Benthic habitat mapping is an emerging discipline in the international marine field in recent years,providing an effective tool for marine spatial planning,marine ecological management,and decision-making applications...Benthic habitat mapping is an emerging discipline in the international marine field in recent years,providing an effective tool for marine spatial planning,marine ecological management,and decision-making applications.Seabed sediment classification is one of the main contents of seabed habitat mapping.In response to the impact of remote sensing imaging quality and the limitations of acoustic measurement range,where a single data source does not fully reflect the substrate type,we proposed a high-precision seabed habitat sediment classification method that integrates data from multiple sources.Based on WorldView-2 multi-spectral remote sensing image data and multibeam bathymetry data,constructed a random forests(RF)classifier with optimal feature selection.A seabed sediment classification experiment integrating optical remote sensing and acoustic remote sensing data was carried out in the shallow water area of Wuzhizhou Island,Hainan,South China.Different seabed sediment types,such as sand,seagrass,and coral reefs were effectively identified,with an overall classification accuracy of 92%.Experimental results show that RF matrix optimized by fusing multi-source remote sensing data for feature selection were better than the classification results of simple combinations of data sources,which improved the accuracy of seabed sediment classification.Therefore,the method proposed in this paper can be effectively applied to high-precision seabed sediment classification and habitat mapping around islands and reefs.展开更多
As the main geomaterials for coral reefs oil or gas extraction and underground infrastructure construction,coral reef limestone demonstrates significantly distinct mechanical responses compared to terrigenous rocks.To...As the main geomaterials for coral reefs oil or gas extraction and underground infrastructure construction,coral reef limestone demonstrates significantly distinct mechanical responses compared to terrigenous rocks.To investigate the mechanical behaviour of coral reef limestone under the coupling impact of size and strain rate,the uniaxial compression tests were conducted on reef limestone samples with length-to-diameter(L/D)ratio ranging from 0.5 to 2.0 at strain rate ranging from 10^(−5)·s^(−1)to 10^(−2)·s^(−1).It is revealed that the uniaxial compressive strength(UCS)and residual compressive strength(RCS)of coral reef limestone exhibits a decreasing trend with L/D ratio increasing.The dynamic increase factor(DIF)of UCS is linearly correlated with the logarithm of strain rate,while increasing the L/D ratio further enhances the DIF.The elastic modulus increases with strain rate or L/D ratio increasing,whereas the Poisson’s ratio approximates to a constant value of 0.24.The failure strain increases with strain rate increasing or L/D ratio decreasing,while the increase in L/D ratio will inhibit the enhancing effect of the strain rate.The high porosity and low mineral strength are the primary factors contributing to a high RCS of 16.7%–64.9%of UCS,a lower brittleness index and multiple irregular fracture planes.The failure pattern of coral reef limestone transits from the shear-dominated to the splitting-dominated failure with strain rate increasing or L/D ratio decreasing,which is mainly governed by the constrained zones induced by end friction and the strain rate-dependent crack propagation.Moreover,a predictive formula incorporating coupling effect of size and strain rate for the UCS of reef limestone was established and verified to effectively capture the trend of UCS.展开更多
Catastrophic failure in engineering structures of island reefs would occur when the tertiary creep initiates in coral reef limestone with a transition from short-to long-term load.Due to the complexity of biological s...Catastrophic failure in engineering structures of island reefs would occur when the tertiary creep initiates in coral reef limestone with a transition from short-to long-term load.Due to the complexity of biological structures,the underlying micro-behaviors involving time-dependent deformation are poorly understood.For this,an abnormal phenomenon was observed where the axial and lateral creep deformations were mutually independent by a series of triaxial tests under constant stress and strain rate conditions.The significantly large lateral creep deformation implies that the creep process cannot be described in continuum mechanics regime.Herein,it is hypothesized that sliding mechanism of crystal cleavages dominates the lateral creep deformation in coral reef limestone.Then,approaches of polarizing microscope(PM)and scanning electronic microscope(SEM)are utilized to validate the hypothesis.It shows that the sliding behavior of crystal cleavages combats with conventional creep micro-mechanisms at certain condition.The former is sensitive to time and strain rate,and is merely activated in the creep regime.展开更多
