Yellow Sea Of China Research Articles

Changes in the structure of the microbial community within the phycospheric microenvironment and potential biogeochemical effects induced in the demise stage of green tides caused by Ulva prolifera

Green tides caused by Ulva prolifera occur annually in the Yellow Sea of China, and the massive amount of biomass decomposing during the demise stage of this green tide has deleterious ecological effects. Although microorganisms are considered key factors influencing algal bloom demise, an understanding of the microbial-algae interactions within the phycospheric microenvironment during this process is still lacking. Here, we focused on the variations in phycospheric microbial communities during the late stage of the green tide in three typically affected areas of the Yellow Sea via metagenomic sequencing analysis. In total, 16.9 million reads obtained from 18 metagenome samples were incorporated into the assembled contigs (13.4 Gbp). The phycosphere microbial community composition and diversity changed visibly during the demise of U. prolifera. The abundances of algae-lysing bacteria, Flavobacteriaceae at the family level and Alteromonas, Maribacter, and Vibrio at the genus level increased significantly in the phycosphere. In addition, the levels of glycoside hydrolases (GHs) and polysaccharide lyases (PLs) enzymes, which decompose U. prolifera polysaccharides in the phycosphere, were greater. Therefore, the degradation of algal polysaccharides can increase the efficiency of carbon metabolism pathways in the phycospheric microenvironment. Most of the genes detected in the phycosphere, especially norC, nrfA, and nasA, were associated with nitrogen metabolism pathways and showed dynamics related to the demise of the large amount of organic matter released by a green tide. Therefore, the demise of green tide algae may affect the potential carbon and nitrogen cycles of the phycospheric microenvironment by driving changes in the structure and diversity of microbial communities. Our research provides a novel perspective to better understand the ecological impact of U. prolifera during the green tide demise stage.

Assessment of heavy metal ecological risk in typical seagrass beds of the China Yellow Sea

Assessment of heavy metal ecological risk in typical seagrass beds of the China Yellow Sea

Assessment and prediction of Water Quality Index (WQI) by seasonal key water parameters in a coastal city: application of machine learning models.

The Water Quality Index (WQI) provides comprehensive assessments in river systems; however, its calculation involves numerous water quality parameters, costly in sample collection and laboratory analysis. The study aimed to determine key water parameters and the most reliable models, considering seasonal variations in the water environment, to maximize the precision of WQI prediction by a minimal set of water parameters. Ten statistical or machine learning models were developed to predict the WQI over four seasons using water quality dataset collected in a coastal city adjacent to the Yellow Sea in China, based on which the key water parameters were identified and the variations were assessed by the Seasonal-Trend decomposition procedure based on Loess (STL). Results indicated that model performance generally improved with adding more input variables except Self-Organizing Map (SOM). Tree-based ensemble methods like Extreme Gradient Boosting (XGB) and Random Forest (RF) demonstrated the highest accuracy, particularly in winter. Nutrients (Ammonia Nitrogen (AN) and Total Phosphorus (TP)), Dissolved Oxygen (DO), and turbidity were determined as key water parameters, based on which, the prediction accuracy for Medium and Low grades was perfect while it was over 80% for the Good grade in spring and winter and dropped to around 70% in summer and autumn. Nutrient concentrations were higher at inland stations; however, it worsened at coastal stations, especially in summer. The study underscores the importance of reliable WQI prediction models in water quality assessment, especially when data is limited, which are crucial for managing water resources effectively.

Wind speed retrieval from X-Band marine radar based on the attenuation horizontal component and azimuth scale expansion method

ABSTRACT A method based on attenuation horizontal component and azimuth scale expansion is proposed to extract wind speed from X-band marine radar images. The attenuation horizontal component of each azimuth is first retrieved by ideal attenuation model, and the wind direction is extracted by the azimuthal dependence of the attenuation horizontal component. To overcome the influence of the occlusion area, the azimuth scale expansion method is used to extract the wind direction. Then the attenuation model in the upwind direction is determined according to the attenuation horizontal component. Finally, an empirical function model relationship between the full-range integral area of the attenuation function in the upwind direction and the reference wind speed is established. The radar data used to test the algorithm were collected from a ship in the Yellow China Sea. The real-time reference wind parameters were obtained by an anemometer installed on the main mast of the ship. The experimental results show that the algorithm improves the accuracy of wind speed retrieval, effectively reduces the error caused by outlier interference in radar images, and overcomes the interference of occlusion area by combining the azimuth scale expansion method.

