Coastal Areas Of China Research Articles

Rapid Damage Prediction and Risk Assessment for Tropical Cyclones at a Fine Grid in Guangdong Province, South China

Rapid damage prediction for wind disasters is significant in emergency response and disaster mitigation, although it faces many challenges. In this study, a 1-km grid of wind speeds was simulated by the Holland model using the 6-h interval records of maximum wind speed (MWS) for tropical cyclones (TC) from 1949 to 2020 in South China. The MWS during a TC transit was used to build damage rate curves for affected population and direct economic losses. The results show that the Holland model can efficiently simulate the grid-level MWS, which is comparable to the ground observations with R2 of 0.71 to 0.93 and mean absolute errors (MAEs) of 3.3 to 7.5 m/s. The estimated damage rates were in good agreement with the reported values with R2 = 0.69–0.87 for affected population and R2 = 0.65–0.84 for GDP loss. The coastal areas and the Guangdong-Hong Kong-Macao Greater Bay Area have the greatest risk of wind disasters, mainly due to the region’s high density of population and developed economy. Our proposed method is suitable for rapid damage prediction and supporting emergency response and risk assessment at the community level for TCs in the coastal areas of China.

Spatio-temporal distribution, composition and influencing factors of economic losses from storm surge disasters: An empirical study from China (2007–2016)

Storm surge disasters (SSD) have caused severe damage to China's coastal areas, and they have become an essential influencing factor for the social and economic development of China. This study uses an input-output model to assess the storm surge economic losses in 11 coastal regions of China for the period of 2007–2016, and also explores its influencing factors. The results show that: (1) From 2007 to 2016, the southeastern coastal areas were the most severely impacted by SSD, the Total Economic Losses (TEL) reached 742.8 billion CNY. Among them, Guangdong, Fujian and Zhejiang Provinces suffered the worst economic losses, with 81.3% contribution to TEL; (2) The Indirect Economic Losses (IEL) from SSD accounted for a total percentage of 74%–96%, and the TEL have not decreased over the years; (3) SSD have seriously impacted the Chinese manufacturing industry, accounting for an average of 50% of the TEL per year; (4) Different regions had different sectoral distributions of IEL, while the manufacturing and service industries were still the most affected sectors; (5) The more frequent the occurrence of SSD, the greater the losses caused by SSD, with no such correlation observed for the intensity of SSD; (6) The aggregation of marine industries and populations can significantly increase the damage from SSD, while the development of science and technology can reduce the damage from SSD. Overall, this study evaluates China's SSD economic losses on a long-term scale, which is of great significance for future disaster prevention and mitigation.

Carbon sink potential and environmental benefits of seaweed: A case study of the seaweed cultivation industry on China coast

Initiatives to mitigate climate change have recently aroused great interest in the role of natural carbon sinks in coastal ecosystems. Seaweeds are widely distributed in the world and represent a large biomass. Since they are part of the global carbon reserves, they remove carbon dioxide and influence climate change. Using the recent 20 years of seaweed mariculture in China's coastal areas as a case, this paper quantifies the carbon storage in cultivated seaweed biomass, and evaluates the carbon sink potential, the remediation ability of nitrogen and phosphorus and other environmental benefits. The carbon sink potential of cultivated seaweeds exhibits a rising trend from 2000 to 2019. The total carbon, nitrogen, and phosphorus removal amount of seaweed were 3,551,754.9 ± 177,587.75, 297,772.25 ± 14,888.61, 39,967.15 ± 1998.36 tons according to the seaweed cultivation yield in China coast. The total benefit of carbon sequestration was 22,405.67 ± 259.59 million CNY, and the average benefit was 1120.28 ± 263.27 million CNY, with the average annual growth rate of 4.00%. The total environmental benefit was 1,962,020.88 ± 22,747.42 million CNY, and the average benefit was 98,103.04 ± 23,073.08 million CNY, with the average annual growth rate of 4.00%. The present study illustrates distinctly the ecological value of large-scale cultivated seaweeds in increasing marine carbon sequestration and resolving offshore environmental issues, which is an efficient approach and comparable to other key marine ecosystems. Based on the carbon sink role of seaweed mariculture, and with the goal of global carbon neutrality, more attention should be paid to the carbon sink capacity of large-scale seaweed cultivation industry and be vigorously developed worldwide.