Coral reef limestone(CRL)constitutes a distinctive marine carbonate formation with complex mechanical properties.This study investigates the multiscale damage and fracture mechanisms of CRL through integrated experime...Coral reef limestone(CRL)constitutes a distinctive marine carbonate formation with complex mechanical properties.This study investigates the multiscale damage and fracture mechanisms of CRL through integrated experimental testing,digital core technology,and theoretical modelling.Two CRL types with contrasting mesostructures were characterized across three scales.Macroscopically,CRL-I and CRL-II exhibited mean compressive strengths of 8.46 and 5.17 MPa,respectively.Mesoscopically,CRL-I featured small-scale highly interconnected pores,whilst CRL-II developed larger stratified pores with diminished connectivity.Microscopically,both CRL matrices demonstrated remarkable similarity in mineral composition and mechanical properties.A novel voxel average-based digital core scaling methodology was developed to facilitate numerical simulation of cross-scale damage processes,revealing network-progressive failure in CRL-I versus directional-brittle failure in CRL-II.Furthermore,a damage statistical constitutive model based on digital core technology and mesoscopic homogenisation theory established quantitative relationships between microelement strength distribution and macroscopic mechanical behavior.These findings illuminate the fundamental mechanisms through which mesoscopic structure governs the macroscopic mechanical properties of CRL.展开更多
Global coral reef ecosystems have been severely degraded due to the combined effects of climate change and human activities.Changes in the seawater carbonate system of coral reef ecosystems can reflect their status an...Global coral reef ecosystems have been severely degraded due to the combined effects of climate change and human activities.Changes in the seawater carbonate system of coral reef ecosystems can reflect their status and their responses to the impacts of climate change and human activities.Winter and summer surveys in 2019 found that the ecological community of the Luhuitou coral reef flat was dominated by macroalgae and corals,respectively,contrasting with the conditions 10 years ago.The Luhuitou fringing reefs were sources of atmospheric CO_(2) in both seasons.In winter,the daily variation range of dissolved inorganic carbon(DIC)in Luhuitou coral reefs was up to 450μmol/kg,while that of total alkalinity(TA)was only 68μmol/kg.This indicated that the organic production was significantly higher than the calcification process during this period.The TA/DIC was approximately 0.15,which was less than half of that in healthy coral reefs;hence,photosynthesis-respiration processes were the most important factors controlling daily changes in the seawater carbonate system.The net community production(NCP)of the Luhuitou coral reef ecosystem in winter was as high as 47.65 mmol C/(m^(2)·h).While the net community calcification(NCC)was approximately 3.35 and-4.15 mmol CaCO_(3)/(m^(2)·h)during the daytime and nighttime respectively.Therefore,the NCC for the entire day was-21.9 mmol CaCO_(3)/(m^(2)·d),indicating a net autotrophic dissolved state.In summer,the acidification was enhanced by thunderstorms and heavy rain with the highest seawater partial pressure of CO_(2)(p CO_(2))and lowest pH T.Over the past 10 years,the increase rate of seawater p CO_(2) in Luhuitou reef was approximately 13.3μatm/a***,six times that of the open ocean,while the decrease rate of pH was approximately 0.0083/a,being five times that of the global ocean.These findings underscore the importance of protecting and restoring Luhuitou fringing reef,as well as similar reefs worldwide.展开更多
The origins of peloidal micrites in reefal limestone are not yet well understood.Moscovian microbial reefs with abundant peloidal micrites from Guizhou,South China,provide an opportunity to study the peloids and their...The origins of peloidal micrites in reefal limestone are not yet well understood.Moscovian microbial reefs with abundant peloidal micrites from Guizhou,South China,provide an opportunity to study the peloids and their geological significance for this time interval.Three types of peloids are differentiated:microbial,lithic,and bioclastic peloids.Microbial peloids that are well-sorted and may form in situ by microbial activities.The poorly sorted lithic peloids are derived from erosion and redeposition of the micrite matrix caused by the bottom turbulence induced by periodic storms.Bioclastic peloids are completely micritized fragments of hard parts and shells.Microbial boring and encrustations promote the processes of micritization.Microbial peloids commonly develop in zones with low or normal energy levels,and contribute to the construction and stabilization of the framework.In contrast,the occurrence of lithic peloids reflects that the reefs are destroyed by bottom turbulence during growth.It is suggested that the microbial reefs were deposited under a dynamic balance between constructional versus destructive processes.By comparative analysis,the peloids as microbial in origin play a key role in the growth and stabilization of bioconstructions during Carboniferous,which should be paid more attention in the studies of Carboniferous buildups.展开更多
The environmental impact of microplastic pollution has triggered the alarm of public for over 20 years.The South China Sea,situated as a marginal sea in the tropical region,is surrounded by unique blue-carbon ecosyste...The environmental impact of microplastic pollution has triggered the alarm of public for over 20 years.The South China Sea,situated as a marginal sea in the tropical region,is surrounded by unique blue-carbon ecosystems and densely populated provinces that produce a substantial amount of industrial plastic waste.Understanding the source-sink relationship and distribution of microplastics in rivers,nearshores,and estuaries is crucial for safeguarding the ecological integrity of estuarine environments.In this review,a comprehensive review of recent researches on the distribution and source-sink relationships of microplastics in rivers and nearshore and offshore regions in the South China Sea have been discussed.Due to atmospheric deposition and precipitation,microplastics exhibit spatial heterogeneity in terms of abundance and distribution in areas surrounding the South China Sea.The major pollution sources include river inputs,industrial wastewater discharge,aquaculture activities,and shipping operations.Anthropogenic and other biological factors such as fish ingestion and vegetation entrapment also affect the distribution and transport of microplastics.To quantify the abundance and distribution of microplastics and elucidate their transport mechanisms,it is recommended to strengthen the detection and management of microplastics in the South China Sea region,standardize sampling methods and units,establish shared databases,and explore effective governance pathways.展开更多