Continuous Field Determination and Ecological Risk Assessment of Pb in the Yellow Sea of China

Continuous Field Determination and Ecological Risk Assessment of Pb in the Yellow Sea of China

Thalassospira aquimaris sp. nov. and Winogradskyella marincola sp. nov. two marine bacteria isolated from an agar-degrading co-culture.

Two novel Gram-stain-negative, aerobic, and non-motile strains, designated FZY0004T and YYF002T, were isolated from an agar-degrading co-culture, which was obtained from seawater of the intertidal zone of Yancheng City, the Yellow Sea of China. Strain FZY0004T optimally grew at 28°C, pH 7.0, and 2-6% NaCl, while strain YYF002T optimally grew at 28°C, pH 7.5, and 2-4% NaCl. Strain FZY0004T possessed Q-9 as the major respiratory quinone, and its major fatty acids (> 10%) were summed feature 8 (C18:1 ω7c), C16:0, and summed feature 3 (C16:1 ω7c/C16:1 ω6c). The polar lipids identified in strain FZY0004T were phosphatidylethanolamine (PE), phosphatidylglycerol (PG), and several unidentified phospholipids (PL) and lipids (L). On the other hand, strain YYF002T had MK-6 as the predominant respiratory quinone and its major fatty acids consisted of iso-C15:0, iso-C15:1 G, and iso-C15:0 3-OH. The polar lipids identified in strain YYF002T were aminolipid (AL), PE, and several unidentified lipids. Strain FZY0004T shared 99.5% 16S rRNA gene sequence similarity and 90.1% average nucleotide identity (ANI) with T. povalilytica Zumi 95T, and strain YYF002T shared 99.2% 16S rRNA gene sequence similarity and 88.2% ANI with W. poriferorum JCM 12885T. The genomic DNA G + C contents of strains FZY0004T and YYF002T were 54.5% and 33.5%, respectively. The phylogenetic, phenotypic, and physiological characteristics permitted the distinction of the two strains from their neighbors, and we thus propose the names Thalassospira aquimaris sp. nov. (type strain FZY0004T = JCM 35895T = MCCC 1K08380T) and Winogradskyella marincola sp. nov. (type strain YYF002T = JCM 35950T = MCCC 1K08382T).

Methods for detecting green tide in the Yellow Sea using Google Earth Engine platform

The green tide was a blooming phenomenon consisting of outbreaks and aggregations of marine macroalgae, causing severe damage to the ecosystem of the Yellow Sea in China. Remote sensing technology was considered an effective means of green tide detection. Currently, commonly used low spatial resolution satellites cannot satisfy the green tide detection in the fine-scale range. To better improve the accuracy of green tide identification, based on the Commission Internationale del'éclairage (CIE) system, two new green tide detection algorithms (CIE xy, hue angle α) were established using Sentinel-2 MultiSpectral Instrument (MSI) and Landsat-8 Operational Land Imager (OLI) data on the Google Earth Engine (GEE) platform. These algorithms were validated by introducing the quantitative index Dgw from "Interclass Distance". The CIE xy algorithm and the hue angle α algorithm based on Sentinel-2 MSI exhibited higher Dgw values of 10.29 and 5.87, respectively, surpassing the performance of the two algorithms based on the Landsat-8 OLI in green tide identification (Dgw values of 3.36 and 5.17, respectively). Meanwhile, the proposed algorithms were compared with normalized difference vegetation index (NDVI), difference vegetation index (DVI), ratio vegetation index (RVI), floating algae index (FAI), enhanced vegetation index (EVI), and algal bloom detection index (ABDI) algorithms using Sentinel-2 MSI images. The results showed that the CIE xy algorithm and the NDVI algorithm outperformed the other algorithms. Especially in turbid water, the CIE xy algorithm exhibited significant advantages. However, the hue angle α algorithm still showed some potential in identifying green tide, particularly in the presence of thin cloud interference. These findings can provide effective information support for the monitoring of green tide in the Yellow Sea.

