organic carbon (LOC) and soil organic carbon (SOC) are coupled and how they influence each other in coastal wetland. The present work investigated the trends of soil carbon fractions among mangrove and Spartina alterniflora communities with different stand ages (1, 5, 10, and 15 years), at Quanzhou Bay Estuary Wetland Nature Reserve, China. We found that SOC in a mangrove ecosystem increased over time, while there was no significant trend in S. alterniflora dominated ecosystems. The highest LOC of mangrove appeared in 5-year-old communities, and then decreased with stand age. In S. alterniflora communities, content of labile fractions increased with the stand age. These trends indicated different soil carbon dynamics when comparing mangrove and S. alterniflora ecosystems. The development of mangroves promoted accumulation of recalcitrant carbon, while S. alterniflora ecosystems contributed to an increase of labile carbon. This phenomenon is probably caused by the characteristics of vegetation and the hydrological conditions. Mangroves contribute more refractory organic carbon to the soil carbon pool, while accumulation of LOC in S. alterniflora communities may inhibit the stabilization of SOC. Our study on the relationship of LOC and SOC implies that complex interactions occur among soil carbon pools and environmental conditions in coastal wetlands, suggesting soil carbon models should take into account decoupled dynamics of LOC and SOC.

Analysis of the wind field characteristics induced by the 2019 Typhoon Bailu for the high-speed railway bridge crossing China’s southeast bay

There are a number of long-span bridges located in the southeast coastal bay of China which is prone to typhoons. Very limited studies have been made of the wind field characteristics in this bay which is special as it has various changes in fetch from sea to land and vice versa, depending on the wind direction. Thus, a detailed analysis of the wind properties of the 2019 Typhoon Bailu has been carried out and the findings are presented in this paper. The measurements were made from sensors on a 40 ​m-high meteorological mast in the vicinity of Quanzhou Bay Sea-Crossing High-Speed Railway Bridge. First, the characteristics of mean wind and turbulence are analyzed. The study results show that: the amplitude of the typhoon spectra after the second landfall is smaller than that before the landfall almost in one order of magnitude. The wind profile and turbulence coherence are also a focus of this study. It is revealed that a logarithmic model is more consistent with the measured wind speed profile compared with other commonly specified profiles. Strong coherence of u and w components at low frequencies is demonstrated in this study.

Typhoon Fung-wong (2008) induced heavy metals secondary pollution in Quanzhou Bay, southeast of China

The concentrations of Cr, Ni, Cu, Zn, As, Cd, Pb, and Al in suspended particles were measured, and temperature, salinity, flow velocity and direction during a tidal cycle were observed before and after Typhoon Fung-wong at six stations in Quanzhou Bay, respectively. The comparison results show that, after the typhoon, the salinity in Quanzhou Bay decreased, whereas the concentrations of heavy metals increased by a factor of between 2 and 10, and the high heavy metal concentration corresponded to the low value of ratio between heavy metals and Al (HMs/Al), suggesting that these increased heavy metals were mainly from natural sources. Instantaneous unit width flux calculations for heavy metals at different stations indicate that sediments are an important source of heavy metals in suspended particles under the influence of typhoon, which has significantly contribution to understanding the impact of typhoons on the heavy metal pollution in the coastal area.

Construction management and technology innovation for main projects of Quanzhou Bay Bridge

Construction management and technology innovation for main projects of Quanzhou Bay Bridge

Pareuzebyella sediminis gen. nov., sp. nov., a novel marine bacterium in the family Flavobacteriaceae, isolated from a tidal flat sediment.

