Southern Coast Of China Research Articles

Spatial heterogeneity of resource availability drives soil bacterial community assembly along the sandy coast of Southern China

Resources scarcity is prevalent in natural microbial communities, affecting both biodiversity and coexistence. However, its intricate impacts on community assembly remain incompletely understood. In this study, we examined the bacterial community assembly processes in low-resource soil patches along the sandy coast of Southern China, focused on the relative importance of abiotic and biotic factors. Our study revealed a slightly decreasing trend in bacterial community similarity with increasing geographic distance, whereas the spatial heterogeneity of soil resource availabilities, including total nitrogen (TN), ammonium (NH4+-N), and total phosphorus (TP), explained 75 % of the total variation in the soil bacterial community. Nitrogen was identified as the primary limiting resource, playing a key role in shaping the composition of bacterial communities. Notably, elevated N availability did not alleviate N limitations or promote biodiversity. Instead, it led to deterministic community assembly processes by increasing the overall demand for N and intensifying negative biological interactions among taxa. These processes favored the selection of specific communities dominated by highly competitive species with overlapping niches. Our findings offer novel insights into the biogeographic patterns of soil bacterial communities, highlighting how resource availability shapes their compositions and has potential ecological implications, including effects on seedling establishment and the resilience of belowground communities to disturbances.

Clinicopathologic features and new factors affecting constitution of eyelid neoplasms: a 10-year multicentre experience in southern coastal China

ObjectiveThis study aims to delineate the key characteristics of eyelid neoplasms in central and southern coastal China and to explore potential factors affecting tumour development. MethodsThis was a retrospective, multicentre observational study. In total, 1302 cases of eyelid neoplasms diagnosed in 2 tertiary hospitals were reviewed from January 2013 to May 2023. Histogenesis, pathologic diagnosis, and potential risk factors were investigated, and the findings were compared with data from various regions and countries. Age- and sex-specific incidence rates, time trends, distributions across age groups, and the relationship with the Sociodemographic Index, latitude, and altitude were calculated. ResultsThere were 1162 benign (89.2%) and 140 malignant (10.8%) cases, representing 63 pathologic types. The median age of benign cases (50 years) was significantly lower than that of malignant cases (72 years) (P < 0.05). The most common benign and malignant lesions were intradermal nevus (28.83%) and basal cell carcinoma (BCC) (74.29%). A relatively younger median age (68 years) for sebaceous gland carcinoma (SGC) was observed, with a male preponderance (sex ratio 2:1). Analyses of the proportions of BCC, SGC, and squamous cell carcinoma in eyelid malignancies revealed significant regression equations (P < 0.05). ConclusionsMost eyelid neoplasms are of epithelial and melanocytic origin, with benign tumours being predominant. The regions with greater Sociodemographic Index exhibit a greater incidence of BCC and a lower incidence of squamous cell carcinoma and SGC. BCC appears to have a greater incidence in regions located at higher latitudes.

A Persistent Coast Mode of Precipitation in Southeast China Over the Last Millennium

AbstractInstrumental data set have revealed several summer precipitation patterns in eastern China, being summarized as “tripole,” “dipole” and “coast” modes. The former two have been found to persist at different time scales, leaving the latter unclear in geological records. Here we present 1300‐year hydroclimate records in a tropical maar lake in the southern coast of China using archeal lipid GDGTs, which can reflect lower water redox conditions largely regulated by lake water depth. The down‐core GDGTs reveal a relatively drier condition during the medieval climate anomaly compared to the Little Ice Age, in‐phase with other records in southeast coast of China but opposite to the inland region, hence demonstrating a persistent “coast” mode in eastern China. The thermal state of equatorial Pacific is suggested to play an important role in shaping the “coast” mode by modulating the location and strength of the western Pacific subtropical high and tropical typhoons.