Impact of temperature stress on Pyropia yezoensis and its inhabitant microbiota to promote aquaculture

The diverse inhabitant microbiota of Pyropia yezoensis can establish both beneficial and harmful interactions that effect community structure. It is complex to understand the seaweed microbial diversity and their ecological and functional regulations which are affected by numerous environmental factors. In this study, temperature stress was focused to understand the metagenomics of P. yezoensis microbiota, its functional annotation and the metabolites regulation of P. yezoensis. The samples of P. yezoensis from yellow sea of China were divided into two groups i.e low temperature 5°C (LT) and High temperature 25°C (HT). The genes and functional level analysis were followed by using metagenomic sequencing analysis and sequencing of 16sRNA gene. The Pyropia yezoensis samples were also analyzed through LCMS for metabolites regulation due to effects of microbiota and temperature stress. According to taxonomic classification analysis, Proteobacteria, Bacteroidetes, and Firmicutes were predominant in both samples with over-representation of these species in high temperature stress samples. A diverse relationship between the bacterial communities residing in the LT and HT samples was explored through discriminant analysis. The functional prediction of bacterial communities from KEGG analysis revealed a notable increase in HT predicted genes associated to amino acid metabolism, carbohydrate metabolism, energy metabolism, co-factors and vitamins metabolism, membrane transport, and nucleotide metabolism. The provoked chemical signaling and transportation response from the bacterial community, leading to activation of metabolic genes to utilize the available substrates of seaweed. The LCMS illustrated that the primary metabolites of Pyropia yezoensis were down regulated due to effect of high temperature which indicates a negative effect on the growth and health of Pyropia, while the secondary metabolites were up-regulated showing the defensive mechanism against unbearable stress. These up and down regulated metabolites also activated their respective pathways, suggesting the adoptive mechanism of P. yezoensis in response of high temperature.

Triterpene Glycosides from the Viscera of Sea Cucumber Apostichopus japonicus with Embryotoxicity.

Sea cucumbers release chemical repellents from their guts when they are in danger from predators or a hostile environment. To investigate the chemical structure of the repellent, we collected and chemically analyzed the viscera of stressed sea cucumbers (Apostichopus japonicus) in the Yellow Sea of China. Two undescribed triterpene glycosides (1 and 2), together with a known cladoloside A (3), were identified and elucidated as 3β-O-{2-O-[β-d-quinovopyranosyl]-4-O-[3-O-methyl-β-d-glucopyranosyl-(1→3)-β-d-glucopyranosyl]-β-d-xylopyranosyl}-holosta-9(11),25(26)-dien-16-one (1), 3β-O-{2-O-[β-d-glucopyranosyl]-4-O-[3-O-methyl-β-d-glucopyranosyl-(1→3)-β-d-glucopyranosyl]-β-d-xylopyranosyl}-holosta-9(11),25(26)-dien-16-one (2), 3β-O-{2-O-[3-O-methyl-β-d-glucopyranosyl-(1→3)-β-d-xylopyranosyl-(1→4)-β-d-quinovopyranosyl]-β-d-xylopyranosyl}-holosta-9(11),25(26)-dien-16-one (3) by spectroscopic analysis, including HR-ESI-MS and NMR spectra. Compounds 1, 2, and 3 display embryonic toxicity, as indicated by their 96-hour post-fertilization lethal concentration (96 hpf-LC50) values of 0.289, 0.536, and 0.091 μM, respectively. Our study discovered a class of triterpene glycoside compounds consisting of an oligosaccharide with four sugar units and a holostane aglycone. These compounds possess embryotoxicity and may serve as chemical defense molecules in marine benthic ecosystems.

