Under the background of vigorously developing facilities of island/reef in the world,the economic value and strategic significance of the island/reef have become increasingly important.Unfortunately,they may easily be...Under the background of vigorously developing facilities of island/reef in the world,the economic value and strategic significance of the island/reef have become increasingly important.Unfortunately,they may easily become the attacking target of missiles in the war time.Therefore,aiming at the damage quantification of the targets in the island/reef under the missile attacking,a macroscopic damage assessment model for the target area is proposed in this paper.The model focuses on the construction of the assessment model framework.Firstly,the analytic hierarchy process and the grey relational analysis are applied to measure the importance of each target in the region through four indicators of the target hazard,striking urgency,damage advantage and mission relevance,respectively.Secondly,based on the damage mechanism of shock wave and fragments to target,the corresponding damage model is established,and the damage grade of each target in the evaluated area is obtained according to the damage criteria and grading standard.Finally,the model obtains the overall damage grade of the target area by employing the fuzzy comprehensive evaluation method,with synthesizing the importance and the damage grade of each target.Through the verification of an example,it demonstrates the certain feasibility of the model and provides a certain basis and reference for the subsequent research.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
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
A detailed survey of the reefs in the Nansha Islands＇ sea that are of strategic importance is conducive to their future development. In this study, a total of 50 Landsat 8 operational land imager（OLI） images were u...A detailed survey of the reefs in the Nansha Islands＇ sea that are of strategic importance is conducive to their future development. In this study, a total of 50 Landsat 8 operational land imager（OLI） images were used to analyze the geological features and spectral characteristics of the Nansha reefs. The exposed islands/sandbanks,reef flats and sub-tidal reefs were identified with the near-infrared band, the red and green bands, and the blue band, respectively. Based on the relationships among various characteristics and bands illustrated in the OLI images, the maximum between-cluster variance threshold algorithm（OTSU method） and the mathematical morphology were employed to extract characteristic parameters of the spatial geometry of the reefs from top to bottom, which were subsequently operated by a series of post-processing methods such as vectorization,simplification and topological analysis. Among the 132 standalone reefs and 16 atolls that are identified in the study, four reefs have yet to be named in the Standard Names of Various Islands in the South China Sea and the website Nansha Islands Online（http：//www.nansha.org/）. Another 24 ones are exposed to the atmosphere even during high tides. Taiping Island with an area of 0.57 km^2 represents the largest exposed geological feature. This study demonstrated the applicability of medium-resolution satellite images to derive the coral reef information effectively and thus provided information for the related departments that are responsible to manage the coast.An improved resolution of multispectral bands with the panchromatic band in higher spatial resolution（15 m for OLI image） is expected to provide an optimum satellite based approach to map marine habitats.展开更多
A combination of traditional fish sampling methods(hand-line and gill net) and modern hydroacoustic techniques were used to study fish community structure,distribution,and diel movements of fish on Zhubi Reef to enhan...A combination of traditional fish sampling methods(hand-line and gill net) and modern hydroacoustic techniques were used to study fish community structure,distribution,and diel movements of fish on Zhubi Reef to enhance understanding of the ecosystem.We collected 126 individuals from 29 species,20 genera,17 families,three orders,and two classes using traditional gear.Perciforms were the dominant group in terms of species richness and biomass.The acoustic data indicated that very small(target strength[TS],dB) <-60 dB) and small(-60 dB≤TS<-45 dB) fish contributed the most to abundance and species richness on the coral reef,and that the proportion of medium-sized(-45 dB≤TS<-35 dB) and largesized(-35 dB≤TS) fish increased gradually as depth increased.The single-target detection method revealed two distinct size classes during the day in the 12-16 and 16-20-m layers.One group consisted of very smallsized fish(TS<-60 dB) and the other consisted of medium and large-sized fish(TS>-55 dB).The number of single-target detections was significantly higher during the night than during the day(P<0.05).The singletarget TS frequency distribution during the day was significantly different than during the night at depths of4-8,8-12,12-16,and 16-20 m.Significant differences were observed among the 4-8,8-12,12-16,and16-20-m-depth layers during day and night.Diel vertical movement was evidenced as fish began to spread and move upward just before sunset and began to assemble and descend shortly(15 min) after sunrise.展开更多
Based on the remote sensing information feature of Nansha coral islets and reefs that controlled by the Nansha Islands local area's goological structure and growth law, by means of mathematical model and PC, the N...Based on the remote sensing information feature of Nansha coral islets and reefs that controlled by the Nansha Islands local area's goological structure and growth law, by means of mathematical model and PC, the Nansha Islands coral islets and reefs' top geological data' spatial distribution and local change trend are simulated by using the trend surface system on the remote sensing composite information, and an scientific interpretation and local comparison of Nansha coral islands and islets' spatial distribution feature are made.展开更多
Mapping regional spatial patterns of coral reef geomorphology provides the primary information to understand the constructive processes in the reef ecosystem. However, this work is challenged by the pixel-based image ...Mapping regional spatial patterns of coral reef geomorphology provides the primary information to understand the constructive processes in the reef ecosystem. However, this work is challenged by the pixel-based image classification method for its comparatively low accuracy. In this paper, an object-based image analysis(OBIA)method was presented to map intra-reef geomorphology of coral reefs in the Xisha Islands, China using Landsat 8satellite imagery. Following the work of the Millennium Coral Reef Mapping Project, a regional reef class hierarchy with ten geomorphic classes was first defined. Then, incorporating the hierarchical concept and integrating the spectral and additional spatial information such as context, shape and contextual relationships, a large-scale geomorphic map was produced by OBIA with accuracies generally more than 80%. Although the robustness of OBIA has been validated in the applications of coral reef mapping from individual reefs to reef system in this paper, further work is still required to improve its transferability.展开更多