Genetic Diversity and Profile of Red Algae Pterocladiella capillacea (Gelidiales, Rhodophyta) along the Coast of China

Red algae Pterocladiella capillacea off the coast of China were investigated for genetic diversity. With 176 samples categorized into six populations based on concatenated rbcL and cox1 sequences, the results rang warning bells for the genetic diversity of Pterocladiella capillacea along the Chinese coastline: (1) a good diversity of haplotype (Hd &gt; 0.5) in Naozhou and Hui’an populations situated along the southern coast of China, but highest in the former; (2) less nucleotide diversity in each of the six populations (Pi &lt; 0.005); (3) genetic differentiation occurred between the north population in Changdao and the two southern grown populations in Nan’ao, and Naozhou. To identify molecular markers, an MP phylogenetic tree was used to illustrate genetic profiles in detail, with 161 concatenated sequences clustered into four branches: Changdao (north), Nan’ao (south), Naozhou (south), and the remaining regions (middle). The Fst value for each of Changdao, Nan’ao, and Naozhou was greater than 0.5, which denotes that these three populations are genetically different to those growing in the middle coast. Moreover, a 30-haplotype-based median-joining network corroborated this genetic differentiation, though variations between all the investigated populations were not very high due to the relatively smaller values of genetic distance between the six (Dxy &lt; 0.01). Overall, red algae P. capillacea in Chinese coastal seawater showed a higher haplotype diversity and lower nucleotide diversity. Such a genetic profile indicates that both natural random genetic drift and interference from human activities have possibly affected the distribution of gene frequencies in red algae P. capillacea along the Chinese coastline.

New chronology of K-feldspar isochron optical dating (iIRSL) in the late Pleistocene coastal aeolian deposits of Southeast China

Old red sand (ORS), which developed during the late Pleistocene, is widely distributed along the coasts of the western Pacific and Indian Ocean.The Optically Stimulated Luminescence (OSL) dating technology have primarily determined its sedimentary age. However, in tropical and subtropical regions, chemical weathering can impact the calculation of environmental dose rates, potentially leading to age biases whose magnitude remains uncertain.Recently, advance in the OSL dating technique, the new K-feldspar isochron dating method (iIRSL), have determined its depositional age. This approach effectively enhances the accuracy of age data by accounting for variations in past dose rates caused by chemical weathering and changes in water content during sample burial. This study used the iIRSL method to conduct infrared stimulated luminescence signal tests on ORS samples from the Haitan Island, south China. Five grain sizes of K-feldspar grains were extracted from each sample during experimentation. The single aliquot regenerative dose method (SAR) was utilized to determine the equivalent dose for each grain size and calculate age using the isochron method (iIRSL). Furthermore, it compared the iIRSL ages with quartz age (SAR). The results indicate that: (1) This study obtained four iIRSL ages, which are consistent with the ages obtained from quartz (SAR) within a reasonable range, ranging from 62.13 ± 4.85 to 39.44 ± 4.85 ka BP. (2) Comparison of the simulation results of different weathering degrees using the iIRSL method and K-feldspar two-step IRIR methods indicates that the iIRSL method can effectively mitigate the impact of chemical weathering on age determination, giving more reliable iIRSL ages. (3) The ORS along the southern coast of China mainly deposited during Marine Isotope Stages 5, 4, and 3, exhibiting relatively higher deposition rates during MIS 5 and MIS 3 at approximately 30 cm/ka and 15 cm/ka respectively. This suggests that the ORS was predominantly deposited during periods of elevated sea levels. However, it is important to note that the data from MIS 5 may have been influenced by the absence of samples from this particular stage and limitations in dating methods, resulting in a lower frequency-density of deposition ages during MIS 5 and creating an “illusion” of sediment interruption.

Seagrass decline weakens sediment organic carbon stability

Seagrass meadows are globally recognized as critical natural carbon sinks, commonly known as ‘blue carbon’. However, seagrass decline attributed to escalating human activities and climate change, significantly influences their carbon sequestration capacity. A key aspect in comprehending the impact of seagrass decline on carbon sequestration is understanding how degradation affects the stored blue carbon, primarily consisting of sediment organic carbon (SOC). While it is widely acknowledged that seagrass decline affects the input of organic carbon, little is known about its impact on SOC pool stability. To address this knowledge, we examined variations in total SOC and recalcitrant SOC (RSOC) at a depth of 15 cm in nine seagrass meadows located on the coast of Southern China. Our findings revealed that the ratio of RSOC to SOC (RSOC/SOC) ranged from 27 % to 91 % in the seagrass meadows, and the RSOC/SOC increased slightly with depth. Comparing different seagrass species, we observed that SOC and RSOC stocks were 1.94 and 3.19-fold higher under Halophila beccarii and Halophila ovalis meadows compared to Thalassia hemprichii and Enhalus acoroides meadows. Redundancy and correlation analyses indicated that SOC and RSOC content and stock, as well as the RSOC/SOC ratio, decreased with declining seagrass shoot density, biomass, and coverage. This implies that the loss of seagrass, caused by human activities and climate change, results in a reduction in carbon sequestration stability. Further, the RSOC decreased by 15 %, 29 %, and 40 % under unvegetated areas compared to adjacent Halophila spp., T. hemprichii and E. acoroides meadows, respectively. Given the anticipated acceleration of seagrass decline due to climate change and increasing coastal development, our study provides timely information for developing coastal carbon protection strategies. These strategies should focus on preserving seagrass and restoring damaged seagrass meadows, to maximize their carbon sequestration capacity.

