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Species genetic diversity can reflect their adaptability to environmental changes. Coral reefs worldwide are in rapid decline due to climate change and human activities, highlighting the need for conservation intervention. The South China Sea (SCS) is an important biodiversity hotspot, particularly in the Xisha Islands (XS) that contain the majority of coral species in the SCS. However, few studies exist on coral genetic diversity in the SCS. Montipora digitata is the dominant reef-building coral species in the XS. In this study, two mitochondrial DNA fragments and 11 microsatellite markers were employed to investigate the genetic diversity of coral host of M. digitata, and ITS amplicon sequencing was employed to investigate the Symbiodiniaceae community structure. We sampled five wild populations of M. digitata in Hainan Island and the Xisha Islands. Montipora digitata showed low genetic diversity across populations in the SCS. We found significant genetic differentiation between the Sanya (SY) and XS populations but no significant genetic differentiation within XS populations. We identified four Symbiodiniaceae genera, with Cladocopium and Durusdinium being the most common, as well as Gerakladium and Fugacium. The Symbiodiniaceae types of SY and XS are significantly different, C15 is abundant in all populations, while D1a is also abundant in SY. We analyzed the correlation between 16 environmental factors and the genetic diversity of symbionts, genetic diversity of coral host and Symbiodiniaceae community was significantly correlated with sea surface temperature (SST) and other environmental factors. Our study provided a detailed paradigm from the perspective of genetic diversity of how a dominant coral species can be indicative of poor environmental adaptation potential.

Understanding the wave and current conditions of coral reef ecosystems is essential for maintaining their health, as many reef processes are controlled by these hydrodynamic conditions. In this study, high-frequency measurements of tides, waves, and currents were made using acoustic, electromagnetic, and pressure instruments over a 28-d period on the fore-reef and reef flat of a coral reef atoll in the South China Sea. The research revealed wave transformation, tidal and wave modulation of flow, and wave setup conditions for the first time at this typical atoll. Three large wave processes dominated by gravity waves (GWs) are observed in the fore-reef. The GWs are significantly attenuated on the reef flat, whereas infragravity (IG) waves strengthened. The tidal modulation of GWs and IG waves on the reef flat is significant when the incident wave height exceeded 1 m. In the fore-reef, the modulation of progressive tidal waves and large waves leads to relatively stronger upper-layer currents, and weak near-bottom currents are primarily attributed to the dissipation of tidal wave energy by the rough coral terrain. In calm conditions, flow variations on the reef flat are modulated by tides, thereby allowing seawater flow to pass through the reef flat during spring tides. Conversely, during periods with large waves, tidal modulation of flow on the reef flat is less significant, and the cross-reef flow velocity increases with increasing incident wave height. The occurrence of wave setup on the reef flat enhances cross-reef flow towards the lagoon. The wave setup is positively linearly correlated with the incident wave height. The magnitude of wave setup is associated with the distance between the measurement sites on the fore-reef and reef flat.

Daylighting plays a crucial role in building science, impacting both occupants’ well-being and energy consumption in buildings. Balancing the size of openings with energy efficiency has long been a challenge. To address this, various daylight metrics have been developed to assess interior spaces’ daylight quality. Additionally, architects have been using simulation algorithms to predict postconstruction light conditions. In recent years, machine learning (ML) has revolutionized daylight simulations, offering a way to predict daylight conditions without cumbersome 3D modeling or heavy computational resources. However, accommodating architects’ creativity remains a challenge for current machine learning-based models. Specifically, the diversity of window shapes and their locations on facades poses difficulties for prediction accuracy. To overcome this limitation, this paper proposes a novel method that transforms wall information into matrices and uses them as input to train an artificial neural network-based model; this model can well predict the annual daylight simulation result generated by the Climate-Based Daylight Modeling tools. This method allows the model to adapt to various real-world design scenarios in real time, and its robust reliability has been demonstrated through evaluations of prediction accuracy concerning different annual daylight metrics. This approach caters to specific cases and opens possibilities for application in other machine learning and deep learning-based methods.