Coral reefs in the Xisha Islands （also known as the Paracel Islands in English）, South China Sea, have experienced dramatic declines in coral cover. However, the current regional scale hard coral distribution of geo...Coral reefs in the Xisha Islands （also known as the Paracel Islands in English）, South China Sea, have experienced dramatic declines in coral cover. However, the current regional scale hard coral distribution of geomorphic and ecological zones, essential for reefs management in the context of global warming and ocean acidification, is not well documented. We analyzed data from field surveys, Landsat-8 and GF-1 images to map the distribution of hard coral within geomorphic zones and reef fiat ecological zones. In situ surveys conducted in June 2014 on nine reefs provided a complete picture of reef status with regard to live coral diversity, evenness of coral cover and reef health （live versus dead cover） for the Xisha Islands. Mean coral cover was 12.5% in 2014 and damaged reefs seemed to show signs of recovery. Coral cover in sheltered habitats such as lagoon patch reefs and biotic dense zones of reef flats was higher, but there were large regional differences and low diversity. In contrast, the more exposed reef slopes had high coral diversity, along with high and more equal distributions of coral cover. Mean hard coral cover of other zones was 〈10%. The total Xisha reef system was estimated to cover 1 060 km2, and the emergent reefs covered -787 km2. Hard corals of emergent reefs were considered to cover 97 km2. The biotic dense zone of the reef flat was a very common zone on all simple atolls, especially the broader northern reef flats. The total cover of live and dead coral can reach above 70% in this zone, showing an equilibrium between live and dead coral as opposed to coral and algae. This information regarding the spatial distribution of hard coral can support and inform the management of Xisha reef ecosystems.展开更多
Beach rock,which forms at the intertidal zone,is a natural barrier to protect beach and island from wave erosion. The formation mechanism of beach rocks is significant in the study of surface carbonate diagenesis and ...Beach rock,which forms at the intertidal zone,is a natural barrier to protect beach and island from wave erosion. The formation mechanism of beach rocks is significant in the study of surface carbonate diagenesis and protection of island. Beach rocks in Qilian Islets and Cays were formed about 500–700 a BP,neither its composition nor sedimentary structure experienced intense post-reformation.Beach rocks in Qilian Islets and Cays are mainly composed of reef-building skeletal fragments and bioclasts without terrigenous sediments. This study focused on the types and morphologies of cements in beach rocks of Qilian Islets and Cays,and its cementation mechanisms and influencing factors. Biological activities,such as micritization caused by microbial activities and algae binding action,play an important role in the initial stage of bioclast transformation and promote the subsequent early marine and early meteoric cementation. Acicular aragonite induced by early marine cementation is well developed in beach rocks,especially in those samples from Medium Islet. Early meteoric cementation is not common as marine cementation,generally presenting granular and meniscus cements. The main factors affecting the formation and development of beach rocks in Qilian Islets and Cays include sediment source,hydrodynamic condition,climate,sea level change and anthropogenic impacts.展开更多
Coral restoration is becoming popular to help restoring degraded coral reefs.However,few studies have tried to monitor the long-term recovery of coral reefs,which makes it diffi cult to assess the performance of the r...Coral restoration is becoming popular to help restoring degraded coral reefs.However,few studies have tried to monitor the long-term recovery of coral reefs,which makes it diffi cult to assess the performance of the restoration.We monitored the growth of three transplanted Acropora corals and naturally-attached Pocillopora damicornis on artifi cial reefs(ARs)from October 2014 to September 2018 during which there were several attacks of typhoons.Results show that two staghorn Acropora species had the highest growth rates(11.0–12.1 cm/a),followed by table coral A.divaricate(5.6 cm/a)and P.damicornis(4.8 cm/a).A linear growth pattern was found for the three Acropora species;the pattern gradually slowed in P.damicornis.There was a strong interspecifi c competition for space among the corals on ARs,and it led to the sharply declined occurrence of slow-growing P.darmicornis colonies in 2017.Coral recovery was successful at the Wuzhizhou Island and quickly increased AR complexity.However,the ARs made of metal frames fail to resist the direct attack from a catastrophic typhoon.Therefore,concrete and environmentalfriendly materials should be used in future restoration.This study is the fi rst report on long-term monitoring and assessment of coral reef restoration in China.The results off er future guide of reef restoration for impaired coral reefs in regions easily aff ected by typhoons.展开更多
Based on the concentrations of the trace elements,rare earth elements(REE),and Sr isotopic compositions in reef carbonates from the well‘Xike-1’reef core of the Xisha Islands,the constraints on sediment provenance a...Based on the concentrations of the trace elements,rare earth elements(REE),and Sr isotopic compositions in reef carbonates from the well‘Xike-1’reef core of the Xisha Islands,the constraints on sediment provenance and paleoenvironment were defined.Variations of the terrigenous input into the paleoseawater were traced in detail and the paleoenvironment and sediment provenance were further investigated.The results show that the HREE/LREE values in the reef carbonates are negatively associated with their Th and Al concentrations;however,their Al and Th concentrations show positive correlation.The lowest 87 Sr/86 Sr values in the reef carbonates generally coincide with the lowest values of Al,Th concentrations and the highest values of HREE/LREE.These data indicate that the HREE/LREE,Al concentrations,and Th concentrations of the reef carbonates are useful indexes for evaluating the influence of the terrigenous inputs on the seawater composition in the study area.From top to bottom,the changing process of the HREE/LREE values and Al,Th concentrations can be divided into 6 intervals;they are H1(0–89.30 m,about 0–0.11 Myr),L1(89.30–198.30 m,about 0.11–2.2 Myr),H2(198.30–374.95 m,about 2.2–5.3 Myr),D(374.95–758.40 m,about 5.3–13.6 Myr),L2(758.40–976.86 m,about 13.6–15.5 Myr),and H3(976.86–1200.00 m,about 15.5–21.5 Myr).Moreover,the changing trend of the HREE/LREE values coincides with that of the seawater δ^13C values recorded by benthonic foraminiferal skeletons from the drill core of ODP site 1148 in the South China Sea(SCS),but not with that of the seawaterδ18O values.The high uplifting rates of the Qinghai-Tibet Plateau coincide with the high Th and Al concentrations and the low HREE/LREE values in the reef carbonates.These data indicate that the main factors controlling the changes of terrigenous flux in the SCS are the tectonic activities associated with Qinghai-Tibet Plateau uplifting and the variations of uplifting rates rather than paleoclimatic changes.展开更多