Air pollution and stroke hospitalization in the Beibu Gulf Region of China: A case-crossover analysis

BackgroundThe relationship between air pollution and stroke has been extensively studied, however, the evidence regarding the association between air pollution and hospitalization due to stroke and its subtypes in coastal areas of China is limited. ObjectiveTo estimate the associations between air pollution and hospitalizations of stroke and its subtypes in the Beibu Gulf Region of China. MethodsWe conducted a time-stratified case-crossover study in 15 cities in Beibu Gulf Region in China from 2013 to 2016. Exposures to PM1, PM2.5, PM10, SO2, NO2, O3, and CO on the case and control days were assessed at residential addresses using bilinear interpolation. Conditional logistic regressions were constructed to estimate city-specific associations adjusting for meteorological factors and public holidays. Meta-analysis was further conducted to pool all city-level estimates. ResultsThere were 271,394 case days and 922,305 control days. The odds ratios (ORs) for stroke hospitalizations associated with each interquartile range (IQR) increase in 2-day averages of SO2 (IQR: 10.8 µg/m3), NO2 (IQR: 11.2 µg/m3), and PM10 (IQR: 37 µg/m3) were 1.047 (95 % CI [confidence interval]: 1.015–1.080), 1.040 (95 % CI: 1.027–1.053), and 1.018 (95 % CI: 1.004–1.033), respectively. The associations with hospitalizations of ischemic stroke were significant for all seven pollutants, while the association with hemorrhagic stroke was significant only for CO. The associations of SO2, NO2, and O3 with stroke hospitalization were significantly stronger in the cool season. ConclusionsShort-term increase in SO2, NO2, and PM10 might be important triggers of stroke hospitalization. All seven air pollutants were associated with ischemic stroke hospitalization, while only CO was associated with hemorrhagic stroke hospitalization. These results should be considered in public health policy.

Spatial evolution of water transportation industry based on multi-source data: understanding the structural consolidation and integration demand in coastal cities

Under the sustainability goals, how to promote the integration of port resources and reduce the ecological risks is important for the water transportation industry. Port cities in Jiangsu Province, a major coastal area in China, face a huge risk of resource waste. This paper aims to take Jiangsu as an example, understand the evolution of the spatial structure and the evolution of the water transportation industry, and explore the factors affecting development from the perspective of low-carbon development. Based on ArcGIS and multi-source data, methods such as Standard Deviation Ellipse (SDE) were used to understand the evolution, and the factors influencing the evolution at different stages were explored based on the green total factors such as industrial pollutions. It shows that the scale of the water transportation is expanding, but the industrial upgrading is not realized and has multiple agglomeration cores. The evolution was initially more affected by non-interventional factors such as geographical environment, while later the influence weakened significantly. The disordered development of water transportation industry has been worsening the current inefficient industrial structure and environmental risks. Further integration of industrial structure is needed, and strong administrative means are needed to help tap the unrealized spatial potential of resource integration.

Spatio-temporal distribution of harmful algal blooms and their correlations with marine hydrological elements in offshore areas, China