Chase the Dream of Coral is an inspiring book that shines a light on the brave scientists dedicated to saving our coral reefs.Coral reefs are often called the rainforests of the sea because they support a vast number ...Chase the Dream of Coral is an inspiring book that shines a light on the brave scientists dedicated to saving our coral reefs.Coral reefs are often called the rainforests of the sea because they support a vast number of marine species.However,they are facing serious threats from climate change,pollution and overfishing.This book highlights the urgent need to protect these beautiful and vital ecosystems.展开更多
Analyzing coral reef topography is critical for understanding both the formation mechanisms of coral reefs and coral spatial distribution patterns.However,most topographic studies have focused on small-scale or locali...Analyzing coral reef topography is critical for understanding both the formation mechanisms of coral reefs and coral spatial distribution patterns.However,most topographic studies have focused on small-scale or localized survey sites,and investigations of reef macro-topography patterns and their relationship with coral distribution are scant.To address this gap,we conducted a comprehensive investigation of macro-topographic patterns across 12 coral reefs covering 607 km2 in the Xisha Islands,South China Sea.Using digital elevation models constructed from satellite bathymetric data with 16 m resolution,we analyzed spatial variations of seven topographic indices at the reef,geomorphic zone,and reef slope orientation levels in shallow waters.Field surveys were integrated with topographic indices to interpret and model coral distribution patterns.Our results revealed significant topographic heterogeneity,particularly in reef slopes and lagoon patch reefs.Reef slopes ranged from 0°to 33°,with rugosity values between 1.00 and 1.19.The steepness of reef slopes varied by orientation,being steepest in the west,southwest,and south,while the consistency of slope gradients was highest in the south,east,and northeast.Furthermore,stress-tolerant coral cover on reef slopes was effectively predicted by the factors of topographic indices,water depth,and slope aspect.Additionally,the topographic changes in reef flats and shallow lagoons were minimal.These findings advance our understanding of coral reef formation mechanisms in the Indo-Pacific region and provide a theoretical foundation for the conservation and restoration of coral reef ecosystems.展开更多
Reef limestone is buried in the continental shelf and marine environment.Understanding the mechanisms governing filter cake formation in coral reef limestone strata is essential for various engineering activities in c...Reef limestone is buried in the continental shelf and marine environment.Understanding the mechanisms governing filter cake formation in coral reef limestone strata is essential for various engineering activities in coastal areas,including slurry pressure balanced(SPB)shield tunneling,which are currently not well understood.This study systematically investigates the slurry infiltration characteristics of different coral reef limestone types with inherent anisotropy,identified by growth line orientations,through a series of micro-infiltration column tests.Multiple slurry concentrations and pressures were used to analyze their effects on slurry infiltration dynamics and filter cake formation.Pre-and post-infiltration CT scanning was conducted to examine skeletal morphology and reconstruct the pore network structure of coral reef limestone samples.The results show that while increased slurry concentrations and pressures generally improve filter cake formation,excessive pressure can compromise filter cake integrity.By employing Dijkstra’s algorithm in a pore network model,the study identified primary seepage pathways,highlighting the significant role of near-vertical throat clusters in the infiltration process.A comprehensive analysis of pore structure and connectivity indices before and after infiltration revealed that the orientation of growth lines in coral reef limestone is the primary factor influencing macroscopic slurry infiltration behavior.These findings offer valuable insights for the design and execution of tunneling projects through coral reef limestone formations,especially in coastal regions.展开更多
