China Sea Research Articles

Effect of antibiotics, antibiotic-resistant bacteria, and extracellular antibiotic resistance genes on the fate of ARGs in marine sediments

Surface runoff is a prevalent source via which emerging pollutants (i.e., antibiotics, antibiotic-resistant bacteria (ARB), and antibiotic resistance genes (ARGs)) enter marine sediments. However, few studies have investigated the effect of emerging pollutants on the fate of ARGs in marine sediments. Therefore, three systems were established to measure the relative abundances of four common ARGs (i.e., blaTEM, tetA, tetC, and aphA) and the integron-integrase gene (intI1) after exposure to emerging pollutants in marine sediments from the Bohai Sea, the Yellow Sea, the East China Sea, and the South China Sea in China. The results revealed that antibiotic exposure could decrease the relative abundance of most ARGs (including blaTEM, tetA, and tetC) in these marine sediment samples. The exceptions were the relative abundance of blaTEM in the Bohai Sea marine sediments under ampicillin exposure and tetC in the Yellow Sea marine sediments under tetracycline exposure, which increased significantly. Among marine sediments challenged with ARB, the relative abundance of aphA in all four marine sediments displayed a decreasing trend, whereas the abundances of blaTEM and tetA in the marine sediments from the Bohai Sea and the South China Sea showed an increasing trend. The relative abundance of tetA in the marine sediments from the Yellow Sea and the East China Sea dropped markedly when exposed to extracellular ARG (eARG). Significant changes in blaTEM abundance were observed in the four marine sediments under eARG exposure. Gene aphA abundance showed the same trend as the intI1 abundance. IntI1 showed a decreasing trend under the exposure of antibiotic, ARB, or eARG, apart from the East and the South China Sea marine sediments under ampicillin conditions and the South China Sea marine sediments under RP4 plasmid condition. These findings suggest that dosing with emerging pollutants does not increase ARG abundance in marine sediments.

An improved algorithm for detecting mesoscale ocean fronts from satellite observations: Detailed mapping of persistent fronts around the China Seas and their long-term trends

Mesoscale fronts are highly energetic ocean processes that dominate local biogeochemical processes and air-sea interactions and exert significant effects on ocean dynamics, ecology, and climate. An automatic front detection algorithm applied to satellite-based observations is a fundamental approach to acquiring frontal occurrence information. Histogram-based algorithms have been widely used in previous studies, and, despite being the most popular front detection algorithm, continuous improvements have been needed to address imperfect detection issues (undetected coastal fronts, discontinuities of fronts and repeated detection of fronts). In this study, a new algorithm is proposed to address the issues by coupling inverse distance weighting and mathematical morphology operators. Using 14,610 images acquired from 1982 to 2021, a series of comparisons between the new and existing algorithms have been implemented to validate the improvements. Statistical results suggest that the number of frontal pixels detected by our algorithm increased by 58.45% in the coastal domain when compared to previous methods. Statistical analysis also shows most of these increased fronts can be supported by a classic gradient-based method which is superior in detecting coastal fronts, which demonstrates the improvement of new algorithm in detecting coastal fronts. Furthermore, visual analyses suggest that our algorithm can better connect discontinuous fronts and reduce repeated detections, and statistical comparisons in the open seas present a 34.50% improvement in the average length of frontal segments. Moreover, based on an automated objective delineation method, an analysis of 40 years of seasonal frontal occurrences (as detected by our algorithm) produced a dataset that shows a detailed map of 59 persistent fronts around the China Seas. This map updates previously hand-delineated frontal positions and identifies some previously unreported persistent fronts. Further analyses show that the frontal occurrence or intensity of a majority of persistent fronts around the China Seas presents significant (P < 0.05) long-term variability over the last 40 years. The improved algorithm, together with its application in identifying persistent fronts around the China Seas, is expected to be extended to other waters to better investigate the response of marine ecosystems to front dynamics and predict the distribution of marine organisms within a changing climate.