Identification and simulation the response of storm-induced coastal erosion in the China Yellow sea

Storm events have a significant impact on coastal topography, which can subsequently lead to coastal erosion and ecological deterioration. Traditional field measurements are affected by environmental factors and consume substantial resources, making it difficult to conduct large-scale terrain, hydrodynamic and other monitoring tasks. Significant challenges still remain to identify the response of coastal processes to storm events due to the lack of field measured data. In this study, the response of coastal morphodynamical variations to extreme storm events was simulated by the coupled XBeach and FVCOM models and the storm-induced coastal evolution was evaluated in the China Yellow Sea. The costal morphodynamical variations under different wind conditions were also quantified. The results reveal that erosion dominated the supratidal zone while accretion mainly occurred in the subtidal zone. Comparing the coastal morphology before and after the storm, we found the alongshore currents were the primary factors influencing sediment transport. The degree of coastal erosion and accretion shift was positively correlated with the wind speed and direction. The present nested model may serve as a valuable tool for predicting future coastal erosion and accretion, contributing to more scientifically informed coastal management decisions. The study also provides a scientific basis for understanding the response mechanism of coastal morphodynamical process to extreme storm events and coastline evolution under global change.

Sea Cucumber Viscera Contains Novel Non-Holostane-Type Glycoside Toxins that Possess a Putative Chemical Defense Function.

Sea cucumbers frequently expel their guts in response to predators and an aversive environment, a behavior perceived as releasing repellents involved in chemical defense mechanisms. To investigate the chemical nature of the repellent, the viscera of stressed sea cucumbers (Apostichopus japonicus) in the Yellow Sea of China were collected and chemically analyzed. Two novel non-holostane triterpene glycosides were isolated, and the chemical structures were elucidated as 3ꞵ-O-[ꞵ-D-glucopyranosyl-(1→2)-ꞵ-D-xylopyranosyl]-(20S)-hydroxylanosta-7,25-diene-18(16)-lactone (1) and 3ꞵ-O-[ꞵ-D-quinovopyranosyl-(1→2)-ꞵ-D-xylopyranosyl]-(20S)-hydroxylanosta-7,25-diene-18(16)-lactone (2) by spectroscopic and mass-spectrometric analyses, exemplifying a triterpene glycoside constituent of an oligosaccharide containing two sugar-units and a non-holostane aglycone. Zebrafish embryos were exposed to various doses of 1 and 2 from 4 to 96 hpf. Compound 1 exposure showed 96h-LC50 41.5 µM and an increased zebrafish mortality rates in roughly in a dose- and time-dependent manner. Compound 2, with different sugar substitution, exhibited no mortality and moderate teratogenic toxicity with a 96h-EC50 of 173.5 µM. Zebrafish embryos exhibited teratogenic effects, such as reduced hatchability and total body length. The study found that triterpene saponin from A. japonicus viscera had acute toxicity in zebrafish embryos, indicating a potential chemical defense role in the marine ecosystem.

Water stratification alters phytoplankton assemblages in scallop farming waters of the North Yellow Sea in China

As evaluation indicators of the primary productivity, the phytoplankton biomass and community structure are of great significance to the fishery industry, which can be driven by ocean currents, nutrients and water stratification. In the present study, the characteristics of phytoplankton assemblages in different water layers of a typical Yesso scallop farming area in Zhangzi Island, the North Yellow Sea were investigated from March 2021 to January 2022. According to the vertical distribution of temperature, water stratification was observed from June to August (stratification period), and disappeared in March, October and the following January with vertical homogeneity (mixing period). 18S rRNA gene sequencing results revealed that Pyrrophyta was the most dominant phylum during the sampling period, with high gene proportions in the stratification (63.36%) and mixing periods (77.35%). The gene proportion of Bacillariophyta in the stratification period was 5.44%, which was significantly lower than that in the mixing period of 8.93% (p < 0.05). Moreover, Pseudo-nitzschia, a toxin-producing taxon affiliated with Bacillariophyta, exhibited a significantly higher proportion in the stratification period than in the mixing period. During the stratification period, a number of toxin-producing taxa such as Pseudo-nitzschia and Karlodinium were enriched in the bottom layer, which was 1.29-fold and 1.37-fold of that in the surface layer, respectively. Redundancy analysis showed that phosphate and water temperature were major environmental factors driving the vertical distribution of phytoplankton assemblages. The phosphate (0.11 μM) and silicate (2.09 μM) concentrations in the surface layer approached the minimum threshold for phytoplankton growth, and the stoichiometric limitation of phosphate was detected in the surface and middle layers. Collectively, these results indicated that the decreased proportion ratio of Bacillariophyta to Pyrrophyta and unfavorable community composition of Bacillariophyta for scallops were observed during summer, which might result from the phosphate limitation driven by water stratification. The results will further our understanding of the dynamics of phytoplankton communities under the background of intensifying ocean stratification and provide ecological guidance for mollusc mariculture.