Halimeda is one of the major reef-building algas in the middle Miocene of Xisha, and one of the significant reef-building algas in the algal reef oil and gas field of the South China Sea. However, there have been few ...Halimeda is one of the major reef-building algas in the middle Miocene of Xisha, and one of the significant reef-building algas in the algal reef oil and gas field of the South China Sea. However, there have been few reports regarding the characteristics of mineral rocks, reservoir porosity and permeability layers, and sedimentation-diagenetic-evolution of fossil Halimeda systems. The present paper briefly introduces the relevant studies on chlorophyta Halimeda and the research status of oil and gas exploration. Through the 1 043 m core of the Xichen-1 well, we studied the characteristics of the mineral rocks and porosity and permeability of the middle Miocene Halimeda of the Yongle Atoll, identified and described the segments of fossil Halimeda, and pointed out that most of the segment slides are vertical sections in ovular, irregular or long strips. The overwhelming majority of these fossil Halimeda found and studied are vertical sections instead of cross sections. In this paper, knowledge regarding the cross sections of fossil Halimeda is reported and proven to be similar with the microscopic characteristics of modern living Halimeda;fossil Halimeda are buried in superposition;it is shown that there are different structures present, including typical bio-segment structure, and due to its feature of coexisting with red alga, tying structure, twining structure and encrusting structure are all present;and finally, it is suggested to classify the fossil Halimeda into segment algal reef dolomites. In addition, all of the studied intervals are moderately dolomitized. Secondary microcrystalline-dolosparite dominates the original aragonite raphide zones, and aphanitic-micrite dolomite plays the leading role in the cortexes and medullas;in the aragonite raphide zones between medulla and cysts, secondary dissolved pores and intercrystalline pores are formed inside the segments, and algal frame holes are formed between segments;therefore, a pore space network system （dissolved pores＋intragranular dissolved pores—intercrystalline pores＋algal frame holes） is established. Segment Halimeda dolomite has a porosity of 16.2%–46.1%, a permeability of 0.203×10^–3–2 641×10^–3μm^2, and a throat radius of 23.42–90.43μm, therefore it is shown to be a good oil and gas reservoir. For the reasons mentioned above, we suggest building the neogene organic reef-modern reef sedimentation-diagenetic-evolution models for the Xisha Islands.展开更多
Chinese government has provided vigorous financial supports to artificial reef(AR)projects to repair marine ecosystem.Qiansandao AR,an important AR project of Fishery Resource Restoration Program in Shandong Province,...Chinese government has provided vigorous financial supports to artificial reef(AR)projects to repair marine ecosystem.Qiansandao AR,an important AR project of Fishery Resource Restoration Program in Shandong Province,was built during 2002 to 2007.It has enhanced the local fishery harvest and generated positive economic benefits.Fat greenling(Hexagrammos otakii)is a major commercial reef fish in Qiansandao with high economic values.Its distribution characteristics need to be further studied.In this research,we studied the potential influence of environmental variables and distance from ARs on catch per unit effort(CPUE)and body length of fat greenlings.The results showed that the average body length of fat greenlings distributed within 10 m from ARs was longer than that of fat greenlings distributed more than 600 m away from ARs.Body length also increased with the increased salinity,while it declined as temperature increased.The probability of the presence of fat greenling increased when temperature was below 20℃,then it slightly decreased.CPUE decreased as the distance increased.Our results elucidate the potential effects of environmental variables and distance from ARs on the distribution of fat greenling,which may also be helpful to the distribution research of other reef fish species.展开更多
The persistence and habitability of coral reef islands in future extreme oceanographic conditions has received increasing attention in the recent decade,concerning that the sea level rise(SLR)and more frequent and int...The persistence and habitability of coral reef islands in future extreme oceanographic conditions has received increasing attention in the recent decade,concerning that the sea level rise(SLR)and more frequent and intense storms in the context of global climate change are expected to destabilize those islands.Here,we conduct a set of wave-flume laboratory experiments focusing on the morphodynamic change of reef islands to varying ocean forcing conditions(wave height and SLR).Subsequently,a phase-resolving XBeach numerical model is adopted to simulate the monochromatic wave process and its associated sediment dynamics.The adopted model is also firstly validated by laboratory experimental results as reported in this study.It is then used to examine the impacts of island morphological factors(island width,island height,island location and island side slope)on the island migration.The combined laboratory/physical and numerical experiment outputs suggest that reef islands can accrete vertically in response to the sea level rise and the increased storminess.展开更多
Qilianyu Islands coral reefs(QICR),located in the northeastern part of the South China Sea,has been affected by human activities and natural disturbance.To characterize the trophic structure,ecosystem properties and k...Qilianyu Islands coral reefs(QICR),located in the northeastern part of the South China Sea,has been affected by human activities and natural disturbance.To characterize the trophic structure,ecosystem properties and keystone species of this region,a food-web model for the QICR is developed using methods involving a mass-balance approach with Ecopath with Ecosim software.Trophic levels range from 1.00 for detritus and primary producers to 3.80 for chondrichthyes.The mean trophic transfer efficiency for the entire ecosystem is 13.15%,with 55%of total energy flow originating from primary producers.A mixed trophic impact analysis indicates that coral strongly impacts most components of this ecosystem.A comparison of our QICR model with that for other coral reef ecosystems suggests that the QICR ecosystem is immature and/or is degraded.展开更多
To solve the durability of island and reef concrete engineering in the harsh environment of high temperature,high salt,high humidity and windy,the strength grade of concrete and the type of corrosion inhibitor were us...To solve the durability of island and reef concrete engineering in the harsh environment of high temperature,high salt,high humidity and windy,the strength grade of concrete and the type of corrosion inhibitor were used as the influence factors,while the relative dynamic elastic modulus was used as the evaluation index.In addition,the law and time variability of the deterioration of concrete,the size effect,environmental similarity and the service life model were studied.The results showed that improving the strength grade of concrete could improve the durability of concrete,and corrosion inhibitor could slightly improve the durability of concrete.Time-varying law of the deterioration of concrete conformed to the univariate quadratic polynomial.Combined with the concrete damage equivalent theory,a size effect model based on the relative dynamic elastic modulus was proposed and verified,and the size effect coefficient was also given.An environmental similarity model between simulated and practical island and reef environment was proposed.Combined with the reliability theory and the first order second moment method,a new service life model of concrete structure was proposed.The authors were convinced that the research will be advantageous to researchers.展开更多