Coral reefs are essential for marine ecology and biodiversity. Global climate change has resulted in severe coral reef degradation, partly via coral bleaching, which is caused by rising sea temperatures and solar light intensity. In this study, we examined the impact of strong light (300 µmol.m−2.s−1) and high temperature (33°C) on the growth, immunity, and gene expression of Galaxea fascicularis. Strong light caused coral bleaching in the absence of high sea temperatures, while no obvious bleaching was observed under high temperature alone. The effect of strong light on calcification rate of G. fascicularis is significantly weaker than that of high temperature. Both strong light and high temperatures significantly affected the immune enzyme activity of G. fascicularis symbionts, with the former having a strong effect on their photosystem. Temperature affected the digestive system, replication and repair, and cell growth and death of coral hosts, as indicated by transcriptomics analysis. These results provide a valuable for strategies to mitigate coral bleaching. Teaser: We explored the effects of strong light exposure and high temperature on coral reefs and their symbiont algae.

The Sakyamuni Pagoda of Fogong Temple, also known as the Yingxian Wooden Pagoda or the Wooden Pagoda of Ying County, is China’s oldest and tallest wooden pagoda. This pagoda was constructed in 1056 and has faced many challenges, including earthquakes, wars, and mistreatment. However, it is currently in danger of potential collapse due to severe structural challenges. Preserving this historic monument requires interdisciplinary collaboration across architectural history, materials science, and engineering. This paper proposes the development of a parametric model to build the pagoda that can be used for future preservation efforts. While not precisely reflecting the pagoda’s current condition, with the changes in inputs, the geometries of the structural members can be updated in real time, which offers adaptability crucial for preservation efforts. With the understanding of the original construction techniques, including its leaning column systems, the model not only helps preservation but also reveals the creativity of the architects or the craftsmen at the time. The 3D model, which includes more than 32,000 pieces along with the parametric files that can generate the column grid and dougongs, has been published along with this paper, and those files are available in the Data Availability Statement. In summary, the full digital model presented alongside this paper, unavailable elsewhere to the general public, serves as a practical preservation tool that can also be used for raising awareness for this cultural heritage site.

Coral reefs represent distinctive yet vulnerable marine ecosystems. Recently, these ecosystems have faced threats and degradation from multiple factors. A comprehensive understanding of coral distribution and niche information forms the theoretical foundation for addressing the ongoing coral crisis. This study employed the MaxEnt model to predict coral distribution in the central and southern regions of the South China Sea (SCS), while also obtaining ecological niche information. Utilizing CMIP6 data, the future exposure risk of corals was evaluated under two forcing scenarios (SSP245 and SSP585). The findings revealed that the highly suitable areas for corals in the SCS were approximately 31,360 km2, mainly distributed in the middle and east of Xisha, Zhongsha Atoll, Huangyan Island, and the north of the Nansha Islands. The probability of coral presence in the north and west of Xisha and the south of Nansha was low. The key environmental factors exerting significant influences on coral occurrence included seawater temperature, photosynthetically active radiation, current velocity, and dissolved oxygen. Among them, seawater velocity and nitrate emerged as the primary factors discerning differences in coral fitness across the study regions, which also verified the results of principal component analysis. Under extreme scenarios predicted by the end of this century (SSP585-2090s), over 43 % of coral distribution areas would face the highest exposure risk, mainly concentrated in southern Nansha. The primary drivers of this increased risk were the substantial changes occurring in temperature, dissolved oxygen, and nitrate. This research serves as a reference for coral conservation under climate change in the future.