Incident component extraction from disturbed waves around large fixed cylindrical structures

The parameters of incident waves are critical for real-time wave load estimation of structures in service. Nonetheless, it is challenging to characterize incident waves accurately using the measured wave surface elevation around large fixed cylindrical structures due to the interaction with the structure in the wave field. To provide a better understanding of incident waves, which are usually buried in directly measured waves, a new time-domain method for the extraction of first-order and second-order incident waves around large fixed cylindrical structures is proposed. In contrast to most existing separation methods that are suitable for structures with equal reflection coefficients, the amplitude and phase changes of near-field waves around cylindrical structures can be determined by considering the significant diffraction effect, and then the time-frequency characteristic of the wavelet transform is employed, which enables the extraction of incident waves in the time domain. The accuracy of the proposed method is studied using several examples with known incident waves which are generated with the OpenFOAM. The numerical results show that the deviations between the exact and extracted incident waves change from 6.16% to 16.77% for different wave conditions. To further investigate the performance of the proposed method, an experimental study on waves around a mono-pile offshore wind turbine (OWT) is conducted in the laboratory of the Ocean University of China. The predicted results basically agree well with the target waves in terms of amplitude and phase. The deviations between predicted waves using the proposed method and target waves are 110% smaller than those between directly experimental measured waves and target waves for all tested conditions. Finally, 48 h of measured wave data were obtained during calm and typhoon periods around a mono-pile OWT located near Rudong County, Jiangsu Province, in the Yellow Sea of China. There are almost 150% and 30% differences between the extraction results and measured data in the time series and statistical wave heights, respectively, which means that employing disturbed wave data as the input for calculating real-time wave loads leads to deviations that cannot be ignored.

All-Weather Monitoring of Ulva prolifera in the Yellow Sea Based on Sentinel-1, Sentinel-3, and NPP Satellite Data

Ulva prolifera (U. prolifera), a global eco-environmental issue, has been recurring annually in the Yellow Sea of China since 2007, leading to significant impacts on the coastal ecosystem and the economies of coastal cities. To enhance the frequency of daily monitoring for U. prolifera and to advance the multi-source remote sensing monitoring system, a combination of the Sentinel-1 SAR remote sensing satellite and the Sentinel-3 OLCI and NPP VIIRS optical remote sensing satellites was employed. This comprehensive analysis encompassed the examination of Sentinel-1 C band characteristics, the range of influence of U. prolifera, and the migration trajectory of its enrichment zones. On 6 June 2021, three satellite images depicted the northwest drift of U. prolifera, followed by a southward movement after making contact with the coast of Qingdao, China, on 12 June. The most extensive impact area caused by U. prolifera was observed on 18 June. Subsequently, the images revealed a contraction and enrichment of U. prolifera in an eas–-west direction. The amalgamation of radar and optical remote sensing satellites in a multi-frequency monitoring approach allows for a continuous all-weather surveillance mechanism for U. prolifera. This mechanism serves to provide timely alerts for the prevention and management of U. prolifera outbreaks.

Ulva prolifera Stress in the Yellow Sea of China: Suppressed Antioxidant Capacity and Induced Inflammatory Response of the Japanese Flounder (Paralichthys olivaceus).