Distribution and Risk Assessment of Organophosphate Esters in Agricultural Soils and Plants in the Coastal Areas of South China.

Organophosphate esters (OPEs) are frequently used as flame retardants and plasticizers in various commercial products. While initially considered as substitutes for brominated flame retardants, they have faced restrictions in some countries due to their toxic effects on organisms. We collected 37 soil and crop samples in 20 cities along the coast of South China, and OPEs were detected in all of them. Meanwhile, we studied the contamination and potential human health risks of OPEs. In soil samples, the combined concentrations of eight OPEs varied between 74.7 and 410 ng/g, averaging at 255 ng/g. Meanwhile, in plant samples, the collective concentrations of eight OPEs ranged from 202 to 751 ng/g, with an average concentration of 381 ng/g. TDCIPP, TCPP, TCEP, and ToCP were the main OPE compounds in both plant and soil samples. Within the study area, the contaminants showed different spatial distributions. Notably, higher OPEs were found in coastal agricultural soils in Guangdong Province and crops in the Guangxi Zhuang Autonomous Region. The results of an ecological risk assessment show that the farmland soil along the southern coast of China is at high or medium ecological risk. The average non-carcinogenic risk and the carcinogenic risk of OPEs in soil through ingestion and dermal exposure routes are within acceptable levels. Meanwhile, this study found that the dietary intake of OPEs through food is relatively low, but twice as high as other studies, requiring serious attention. The research findings suggest that the human risk assessment indicates potential adverse effects on human health due to OPEs in the soil-plant system along the coast of South China. This study provides a crucial foundation for managing safety risks in agricultural operations involving OPEs.

Variation in adaptation and growth among Corymbia citriodora natural-stand and landrace seed sources in southern China

ABSTRACT Corymbia citriodora subsp. citriodora has a long history of cultivation as a multipurpose tree in China and many other countries in Southeast and South Asia. Despite this history and longstanding interest in the species, published studies examining genetic variation among and/or within provenances/seed sources are scarce. Recognising this and to initiate an improvement program for this species, a field trial was established in southern coastal China in 2015 with 171 open-pollinated single mother-tree family seedlots representing five natural-stand seed sources in Australia and six planted seed sources in China. Large significant variation was found among seed sources for pest and disease resistance, survival, growth and stem form up to age 81 months. Australian seed sources were generally superior to Chinese ones for most traits. Phenotypic correlations among traits, at both the individual tree and seed-source mean levels, were favourable, with the strongest individual tree correlations found between disease susceptibility at 10 months and various tree growth traits. Overall, the variation observed in this field trial indicates the potential gains in this species from seed-source selection and ongoing breeding.

Recurrence Rate and Influencing Factors of Helicobacter Pylori Infection After Successful Eradication in Southern Coastal China.