Two marine bacterial strains, designated S2-4-21T and MT2-5-19, were isolated from two tidal flat sediments of cordgrass Spartina alterniflora and adjacent oyster culture field in Quanzhou bay, China, respectively. Both strains were Gram-staining-negative, rod-shaped, non-flagellated, non-motile, aerobic, had NaCl requirements, and contained carotenoid and flexirubin pigments. The 16S rRNA gene sequence similarity (99.8%), average nucleotide identity value (99.4%) and average amino acid identity (99.3%) between strain S2-4-21T and strain MT2-5-19 strongly supported that they belonged to a single species. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain S2-4-21T and strain MT2-5-19 formed a monophyletic branch affiliated to the family Flavobacteriaceae, sharing similarities of 94.6% with Euzebyella marina CY01T and E. saccharophila 7SM30T, and of 94.1 and 92.8% with E. algicola MEBiC 12267T and Pseudozobellia thermophile DSM 19858T, respectively. Phylogenomic analysis based on the whole genome sequences supported that the two strains formed a distinct monophyletic clade within Flavobacteriaceae members, which was phylogenetically different from the clades of Euzebyella and Pseudozobellia. The major respiratory quinone was menaquinone MK-6. The major fatty acids (>10%) consisted of C15 : 0 iso, C16 : 0, summed feature 9 (C17 : 1 iso ω9c/C16 : 0 10-methyl) and C17 : 0 iso 3-OH. The polar lipid profiles of strain S2-4-21T and strain MT2-5-19 are identical, including phosphatidylethanolamine, four unidentified aminolipids, and four unidentified lipids. The genomic size was 4.9-5.0 Mb with genomic DNA G+C content of 41.5 mol%. Based on the above characteristics, strains S2-4-21T and MT2-5-19 represented a novel species of a novel genus in the family Flavobacteriaceae. Thus, Pareuzebyella sediminis gen. nov. sp. nov. is proposed with type strain S2-4-21T (=MCCC 1K03818T=KCTC 72152T), and another strain MT2-5-19 (=KCTC 72539=MCCC 1K03874).

Characterization of bacterial communities associated with the exotic and heavy metal tolerant wetland plant Spartina alterniflora

Heavy metal pollution has seriously disrupted eco-balance and transformed estuaries into sewage depots. Quanzhou bay is a typical heavy metal-contaminated estuary, in which Spartina alterniflora has widely invaded. Plant-associated microbial communities are crucial for biogeochemical cycles, studies of which would be helpful to demonstrate the invasion mechanisms of plants. Meanwhile, they are indispensable to phytoremediation by enhancing the heavy metal tolerance of plants, facilitating heavy metal absorption rate and promoting growth of plants. In the present study, S. alterniflora-associated rhizo- and endobacterial communities from 3 experimental sites were investigated by 454-pyrosequencing. Heavy metal screening generated 16 culturable isolates, further biochemical assays suggested these clones possess various abilities such as phosphate solubilization, indole-3-acetic acid (IAA) production and 1-aminocyclopropane-1-carboxylate (ACC) deaminase production to accelerate heavy metal uptake and growth of the host. This study revealed the bacterial community structures and characterized the predominant resident bacterial strains of S. alterniflora-associated rhizo- and endobacteria under heavy metal stress, and isolated several bacterial species with potential ecological function.

Description of Maribellus sediminis sp. nov., a marine nitrogen-fixing bacterium isolated from sediment of cordgrass and mangrove

Two marine bacterial strains designated Y2-1-60T and GM1-28 were isolated from sediments of cordgrass and mangrove along the Luoyang estuary in Quanzhou Bay, China, respectively. Both strains were Gram-staining-negative, straight rod-shaped, non-flagellum, facultatively anaerobic, nitrogen-fixing, and did not contain carotenoid pigment. Catalase activities were found to be weak positive and oxidase activities negative. The 16S rRNA gene sequences of the two strains were identical and had maximum similarity of 98.0% with Maribellus luteus XSD2T, and of <94.5% with other species. ANI value (96.9%) and DDH estimate (71.5%) between the two strains supported that they belonged to the same species. ANI value and DDH estimate between the two strains and M. luteus XSD2T was 74.3% and 19.4%, respectively, indicating that they represent a novel species. Phylogenetic analysis based on 16S rRNA gene and phylogenomic analysis indicated that strains Y2-1-60T and GM1-28 formed a monophyletic branch within the genus Maribellus. The respiratory quinone was menaquinone MK-7. The major fatty acid (>10%) consisted of iso-C15:0, and iso-C17:0 3-OH. The polar lipids consisted of phosphatidylethanolamine and several unidentified lipids. The genomic G+C contents were 41.9–42.0mol%. Gene annotation revealed that strains Y2-1-60T and GM1-28 contained a set of nif gene cluster (nifHDKENB) responsible for nitrogen fixation. Based on the above characteristics, strains Y2-1-60T and GM1-28 represent a novel species within the genus Maribellus. Thus, Maribellus sediminis sp. nov. is proposed with type strain Y2-1-60T (=MCCC 1K04285T=KCTC 72884T), isolated from cordgrass sediment and strain GM1-28 (=MCCC 1K04384=KCTC 72880), isolated from mangrove sediment.