BACKGROUND The frequent occurrence of respiratory diseases in the island reef environment of the navy severely affects the health of personnel and the combat effectiveness of the troops.Current common screening method...BACKGROUND The frequent occurrence of respiratory diseases in the island reef environment of the navy severely affects the health of personnel and the combat effectiveness of the troops.Current common screening methods can only indicate whether there is an infection with pathogenic microorganisms but not the degree of disease progression.Therefore,it is necessary to identify simple-to-operate and cost-effective methods that indicate the degree of disease progression,based on traditional screening methods.AIM To explores correlation between serum concentrations of nicotinamide phosphoribosyltransferase(NAMPT),nicotinamide nucleotide adenylyltransferase 1(NMNAT1),and the risk of upper respiratory infections in the island reef envirsonment.METHODS A total of 600 cases of upper respiratory infections among naval officers and soldiers were included.Types of infection were confirmed through sputum culture combined with multiplex polymerase chain reaction.The serum concentrations of NAMPT and NMNAT1 were measured using ELISA,and infection severity was assessed using the pneumonia severity index(PSI).Statistical analysis was performed using nonparametric tests and Spearman correlation analysis.RESULTS The serum concentrations of NAMPT and NMNAT1 in high-risk group patients with PSI were significantly lower than those in the medium and low-risk groups(P<0.05),and the concentrations increased in a stepwise manner with disease progression.However,within the same risk group,the differences in concentrations of NAMPT and NMNAT1among patients infected with different pathogens were not significant(P>0.05).CONCLUSIONConcentrations of NAMPT and NMNAT1 are closely related to severity of upper respiratory infections,and theircommon regulatory mechanisms provide new directions for development of broad-spectrum anti-infectionstrategies.展开更多
The first thing to know about the Museum of Underwater Art(MOUA)is that it is not a traditional museum housed in a building—it's a series of installations(现代雕塑装置)and sculptures within the Great Barrier Reef...The first thing to know about the Museum of Underwater Art(MOUA)is that it is not a traditional museum housed in a building—it's a series of installations(现代雕塑装置)and sculptures within the Great Barrier Reef Marine Park.展开更多
According to the field survey and ^14C dating at Luhuitou, southern Hainan Island, a subsiding area, the authors conclude the high sea level history recorded by coral reef in the Holocene. At least 4 sea level high-st...According to the field survey and ^14C dating at Luhuitou, southern Hainan Island, a subsiding area, the authors conclude the high sea level history recorded by coral reef in the Holocene. At least 4 sea level high-stands can be identified from the distribution of coral reef ages： 7300 - 6000 cal.aBP, 4800 - 4700 cal.aBP, 4300 - 4200 cal.aBP and 3100 - 2900 cal.aBP. The highest sea level occurred around 7300 - 6700 cal.aBP, and biological-morphological zones took their shape during the stage. The later coral reefs developed in ponds, depressions, and developed outwards on both sides of Luhuitou peninsula. The modern coral reefs are developing in out reef flat and reef-front slope. Moreover, the time of high sea levels in the northern South China Sea recorded by coral reefs in the Luhuitou peninsula can link up with that in other parts of South China Sea. That means the high sea levels in the South China Sea during the Holocene, which are relative to the warming climate, have the global background.展开更多
By the means of technology of CFD （Computational Fluid Dynamics）, this research has studied the surrounding flow field effect of different combination of artificial reefs. In the study, four kinds of configurations ...By the means of technology of CFD （Computational Fluid Dynamics）, this research has studied the surrounding flow field effect of different combination of artificial reefs. In the study, four kinds of configurations are used to simulate numerically and these are ＂444＂ three columns, ＂464＂ three columns, ＂12345＂ five triangles and the ＂34543＂ five column regular hexagon .The result shows that the combination of artificial reefs of Dashentang can play a good role in regulating the reefs.展开更多
基金Supported by the National Natural Science Foundation of China(Nos.42376185,41876111)the Shandong Provincial Natural Science Foundation(No.ZR2023MD073)。
文摘Benthic habitat mapping is an emerging discipline in the international marine field in recent years,providing an effective tool for marine spatial planning,marine ecological management,and decision-making applications.Seabed sediment classification is one of the main contents of seabed habitat mapping.In response to the impact of remote sensing imaging quality and the limitations of acoustic measurement range,where a single data source does not fully reflect the substrate type,we proposed a high-precision seabed habitat sediment classification method that integrates data from multiple sources.Based on WorldView-2 multi-spectral remote sensing image data and multibeam bathymetry data,constructed a random forests(RF)classifier with optimal feature selection.A seabed sediment classification experiment integrating optical remote sensing and acoustic remote sensing data was carried out in the shallow water area of Wuzhizhou Island,Hainan,South China.Different seabed sediment types,such as sand,seagrass,and coral reefs were effectively identified,with an overall classification accuracy of 92%.Experimental results show that RF matrix optimized by fusing multi-source remote sensing data for feature selection were better than the classification results of simple combinations of data sources,which improved the accuracy of seabed sediment classification.Therefore,the method proposed in this paper can be effectively applied to high-precision seabed sediment classification and habitat mapping around islands and reefs.