Recurrence rate of Helicobacter pylori (H. pylori) infection after successful eradication have gained attention. This study was to assess the recurrence rate of H. pylori infection after successful eradication in the southern coastal provinces of China and to analyze its factors. 975 patients with upper gastrointestinal symptoms who were diagnosed with H. pylori infection using the 13C or 14C-urea breath test (UBT) underwent eradication treatment between August 2021 and December 2022. After eight to twelve weeks, repeat UBT was performed. Besides, 824 patients with successful eradication underwent a repeat UBT by completing questionnaires after a year. The 1-year recurrence rate was calculated, and the differences were analyzed based on baseline data, sociological characteristics, and lifestyle. A total of 734 patients completed the 1-year follow-up, out of which 26 (3.5%) patients experienced a recurrence of H. pylori infection. Exposure to other individuals infected with H. pylori (χ2=12.852, P<0.001), poor hygiene conditions at dining out places (χ2=6.839, P=0.009), frequent dining out (χ2=24.315, P<0.001), smoking (χ2=7.510, P=0.006), consumption of non-purified water (χ2=16.437, P<0.001), consumption of pickled foods (χ2=5.682, P=0.017), irregular meal patterns (χ2=16.877, P<0.001) and age (χ2=9.195, P=0.010) were significant factors for H. pylori infection recurrence. Exposure to other individuals infected with H. pylori, poor hygiene conditions at dining out places, consumption of non-purified water, frequent dining out and irregular meal patterns were independent risk factors (P=0.022, 0.016, 0.002, <0.001, <0.001; 95% CI 0.146-0.861, 0.121-0.806, 1.715-10.845, 0.085-0.521, 2.291-14.556). The one-year recurrence rate of H. pylori infection post-eradication in the southern coastal provinces of China is 3.5%. Contacting with infected individuals, poor hygiene in dining places, consumption of non-purified water, frequent dining out, and irregular meal patterns were identified as significant independent factors influencing H. pylori recurrence.

Characteristics of storm deposits in Wangcun Lagoon on the southern China coast during Typhoon Rammasun

Through study of the 210Pb, sedimentology, geochemistry, and microfossil characteristics of six core samples taken in Wangcun Lagoon on the Guangdong Province coast (China) before and after the passage of Typhoon Rammasun (2014), we determined the modern storm depositional dynamic process and its deposition characteristics. During Typhoon Rammasun, a storm deposit with thickness of 40–70 cm was formed in Wangcun Lagoon. The storm deposit gradually thickened from the entrance to the interior of the lagoon, and from the edge of the tidal channel to the tidal flat, and it showed an obvious three-layered structure. The lowest layer had finer grain size, higher total organic carbon (TOC) and C/N contents, and higher abundance of diatoms. The middle layer had coarser grain size, lower TOC and C/N contents, and lower abundance of diatoms, especially near the entrance and the tidal channel. The upper layer mainly existed in the interior of the lagoon, with finer grain size, higher TOC content, higher (lower) C/N contents in the tidal channel (tidal flat), and the second-highest diatom abundance. The fragmentation rate of diatoms was very high in all storm deposit layers. We believe the most likely explanation for the formation of such storm deposit layers is attributable to special storm dynamic processes that are influenced by tides and storm waves. The erosion maximum was reached when the hydrodynamic force was strongest, and then a fine-grained layer was formed during the sedimentary window that occurred as the hydrodynamic force of the ebb tide weakened. Later, part of the fine-grained matter was resuspended under the sub-strong dynamic environment of the subsequent flood tide. Finally, as the hydrodynamic force of the storm weakened further, two layers that were coarser at the bottom and finer at the top were formed. The numbers of storm sediment sequences depend on whether there are multiple sedimentary windows in which sediments can be retained. Storm deposits can be recorded continuously and completely in a lagoon, different from event sedimentary records, and they have specific sedimentological, geochemical, and microfossil characteristics.

The complete chloroplast genome and phylogenetic analysis of Cyperus malaccensis Lam (Cyperaceae)

Cyperus malaccensis Lam is a perennial herbaceous plant that is distributed over a large area along the southern coast of China. Some plants of the Cyperaceae family are highly similar morphologically, which makes them difficult to classify and identify. In this study, the complete chloroplast genome of C. malaccensis was sequenced and assembled. The chloroplast genome is 186,098 bp long with a 33.18% content of GC. The structure of chloroplast genome includes a quadripartite structure that is composed of a pair of inverted repeats (IRs) of 37,434 bp, a small single copy (SSC) region of 10,296 bp, and a large single copy (LSC) region of 100,934 bp. The genome contains 141 genes, including 94 protein-coding genes, 39 tRNA genes, and 8 rRNA genes. A phylogenetic analysis showed that C. malaccensis is the most closely related to the congeneric species C. rotundus. These results enrich the genetic resources of the Cyperaceae and provide a molecular basis for further study on the phylogeny of this family.