As the largest green macroalgal bloom in the Yellow Sea of China, the overgrowth and degradation of Ulva prolifera (U. prolifera) have a harmful effect on marine organisms and the aquaculture industry. However, the regulation mechanism of U. prolifera stress on the antioxidant capacity and inflammatory response of marine fish is still not completely understood. A 15-day exposure experiment was conducted to evaluate the effects of U. prolifera stress on the antioxidant capacity and inflammatory response of the Japanese flounder (Paralichthys olivaceus) (283.11 ± 6.45 g). The results showed that U. prolifera stress significantly decreased their survival rate. Serum total antioxidant capacity (T-AOC) and non-specific immune-related enzyme activities were significantly impacted under U. prolifera conditions. Moreover, U. prolifera stress significantly decreased T-AOC, superoxide dismutase (SOD) activity, and catalase (CAT) activities in the liver, while malondialdehyde (MDA) contents were significantly increased. Similarly, antioxidant-related gene (cat, nrf2, and keap1) expressions were synchronously downregulated in the liver under U. prolifera stress. Furthermore, U. prolifera stress significantly upregulated pro-inflammatory gene (tnf-α, il-1β, ifn-γ, and p65) expressions and the phosphorylation levels of the p38 and JNK MAPK pathways in the head kidney. In addition, endoplasmic reticulum (ER) stress-related gene and protein expressions were also upregulated in the head kidney. Overall, these results revealed that U. prolifera stress suppressed the antioxidant capacity and induced an inflammatory response in the Japanese flounder. This study could advance the understanding of the adverse effects of U. prolifera stress on marine benthic fish and promote the sustainable development of aquaculture.

Effects of Ulva prolifera Degradation on Growth Performance and Antioxidant Capacity of Japanese Flounder (Paralichthys olivaceus) Family

Massive macroalgae blooms, primarily caused by the overgrowth of Ulva prolifera (U. prolifera) in the Yellow Sea of China, pose a severe risk to both marine organisms and the aquaculture industry. This study’s aim was to evaluate the impact of U. prolifera degradation on the growth performance and antioxidant capacity of Japanese flounder (Paralichthys olivaceus) and select some potential Japanese flounder families (labeled 2101–2108, established by crossbreeding) tolerating U. prolifera degradation conditions. Thus, a 60-day U. prolifera exposure experiment was conducted. The results showed that the contents of Na, K, Mg, and Fe elements in the U. prolifera degradation water were significantly increased. The specific growth rate and survival rate of flounder were significantly decreased under the U. prolifera degradation condition, while the 2101 and 2103 flounder families showed a better growth performance compared with the positive control (PC) group. Moreover, the results showed that activities of total antioxidant capacity (T-AOC), transaminases, and alkaline phosphatase (AKP) in serum were significantly decreased, while the 2103 flounder family showed higher activities. Furthermore, U. prolifera degradation significantly increased superoxide dismutase (SOD) activity and glutathione (GSH) content while decreasing catalase (CAT) activity and malondialdehyde (MDA) content in the liver. Specifically, SOD and CAT activities of the 2103 flounder family were higher than the 2101 flounder family and PC group. In addition, the gill SOD and CAT activities of the 2103 flounder family were significantly higher than the PC group. Similarly, the antioxidant-related gene (sod and cat) expressions were synchronously upregulated or downregulated in the liver and gills in response to U. prolifera degradation. These results revealed that U. prolifera degradation decreased the growth performance and influenced the antioxidant capacity of Japanese flounder, while the 2103 flounder family had better advantages in the U. prolifera degradation condition. Therefore, the 2103 flounder family could be regarded as the potential flounder family tolerating U. prolifera degradation. The increased Fe content in the U. prolifera degradation water may be one of the main causes of the physiological alterations observed in Japanese flounder.

Effect of land–sea air mass transport on spatiotemporal distributions of atmospheric CO2 and CH4 mixing ratios over the southern Yellow Sea

Abstract. To reveal the spatiotemporal distributions of atmospheric CO2 and CH4 mixing ratios and regulation mechanisms over the China shelf sea, two field surveys were conducted in the southern Yellow Sea in China in November 2012 and June 2013, respectively. The results observed showed that mean background atmospheric CO2 and CH4 mixing ratios were 403.94 (±13.77) ppm and 1924.8 (±27.8) ppb in November 2012 and 395.90 (±3.53) ppm and 1918.0 (±25.7) ppb in June 2013, respectively. An improved data-filtering method was optimised and established to flag atmospheric CO2 and CH4 emission from different sources in the survey area. We found that the spatiotemporal distributions of atmospheric CO2 and CH4 mixing ratios over the southern Yellow Sea were dominated by land–sea air mass transport, which was mainly driven by seasonal monsoon, while the influence of air–sea exchange was negligible. In addition, atmospheric CO2 and CH4 mixing ratios over the southern Yellow Sea could be elevated remarkably at a distance of approximately 20 km offshore by land-to-sea air mass transportation from the Asian continent during the early-winter monsoon.