It is exceedingly important to estimate the stability of coral reefs. In recent years, growing construction projects have been carried out on the reef flat in the South China Sea. As a special marine geotechnical medi...It is exceedingly important to estimate the stability of coral reefs. In recent years, growing construction projects have been carried out on the reef flat in the South China Sea. As a special marine geotechnical medium, it is made of the reef debris underwent overwhelmingly long geological age. Reefs grow thickly on the carbonate platform after the Late Oligocene and have five to six main sedimentary facies. It can be used as a recorder to measure the occurrence time of recent earthquake. A model of reef body is presented to study the influence of earthquakes according to the geological structure characteristic of reefs in the Nansha Islands. Furthermore, Geo Studio is used to simulate stress and deformation situations within it under various earthquake intensities. A safety factor is calculated by the limit equilibrium method, and the possible scenarios of earthquake-induced landslides and sliding scale are defined with a Newmark sliding block method, as well as stress distribution and deformation behaviors. Therefore, the numerical results suggest that the connections between the coral reef and the earthquake are as follows：（1） the reef body has a good stability under self-gravity state;（2） after the earthquake, it may cause slope＇s instability and bring out slumping when the safety factor is smaller than 1（FS〈1）;（3） the safety factor decreases with the increasing earthquake intensity, and fluctuates around a particular value after a while;and（4） as a new developed part of the reef, the smaller shallow landslide will be easily subject to collapse caused by the earthquake. It is concluded that it is feasible to provide a reference for evaluating the stability of coral reef using a geotechnical engineering simulation method. This can help the engineering constructions in the South China Sea.展开更多
Reef limestone is a biogenic sedimentary rock widely distributed in coral reef areas, acting as an important foundation for coast construction. Due to its special biogenic origin, reef limestone is different from conv...Reef limestone is a biogenic sedimentary rock widely distributed in coral reef areas, acting as an important foundation for coast construction. Due to its special biogenic origin, reef limestone is different from conventional rocks both in terms of rock structure and mechanical properties. In this study, mesoscale uniaxial compression experiments with five different loading directions were conducted on two kinds of reef limestones from the Maldives Islands and the South China Sea, respectively. The real-time high-resolution videos and images of failure processes were recorded simultaneously to investigate the fracture evolution and fracture surface roughness of reef limestones. It demonstrated that the reef limestones belonged to extremely soft to soft rocks, and their uniaxial compressive strength (UCS) values fluctuated with high discreteness. The mesoscale mechanical properties of reef limestones were highly anisotropic and mainly controlled by pore structure. The occurrence of dissolution pores in reef limestone tended to intensify mechanical anisotropy. With the integration of the fracture initiation and propagation features of reef limestones, it is supposed that the intrinsic mechanism of anisotropy was probably attributed to the differences in coral growth direction and dissolution. Furthermore, the quantified fracture surface roughness was revealed to have a good consistency with density and UCS for the reef limestones from the South China Sea. The findings are helpful for providing theoretical and experimental references for engineering construction in coral reef areas.展开更多
Coral reefs of Ku Lao Cham Islands in the Central Vietnam were studied over a quarter of a century. It was established that the reefs of these Islands were lost after the Sangshen typhoon and a heavy flood, which happ...Coral reefs of Ku Lao Cham Islands in the Central Vietnam were studied over a quarter of a century. It was established that the reefs of these Islands were lost after the Sangshen typhoon and a heavy flood, which happened in 2006. As a result of these natural phenomena a significant part of coral populations was physically destroyed, and a powerful export of clay substances from the nearest Vietnamese coast and from the Bung River, flowing into the sea opposite the Islands, causing abundant sedimentation and death of almost all the remaining scleractinian corals. At present, where formerly there were coral reefs, now there is algal-alcyonarian stage of succession of reef communities. This is typical, as a rule, for restoration of reefs after a destructive typhoon effect.展开更多
Fringing the reefs of the island Tho Chu explored a quarter century later now reexamined in the Gulf of Thailand of the South China Sea. It was found that most of the reefs of the island were lost after the passage of...Fringing the reefs of the island Tho Chu explored a quarter century later now reexamined in the Gulf of Thailand of the South China Sea. It was found that most of the reefs of the island were lost after the passage of typhoon “Ketsana” accompanied by heavy rains and strong sea waves higher than 2 meters in October 2009. Because of these natural phenomena, physical destruction of much of the coral communities occurred. Removal of terrigenous sediments from the islands in the water has led to increased sedimentation and loss of almost all the scleractinian family Acroporidae, the main building corals on the reefs of the Indo-Pacific. At present, in places where once there was full-reef community succession is restoring the reef due to the survivors of the typhoon colonies of coral genera Pocillopora and Acropora.展开更多
文摘Under the background of vigorously developing facilities of island/reef in the world,the economic value and strategic significance of the island/reef have become increasingly important.Unfortunately,they may easily become the attacking target of missiles in the war time.Therefore,aiming at the damage quantification of the targets in the island/reef under the missile attacking,a macroscopic damage assessment model for the target area is proposed in this paper.The model focuses on the construction of the assessment model framework.Firstly,the analytic hierarchy process and the grey relational analysis are applied to measure the importance of each target in the region through four indicators of the target hazard,striking urgency,damage advantage and mission relevance,respectively.Secondly,based on the damage mechanism of shock wave and fragments to target,the corresponding damage model is established,and the damage grade of each target in the evaluated area is obtained according to the damage criteria and grading standard.Finally,the model obtains the overall damage grade of the target area by employing the fuzzy comprehensive evaluation method,with synthesizing the importance and the damage grade of each target.Through the verification of an example,it demonstrates the certain feasibility of the model and provides a certain basis and reference for the subsequent research.