Harmful algal blooms (HABs) occur frequently in Chinese coastal areas, causing major economic losses and seriously threatening coastal marine environments. HAB research using remote sensing technology focuses on detecting and monitoring HABs. However, no study has explored the occurrence of HABs in response to hydrological factors based on remote sensing. This study used 30 years (1990–2019) of data to analyze the spatial and temporal characteristics of Chinese coastal HABs. The development and change trends of marine hydrological factors (sea surface salinity (SSS), sea surface temperature (SST), and chlorophyll (Chl) concentration) during the occurrence and disappearance of HABs were clarified, and correlations between marine hydrological parameters and HABs were described (Ahn and Shanmugam, 2006). From 1990 to 2019, 1,557 HABs occurred in coastal areas of China, and 961 HABs occurred from 2001 to 2012, accounting for 62.00% of the total. From 1998 to 2019, the total of 1393 HABs occurred, and 813, 249, 198 and 133 HABs occurred in the East China Sea, South China Sea, Bohai Sea, and Yellow Sea, respectively. From 2009 to 2019, the total of 612 HABs occurred, and 536 HABs occurred from April to September, accounting for 87.58% (Anderson et al., 2021). Spatially, kernel density estimation showed that most HABs were concentrated in the Bohai Bay and Yangtze and Pearl River deltas (Bao and Ren, 2014). During HABs, SST increased by 0.72–6.41 °C, Chl increased by 11.00–95.36 mg × m−3, and SSS decreased by 0.10–4.34 PSU. When HABs disappeared, SST decreased by 1.14–6.01 °C, Chl decreased by 4.50–96.46 mg × m−3, and SSS increased by 0.08–3.431 PSU. The SSS of a HAB year was relatively low, while the Chl was relatively high. SST between 8.00 °C and 28.00 °C induced HABs. The research illustrates the spatiotemporal characteristics of HABs in coastal areas of China and their sensitivity to marine hydrological factors. These findings are of great importance in regard to the impacts on human health and ecological damage caused by HABs.

East Asian monsoon manipulates the richness and taxonomic composition of airborne bacteria over China coastal area

Airborne bacteria may have significant impacts on aerosol properties, public health and ecosystem depending on their taxonomic composition and transport. This study investigated the seasonal and spatial variations of bacterial composition and richness over the east coast of China and the roles of East Asian monsoon played through synchronous sampling and 16S rRNA sequencing analysis of airborne bacteria at Huaniao island of the East China Sea (ECS) and the urban and rural sites of Shanghai. Airborne bacteria showed higher richness over the land sites than Huaniao island with the highest values found in the urban and rural springs associated with the growing plants. For the island, the maximal richness occurred in winter as the result of prevailing terrestrial winds controlled by East Asian winter monsoon. Proteobacteria, Actinobacteria and Cyanobacteria were found to be top three phyla, together accounting for 75 % of total airborne bacteria. Radiation-resistant Deinococcus, Methylobacterium belonging to Rhizobiales (related to vegetation) and Mastigocladopsis_PCC_10914 originating from marine ecosystem were indicator genera for urban, rural and island sites, respectively. The Bray-Curits dissimilarity of taxonomic composition between the island and two land sites was the lowest in winter with the representative genera over island also typically from the soil. Our results reveal that seasonal change of monsoon wind directions evidently affects the richness and taxonomic composition of airborne bacteria in China coastal area. Particularly, prevailing terrestrial winds lead to the dominance of land-derived bacteria over the coastal ECS which may have a potential impact on marine ecosystem.

Sublethal effects on the hard clam Mercenaria mercenaria after exposure to Aureococcus anophagefferens Chinese strain isolates

Brown tides caused by Aureococcus anophagefferens occur frequently worldwide and have contributed to the collapse of Mercenaria mercenaria farming in the United States. This economically valuable hard clam has been used in China for more than 20 years. To date, it has remained unknown whether A. anophagefferens Chinese strain has an impact on hard clam cultivation in the coastal areas of China or other sea areas worldwide if it enters through ship ballast water and other ways. In this study, a Chinese strain of A. anophagefferens isolated from the brown tide waters of Bohai Bay, China, was selected to explore its influence on the feedback of hard clams. After being fed with A. anophagefferens, hard clams showed characteristics similar to starvation. The reduced feeding efficiency of hard clams leads to reduced energy intake. However, the immune response and oxidative stress, result in increased energy consumption. An imbalance in the energy budget may be an important reason for hard clam starvation. This study has described the response characteristics of the A. anophagefferens Chinese strain to M. mercenaria, explored the reasons for the negative impact of A. anophagefferens on hard clams, and provides ideas for reducing shellfish aquaculture caused by brown tides.