Sediment settling process revealed by a bottom-tethered sediment trap at the east tip of the Shandong Peninsula

This paper investigates sediment settling process during summer seasons based on in-situ observation and sediment analysis at the east tip of the Shandong Peninsula, which is a pathway for sediments from the Bohai Sea and the North Yellow Sea to enter the South Yellow Sea in China. Bottom-tethered sediment traps, together with platforms equipped with current profilers/meters and temperature/salinity and turbidity sensors, were deployed for approximately 10 days in August 2017 over an elongated deposit off the coast of the Shandong Peninsula. A computed tomography (CT) scan and grain size and 210Pb analyses of trap sediment were carried out to determine the settling process of suspensions at the study site. Twenty-three couplets were found in the CT images of the trap, the time series of which was established using intervalometer disks. Quantitative characterization of rhythmites using a hounsfield unit indicates that the period of couplets is approximately quarter-diurnal, and the settling process could be divided into three stages during Aug. 21st – 27th. Current, wave, wind, and SSC data illustrate that the diversion of the bottom current leads to the formation of couplets, and the thickness of the couplet is controlled by the vertical current velocity and wind direction. Northerly winds enhance the difference in settlement between flood and ebb tides, whereas southerly winds smoothen the difference. The gale event inhibited the settlement of the suspended matter, and the source of the suspensions was converted from local to remote after the event, as evidenced by 210Pb data. No evident erosion can be detected in the sediment traps. The results are of significance to better understand the sedimentary dynamics near the Shandong clinoform and inspire the practical efficiency of bottom-tethered sediment traps in the settling process in coastal areas.

Evaluation of SST Data Products from Multi-Source Satellite Infrared Sensors in the Bohai-Yellow-East China Sea

The measurement of sea surface temperature (SST) is of utmost importance in the realm of oceanography. The increasing utilization of satellite data in SST research has highlighted the crucial need to compare and evaluate various satellite data sources. Using iQuam2 in situ SST data, this study aims to assess the accuracy of SST datasets obtained from three polar-orbiting satellites (AVHRR, Modis-Aqua, and Modis-Terra) and one geostationary satellite (Himawari-8) in the Bohai-Yellow-East China Sea (BYECS) throughout 2019. The results showed a strong correlation between satellite and in situ data, with R correlation coefficients exceeding 0.99. However, the accuracy of the satellite datasets exhibited some variability, with Himawari-8 showing the highest deviation error and MODIS-Aqua showing the least. Subsequently, the Modis-Aqua data were used as a benchmark to evaluate the SST data of the other three satellites over the previous six years (July 2015–June 2021). The results indicate that, in addition to intricate temporal variations, the deviations of the three satellites from Modis-Aqua also show significant spatial disparities due to the effect of seawater temperature. Compared to Modis-Aqua, the deviation of Himawari-8 generally displayed a negative trend in BYECS and showed pronounced seasonal variation. The deviation of AVHRR showed a negative trend across all regions except for a substantial positive value in the coastal region, with the time variation exhibiting intricate features. The SST values obtained from MODIS-Terra exhibited only marginal disparities from MODIS-Aqua, with positive values during the day and negative values at night. All three satellites showed significantly abnormal bias values after December 2020, indicating that the MODIS-Aqua-derived SST reference dataset may contain outliers beyond this period. In conclusion, the accuracy of the four satellite datasets varies across different regions and time periods. However, they could be effectively utilized and integrated with relevant fusion algorithms to synthesize high-precision datasets in the future.

Distribution, sources and risk assessment of polycyclic aromatic hydrocarbons in surface sediments from the Yellow Sea coast, China

To study the distribution, sources, ecological/health risks, and the impact of regional economic variations on polycyclic aromatic hydrocarbons (PAHs) contaminations along the coast of the Yellow Sea in China, sediments from a broad coastal coverage were collected and analyzed. The total contents of 16 priority PAHs varied between 1.4 and 1675.9 ng/g except in the site of H18 (3191.4 ng/g) adjacent to Qingdao City, with an average value of 295.7 ng/g. PAH pollution along the coast presented a distinctive geographical feature, which was closely linked to local human activities, such as Rongcheng with industrial zones and aquacultural areas, and Yancheng Wetland with developed aquaculture. The source analysis results indicated that PAHs were mainly from pyrolytic sources, with smaller contributions from petroleum spills and combustion. Risk assessment suggested that PAH pollution along the Yellow Sea coast showed negligible biological risks and health risks in most areas.