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.
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The National High Technology Research and Development Program of China(863 Program)under contract No.2012AA12A406the National Natural Science Foundation of China under contract Nos 41471068,41171325,and J1103408+1 种基金the Program for New Century Excellent Talents in University under contract No.NCET-12-0264the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘A detailed survey of the reefs in the Nansha Islands＇ sea that are of strategic importance is conducive to their future development. In this study, a total of 50 Landsat 8 operational land imager（OLI） images were used to analyze the geological features and spectral characteristics of the Nansha reefs. The exposed islands/sandbanks,reef flats and sub-tidal reefs were identified with the near-infrared band, the red and green bands, and the blue band, respectively. Based on the relationships among various characteristics and bands illustrated in the OLI images, the maximum between-cluster variance threshold algorithm（OTSU method） and the mathematical morphology were employed to extract characteristic parameters of the spatial geometry of the reefs from top to bottom, which were subsequently operated by a series of post-processing methods such as vectorization,simplification and topological analysis. Among the 132 standalone reefs and 16 atolls that are identified in the study, four reefs have yet to be named in the Standard Names of Various Islands in the South China Sea and the website Nansha Islands Online（http：//www.nansha.org/）. Another 24 ones are exposed to the atmosphere even during high tides. Taiping Island with an area of 0.57 km^2 represents the largest exposed geological feature. This study demonstrated the applicability of medium-resolution satellite images to derive the coral reef information effectively and thus provided information for the related departments that are responsible to manage the coast.An improved resolution of multispectral bands with the panchromatic band in higher spatial resolution（15 m for OLI image） is expected to provide an optimum satellite based approach to map marine habitats.
基金Supported by the National Key Technology Research and Development Program(No.2013BAD13B06)the Financial Project of the Ministry of Agriculture(No.NFZX2013)+1 种基金the Special Scientific Research Funds for Central Non-profit Institutes,Chinese Academy of Fishery Sciences(Nos.2014TS18,2013ZD03)the National Agricultural Finance Project "South China Sea Fishing Information Dynamic Acquisition"
文摘A combination of traditional fish sampling methods(hand-line and gill net) and modern hydroacoustic techniques were used to study fish community structure,distribution,and diel movements of fish on Zhubi Reef to enhance understanding of the ecosystem.We collected 126 individuals from 29 species,20 genera,17 families,three orders,and two classes using traditional gear.Perciforms were the dominant group in terms of species richness and biomass.The acoustic data indicated that very small(target strength[TS],dB) <-60 dB) and small(-60 dB≤TS<-45 dB) fish contributed the most to abundance and species richness on the coral reef,and that the proportion of medium-sized(-45 dB≤TS<-35 dB) and largesized(-35 dB≤TS) fish increased gradually as depth increased.The single-target detection method revealed two distinct size classes during the day in the 12-16 and 16-20-m layers.One group consisted of very smallsized fish(TS<-60 dB) and the other consisted of medium and large-sized fish(TS>-55 dB).The number of single-target detections was significantly higher during the night than during the day(P<0.05).The singletarget TS frequency distribution during the day was significantly different than during the night at depths of4-8,8-12,12-16,and 16-20 m.Significant differences were observed among the 4-8,8-12,12-16,and16-20-m-depth layers during day and night.Diel vertical movement was evidenced as fish began to spread and move upward just before sunset and began to assemble and descend shortly(15 min) after sunrise.
文摘Based on the remote sensing information feature of Nansha coral islets and reefs that controlled by the Nansha Islands local area's goological structure and growth law, by means of mathematical model and PC, the Nansha Islands coral islets and reefs' top geological data' spatial distribution and local change trend are simulated by using the trend surface system on the remote sensing composite information, and an scientific interpretation and local comparison of Nansha coral islands and islets' spatial distribution feature are made.