Vulnerability of the rip current phenomenon in marine environments using machine learning models

Hidden and perilous rip currents are one of the primary factors leading to drownings of beach swimmers. By identifying the coastal areas with the highest likelihood of generating rip currents, it becomes possible to prevent fatalities and mitigate economic losses associated with these hazardous currents. Rip currents are characterized as streams of water moving towards the open sea, forming within the area where waves break, due to variations in wave-induced radiation stresses and pressure along the coastline. This study utilized nine different Machine Learning (ML) models, including M5 Model Tree (MT), Multivariate Adaptive Regression Spline (MARS), Gene Expression Programming (GEP), Evolutionary Polynomial Regression (EPR), Random Forest (RF), Support Vector Machine (SVM), Extreme Gradient Boosting (XGBoost), Adaptive Boosting (AdaBoost), and Stacked ML models, to estimate the Relative Tide Range (RTR) values for 50 southern beaches in China. Through this approach, we gathered a reliable dataset from prior research conducted on the southern coast of China. In this study, two parameters, namely dimensionless fall velocity parameter (Ω) and tide range (TR) are used to predict the vulnerability of rip current event. The results of the AI models were assessed by various statistical analyses (Correlation of Coefficient [R], Root Mean Square Error [RMSE], violin diagram, heatmap, and taylor diagram) for training and testing stages. Accordingly, the MARS model exhibited superior performance compared to other AI models in accurately predicting the RTR value. The outcomes substantiated the significant effectiveness and capability in estimating the RTR with high accuracy. Southern China coasts have relative high risk level of rip current, necessitating the attention and strategic management of this dangerous current by the beach managers.

Seascapes Shaped the Local Adaptation and Population Structure of South China Coast Yellowfin Seabream (Acanthopagrus latus).

Understanding the genetic composition and regional adaptation of marine species under environmental heterogeneity and fishing pressure is crucial for responsible management. In order to understand the genetic diversity and adaptability of yellowfin seabream (Acanthopagrus latus) along southern China coast, this study was conducted a seascape genome analysis on yellowfin seabream from the ecologically diverse coast, spanning over 1600 km. A total of 92 yellowfin seabream individuals from 15 sites were performed whole-genome resequencing, and 4,383,564 high-quality single nucleotide polymorphisms (SNPs) were called. By conducting a genotype-environment association analysis, 29,951 adaptive and 4,328,299 neutral SNPs were identified. The yellowfin seabream exhibited two distinct population structures, despite high gene flow between sites. The seascape genome analysis revealed that genetic structure was influenced by a variety of factors including salinity gradients, habitat distance, and ocean currents. The frequency of allelic variation at the candidate loci changed with the salinity gradient. Annotation of these loci revealed that most of the genes are associated with osmoregulation, such as kcnab2a, kcnk5a, and slc47a1. These genes are significantly enriched in pathways associated with ion transport including G protein-coupled receptor activity, transmembrane signaling receptor activity, and transporter activity. Overall, our findings provide insights into how seascape heterogeneity affects adaptive evolution, while providing important information for regional management in yellowfin seabream populations.

Detection of large-scale Spartina alterniflora removal in coastal wetlands based on Sentinel-2 and Landsat 8 imagery on Google Earth Engine

The invasion of Spartina alterniflora has posed significant threats to the ecosystem health and biodiversity in coastal wetlands in China. In recent years, China has enacted large-scale S. alterniflora removal projects. Accurate monitoring of the S. alterniflora removal dynamics is crucial for evaluating the effectiveness of the removal projects and coastal wetland management. In this study, we presented a novel method for automatic and rapid detection of S. alterniflora removal events and removal timing at large scale based on time series Sentinel-2 and Landsat 8 imagery on Google Earth Engine. The method first detected and reconstructed the tidal-inundation-related Normalized Difference Vegetation Index (NDVI) using a newly proposed Tide Gap Filling algorithm, aiming to alleviate the impact of tidal inundation on S. alterniflora removal detection; then, the potential removal period were extracted based on the reconstructed NDVI time series; finally, the removal event and the corresponding removal timing were identified and mapped within the potential removal period by considering the phenological characteristics of the undisturbed S. alterniflora. We took the Shandong Province in northern coastal China and Fujian Province in southern coastal China as our study areas, where large-scale S. alterniflora removal projects were carried out in 2021 and 2022, respectively. Accuracy assessment based on field surveys and high-spatial-resolution PlanetScope imagery showed that the method achieved good accuracies for removal detection, with overall accuracies of 88.89 % for Shandong and 81.33 % for Fujian, respectively. The mean absolute error day (MAED) between the detected removal timing and the reference removal timing was 6.77 days in Shandong and 13.75 days in Fujian. Both provinces have successfully implemented the S. alterniflora removal projects. In Shandong, 82.32 % (7,243.94 ha) of S. alterniflora were removed during July to December in 2021; in Fujian, 88.81 % (6,649.21 ha) of S. alterniflora were removed during July to December in 2022. We expect that the method has great potential to be applied at national scale to provide baseline data for coastal wetland restoration and management.