Climate Change and the Change of Trophic Level Interaction in Coral Reefs Based on South China Sea in China

In recent years, coral reefs have been seriously affected by human and natural factors, some of influences are even irreversible. Among them, the impacts of climate change have gradually deepened and attracted people's attention. Other papers which tell about the familiar topic failed to focus on discussing specific questions in certain area of coral reefs. The paper mainly analyzes the interspecific relationship change when facing the climate change of coral reef ecology in the South China Sea. Content of this paper first discusses the severe condition of climate change, like the instability of global climate system. Also, the situation about South China Sea and the effects of climate change are discussed and analyzed. Then, the interspecific relationships of predation, competition, parasitism, and mutualism were discussed. Further, discussed the increase of benthic algae and symbiotic organism reactions. The response from higher trophic level to low level and some researches are determined, too. On this basis, consider the interspecific relationships in the same trophic level. In the future, higher trophic level changes should be determined. Also, people should focus on the change after coral reefs recovering from albinism, about whether their population would change even extinct with the effect of climate change on coral reefs and reefs make a response to it through trophic level relationship change. This paper can provide some corresponding research ideas for more future researches.

Adaptive Graph-Learning Convolutional Network for Multi-Node Offshore Wind Speed Forecasting

Multi-node wind speed forecasting is greatly important for offshore wind power. It is a challenging task due to unknown complex spatial dependencies. Recently, graph neural networks (GNN) have been applied to wind forecasting because of their capability in modeling dependencies. However, existing methods usually require a pre-defined graph structure, which is not optimal for the downstream task and limits the application scope of GNN. In this paper, we propose adaptive graph-learning convolutional networks (AGLCN) that can automatically infer hidden associations among multi-nodes through a graph-learning module. It simultaneously integrates the temporal and graph convolutional modules to capture temporal and spatial features in the data. Experiments are conducted on real-world multi-node wind speed data from the China Sea. The results show that our model achieves state-of-the-art results in all multi-scale wind speed predictions. Moreover, the learned graph can reveal spatial correlations from a data-driven perspective.

Description of a New Species of Parathalestris Brady &amp; Robertson, 1873 (Copepoda: Harpacticoida: Thalestridae) from China, with a Key to Its Affiliated Species Group

A new species belonging to the genus Parathalestris Brady &amp; Robertson, 1873 was identified and described here based on samples recently collected from a survey on fouling organisms at the Zhonggang wharf in Qingdao, China. The new species differs from its congeners in the following characteristics: caudal rami 2.0 times longer than wide, with bulbous setae II and setae III of caudal ramus issuing terminally and laterodistally, respectively; exopod of antenna two-segmented, with two setae on first segment and four setae on second one;maxilla with two bipinnate setae on proximal endite, and three spinulose setae on middle and distal endites; basis of maxilliped with concave inner edge; P1 exopod and endopod approximately same length, enp-1 about 6.7 times as long as greatest width, with inner seta reaching proximal 2/3 of segment; baseoendopod and exopod of female P5 with transversal rows of spinules on its surface, exopod bearing six marginal setae; male P1 carrying an inner curved spine on basis; exopod of male P5 bearing six elements. The DNA barcode (COI) sequence of the new species was obtained and submitted to GenBank. This is the first report of Parathalestris from the China Seas.

Perfluoroalkyl substances (PFASs) in aquatic products from the Yellow-Bohai Sea coasts, China: Concentrations and profiles across species and regions