The trade patterns of the South China Sea during the Song period

This paper aims to outline two different trade patterns in the South China Sea during the Song period by examining the distribution pattern of cargos on the Intan, Cirebon, Nanhai No.1 (南海I号) and Quanzhou Bay 泉州湾 wrecks. Through the detailed analysis, it is argued that the voyage of some merchant ships would be conducted at the request of a single authority, from a few available, who handled bulk selling while the remaining spaces on the ship would be leased to some individual traders who did retail business. The major cargo on board would be aimed toward a single directional destination, as is represented by the Inan and Cirebon wrecks. In other cases, the sea-going journey would be a joint operation involving multiple traders and the major cargo would be handled by peddlers and possibly sold at a number of ports-of-call, as is seen with the Nanhai No.1 and Quanzhou Bay wreck.

Composition and distribution characteristics of macroinvertebrates in subtidal zone of the main marine bays in Fujian Province, China

With data for distributions and diversities of macroinvertebrates from 12 main subtidal zones in the bays of Fujian on August 2010, we investigated species composition, biodiversity and community structure, as well as their relationships with environmental factors. The results showed that 382 macroinvertebrates were recorded, which included 170 annelids, 75 crustaceans, 78 mollusks, 19 echinodermata, and 40 other species. The species richness, individual abundance, biomass and biodiversity indices showed significantly spatial variability. The average of species richness was (55±21), with the highest (92) in Luoyuan Bay and the lowest species (25) in Jiuzhen Bay. Polychaetes was dominant species in each bay, with an average percentage of (51.8±5.5)%. Zhaoan Bay had the highest average individual abundance with (1330±1094) ind·m-2, followed by Fuqing Bay, Xiamen Bay and Meizhou Bay, while Quanzhou bay had the lowest. Xinghua Bay had the highest average biomass with (821.2±2387.7) g·m-2, followed by Fuqing Bay and Xiamen Bay. Both richness index and Shannon diversity were much higher in Luoyuan Bay, Meizhou Bay, Shenhu Bay, Xiamen Bay and Dongshan Bay, and their values were low in Fuqing Bay and Jiuzhen Bay. The mean value for d and H across all bays was (0.80±0.09) and (2.73±0.64), respectively. The macroinvertebrates of the study area were divided into 14 groups using a criterion of 20% similarity. The stations in Luoyuan Bay had the highest similarity and the lowest spatial variability, and followed by Sansha Bay, Fuqing Bay, Shenhu Bay and Zhaoan Bay. The higher variability of community composition was found among the stations for the rest bays. On the basis of Spearman correlations among species richness, biodiversity indices and environmental factors, as well as PCA analy-sis, Cu in the sediment, water depth, and dissolved inorganic phosphorus in bottom water were the main factors driving the spatial variability of composition and distribution of macroinvertebrates in the study area.

Dynamic evaluation and driving forces of ecosystem services in Quanzhou bay estuary wetland, China

Ecosystem service value (ESV) in 1997, 2005, 2013 and 2015 of Quanzhou Bay estuary wetland was evaluated dynamicly by market value, alternative value and opportunity cost methods, combined with classification of service indicators and deduplicate computing. The main driving forces for the changes of ESV and the pathway and intensity of their actions were identified using stepwise regression and path analysis methods. The results showed that the main ecosystem services of Quanzhou Bay estuary wetland were flood regulation, climate regulation, and food supply, which were directly driven by water supply, mariculture carrying capacity, and gross value of the regional production. Other drivers exerted indirect effect on the changes of main ESVs.

Background determination, pollution assessment and source analysis of heavy metals in estuarine sediments from Quanzhou Bay, southeast China

The concentrations of ten heavy metals (Cr, Cu, Zn, Cd, Pb, Co, Ni, Fe, Mn, and Hg) and Pb isotope compositions were investigated in two estuarine sediment cores collected in Quanzhou Bay, southeast China. The regional background levels of heavy metals in the estuarine sediments from Quanzhou Bay were established using the fine fractions (<63 μm) obtained from the sediment cores. The background values of Cr, Cu, Zn, Cd, Pb, Co, Ni, Mn, Hg, and Fe were 37.14 mg kg−1, 19.79 mg kg−1, 130.86 mg kg−1, 0.24 mg kg−1, 42.18 mg kg−1, 10.31 mg kg−1, 20.89 mg kg−1, 612.60 mg kg−1, 0.07 mg kg−1 and 3.17%, respectively. The background values of most elements (Cr, Cd, Pb, Co, Ni, Mn, Hg, and Fe) detected for the estuarine sediments from Quanzhou Bay in this study were in the middle of the obtained ranges for other locations in China. However, the Pb and Zn background values in Quanzhou Bay were significantly higher than the Chinese average. The enrichment factor (EF), geoaccumulation index (Igeo), and contamination factor (CF) values indicated that sediment contamination associated with Cu, Zn, Pb, Mn, and Cd has occurred since the nineteenth century. Based on principal component analysis (PCA) and cluster analysis (CA), Cu, Zn, and Pb were clustered into a group, and their sources could be related to the mining of metallic ore deposits. The Pb isotope composition data from the dated sediment cores further suggested that the Pb sources transitioned from natural sources during 1715–1788 CE to Pb-Zn ore deposits during 1788–1935 CE and then to multiple anthropogenic sources, including Pb-Zn ore deposits and industrial and domestic emissions, in recent decades (1935–2009 CE).