Effects of UVR on Photosynthesis in Sargassum horneri (Turner) C. Agardh Adapted to Different Nitrogen Levels

In recent years, golden tides caused by drifting Sargassum horneri (Turner) C. Agardh have caused serious ecological disasters in coastal areas of China. Eutrophication is an important cause of the formation of the golden tide. Additionally, the drifting population on the surface of the ocean is exposed to more ultraviolet radiation (UVR) than the attached population on the sea floor. In this study, the thalli of S. horneri were cultivated under two levels of nitrogen (LN: natural seawater, in which the concentration of NO3−-N was 1 µmol L−1; HN: NO3−-enriched seawater, in which the concentration of NO3−-N was 200 μmol L−1) for 6 days with low photosynthetically active radiation (PAR), and then exposed to three levels of radiation (P: photosynthetically active radiation (PAR), 400–700 nm; PA: PAR + UVA, 320–700 nm; PAB: PAR + UVA + UVB, 280–700 nm) under each level of nitrogen for 2 h to investigate the effects of high UVR and nitrogen on photosynthesis. The results showed that the high level of N (HN) only enhanced the synthesis of pigments after 6 days of pre-cultivation under low PAR. After 2 h of high UVR exposure, high P, PA, and PB decreased the maximum photochemical quantum yield (Fv/Fm) and increased non-photochemical quenching (NPQ) in S. horneri regardless of the N level, and PAB significantly decreased Fv/Fm compared to PA under the LN condition alone. Under the LN condition, compared to the P group, PA and PAB significantly promoted the synthesis of carotenoids. Under the HN condition, compared to the P group, PAB increased the absorbed flux by active RCs (ABS/RC) and dissipated the energy flux by active RCs (DI0/RC) in S. horneri alone. Furthermore, HN increased Fv/Fm, ABS/RC, and DI0/RC more in S. horneri with PAB in comparison to those in the LN and PAB group. However, no significant differences in these parameters were observed between the LN and HN conditions under the same UVR treatments. These results demonstrate that drifting S. horneri on the surface of seawater could be inhibited by the high P; however, S. horneri living in eutrophic high-nitrogen seawater may have a stronger ability to resist high UVR damage, especially with regard to PAB radiation, which may be one of the reasons for the formation of golden tides in coastal seawater.

Effects of tropical cyclones with different tracks on ozone pollution over the Pearl River Delta region

Tropical cyclone's activities can affect the ozone pollution characteristics to a certain extent over the Pearl River Delta (PRD) region based on different track types of tropical cyclones. In this study, we utilize the Finite Mixture Model algorithm to classify tropical cyclones which land on the South China coastal area between 2009 and 2018 into 6 track's types, and those types are land on the PRD region directly (A1 type), the east of the PRD region (B1 and B2 types) and the west of the PRD region (C1, C2 and C3 types) respectively. Combined with observation data, the results indicate that the A1 type, B1 type and B2 type tropical cyclones can increase the ozone concentration about 44.9% ∼ 65.3% in the PRD region before landfall accompanied with stagnant meteorological conditions usually, such as high temperature (>27 °C), low humidity (<80%) or weak wind (<3 m/s). And it should be emphasized that, due to the northward or northeastward deflection of the tracks, the ozone concentration in the PRD region does not decrease obviously (<10%) on the landing-day under B1 and B2 types, and ozone pollution maybe persistent longer than other types. By simulating typical cases of each track's type within WRF-Chem model coupled with process analysis method, and the results indicate that tropical cyclone's peripheral subsidence airflow is more obvious over the PRD region under A1, B1 and B2 cases before landfall, and it maybe an external condition which can limit the development of boundary layer and vertical diffusion of ozone, rather than transporting ozone downward from the upper atmosphere to the near surface level. In addition, based on process analysis result, the chemical reaction with strong radiation condition maybe the essential cause of ozone production and pollution, and the physical process can cause the ozone consumption.