Perfluoroalkyl substances (PFASs) are emerging contaminants capable of harming human health, primarily via ingesting aquatic products. The current study monitored a survey of 23 PFASs in 1049 aquatic products from the coasts of the Yellow-Bohai Sea in China to comprehensively investigate the concentrations and distributions of PFASs. PFOA, PFOS, PFNA, PFOSA, and PFUdA were more predominantly and frequently detected than other PFASs in all samples, dominating PFAS patterns in aquatic products. The mean levels of ∑PFASs in different species followed the order: marine shellfish > marine crustaceans > fish > cephalopods > sea cucumber. Profiles of PFASs differ between species, suggesting species-specific accumulation plays a role. Various aquatic species are potential environmental bioindicators that signal individual PFAS contamination. For instance, clams can act as a potential PFOA bioindicator. High ∑PFAS levels in some sites (such as Binzhou, Dongying, Cangzhou, and Weifang) could be attributed to industrial activities involving fluoropolymer manufacture. The differences between PFAS concentrations and profiles in aquatic products across the study regions have been proposed as PFAS fingerprints of the Yellow-Bohai Sea coasts. Analyses of principal components and Spearman correlations indicated that the precursor biodegradation possibly contribute to C8–C10 PFCAs in the study samples. This study reported a wide presence of PFASs in different species of aquatic products across the Yellow-Bohai Sea coasts. The potential health risks that PFASs pose in certain species (such as marine shellfish and marine crustaceans) should not be neglected.

A multidimensional approach for microplastics monitoring in two major tropical river basins, Malaysia

Microplastics (MPs) with the size of 1 μm–5 mm are pollutants of great concern ubiquitously found in the environment. Existing efforts have found that most of the MPs present in the seas mainly originated from land via riverine inputs. Asian rivers are known to be among the top in microplastic emissions. However, field data are scarce, especially in Malaysia. This study presents the distribution and characteristics of MPs in the surface water of two major river basins of Malaysia, namely Langat River (West Coast/Straits of Malacca) and Kelantan River (East Coast/South China Sea). Water samples were collected at 21–22 locations in Kelantan and Langat rivers, covering the river, estuary and sea. MPs were physically classified based on sizes, shapes, colours and surface morphology (SEM-EDS). The average of 179.6 items/L and 1464.8 items/L of MPs had been quantified from Kelantan and Langat rivers, respectively. Fibre (91.90%) was highly recorded at Kelantan, compared to Langat whereby both fibre (59.21%) and fragment (38.87%) were prevalence. Anthropogenic activities and urbanised areas contribute to high microplastic abundance, especially in the Langat River. Micro-FTIR analysis identified 14 polymers in Kelantan River, whereas 20 polymers were found in Langat River. Polypropylene, polyethylene, polyethylene terephthalate, nylon, phenoxy resins, poly(methyl acrylate), poly(methyl methacrylate), polystyrene, polytetrafluoroethylene, polyurethane and rayon were discovered in both rivers, although only polyethylene was significant (>1 ppm) when further analysed using pyrolysis-GC/MS. Correlation analysis and multiple linear regression were used to explain the relationship between water quality and MP abundance, suggesting only turbidity was positively significant to the microplastic occurrence. This comprehensive study is first to suggest a full-scale monitoring protocol for MPs in Malaysian riverine system and is significant in understanding MPs abundance in correlation to in-situ environmental factors. Consequently, this will allow the right authorities to develop mitigation strategies to address riverine plastic pollution in major river basins in Malaysia and the South East Asia.

Unraveling seasonal and interannual nutrient variability shows exceptionally high human impact in eutrophic coastal waters

AbstractNutrient import into eutrophic estuarine‐coastal zones is modulated by river discharge and anthropogenic activities (agriculture, industry, sewage, etc.). Comparing anthropogenic vs. hydrological influences on nutrient loading is important for ecosystem managers but has been a long‐standing challenge. As an attempt to fill this gap, a retrospective study was conducted using multiyear (2012–2022) data in one of the most eutrophic coastal seas in China, the Jiangsu coastal waters. Of the two main pollutants on the Jiangsu coast, dissolved inorganic nitrogen (DIN) is extremely overloaded relative to phosphate (PO4). Their spatial distribution shows clear terrestrial sources as concentrations decrease offshore. Although in each survey DIN and PO4 are enriched in low‐salinity waters, their spatially averaged concentrations are out of phase with river discharge on the seasonal and interannual scales. A box model was applied to decompose contributions of river discharge and nutrient import by anthropogenic activities. Results show that the human impacts on the interannual nutrient variability exceed those of hydrological factors on the Jiangsu coast. Anthropogenic nutrient loading decreases during 2012–2020, paralleled with the reduced fertilizer use and other nonpoint sources. Sporadic nutrient fluxes from point sources are likely responsible for the aseasonal nutrient‐rich patches. Our study demonstrates that water quality in the Jiangsu coastal waters is highly affected by anthropogenic activities. Findings in this study have broad implications for local monitoring strategies and restoration efforts and provide insight into assessing human stress from field data in global eutrophic ecosystems.