Applying an ensemble of small models in predicting habitat suitability of invasive M. sallei along the southern coast of China

A false mussel Mytilopsis sallei has caused serious ecological and economic losses after invading in China. In this research, we first assessed the niche differentiation between its native range and invasive range in China and then predicted the habitat suitability along the southern coast of China under present and future climatic circumstances. Distance to shore and water depth were the first two important factors in affecting the distribution of M. sallei, followed by minimum chlorophyll concentration and salinity. The niche of M. sallei shows significant expansion and unfilling. The ensemble of small models can account for few occurrences and presents high predictive performance. A general reduction and northward movement of suitable areas were found in the southern coast of China in the future. This study furnished significant insights regarding the areas under invasive risks, and provided valuable information for preventing the further invasion of M. sallei in China.

Phylogenetics and Population Genetics of the Petrolisthes lamarckii-P. haswelli Complex in China: Old Lineage and New Species.

Petrolisthes lamarckii (Leach, 1821) and P. haswelli Miers, 1884 are a pair of sister species of porcelain crabs, both of which are common in the intertidal zone of southern China, typically found under rocks and in the crevices of coral reefs. However, the distribution, genetic relationship and diversity of the two species in China have not been rigorously studied. Meanwhile, P. lamarckii is considered as a complex of cryptic species due to their diverse morphological features. In this study, we identified 127 specimens of the P. lamarckii-P. haswelli complex (LH complex) and recognised a new species through morphological and molecular analysis. Furthermore, we constructed a time-calibrated phylogeny of the LH complex using three mitochondrial and two nuclear genes from all three species, finding that the divergence of the LH complex can be traced back to the Miocene epoch, and that the genetic diversity increased during the Mid-Pleistocene transition period. Glacial refugia formed during the Pleistocene climatic oscillations has been regarded as one of the contributing factors to the diversification of marine organisms in the north-western Pacific. Petrolisthes haswelli demonstrates a wide distribution along the southern coast of China, while other lineages display more restricted distributions. The research on the demographic history and gene flow of P. haswelli revealed that the Chinese coastal populations experienced an expansion event approximately 12.5 thousand years ago (Kya) and the asymmetrical gene flows were observed between the two sides of the Taiwan Strait and Qiongzhou Strait, respectively, which is likely influenced by the restriction of ocean currents.

Chemometric analysis of fish fin ray multi-elemental signatures with differentiation of wild and farmed fourfinger threadfin fish

Fourfinger threadfin (Eleutheronema tetradactylum) are the commercially important fish along the southern coast of China. The economic value of wild E. tetradactylum was much higher than their farmed counterparts, therefore mislabeling of production methods may lead to premium prices. In the present study, multi-element signatures of fin ray were used to determine the wild caught and pond-cultured E. tetradactylum from southern coast of China. The elemental composition of fish calcified structures was related to the ambient water environment, and could record the water chemistry difference between the aquaculture pond and the natural seawater. Our results demonstrated that multi-element compositions of fish fin rays were significantly different between the wild and cultured fish. Linear discriminant analysis (LDA) and random forest (RF) model correctly discriminated the wild and cultured E. tetradactylum. The classification accuracies of wild and cultured E. tetradactylum were 100% by LDA. The classification accuracies of identifying the source of cultured E. tetradactylum were 95%. However, the fin ray elemental signatures could not differentiate the different wild groups. This strategy provides a promising alternative method to protect against mislabeling of E. tetradactylum.