IntroductionSeagrasses play a key role in biodiversity maintenance, sediment stabilization, and carbon reduction. Due to the significant decline of seagrass populations worldwide, many projects to restore seagrass by transplantation have been undertaken in recent decades. However, effective restoration technologies required to rapidly restore seagrass on Hainan Island are yet to be developed.MethodsIn this study, an experiment was carried out to investigate methods for alleviating continuous degradation of seagrass beds on Hainan Island. Seagrass were transplanted by “single-plant-fixed-distance transplantation” method, survival rate, shoot formation rate, coverage and shoot density of transplanting plants were monitored for 23 months.ResultsOver 67% of T. hemprichii and 90% of E. acoroides were still alive, shoot density were over 11 shoots/m2 and 15 shoots/m2 respectively after almost two years, E. acoroides was more likely to survive than T. hemprichii both in Gaolong Bay and Xincun lagoon. Because of the damage to below-ground tissues, the survival rate, shoot formation rate, coverage and shoot density decreased during the first one year after transplantation, then increased gradually.DiscussionWe considered transplantation established successfully of T. hemprichii and E. acoroides in the new site was about 12 months. In addition, T. hemprichii was suitable for transplanted in Xincun lagoon, and E. acoroides was suitable for transplanted in Gaolong bay. The results demonstrated that the growth of transplanted seagrass was greatly affected by suspend solids and DIN. The results of this study may provide data support and scientific basis for seagrass transplantation in South China.

Seagrass beds have extremely high ecological service value, so their protection and management are very important. The coastal area that stretches from Wenchang to Qionghai in the eastern part of Hainan Island is the largest seagrass bed distribution area in China’s South China Sea Bioregion. Understanding the local distribution and changes in seagrass beds is a prerequisite for implementing the protection and management of seagrass bed resources in this area. In this study, Landsat satellite remote sensing images of the study area from 1986 to 2021 were selected; seagrass bed survey data and field investigation data were combined; the Sum Green Index was used to extract and plot seagrass bed distribution information; the spatial distribution changes in seagrass beds in the region over the past thirty years were analyzed; and the driving factors of these changes are discussed. The following conclusions were drawn: (i) The water quality in the study area is clear, the marine sediment is mainly composed of coral debris and sand, and the seagrass plants are relatively tall. The Sum Green Index can effectively extract seagrass bed information and achieve good mapping accuracy. (ii) Between 1986 and 2021, there were significant changes in seagrass bed distribution in the study area, showing a trend of slow growth followed by rapid decline. Overall, over the past thirty years, the total area of seagrass beds in the study area has declined, coverage has decreased, and patches have become fragmented. (iii) The construction of marine and coastal engineering projects, as well as large-scale aquaculture, are important reasons for the decline of seagrass beds in the study area. Other types of mechanical physical damage, such as shipping and shells raking can also have serious impacts on seagrass beds. This study is the first to conduct distribution range mapping and long time series change monitoring based on satellite remote sensing images for the largest seagrass beds in China’s South China Sea Bioregion, with the aim of providing a reference for the monitoring and protection of seagrass beds in the South China Sea.

Global climate change, human activities, and environmental pollution impact coral reefs worldwide. The South China Sea coral reefs have been severely degraded. Genetic diversity among populations of coral is important to implement appropriate protection and restoration measures. Platygyra daedalea, widely distributed in the South China Sea, is stress-resistant and forms a dominant species in some regions. Analyzing the genetic diversity of P. daedalea may provide clues to enhance the resistance of reef-building corals. In this study, we employed one nuclear DNA fragment (ITS) and sixteen microsatellite loci to investigate the genetic diversity of coral host and high-throughput sequencing to investigate on the Symbiodiniaceae types in P. daedalea. (1) The populations of P. daedalea and Symbiodiniaceae types in P. daedalea on Hainan and Xisha Islands were divided into three groups: northern to western Hainan Island, eastern to southern Hainan Island, and Xisha Islands. The ribotypes distribution of coral hosts and the Symbiodiniaceae community composition were strongly correlated with environmental factors in the three areas, especially phosphate concentration and diffuse attenuation. (2) Environmental heterogeneity significantly affected the genetic diversity of coral hosts and diversity of Symbiodiniaceae types, especially nutrient concentration, which significantly affected the diversity of coral-algal symbiosis of P.daedalea even if the seawater nutrient content was within the normal range of coral life. (3) Coral hosts with different genotypes may prefer different Symbiodiniaceae types. This study provides new insights into the changes in the genetic structure and diversity of reef-building corals in the Indo-Pacific region.