Prevalence of the neurotoxin domoic acid in the aquatic environments of the Bohai and Northern Yellow seas in China

Domoic acid (DA), a natural marine phytotoxin produced by toxigenic algae, is harmful to fishery organisms and the health of seafood consumers. In this study, we performed a whole-sea area investigation of DA in seawater, suspended particulate matter (SPM), and phytoplankton of the Bohai and Northern Yellow seas to clarify the occurrence, phase partitioning, spatial distribution, potential sources, and environmental influencing factors of DA in the aquatic environment. DA in different environmental media was identified using liquid chromatography-high resolution mass spectrometry and liquid chromatography-tandem mass spectrometry. DA was found to be predominantly in a dissolved phase (99.84 %) in seawater with only 0.16 % in SPM. Dissolved DA (dDA) was widely detected in nearshore and offshore areas of the Bohai Sea, Northern Yellow Sea, and Laizhou Bay with concentrations ranging from < limits of detection (LOD) to 25.21 ng/L (mean: 7.74 ng/L), < LOD to 34.90 ng/L (mean: 16.91 ng/L), and 1.74 ng/L to 38.20 ng/L (mean: 21.28 ng/L), respectively. dDA levels were relatively lower in the northern part than in the southern part of the study area. In particular, the dDA levels in the nearshore areas of Laizhou Bay were significantly higher than in other sea areas. This may be due to seawater temperature and nutrient levels exerting a crucial impact on the distribution of DA-producing marine algae in Laizhou Bay during early spring. Pseudo-nitzschia pungens may be the main source of DA in the study areas. Overall, DA was prevalent in the Bohai and Northern Yellow seas, especially in the nearshore aquaculture zone. Routine monitoring of DA in the mariculture zones of the northern seas and bays of China should be performed to warn shellfish farmers and prevent contamination.

Study on the distribution characteristics of faults and their control over petroliferous basins in the China seas and its adjacent areas

Study on the distribution characteristics of faults and their control over petroliferous basins in the China seas and its adjacent areas

Influence of the Moho surface distribution on the oil and gas basins in China seas and adjacent areas

Influence of the Moho surface distribution on the oil and gas basins in China seas and adjacent areas

Integrated gravity and magnetic study on patterns of petroleum basin occurrence in the China seas and adjacent areas

Integrated gravity and magnetic study on patterns of petroleum basin occurrence in the China seas and adjacent areas

Exploring balanced harvest as a potential strategy for highly exploited multispecies fisheries

Abstract Balanced harvest (BH) proposes moderate fishing mortality rates across all species or sizes in proportion to productivity, serving as a possible strategy for ecosystem-based fisheries management. Fishing patterns in some developing countries (e.g. China, the largest producer of seafood) closely resemble BH, where catches have been highly diversified by unselective gears due to market demand for almost all species. In this study, we employed an OSMOSE ecosystem model developed for the Yellow Sea in China to investigate the potential occurrences and advantages of BH in this region with highly exploited multispecies fisheries. Simulations were carried out under four types of fishing scenarios, where various levels of fishing mortality rates for all species or specific functional groups were implemented. Results indicated that the occurrences of BH depended on fishing pressure and targeted functional groups, and that size-level BH was significantly correlated with biomass and yield for most species. In particular, varying fishing pressure for certain functional groups resulted in BH, which produced a high yield for specific species and ensured their biomass sustainability. We concluded that the benefits of BH could be potentially achieved by adjusting fishing pressure for certain functional groups based on the existing fishing pattern in over-exploited ecosystems.