Construction and influencing factors of an early warning system for marine ranching ecological security: Experience from China's coastal areas

Marine ranching has been widely considered as a new mode of marine fishery production. Marine ranching ecological security (MRES) is the basis and premise to ensure the sustainable utilization of marine ranching functions. In this study, an MRES early warning system was constructed based on comprehensive marine ranching ecological security index (CMRESI) and system dynamic model to reveal the main factors affecting the development of marine ranching and explore the changes in MRES under different future development scenarios in China's coastal areas from 2011 to 2035. The results showed that (1) the mean CMRESI of China was only 0.3265 and spatial heterogeneity was significant, showing a general security state; (2) coupling and coordination degree of MRES subsystems was high in Jiangsu, Fujian, Shandong, and Guangdong, and resources was a major constraint on the coordinated development of MRES in the study area (63.6%); (3) Under the ecological priority development scenario, the CMRESI will be the highest in 2035; however, 27% of MRES (in Jiangsu, Fujian, and Hainan) will continue to issue serious early warnings. This study could provide a reference for construction planning, management maintenance, and decision-making of marine ranching.

Risk evolution and prevention and control strategies of maritime accidents in China's coastal areas based on complex network models

The increasingly busy maritime traffic system has resulted in frequent maritime accidents. To prevent maritime accidents, we investigated and studied typical cases of maritime accidents along the coast of China in recent years. Based on the complex network theory, a network model of China's coastal maritime traffic accidents is constructed from the four risk factors of human-ship-environmental-management. On this basis, the overall structural characteristics of the maritime accident network are analyzed according to the characteristic parameters of the complex network. In addition, based on the node betweenness and PageRank value, the network robustness analysis is carried out, the key factors in the maritime accidents are excavated and risk prevention and control measures are proposed. The research shows that the average path length of the marine traffic accident network is short, the clustering coefficient is high, and the risk spreads quickly in the network and passes through fewer nodes, which can lead to the occurrence of accidents. Through the management and control of key risk factors, the evolution of risks can be effectively blocked and the large and above maritime accidents can be reduced.

Comparison and Analysis of Detection Methods for Typhoon-Storm Surges Based on Tide-Gauge Data-Taking Coasts of China as Examples.

Global warming is predicted to lead to a new geographic and spatial distribution of storm-surge events and an increase in their activity intensity. Therefore, it is necessary to detect storm-surge events in order to reveal temporal and spatial variations in their activity intensity. This study attempted to detect storm-surge events from the perspective of detecting outliers. Four common outlier-detection methods, the Pauta criterion (PC), Chauvenet criterion (CC), Pareto distribution (PD) and kurtosis coefficient (KC), were used to detect the storm-surge events from the hourly residual water level data of 14 tide gauges along the coasts of China. This paper evaluates the comprehensive ability of the four methods to detect storm-surge events by combining historical typhoon-storm-surge events and deep-learning target-detection-evaluation indicators. The results indicate that (1) all of the four methods are feasible for detecting storm surge events; (2) the PC has the highest comprehensive detection ability for storm-surge events (F1 = 0.66), making it the most suitable for typhoon-storm-surge detection in coastal areas of China; the CC has the highest detection accuracy for typhoon-storm-surge events (precision = 0.89), although the recall of the CC is the lowest (recall = 0.42), as only severe storm surges were detected. This paper therefore evaluates four storm-surge-detection methods in coastal areas of China and provides a basis for the evaluation of storm-surge-detection methods and detection algorithms.

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.

Sounds of snapping shrimp (Alpheidae) as important input to the soundscape in the southeast China coastal sea

As a biological sound source widely distributed in temperate and tropical coastal waters, snapping shrimp produce strong pulses which can serve as honest signals to indicate habitat-specific soundscape. The past decade has witnessed the growing interest in investigating the acoustical activity of snapping shrimp across many shallow waters including the coastal line of the west Pacific Ocean. It was extended to the Southeast China coastal area where snapping sounds and the associated soundscape were recorded at four sites. Customized codes incorporating bandwidth and amplitude threshold operations were developed to detect snaps from the ambient noise to estimate snap rate and extract snaps individually. The subsequent analysis suggested that snaps recorded at different sites were unanimously stronger than background noise. Sound pressure level of the snaps ranged from 150 dB to 190 dB (re 1 μPa). The characteristics of snaps, including sound pressure level, duration, peak frequency, -3dB bandwidth from different sites are examined to evaluate the variability across the sites. Though snapping pulses had peak frequencies and the -3 dB bandwidth consistently below 10 kHz, snaps had considerable energy extending to the high frequency range over 200 kHz. The analysis of the acoustic data received for 7 consecutive days at one site indicated that the snap rate corresponded to tidal level periodicity. A high tide was accompanied with a local high snap rate regardless of light but this local snap rate peak was much higher at night. The mean rate fluctuated between 2000 and 4000 snaps per minute and more snaps were recorded after sunset suggesting that snapping shrimp living in the area snapped in response to light. These data may indicate that snaps are important communication means in light-limited condition and deepen our understanding on the correlation of snapping behavior and ecological environments.