基金The National Natural Science Foundation of China under contract No.41201328the Science Foundation for Young Scholars of China’s State Oceanic Administration under contract No.2013415
文摘Mapping regional spatial patterns of coral reef geomorphology provides the primary information to understand the constructive processes in the reef ecosystem. However, this work is challenged by the pixel-based image classification method for its comparatively low accuracy. In this paper, an object-based image analysis(OBIA)method was presented to map intra-reef geomorphology of coral reefs in the Xisha Islands, China using Landsat 8satellite imagery. Following the work of the Millennium Coral Reef Mapping Project, a regional reef class hierarchy with ten geomorphic classes was first defined. Then, incorporating the hierarchical concept and integrating the spectral and additional spatial information such as context, shape and contextual relationships, a large-scale geomorphic map was produced by OBIA with accuracies generally more than 80%. Although the robustness of OBIA has been validated in the applications of coral reef mapping from individual reefs to reef system in this paper, further work is still required to improve its transferability.
基金Supported by the National High Technology Research and Development Program of China(863 Program)(No.2012AA12A406)the National Natural Science Foundation of China(No.41271409)the National Science and Technology Major Project(No.00-Y30B15-9001-14/16-5)
文摘Coral reefs in the Xisha Islands （also known as the Paracel Islands in English）, South China Sea, have experienced dramatic declines in coral cover. However, the current regional scale hard coral distribution of geomorphic and ecological zones, essential for reefs management in the context of global warming and ocean acidification, is not well documented. We analyzed data from field surveys, Landsat-8 and GF-1 images to map the distribution of hard coral within geomorphic zones and reef fiat ecological zones. In situ surveys conducted in June 2014 on nine reefs provided a complete picture of reef status with regard to live coral diversity, evenness of coral cover and reef health （live versus dead cover） for the Xisha Islands. Mean coral cover was 12.5% in 2014 and damaged reefs seemed to show signs of recovery. Coral cover in sheltered habitats such as lagoon patch reefs and biotic dense zones of reef flats was higher, but there were large regional differences and low diversity. In contrast, the more exposed reef slopes had high coral diversity, along with high and more equal distributions of coral cover. Mean hard coral cover of other zones was 〈10%. The total Xisha reef system was estimated to cover 1 060 km2, and the emergent reefs covered -787 km2. Hard corals of emergent reefs were considered to cover 97 km2. The biotic dense zone of the reef flat was a very common zone on all simple atolls, especially the broader northern reef flats. The total cover of live and dead coral can reach above 70% in this zone, showing an equilibrium between live and dead coral as opposed to coral and algae. This information regarding the spatial distribution of hard coral can support and inform the management of Xisha reef ecosystems.
基金supported by the National Natural Science Foundation of China (Nos. 41672107, 41372119, 41440040)supports provided by the Marine Environmental Observation and Research Station at the Xisha Islands, the South China Sea Institute of Oceanology, CAS during the fieldwork
文摘Beach rock,which forms at the intertidal zone,is a natural barrier to protect beach and island from wave erosion. The formation mechanism of beach rocks is significant in the study of surface carbonate diagenesis and protection of island. Beach rocks in Qilian Islets and Cays were formed about 500–700 a BP,neither its composition nor sedimentary structure experienced intense post-reformation.Beach rocks in Qilian Islets and Cays are mainly composed of reef-building skeletal fragments and bioclasts without terrigenous sediments. This study focused on the types and morphologies of cements in beach rocks of Qilian Islets and Cays,and its cementation mechanisms and influencing factors. Biological activities,such as micritization caused by microbial activities and algae binding action,play an important role in the initial stage of bioclast transformation and promote the subsequent early marine and early meteoric cementation. Acicular aragonite induced by early marine cementation is well developed in beach rocks,especially in those samples from Medium Islet. Early meteoric cementation is not common as marine cementation,generally presenting granular and meniscus cements. The main factors affecting the formation and development of beach rocks in Qilian Islets and Cays include sediment source,hydrodynamic condition,climate,sea level change and anthropogenic impacts.
基金Supported by the National Key R&D Program of China(No.2018YFC1406503),the Scientifi c Research Foundation of Third Institutes of Oceanography“Fujian Provincial Station for Field Observation and Research of Island and Coastal Zone in Zhangzhou”(No.TIO 2019017)the National Natural Science Foundation of China(No.41976127)the China-ASEAN Maritime Cooperation Fund Project“Monitoring and Conservation of coastal ecosystems in the South China Sea”and“China-ASEAN Countries Collaboration on Marine Endangered Species Researches(MESR)”。
文摘Coral restoration is becoming popular to help restoring degraded coral reefs.However,few studies have tried to monitor the long-term recovery of coral reefs,which makes it diffi cult to assess the performance of the restoration.We monitored the growth of three transplanted Acropora corals and naturally-attached Pocillopora damicornis on artifi cial reefs(ARs)from October 2014 to September 2018 during which there were several attacks of typhoons.Results show that two staghorn Acropora species had the highest growth rates(11.0–12.1 cm/a),followed by table coral A.divaricate(5.6 cm/a)and P.damicornis(4.8 cm/a).A linear growth pattern was found for the three Acropora species;the pattern gradually slowed in P.damicornis.There was a strong interspecifi c competition for space among the corals on ARs,and it led to the sharply declined occurrence of slow-growing P.darmicornis colonies in 2017.Coral recovery was successful at the Wuzhizhou Island and quickly increased AR complexity.However,the ARs made of metal frames fail to resist the direct attack from a catastrophic typhoon.Therefore,concrete and environmentalfriendly materials should be used in future restoration.This study is the fi rst report on long-term monitoring and assessment of coral reef restoration in China.The results off er future guide of reef restoration for impaired coral reefs in regions easily aff ected by typhoons.