Spatial distribution of antibiotics and antibiotic resistance genes in tidal flat reclamation areas in China.

Tidal flat areas are important resources for land development and are becoming antibiotic resistance receivers that trigger major health concerns. The spatial distributions of forty-nine antibiotics, nine antibiotic resistance genes (ARGs), one mobile gene element (MGE) gene, and nine available metals in the soils and sediments along the coastlines of the Yellow Sea in China were quantified. Hierarchical linear model analysis was used to explore relationships between the antibiotics and ARGs across multiple effects resulting from human activities and environmental factors. Fish farm sediments and farmland soils showed high levels of quinolones (QNs) (maximum 637ng·g-1), sulfonamides (SAs) (maximum 221ng·g-1), and corresponding ARGs. Significant positive correlations (P from 5.47 × 10-14 to 0.0487) were observed between the antibiotics (QNs, SAs, and chlortetracycline) and their corresponding ARGs (qnrA, qnrD, aac(6')-Ib-cr, dfrA, sul2, and tetA), indicating the selective pressure from antibiotics in soils and sediments. Nine available metals had positive correlations with at least one ARG, indicating heavy metal pollution could enhance the ARGs. Sheep and poultry husbandry and marine aquaculture contribute the most to the antibiotic resistance in the coastlines. In conclusion, antibiotic pollutions have promoting effects at sub-inhibitory concentrations and more attention should be given to inhibit the enrichment of ARGs during tidal flat reclamation processes. The study also suggests the induction effects from metal pollutions, MGE spread, and the antibiotic pollutions from the usage in livestock and aquaculture.

Temporal dynamics of zooplankton community in an oyster farming area of the Yellow Sea in China via metabarcoding

IntroductionThe coastal ecosystem is a hub of both marine organisms and human activities. It plays a crucial role in human food production and affects facilities through biofouling. Long-read amplicon sequencing provides more accurate species identification and demonstrates numerous advantages in community diversity studies, making it an effective tool for ecological monitoring.MethodsTo investigate the zooplankton community characteristics in the oyster aquaculture area, the composition and temporal dynamics of zooplankton near Longwan Bay, Qingdao, China, were determined by the 18S rRNA gene long reads sequencing technique.ResultsA total of 89 zooplankton species were identified, among which copepods were the most abundant. Zooplankton composition and proportional abundances showed significant seasonal variations. The species richness in summer was the highest, while the species abundance in spring was the highest. Oyster farming showed weak influence on the zooplankton community variation. Paracalanus parvus abundance was higher in most assayed months. Chthamalus stellatus showed a strong temporal preference, with the highest percentage in May. Sea water temperature and species-species interactions were revealed to be the main contributors to the shifts in the community composition. DiscussionThe ubiquitous positive correlation between zooplankton suggests that species interactions are important in adaptation to the changing environment. The results reveal the seasonal occurrence of several major biofouling organisms and help improve biofouling management efficiency.

One new species of Oxyonchus ( ) (Enoplida: Nematoda) from the Yellow Sea of China

During the diversity assessment of marine nematodes in the China seas, a new species of Oxyonchus (Filipjev, 1927) De Coninck & Schuurmans Stekhoven 1933 was discovered from the Yellow Sea of China. O. boucheri sp. nov. is characterized by cuticle smooth; mouth opening surrounded by three lips separated by deep clefts; cephalic region with developed cephalic capsule; mandibles arch-shaped, rods linked with anteriorly transverse bar, two subventral teeth extend to the mandibles' anterior ends; thick outer and inner labial setae; six files of 2–4 cervical setae; conico-cylindrical tail without terminal seta; curved spicules with tapered distal ends; gubernaculum with dorso-caudal apophysis; a ventral tubular and 6–8 pairs subventral spinous precloacal supplements. The new species differs from other 17 congeners mainly in its conical inner and thick outer labial setae (vs. slender labial setae), files of 2–4 cervical setae present (vs. cervical setae absent), slender spicules with tapered distal ends (vs. spicules with capitulum), both ventral tubular and subventral spinous precloacal supplements (vs. only tubular supplement in males). Updated dichotomous key to the genus Oxyonchus were provided.