Epidemiological Characteristics and Spatiotemporal Distribution Patterns of Human Norovirus Outbreaks in China, 2012–2018

ObjectiveTo clarify the epidemiological characteristics and spatial distribution patterns of human norovirus outbreaks in China, identify high-risk areas, and provide guidance for epidemic prevention and control. MethodsThis study analyzed 964 human norovirus outbreaks involving 50,548 cases in 26 provinces reported from 2012 to 2018. Epidemiological analysis and spatiotemporal scanning analysis were conducted to analyze the distribution of norovirus outbreaks in China. ResultsThe outbreaks showed typical seasonality, with more outbreaks in winter and fewer in summer, and the total number of infected cases increased over time. Schools, especially middle schools and primary schools, are the most common settings of norovirus outbreaks, with the major transmission route being life contact. More outbreaks occurred in southeast coastal areas in China and showed significant spatial aggregation. The highly clustered areas of norovirus outbreaks have expanded northeast over time. ConclusionBy identifying the epidemiological characteristics and high-risk areas of norovirus outbreaks, this study provides important scientific support for the development of preventive and control measures for norovirus outbreaks, which is conducive to the administrative management of high-risk settings and reduction of disease burden in susceptible areas.

Warning water level determination and its spatial distribution in coastal areas of China

Abstract. The warning water level is the default water level at which storm surges may occur along a coast and indicates a stage of alert. This level forms the basis for storm-surge forecasting, and prewarning is an important reference for governments and aids in the decision-making process for storm-surge prevention and disaster risk mitigation. The warning water level has four categories (blue, yellow, orange, and red) based on water level observational data. Taking into account the actual defense capability of the shore, we determined the warning water level by comprehensively analyzing factors, including the high water level at the typical return period of each shore section, wave exposure degree and defense capability of storm-surge protection facilities, and the shore-section importance level. Here, we proposed a quantitative method for determining the warning water level, and the application of this method was introduced by determining the warning water level at the shore section of Zhifu District (Yantai City, Shandong Province, China) as an example. We analyzed the spatial distribution characteristics of the warning water levels for 259 shore sections along the coast and revealed their current marine disaster prevention capabilities. Our findings provide a valid direction for determining future warning water levels and a reliable scientific reference for redetermining warning water levels in coastal areas while improving marine disaster prevention and protection capabilities.

Chromaticity characteristics of soil profiles in the coastal areas of Fujian and Guangdong, southern China and their climatic significance

In recent years, there has been an increasing interest in the use of soil color as a climatic proxy. We investigated the variation of soil chromaticity parameters in subtropical and tropical coastal areas in China and their relationships with climatic factors (mean annual precipitation and temperature). Latitudinal zonal soil profiles in the coastal areas of Fujian and Guangdong were selected for study, and chromaticity analysis of soil samples was performed using the CIELAB color system. The principal results are as follows: (1) Soil color in the coastal areas of Fujian and Guangdong is mainly controlled by hematite and goethite. Redness (a∗) varies significantly with depth within the soil profiles, and two types of profile can be defined: type I in which a∗ decreases with increasing depth within the profile, and type II in which a∗ increases with increasing depth within the profile. (2) Overall, a∗, b∗ (yellowness) and the b∗/a∗ ratio do not show a significant relationship with latitude. The a∗ of some of the Fujian profiles and the Guangdong soil profiles are significantly negatively correlated with the MAP, the b∗/a∗ of some of the Fujian is highly positively correlated with MAP. A precipitation threshold may exist for both sets of profiles. There is a high correlation coefficient between b∗/a∗ and MAT, and a temperature threshold of ∼23 °C is evident. b∗/a∗ is correlated with MAP and MAT, and it can potentially be used as a climate proxy.