Changes in marine hot and cold extremes in the China Seas during 1982–2020

Extremes in sea surface temperature (SST) have the potential to threaten marine biodiversity, ecosystem functions, and regional services. Using the OISST v2 data, we analyzed the spatial and temporal variability of marine hot and cold events in the China Seas during 1982–2020. Results showed that in majority of the China Seas, frequency of Hot Days (HDs) and Marine heatwaves (MHWs) has significantly increased; severe MHWs (SMHWs) have become more intense. Frequency of Cold Days (CDs) and Marine cold-spells (MCSs) has fallen dramatically; severe MCSs (SMCSs) have become weaker. All of the trend distributions are heterogeneous, with the largest magnitudes along the coast. Long-term temporal analysis revealed that cold extremes (CDs, MCSs, SMCSs) decreased significantly, while hot extremes (HDs, MHWs, SMHWs) increased at a higher confidence level and at a faster rate. Asymmetry characterizes the tendencies of hot and cold extremes. Further study demonstrated that mean SST warming, not SST variability, was the primary driver of trends in both MHW and MCS metrics. MHWs/MCSs related to the anthropogenic or natural forcing increased very rapidly in the post-1998 era.

Influence of Ocean Tidal Loading on Continuous Gravity Observations in Eastern China

Global and regional ocean tide models are used to analyze the gravity effect of ocean tidal loading (OTL) for gravity stations in East China. The accuracies of OTL correction results for 21 gravity stations in East China are evaluated. The global ocean tide model is the most effective for the OTL correction of inland gravity stations (up to 90%) but is less effective for coastal gravity stations (only 60%). Considering regional ocean tide models, the applicability of OTL correction increased to 80% in coastal gravity stations. Based on the root sum square (RSS) method, among 16 combination models, the optimal combination model for OTL correction is the global model FES2014b by combing the regional model OSU.Chinasea.2010 (F14O). The RSS, which has reached 7.1 nms−2, is the minimum of the 16 combination models. Simulating with the F14O in the China Sea and adjacent areas, the gravity amplitude of the OTL is about 10 nms−2 in inland areas and > 50 nms−2 along the coastline. Especially in Southeastern China coastal areas and the southwestern coastal areas of the Korean Peninsula, the gravity amplitude of the OTL reaches about 80 nms−2. Moreover, the OTL changes drastically possibly owing to coastal topography. The results of this study provide a reference for selecting ocean tide models for high-precision analysis of continuous gravity observations in East China.

Vision-Based Target Detection and Positioning Approach for Underwater Robots

The accurate target detection under different environmental conditions and the real-time target positioning are vital for the successful accomplishment of underwater missions of Remotely operated vehicles (ROVs). In this paper, we propose a vision-based underwater target detection and positioning approach to detect and estimate the position and attitude of artificial underwater targets. The proposed approach is composed of an underwater target detection algorithm YOLO-T and a target positioning algorithm. Firstly, we modify the structure of YOLOv5 algorithm using Ghost module and SE attention module to improve the calculation time of target detection. Secondly, a series of image processing operations are performed on the improved YOLOv5 detection results to increase the detection accuracy. Thirdly, a cooperative marker is designed as the artificial underwater target, and the corresponding positioning algorithm is presented to calculated the position and attitude of the target according to the geometric information of the designed marker. We validate our approach through experimental tests respectively in a water tank, an anechoic tank, and the sea trial in Huanghai Sea in China. The results demonstrate the accurate performance of the proposed detection and positioning method.

Modeling the leeway drift characteristics of persons-in-water at a sea-area scale in the seas of China

Drowning events are becoming more common. It is important to accurately predict the drift trajectory of floating objects. This study proposes a sea-area-scale drift modeling method to determine the drift trajectory of persons-in-water in offshore China. The proposed method divided offshore China into 18 areas, and field experiments were carried out in the northern East China Sea (N_ES) and the Taiwan Strait (TS). First, a series of models were created, namely N_ES_I (N_ES upright), N_ES_II (N_ES facedown), TS_I (TS upright), TS_II (TS facedown), C_I (comprehensive upright), and C_II (comprehensive facedown). The leeway coefficients and jibing frequencies were then determined, and the positive crosswind speed (+CWL) probabilities under different marine environments were analyzed. A large volume of information from open-source channels was used to establish a database of historical drift cases. The driven model was validated using a combination of field experiments and historical drift information. The results indicate that the trajectories simulated using the sea-area-scale models proposed in this study are more consistent with the actual trajectories than those using the constant coefficients. The prediction areas are sensitive to the +CWL probability and the jibing frequencies. This study can help to improve the ability of the drift trajectory in China.