Montipora digitata is a species belonging to the Acroporidae. In the Indo-Pacific region, M. digitata is widely distributed and is the dominant species of scleractinian coral in the South China Sea, however, there are currently no molecular markers suitable for assessing the species genetic diversity. Here, restriction-site associated DNA sequencing (RAD-seq) was used to isolate and characterize polymorphic microsatellite loci. A total of 317,361 RAD-tags were obtained using RAD-seq, including 6,778 microsatellite loci. Primer pairs for 106 loci were ordered and twenty-one polymorphic loci, that amplified reliably were identified. The number of alleles per locus were 2-7, observed heterozygosity was 0.111-0.556 with an average value of 0.285, and expected heterozygosity was 0.105- 0.802, with an average value of 0.536. Before Bonferroni correction 13 loci deviated significantly from the expectations of Hardy-Weinberg equilibrium (P < 0.05), after correction, two microsatellite loci deviated significantly (P < 0.0002). The polymorphic information content (PIC) ranged from 0.100-0.778, with 12 loci highly polymorphic (PIC > 0.5), six moderately polymorphic (0.25 < PIC < 0.5), and three loci with low polymorphism (PIC < 0.25). The microsatellite loci developed here will be effective tools for conservation genetic research on M. digitata.

Rip currents are fast offshore currents generated during the breaking process of waves propagating nearshore, posing a potential life safety threat to coastal bathers. This study utilizes a Boussinesq phase-resolving model to investigate the formation mechanism of rip currents at Dadonghai Beach, based on its actual topography, and explores the characteristics of rip current formation under various wave conditions, with an emphasis on analyzing vortices, the mean water level and the spatial distribution of average velocity. The results indicate that rip current formation is significantly influenced by wave height and period. The increase in wave height and period results in more intense rip currents and higher water level fluctuations on arc-shaped beaches and on both sides of the bay, leading to complex vortex distributions. An increase in the angle of wave incidence hinders rip current formation in arc-shaped beach areas but is favorable to the generation of deflection rips on both sides of the bay. Furthermore, an increase in bottom friction inhibits rip current formation. When the water depth decreases in the channels, rip currents transition into longshore currents. The findings of this research offer valuable scientific insights into the formation mechanisms of rip currents and contribute to their prediction and prevention.

Seagrass plays a vital role in the stability of marine ecology. The human development of marine resources has greatly affected the survival of seagrass. Seawater salinity is one of the important factors affecting its survival. Seagrass can survive in high saline environments for a long time and has evolved a variety of effective tolerance mechanisms. However, little is known about the molecular mechanisms underlying salinity tolerance by seagrass. Thalassia hemprichii is a seagrass species with a global distribution. It is also an ecologically important plant species in coastal waters. Nevertheless, the continuous environmental deterioration has gradually reduced the ecological niche of seagrasses. In this study, experiments were conducted to examine the effects of salinity changes on T. hemprichii. The result showed that the optimal salinity for T. hemprichii is 25 to 35 PSU. Although it can survive under high and low salinity, high mortality rates are common in such environments. Further analyses revealed that high salinity induces growth and developmental retardation in T. hemprichii and further causes yellowing. The parenchyma cells in T. hemprichii also collapse, the structure changes, soluble sugar accumulates rapidly, soluble proteins accumulate rapidly, the malondialdehyde (MDA) content reduces, and lipid peroxidation reduces in plant membranes. The molecular mechanisms of salt tolerance differ significantly between marine and terrestrial plants. We found 319 differentially expressed genes (DEGs). These genes regulate transport and metabolism, promoting environmental adaptation. The expression of these genes changed rapidly upon exposure of T. hemprichii to salinity stress for three hours. This is the first report on the physiological and biochemical changes and gene expression regulation of T. hemprichii under different salinity conditions. The findings of this study well deepen our understanding of T. hemprichii adaptations to changes in the shoal living environment.