Croceicoccus sediminis sp. nov., isolated from coastal sediment.

A Gram-stain-negative, cocci or short rod-shaped, yellow-pigmented bacterium, designated strain S2-4-2T, was isolated from coastal sediment of Spartina alterniflora in Quanzhou Bay, PR China. Growth was observed at 15-40 °C (optimum, 30 °C) and pH 6.0-8.0 (optimum, pH 7.0). Strain S2-4-2T tolerated 0-10 % NaCl (optimum, 1 %). The 16S rRNA gene of strain S2-4-2T showed highest sequence similarity to Croceicoccus pelagius Ery9T (98.2 %), followed by Croceicoccus naphthovorans PQ-2T, Croceicoccus marinus E4A9T and Croceicoccus mobilis Ery22T (97.6%, 96.3 and 96.3 %, respectively). Phylogenetic analysis based on 16S rRNA gene sequences and phylogenomic analysis based on 92 up-to-date bacterial core gene sets indicated that strain S2-4-2T forms a distinct monophyletic branch affiliated to the genus Croceicoccus. The average nucleotide identity value between strain S2-4-2T and its close relatives were estimated to be 74.8-85.7 %. The respiratory quinone was found to be Q-10. The predominant fatty acids (>10 %) were identified as summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c) and summed feature 3 (C16 : 1ω7c and C16 : 1ω6c). The polar lipids were identified as phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, sphingoglycolipid and an unidentified phospholipid. The draft genome size of strain S2-4-2T was 3.5 Mb with a genomic G+C content of 63.0 mol%. Based on these results, strain S2-4-2T is concluded to represent a novel species within the genus Croceicoccus, for which the name Croceicoccus sediminis sp. nov. is proposed with the type strain S2-4-2T (=MCCC 1K03706T=KCTC 72146T).

Pleionea sediminis sp. nov., isolated from coastal sediment and emendation of the description of the genus Pleionea.

A Gram-stain-negative, rod-shaped and non-motile bacterium, designated strain S1-5-21T, was isolated from coastal sediment in Quanzhou Bay, PR China, and subjected to taxonomic characterization. Growth of strain S1-5-21T was observed at 15-40 °C (optimum, 30-35 °C), NaCl tolerance of 0.5-10 % NaCl (w/v; optimum, 1 %), and pH range of 5-8 (optimum, pH 7). Catalase activity and oxidase activity were found to be positive. The nearly complete 16S rRNA gene sequence of strain S1-5-21T shows maximum sequence similarity to Pleionea mediterranea MOLA115T (95.7 %), followed by Kangiella chungangensis CAU 1040T (90.4 %) and Aliikangiella marina GYP-15T (90.1 %). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain S1-5-21T forms a distinct monophyletic branch affiliated to the genus Pleionea. The ANI value between strain S1-5-21T and close relative P. mediterranea MOLA115T was estimated to be 70.8 %. The respiratory quinone was found to be Q-8. The predominant fatty acids (>10 %) were identified as iso-C15 : 0, summed feature 9 (iso-C17 : 1 ω9c and/or C16 : 0 10-methyl) and iso-C16 : 0. The polar lipids were identified as phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, two aminolipids, three phospholipids and five unidentified polar lipids. The draft genome size of strain S1-5-21T is 5.2 Mb with genomic G+C content of 40.1 mol%. Based on these results, strain S1-5-21T is concluded to represent a novel species within the genus Pleionea, for which the name Pleioneasediminis sp. nov. is proposed with the type strain S1-5-21T (=MCCC 1K03814T=KCTC 72149T).