基金supported by the National Natural Science Foundation of China(Nos.52222110,52401354,and 52301353).
文摘As the main geomaterials for coral reefs oil or gas extraction and underground infrastructure construction,coral reef limestone demonstrates significantly distinct mechanical responses compared to terrigenous rocks.To investigate the mechanical behaviour of coral reef limestone under the coupling impact of size and strain rate,the uniaxial compression tests were conducted on reef limestone samples with length-to-diameter(L/D)ratio ranging from 0.5 to 2.0 at strain rate ranging from 10^(−5)·s^(−1)to 10^(−2)·s^(−1).It is revealed that the uniaxial compressive strength(UCS)and residual compressive strength(RCS)of coral reef limestone exhibits a decreasing trend with L/D ratio increasing.The dynamic increase factor(DIF)of UCS is linearly correlated with the logarithm of strain rate,while increasing the L/D ratio further enhances the DIF.The elastic modulus increases with strain rate or L/D ratio increasing,whereas the Poisson’s ratio approximates to a constant value of 0.24.The failure strain increases with strain rate increasing or L/D ratio decreasing,while the increase in L/D ratio will inhibit the enhancing effect of the strain rate.The high porosity and low mineral strength are the primary factors contributing to a high RCS of 16.7%–64.9%of UCS,a lower brittleness index and multiple irregular fracture planes.The failure pattern of coral reef limestone transits from the shear-dominated to the splitting-dominated failure with strain rate increasing or L/D ratio decreasing,which is mainly governed by the constrained zones induced by end friction and the strain rate-dependent crack propagation.Moreover,a predictive formula incorporating coupling effect of size and strain rate for the UCS of reef limestone was established and verified to effectively capture the trend of UCS.
基金supported by the National Natural Science Foundation of China(Grant Nos.41877267,41877260)the Priority Research Program of the Chinese Academy of Science(Grant No.XDA13010201).
文摘Catastrophic failure in engineering structures of island reefs would occur when the tertiary creep initiates in coral reef limestone with a transition from short-to long-term load.Due to the complexity of biological structures,the underlying micro-behaviors involving time-dependent deformation are poorly understood.For this,an abnormal phenomenon was observed where the axial and lateral creep deformations were mutually independent by a series of triaxial tests under constant stress and strain rate conditions.The significantly large lateral creep deformation implies that the creep process cannot be described in continuum mechanics regime.Herein,it is hypothesized that sliding mechanism of crystal cleavages dominates the lateral creep deformation in coral reef limestone.Then,approaches of polarizing microscope(PM)and scanning electronic microscope(SEM)are utilized to validate the hypothesis.It shows that the sliding behavior of crystal cleavages combats with conventional creep micro-mechanisms at certain condition.The former is sensitive to time and strain rate,and is merely activated in the creep regime.