Gonad transcriptome analysis reveals the differences in gene expression related to sex-biased and reproduction of clam Cyclina sinensis

Sexual differentiation and gonad development are important biological processes for bivalve species. The clam Cyclina sinensis is an important cultured marine bivalve widely distributed along with the coastal areas of China. However, the information related to sexual determination/differentiation and gonadal development of C. sinensis almost has no reported. To study the molecular mechanisms of its sexual determination/differentiation and gonadal development, transcriptome analysis was performed in the gonad of C. sinensis, and the potential biological functions of reproduction-related gene were also investigated in this study. The results showed that 1 013 and 427 genes were differentially expressed in the ovary and testis, respectively. KEGG enrichment analysis showed that the DEGs in the gonad were significantly clustered in progesterone-mediated oocyte maturation, cell cycle and oocyte meiosis. Further analysis showed that 23 genes were mainly involved in sex determination/differentiation, including Dmrt1, Sox2/4/9, Foxl2, β-catenin and GATA-type zinc finger protein 1-like. Twenty key genes were mainly involved in the process of spermatogenesis, and five genes encode steroid biosynthesis and metabolism. Fifteen genes related to ovarian development were also identified in this study, such as Vitellogenin, MAM and LDL-receptor class A domain-containing protein 1 and Cell division cycle protein 20 homolog. Moreover, 50µg/L estradiol treatment significantly up-regulated the expression levels of CsVg in the ovary and hepatopancreas. These results highlight the genes involved in sexual determination/differentiation and gonadal development, which enhance our understanding for further studies of reproduction and breeding of C. sinensis and other marine bivalves.

The Clustering Characteristics and Driving Mechanisms of Tourist Preference for 5A Scenic Spots from the Dynamic Spatio-Temporal Perspective: A Case of Jiangsu in Eastern Coastal Area of China

In the era of tourism 4.0, the subjective preferences and experiences of tourists directly affects the future development of scenic spots. Among them, 5A scenic spots represent China’s world-class boutique tourist scenic ranking, which pays more attention to humanization and detailing, and better reflect tourists’ general psychological demand for tourist attractions. Therefore, it becomes an important scientific issue to explore the spatial and temporal characteristics of 5A tourists’ preferences and their deeper reasons. China’s eastern coastal provinces have played a very important role in promoting regional tourism culture, promoting regional economic development, and building a strong coastal province. Taking Jiangsu as an example, this study introduces the standard deviation ellipse and kernel density estimation to explore the characteristics and trends of tourist preference clustering in 5A scenic spots and their internal and external driving mechanisms from 2012–2021, which is based on a new perspective of geotemporal dynamic analysis. The empirical results show that: (1) the network attention of 5A scenic spots in Jiangsu generally showed a “barb-type” trend in 2012–2021, the highest network attention is concentrated in April and October, accounting for 82%, and tourists pay the most attention to cultural relics scenic spots, peaking on Sunday; (2) the tourist preference for 5A scenic spots in Jiangsu shows a relative clustering distribution pattern in general, with a slightly higher clustering trend in the northwest-southeast direction than in the northeast-southwest direction. Furthermore, the nucleus of the density values range from 0 to 115.43, showing the spatial pattern of “one belt and two cores”; (3) the internal driving factors include the types, the culture nature, the characteristics nature, the spatial proximity, and the infrastructure of scenic spots, and the external driving factors include geographical location, industrial development policy, climate comfort, economic development level, traffic accessibility, and the impact of COVID-19 epidemic. On this basis, this study puts forward feasible suggestions for improving scenic area management and increasing the reception capacity, so as to provide fine scientific guidelines for the high-quality development of 5A scenic spots in Jiangsu and provide reference for further enhancing the attractiveness of 5A scenic spots and their synergistic development in the eastern coastal provinces.