基金financially supported by the National Science and Technology Major Project (No. 2011ZX050 25-002-03)the Project of China National Offshore Oil Corporation (CNOOC) Limited (No. CCL2013ZJFNO729)the National Natural Science Foundation of China (No. 41530963)
文摘Based on the concentrations of the trace elements,rare earth elements(REE),and Sr isotopic compositions in reef carbonates from the well‘Xike-1’reef core of the Xisha Islands,the constraints on sediment provenance and paleoenvironment were defined.Variations of the terrigenous input into the paleoseawater were traced in detail and the paleoenvironment and sediment provenance were further investigated.The results show that the HREE/LREE values in the reef carbonates are negatively associated with their Th and Al concentrations;however,their Al and Th concentrations show positive correlation.The lowest 87 Sr/86 Sr values in the reef carbonates generally coincide with the lowest values of Al,Th concentrations and the highest values of HREE/LREE.These data indicate that the HREE/LREE,Al concentrations,and Th concentrations of the reef carbonates are useful indexes for evaluating the influence of the terrigenous inputs on the seawater composition in the study area.From top to bottom,the changing process of the HREE/LREE values and Al,Th concentrations can be divided into 6 intervals;they are H1(0–89.30 m,about 0–0.11 Myr),L1(89.30–198.30 m,about 0.11–2.2 Myr),H2(198.30–374.95 m,about 2.2–5.3 Myr),D(374.95–758.40 m,about 5.3–13.6 Myr),L2(758.40–976.86 m,about 13.6–15.5 Myr),and H3(976.86–1200.00 m,about 15.5–21.5 Myr).Moreover,the changing trend of the HREE/LREE values coincides with that of the seawater δ^13C values recorded by benthonic foraminiferal skeletons from the drill core of ODP site 1148 in the South China Sea(SCS),but not with that of the seawaterδ18O values.The high uplifting rates of the Qinghai-Tibet Plateau coincide with the high Th and Al concentrations and the low HREE/LREE values in the reef carbonates.These data indicate that the main factors controlling the changes of terrigenous flux in the SCS are the tectonic activities associated with Qinghai-Tibet Plateau uplifting and the variations of uplifting rates rather than paleoclimatic changes.
基金The National Science and Technology Major Project for Large Oil-Gas Fields and Coal-formed Gas Development under contract Nos 2008ZX05023 and 2011ZX05025-002the National Natural Science Foundation of China under contract Nos 49206061 and 41106064the National Basic Research Program(973 Program) of China under contract Nos 2012CB956004 and 2009CB219406
文摘Halimeda is one of the major reef-building algas in the middle Miocene of Xisha, and one of the significant reef-building algas in the algal reef oil and gas field of the South China Sea. However, there have been few reports regarding the characteristics of mineral rocks, reservoir porosity and permeability layers, and sedimentation-diagenetic-evolution of fossil Halimeda systems. The present paper briefly introduces the relevant studies on chlorophyta Halimeda and the research status of oil and gas exploration. Through the 1 043 m core of the Xichen-1 well, we studied the characteristics of the mineral rocks and porosity and permeability of the middle Miocene Halimeda of the Yongle Atoll, identified and described the segments of fossil Halimeda, and pointed out that most of the segment slides are vertical sections in ovular, irregular or long strips. The overwhelming majority of these fossil Halimeda found and studied are vertical sections instead of cross sections. In this paper, knowledge regarding the cross sections of fossil Halimeda is reported and proven to be similar with the microscopic characteristics of modern living Halimeda;fossil Halimeda are buried in superposition;it is shown that there are different structures present, including typical bio-segment structure, and due to its feature of coexisting with red alga, tying structure, twining structure and encrusting structure are all present;and finally, it is suggested to classify the fossil Halimeda into segment algal reef dolomites. In addition, all of the studied intervals are moderately dolomitized. Secondary microcrystalline-dolosparite dominates the original aragonite raphide zones, and aphanitic-micrite dolomite plays the leading role in the cortexes and medullas;in the aragonite raphide zones between medulla and cysts, secondary dissolved pores and intercrystalline pores are formed inside the segments, and algal frame holes are formed between segments;therefore, a pore space network system （dissolved pores＋intragranular dissolved pores—intercrystalline pores＋algal frame holes） is established. Segment Halimeda dolomite has a porosity of 16.2%–46.1%, a permeability of 0.203×10^–3–2 641×10^–3μm^2, and a throat radius of 23.42–90.43μm, therefore it is shown to be a good oil and gas reservoir. For the reasons mentioned above, we suggest building the neogene organic reef-modern reef sedimentation-diagenetic-evolution models for the Xisha Islands.
基金supported by Shandong Ocean and Fishery Department Funded Project ‘Experiment of the Ecological Simulation in the Alongshore Area of the Shandong Peninsula’
文摘Chinese government has provided vigorous financial supports to artificial reef(AR)projects to repair marine ecosystem.Qiansandao AR,an important AR project of Fishery Resource Restoration Program in Shandong Province,was built during 2002 to 2007.It has enhanced the local fishery harvest and generated positive economic benefits.Fat greenling(Hexagrammos otakii)is a major commercial reef fish in Qiansandao with high economic values.Its distribution characteristics need to be further studied.In this research,we studied the potential influence of environmental variables and distance from ARs on catch per unit effort(CPUE)and body length of fat greenlings.The results showed that the average body length of fat greenlings distributed within 10 m from ARs was longer than that of fat greenlings distributed more than 600 m away from ARs.Body length also increased with the increased salinity,while it declined as temperature increased.The probability of the presence of fat greenling increased when temperature was below 20℃,then it slightly decreased.CPUE decreased as the distance increased.Our results elucidate the potential effects of environmental variables and distance from ARs on the distribution of fat greenling,which may also be helpful to the distribution research of other reef fish species.