基金National Key Research and Development Program of China (No.2021YFC3100800)the National Natural Science Foundation of China (Nos.42407235 and 42271026)+1 种基金the Project of Sanya Yazhou Bay Science and Technology City (No.SCKJ-JYRC-2023-54)supported by the Hefei advanced computing center
文摘Coral reef limestone(CRL)constitutes a distinctive marine carbonate formation with complex mechanical properties.This study investigates the multiscale damage and fracture mechanisms of CRL through integrated experimental testing,digital core technology,and theoretical modelling.Two CRL types with contrasting mesostructures were characterized across three scales.Macroscopically,CRL-I and CRL-II exhibited mean compressive strengths of 8.46 and 5.17 MPa,respectively.Mesoscopically,CRL-I featured small-scale highly interconnected pores,whilst CRL-II developed larger stratified pores with diminished connectivity.Microscopically,both CRL matrices demonstrated remarkable similarity in mineral composition and mechanical properties.A novel voxel average-based digital core scaling methodology was developed to facilitate numerical simulation of cross-scale damage processes,revealing network-progressive failure in CRL-I versus directional-brittle failure in CRL-II.Furthermore,a damage statistical constitutive model based on digital core technology and mesoscopic homogenisation theory established quantitative relationships between microelement strength distribution and macroscopic mechanical behavior.These findings illuminate the fundamental mechanisms through which mesoscopic structure governs the macroscopic mechanical properties of CRL.
基金Supported by the National Key Research and Development Program of China(Nos.2021YFC3100500,2022YFC3103602,2021YFF0502800)the National Natural Science Foundation of China(No.U23A2035)+3 种基金the Science and Technology Planning Project of Guangdong Province,China(No.2023B1212060047)the State Key Laboratory of Tropical Oceanography,South China Sea Institute of Oceanology,Chinese Academy of Sciences(No.LTO1919)the Visiting Fellowship Program of the State Key Laboratory of Marine Environmental Science,Xiamen University(No.MELRS1914)the Hainan Province Key R&D Program(No.ZDYF2023SHFZ131)。
文摘Global coral reef ecosystems have been severely degraded due to the combined effects of climate change and human activities.Changes in the seawater carbonate system of coral reef ecosystems can reflect their status and their responses to the impacts of climate change and human activities.Winter and summer surveys in 2019 found that the ecological community of the Luhuitou coral reef flat was dominated by macroalgae and corals,respectively,contrasting with the conditions 10 years ago.The Luhuitou fringing reefs were sources of atmospheric CO_(2) in both seasons.In winter,the daily variation range of dissolved inorganic carbon(DIC)in Luhuitou coral reefs was up to 450μmol/kg,while that of total alkalinity(TA)was only 68μmol/kg.This indicated that the organic production was significantly higher than the calcification process during this period.The TA/DIC was approximately 0.15,which was less than half of that in healthy coral reefs;hence,photosynthesis-respiration processes were the most important factors controlling daily changes in the seawater carbonate system.The net community production(NCP)of the Luhuitou coral reef ecosystem in winter was as high as 47.65 mmol C/(m^(2)·h).While the net community calcification(NCC)was approximately 3.35 and-4.15 mmol CaCO_(3)/(m^(2)·h)during the daytime and nighttime respectively.Therefore,the NCC for the entire day was-21.9 mmol CaCO_(3)/(m^(2)·d),indicating a net autotrophic dissolved state.In summer,the acidification was enhanced by thunderstorms and heavy rain with the highest seawater partial pressure of CO_(2)(p CO_(2))and lowest pH T.Over the past 10 years,the increase rate of seawater p CO_(2) in Luhuitou reef was approximately 13.3μatm/a***,six times that of the open ocean,while the decrease rate of pH was approximately 0.0083/a,being five times that of the global ocean.These findings underscore the importance of protecting and restoring Luhuitou fringing reef,as well as similar reefs worldwide.
基金supported by the National Natural Science Foundation of China(Grant Nos.42272008 and 41972002).
文摘The origins of peloidal micrites in reefal limestone are not yet well understood.Moscovian microbial reefs with abundant peloidal micrites from Guizhou,South China,provide an opportunity to study the peloids and their geological significance for this time interval.Three types of peloids are differentiated:microbial,lithic,and bioclastic peloids.Microbial peloids that are well-sorted and may form in situ by microbial activities.The poorly sorted lithic peloids are derived from erosion and redeposition of the micrite matrix caused by the bottom turbulence induced by periodic storms.Bioclastic peloids are completely micritized fragments of hard parts and shells.Microbial boring and encrustations promote the processes of micritization.Microbial peloids commonly develop in zones with low or normal energy levels,and contribute to the construction and stabilization of the framework.In contrast,the occurrence of lithic peloids reflects that the reefs are destroyed by bottom turbulence during growth.It is suggested that the microbial reefs were deposited under a dynamic balance between constructional versus destructive processes.By comparative analysis,the peloids as microbial in origin play a key role in the growth and stabilization of bioconstructions during Carboniferous,which should be paid more attention in the studies of Carboniferous buildups.