The quality of residential buildings in old urban areas of Beijing is known to be inconsistent, prompting numerous urban renewal projects in the city. This research investigates how building space impacts energy usage and daylighting in courtyard areas of old urban regions in northern China. It also proposes a quick evaluation method for building performance in courtyard spaces, utilizing multi-objective optimization and machine learning classification prediction as a theoretical framework. A study was conducted to gather and organize building space parameters and their corresponding performances using a genetic algorithm. The dataset was then pre-processed and trained using the LightGBM algorithm. The model validation results revealed a recall of 0.9 and an F1-score of 0.8. These scores indicate that the design scheme’s performance level can be accurately identified in practical use. The goal of this study is to propose a set of rapid assessment methods for building performance levels in courtyard spaces. These methods can significantly improve the feedback efficiency between design decision and performance assessment, reduce the time wasted in building performance simulation during the architectural design process, and avoid unreasonable renovation and addition in urban renewal. Furthermore, the research method has universality and can be applied to courtyard-shaped buildings in other regions.

Complete chloroplast genome of Enhalus acodoides was obtained in this work. Circular mapping revealed that the complete chloroplast sequences of E. acodoides was 176,748 bp in length and had an overall GC content of 38.3%, encoded 132 genes which contained 86 protein-coding genes (PCGs), 38 transfer RNA genes (tRNA) and 8 ribosomal RNA genes (rRNA). The phylogenetic tree shows that E. acodoides had a closer relationship with Thalassia hemprichii in Hydrocharitaceae and its analysis will help better understand the evolution of Alismatales species.

This study deals with the correlation between ice extent in the Sea of Okhotsk and the interannual variability of winter (December-February) air temperature over the subtropical Western Pacific from 1979 to 2008. The analysis indicates that the increase in sea ice extent coincides not only with cooling over the Sea of Okhotsk and the adjacent area, but also with significant warming over the subtropical Western Pacific that extends from the surface to the middle troposphere. This meridional dipole pattern of tropospheric temperature anomalies (cooling in the high latitudes and warming in the low latitudes) primarily results from dynamical processes driven by the large-scale atmospheric circulation change. A heat budget diagnosis reveals that when ice extent in the Sea of Okhotsk increases by one standard deviation, the tropospheric air temperature over the subtropical Western Pacific rises by about 0.25°C. It also suggests that the adiabatic heating and stationary eddy heat flux convergence may be the most important factors, which account for 30 and 15% of the warming, respectively. In addition, these two factors also coordinate to result in significant cooling over the Sea of Okhotsk and the adjacent regions. [ABSTRACT FROM AUTHOR]

The Yongxing Island is the biggest island of Xisha Islands in the middle part of the South China Sea. It occupies 1.8 square kilometers of land area and has permanent residence on it. There are only a few papers on the coral community of the Xisha Islands, reporting the species composition, structure and zonations of the hermatypic coral community in 1970s. The present study describes the hermatypic coral community based on the quadrat survey after almost 30 years in Yongxing Island in August 2002. It was the first time to present the percent cover data of live corals of Yongxing Island via a systematic scheme of quantitative quadrat sampling. The average total percent cover of the live coral is 68.4%. We found the total percent cover (TPC) could be an idea proxy of the overall disturbance regime impinging on the coral community. TPC can be used as an integrated measure of disturbance to coral reef. Using this surrogate, the best fit relation between TPC of the live corals and species richness, species diversity, or the species evenness is the unimodal second-order polymorphic parabola equation. This result is expected by the intermediate disturbance hypothesis (IDH). From the fitted parabola equations, we calculated the best TPCs corresponding to the maximal species richness, the highest species diversity, or the most evenness respectively. They are surprisingly stabilized between 55% and 58%. Coral cover is the basic parameter widely available for most observation, research or monitoring programs. The good qualitative characteristics of percent cover provide powerful tool for the experimental, theoretical and modeling studies of coral reef in response to the disturbance. [ABSTRACT FROM AUTHOR]