Evolution of sedimentary organic matter in a small river estuary after the typhoon process: A case study of Quanzhou Bay

Extreme weather events occur frequently under global warming scenarios and have an important impact on the global carbon cycle. Compared to large rivers, small rivers are more sensitive to extreme weather events (such as typhoons). This paper reports the results of a study carried out in the Quanzhou Bay to explore the evolution of small river estuarine sedimentary organic matter after typhoon process using measurements of the grain-size, total organic carbon (TOC), total nitrogen (TN) and δ13C of surface sediment samples collected 2–3 days and a month, respectively, after typhoon Matmo landing in 2014. The results show that the contents of TOC and TN in the sediments, which gradually decrease from the estuary to the outer sea of Quanzhou Bay, decreased approximately 13% and 16%, respectively, a month later compared with 2–3 days after typhoon landing. The significant decrease occurred in the Jinjiang River estuary and along the South Channel of Quanzhou Bay, while the North Channel and Luoyangjiang River estuary retained high levels of TOC and TN. The results of δ13C values and TOC/TN ratios show that the organic matter in the sediment of the Quanzhou Bay was a mixture derived from C3 terrestrial plants and marine algae. The terrestrial organic matter was mainly deposited in the Jinjiang River estuary 2–3 days after typhoon landing and then spread along the tidal channel to the outer sea a month later. It indicates that the hydrodynamic forces stirred sedimentary organic matters that were input and settled during typhoon, and transported later along the North and South Channel to the outer sea. Some of those organic matters were accumulated in the North Channel during the transport process. The results provide significant meaning for the carbon cycle and material flux study on the coastal and margin seas.

Impact of typhoon Matmo (2014) on the distribution of heavy metals in Quanzhou Bay

The typhoon process has a significant influence on the distribution of heavy metals in sediments. Based on the heavy metal (V, Cr, Co, Ni, Cu, Zn, Pb, and Mn) contents in surface sediments collected under normal conditions and post-typhoon Matmo in Quanzhou Bay in 2014, the distributions, sources, and impacts of typhoon processes on heavy metals and pollution conditions were studied and discussed. The results showed that the heavy metals can be divided into two categories: Class I metals (Cu, Zn, Pb, and Mn) were mainly distributed in the estuary and significantly increased after the typhoon and Class II metals (V, Cr, Co, and Ni) were distributed in the coastal intertidal zone and estuary and remained unchanged or decreased after the typhoon. The heavy metal assessment showed that heavy metal pollution in Quanzhou Bay was serious and tended to increase after the typhoon. The increased metal supply and enhanced riverine and tida hydrodynamics after the typhoon may be the main factors influencing the variations in heavy metal content and distribution. This study provided a basis for the accurate evaluation and scientific management of heavy metal pollution caused by typhoon processes in Quanzhou Bay.

Dynamic Analysis of Mangrove Forests Based on an Optimal Segmentation Scale Model and Multi-Seasonal Images in Quanzhou Bay, China

Mangrove forests are important coastal ecosystems and are crucial for the equilibrium of the global carbon cycle. Monitoring and mapping of mangrove forests are essential for framing knowledge-based conservation policies and funding decisions by governments and managers. The purpose of this study was to monitor mangrove forest dynamics in the Quanzhou Bay Estuary Wetland Nature Reserve. To achieve this goal, we compared and analyzed the spectral discrimination among mangrove forests, mudflats and Spartina using multi-seasonal Landsat images from 1990, 1997, 2005, 2010, and 2017. We identified the spatio-temporal distribution of mangrove forests by combining an optimal segmentation scale model based on object-oriented classification, decision tree and visual interpretation. In addition, mangrove forest dynamics were determined by combining the annual land change area, centroid migration and overlay analysis. The results showed that there were advantages in the approaches used in this study for monitoring mangrove forests. From 1990 to 2017, the extent of mangrove forests increased by 2.48 km2, which was mostly converted from mudflats and Spartina. Environmental threats including climate change and sea-level rise, aquaculture development and Spartina invasion, pose potential and direct threats to the existence and expansion of mangrove forests. However, the implementation of reforestation projects and Spartina control plays a substantial role in the expansion of mangrove forests. It has been demonstrated that conservation activities can be beneficial for the restoration and succession of mangrove forests. This study provides an example of how the application of an optimal segmentation scale model and multi-seasonal images to mangrove forest monitoring can facilitate government policies that ensure the effective protection of mangrove forests.