基金Supported by the National Natural Science Foundation of China(No.42077143)the Young Top-notch Talent Cultivation Program of Hubei Province,Outstanding Young and Middle-aged Science and Technology Innovation Team Project of the Hubei Provincial Department of Education(HPDE)(No.T2020016)the Training Fund Program for Scientific Research of Hubei University of Arts and Science(No.2020KYPYTD005)。
文摘The environmental impact of microplastic pollution has triggered the alarm of public for over 20 years.The South China Sea,situated as a marginal sea in the tropical region,is surrounded by unique blue-carbon ecosystems and densely populated provinces that produce a substantial amount of industrial plastic waste.Understanding the source-sink relationship and distribution of microplastics in rivers,nearshores,and estuaries is crucial for safeguarding the ecological integrity of estuarine environments.In this review,a comprehensive review of recent researches on the distribution and source-sink relationships of microplastics in rivers and nearshore and offshore regions in the South China Sea have been discussed.Due to atmospheric deposition and precipitation,microplastics exhibit spatial heterogeneity in terms of abundance and distribution in areas surrounding the South China Sea.The major pollution sources include river inputs,industrial wastewater discharge,aquaculture activities,and shipping operations.Anthropogenic and other biological factors such as fish ingestion and vegetation entrapment also affect the distribution and transport of microplastics.To quantify the abundance and distribution of microplastics and elucidate their transport mechanisms,it is recommended to strengthen the detection and management of microplastics in the South China Sea region,standardize sampling methods and units,establish shared databases,and explore effective governance pathways.
文摘Chase the Dream of Coral is an inspiring book that shines a light on the brave scientists dedicated to saving our coral reefs.Coral reefs are often called the rainforests of the sea because they support a vast number of marine species.However,they are facing serious threats from climate change,pollution and overfishing.This book highlights the urgent need to protect these beautiful and vital ecosystems.
基金The Guangxi Science and Technology Program under contract No.AD25069075the National Natural Science Foundation of China under contract No.42276182+2 种基金the Major Talent Project of Guangxi Zhuang Autonomous Region under contract No.GXR-2BGQ2525027the Natural Science and Technology Innovation Development Doubling Program of Guangxi University under contract No.2023BZRC019the Guangxi Natural Science Foundation of China under contract No.2022GXNSFAA035548.
文摘Analyzing coral reef topography is critical for understanding both the formation mechanisms of coral reefs and coral spatial distribution patterns.However,most topographic studies have focused on small-scale or localized survey sites,and investigations of reef macro-topography patterns and their relationship with coral distribution are scant.To address this gap,we conducted a comprehensive investigation of macro-topographic patterns across 12 coral reefs covering 607 km2 in the Xisha Islands,South China Sea.Using digital elevation models constructed from satellite bathymetric data with 16 m resolution,we analyzed spatial variations of seven topographic indices at the reef,geomorphic zone,and reef slope orientation levels in shallow waters.Field surveys were integrated with topographic indices to interpret and model coral distribution patterns.Our results revealed significant topographic heterogeneity,particularly in reef slopes and lagoon patch reefs.Reef slopes ranged from 0°to 33°,with rugosity values between 1.00 and 1.19.The steepness of reef slopes varied by orientation,being steepest in the west,southwest,and south,while the consistency of slope gradients was highest in the south,east,and northeast.Furthermore,stress-tolerant coral cover on reef slopes was effectively predicted by the factors of topographic indices,water depth,and slope aspect.Additionally,the topographic changes in reef flats and shallow lagoons were minimal.These findings advance our understanding of coral reef formation mechanisms in the Indo-Pacific region and provide a theoretical foundation for the conservation and restoration of coral reef ecosystems.