Cytosolic distribution of copper in the gills of field-collected oysters with different copper bioaccumulation

Oysters can hyper-accumulate copper (Cu) without apparent toxicity, but the mechanism of sequestering excessive cytosolic Cu in oysters remains unclear. We here investigated the Cu distribution in the cytosolic proteins (CPs) in the gills of oysters (Crassostrea hongkongensis) through size-exclusion chromatography coupled to inductively coupled plasma mass spectrometry (SEC-ICP-MS). Oysters collected from the southern coast of China contained a gradient of gill Cu concentrations ranging from 132 to 3540 μg g−1 (dry weight), with 7–41 % of Cu distributed in the CPs fraction. The CPs-Cu concentrations were 8.6 times higher in oysters with high Cu concentrations compared to low concentrations. In the CPs, Cu was dispersed with a broad range of molecular weight, suggesting the involvement of various cytosolic proteins in Cu binding. Among the 10 major Cu peaks, peaks 2 (>600 kDa) and peak 8 (18 kDa) contained substantial Cu and showed obvious differences in response to the variation of CPs-Cu levels. Peak 8 contained metallothionein-like proteins that decreased their role in Cu binding as CPs-Cu concentrations increased. LC-MS/MS analysis revealed that peak 2 contained macromolecular protein complexes (MPCs), which played a critical role in binding excess Cu. The comparison with other bivalve species further suggested that sequestering excess CPs-Cu in MPCs was a special strategy employed by oysters in response to high Cu accumulation. This study provides valuable insights into the mechanism of hyper-accumulation and sequestration of Cu in oysters and helps to better understand Cu biomonitoring by oysters.

Energy System Low-Carbon Transition under Dual-Carbon Goals: The Case of Guangxi, China Using the EnergyPLAN Tool

Guangxi is a typical developing region on the southern coast of China. The current issues encountered in the region’s development are that fossil energy accounts for about 80% of the energy structure, fossil fuels are heavily dependent on imports, and the self-sufficiency rate of resources is only 32%. These challenges have created a disparity between the current regional development state and the country’s dual carbon target. Under the premise of comprehensively considering the multi-sectors of electricity, industry, transportation, and heating, this paper presents a study on the energy system transition towards low-carbon development for Guangxi in four steps. Firstly, to demonstrate EnergyPLAN’s capability in energy modeling, a reference scenario for Guangxi is created using official yearbook data from 2020. Then, a short-term scenario is formulated to analyze the development of Guangxi’s energy system during the 14th Five-Year Plan. Furthermore, two mid-term scenarios are established, revealing that Guangxi is anticipated to reach its carbon emission peak between 2025 and 2030. Finally, three long-term scenarios are proposed for Guangxi’s energy system for 2050. These scenarios encompass the expansion of photovoltaics, nuclear, and wind power in the electricity system and emission reduction policies in the industrial, transportation, and heating sectors. As a result, compared with the 2020REF scenario, Guangxi can achieve a carbon emission reduction exceeding 57% and the share of non-fossil energy consumption can reach about 70% in the 2050 scenarios, despite a substantial increase in energy consumption, which makes it possible to achieve carbon neutrality in 2060 and to establish an energy system with less than 20% of fossil energy consumption.

Population distribution, connectivity and differentiation of Indo‐Pacific humpback dolphins in Chinese waters: Key baselines for improving conservation management

Abstract Humpback dolphins (Sousa spp.), throughout their distribution ranges, are often designated as flagship species for coastal ecosystem conservation. Most of the early research on humpback dolphins was carried out in Chinese waters, and in the last two decades, numerous studies have provided abundant conservation‐valuable findings. In this study, a systematic review was conducted to gain a comprehensive understanding of the distributional ecology of humpback dolphins in Chinese waters, to establish an updated national knowledge base about key conservation baselines on this flagship species. Currently, there are at least eight main distribution areas of humpback dolphins along the coast of southern China, representing a clear picture of place‐based conservation units. However, the overall biogeographical distribution pattern is discontinuous, and existing marine protected areas are far from sufficient to protect these key areas for the survival of humpback dolphins. Based on the photo‐identification technique, cross‐matching of humpback dolphin individuals revealed extremely low inter‐population connectivity among most of the known populations. Genetic studies suggested that several examined populations have low haplotype diversity levels, with limited inter‐population gene flow. Morphological and behavioural evidence also supports population differentiation among geographical locations. These findings provide key baselines for the promotion of conservation management initiatives for humpback dolphins in Chinese waters. All recognizable geographical populations, together with each key habitat, should be considered as independent conservation units. With small distribution areas, low genetic diversity and unfavourable geographical isolation, several populations may be at a high risk of regional extinction. A country‐led scheme with cross‐regional collaboration is required for science‐based, action‐focused and timely conservation efforts. Future conservation management initiatives should aim to increase or at least maintain key habitats, inter‐population connectivity, population‐level genetic diversity and effective population size.