文摘Reef limestone is buried in the continental shelf and marine environment.Understanding the mechanisms governing filter cake formation in coral reef limestone strata is essential for various engineering activities in coastal areas,including slurry pressure balanced(SPB)shield tunneling,which are currently not well understood.This study systematically investigates the slurry infiltration characteristics of different coral reef limestone types with inherent anisotropy,identified by growth line orientations,through a series of micro-infiltration column tests.Multiple slurry concentrations and pressures were used to analyze their effects on slurry infiltration dynamics and filter cake formation.Pre-and post-infiltration CT scanning was conducted to examine skeletal morphology and reconstruct the pore network structure of coral reef limestone samples.The results show that while increased slurry concentrations and pressures generally improve filter cake formation,excessive pressure can compromise filter cake integrity.By employing Dijkstra’s algorithm in a pore network model,the study identified primary seepage pathways,highlighting the significant role of near-vertical throat clusters in the infiltration process.A comprehensive analysis of pore structure and connectivity indices before and after infiltration revealed that the orientation of growth lines in coral reef limestone is the primary factor influencing macroscopic slurry infiltration behavior.These findings offer valuable insights for the design and execution of tunneling projects through coral reef limestone formations,especially in coastal regions.
文摘BACKGROUND The frequent occurrence of respiratory diseases in the island reef environment of the navy severely affects the health of personnel and the combat effectiveness of the troops.Current common screening methods can only indicate whether there is an infection with pathogenic microorganisms but not the degree of disease progression.Therefore,it is necessary to identify simple-to-operate and cost-effective methods that indicate the degree of disease progression,based on traditional screening methods.AIM To explores correlation between serum concentrations of nicotinamide phosphoribosyltransferase(NAMPT),nicotinamide nucleotide adenylyltransferase 1(NMNAT1),and the risk of upper respiratory infections in the island reef envirsonment.METHODS A total of 600 cases of upper respiratory infections among naval officers and soldiers were included.Types of infection were confirmed through sputum culture combined with multiplex polymerase chain reaction.The serum concentrations of NAMPT and NMNAT1 were measured using ELISA,and infection severity was assessed using the pneumonia severity index(PSI).Statistical analysis was performed using nonparametric tests and Spearman correlation analysis.RESULTS The serum concentrations of NAMPT and NMNAT1 in high-risk group patients with PSI were significantly lower than those in the medium and low-risk groups(P<0.05),and the concentrations increased in a stepwise manner with disease progression.However,within the same risk group,the differences in concentrations of NAMPT and NMNAT1among patients infected with different pathogens were not significant(P>0.05).CONCLUSIONConcentrations of NAMPT and NMNAT1 are closely related to severity of upper respiratory infections,and theircommon regulatory mechanisms provide new directions for development of broad-spectrum anti-infectionstrategies.
文摘The first thing to know about the Museum of Underwater Art(MOUA)is that it is not a traditional museum housed in a building—it's a series of installations(现代雕塑装置)and sculptures within the Great Barrier Reef Marine Park.
基金We gratefully acknowledge the financial supports from the National Natural Science Foundation of China(Grant No.49976015).
文摘According to the field survey and ^14C dating at Luhuitou, southern Hainan Island, a subsiding area, the authors conclude the high sea level history recorded by coral reef in the Holocene. At least 4 sea level high-stands can be identified from the distribution of coral reef ages： 7300 - 6000 cal.aBP, 4800 - 4700 cal.aBP, 4300 - 4200 cal.aBP and 3100 - 2900 cal.aBP. The highest sea level occurred around 7300 - 6700 cal.aBP, and biological-morphological zones took their shape during the stage. The later coral reefs developed in ponds, depressions, and developed outwards on both sides of Luhuitou peninsula. The modern coral reefs are developing in out reef flat and reef-front slope. Moreover, the time of high sea levels in the northern South China Sea recorded by coral reefs in the Luhuitou peninsula can link up with that in other parts of South China Sea. That means the high sea levels in the South China Sea during the Holocene, which are relative to the warming climate, have the global background.
基金supported by the Key Laboratory of Marine Oil Spill Identification and Damage Assessment Technology, State Oceanic Administration (201214)Key Laboratory of Pollution Processes and Environmental Criteria (Nankai University), Ministry of Education (KL-PPEC-2013-09)
文摘By the means of technology of CFD （Computational Fluid Dynamics）, this research has studied the surrounding flow field effect of different combination of artificial reefs. In the study, four kinds of configurations are used to simulate numerically and these are ＂444＂ three columns, ＂464＂ three columns, ＂12345＂ five triangles and the ＂34543＂ five column regular hexagon .The result shows that the combination of artificial reefs of Dashentang can play a good role in regulating the reefs.