基金The National Natural Science Foundation of China under contract Nos 51979013 and 51909013the National Key Research and Development Program of China under contract Nos 2021YFC3100502 and 2021YFB2601105the Hainan Provincial Natural Science Foundation of China under contract No.421QN0978.
文摘The persistence and habitability of coral reef islands in future extreme oceanographic conditions has received increasing attention in the recent decade,concerning that the sea level rise(SLR)and more frequent and intense storms in the context of global climate change are expected to destabilize those islands.Here,we conduct a set of wave-flume laboratory experiments focusing on the morphodynamic change of reef islands to varying ocean forcing conditions(wave height and SLR).Subsequently,a phase-resolving XBeach numerical model is adopted to simulate the monochromatic wave process and its associated sediment dynamics.The adopted model is also firstly validated by laboratory experimental results as reported in this study.It is then used to examine the impacts of island morphological factors(island width,island height,island location and island side slope)on the island migration.The combined laboratory/physical and numerical experiment outputs suggest that reef islands can accrete vertically in response to the sea level rise and the increased storminess.
基金The National Key Research and Development Program of China under contract No.2018YFC1406502the National Natural Science Foundation of China under contract No.31902374+1 种基金the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)under contract No.GML2019ZD0605the Central Public-Interest Scientific Institution Basal Research Fund of Chinese Academy of Fishery Sciences under contract No.2020TD05.
文摘Qilianyu Islands coral reefs(QICR),located in the northeastern part of the South China Sea,has been affected by human activities and natural disturbance.To characterize the trophic structure,ecosystem properties and keystone species of this region,a food-web model for the QICR is developed using methods involving a mass-balance approach with Ecopath with Ecosim software.Trophic levels range from 1.00 for detritus and primary producers to 3.80 for chondrichthyes.The mean trophic transfer efficiency for the entire ecosystem is 13.15%,with 55%of total energy flow originating from primary producers.A mixed trophic impact analysis indicates that coral strongly impacts most components of this ecosystem.A comparison of our QICR model with that for other coral reef ecosystems suggests that the QICR ecosystem is immature and/or is degraded.
基金supported by the National Natural Science Foundation of China(Grant Nos.51878350 and 11832013).
文摘To solve the durability of island and reef concrete engineering in the harsh environment of high temperature,high salt,high humidity and windy,the strength grade of concrete and the type of corrosion inhibitor were used as the influence factors,while the relative dynamic elastic modulus was used as the evaluation index.In addition,the law and time variability of the deterioration of concrete,the size effect,environmental similarity and the service life model were studied.The results showed that improving the strength grade of concrete could improve the durability of concrete,and corrosion inhibitor could slightly improve the durability of concrete.Time-varying law of the deterioration of concrete conformed to the univariate quadratic polynomial.Combined with the concrete damage equivalent theory,a size effect model based on the relative dynamic elastic modulus was proposed and verified,and the size effect coefficient was also given.An environmental similarity model between simulated and practical island and reef environment was proposed.Combined with the reliability theory and the first order second moment method,a new service life model of concrete structure was proposed.The authors were convinced that the research will be advantageous to researchers.
基金The National Basic Research Program(973 Program)of China under contract No.2013CB956104the National Natural Science Foundation of China under contract No.41376063the Strategic Priority Research Program of the Chinese Academy of Sciences under contract No.XDA13000000
文摘It is exceedingly important to estimate the stability of coral reefs. In recent years, growing construction projects have been carried out on the reef flat in the South China Sea. As a special marine geotechnical medium, it is made of the reef debris underwent overwhelmingly long geological age. Reefs grow thickly on the carbonate platform after the Late Oligocene and have five to six main sedimentary facies. It can be used as a recorder to measure the occurrence time of recent earthquake. A model of reef body is presented to study the influence of earthquakes according to the geological structure characteristic of reefs in the Nansha Islands. Furthermore, Geo Studio is used to simulate stress and deformation situations within it under various earthquake intensities. A safety factor is calculated by the limit equilibrium method, and the possible scenarios of earthquake-induced landslides and sliding scale are defined with a Newmark sliding block method, as well as stress distribution and deformation behaviors. Therefore, the numerical results suggest that the connections between the coral reef and the earthquake are as follows：（1） the reef body has a good stability under self-gravity state;（2） after the earthquake, it may cause slope＇s instability and bring out slumping when the safety factor is smaller than 1（FS〈1）;（3） the safety factor decreases with the increasing earthquake intensity, and fluctuates around a particular value after a while;and（4） as a new developed part of the reef, the smaller shallow landslide will be easily subject to collapse caused by the earthquake. It is concluded that it is feasible to provide a reference for evaluating the stability of coral reef using a geotechnical engineering simulation method. This can help the engineering constructions in the South China Sea.
基金supported by the National Natural Science Foundation of China(Grant Nos.41977248 and 42207219)the Key Research Program of the Institute of Geology and Geophysics,Chinese Academy of Sciences(CAS)(Grant No.IGGCAS-201903).
文摘Reef limestone is a biogenic sedimentary rock widely distributed in coral reef areas, acting as an important foundation for coast construction. Due to its special biogenic origin, reef limestone is different from conventional rocks both in terms of rock structure and mechanical properties. In this study, mesoscale uniaxial compression experiments with five different loading directions were conducted on two kinds of reef limestones from the Maldives Islands and the South China Sea, respectively. The real-time high-resolution videos and images of failure processes were recorded simultaneously to investigate the fracture evolution and fracture surface roughness of reef limestones. It demonstrated that the reef limestones belonged to extremely soft to soft rocks, and their uniaxial compressive strength (UCS) values fluctuated with high discreteness. The mesoscale mechanical properties of reef limestones were highly anisotropic and mainly controlled by pore structure. The occurrence of dissolution pores in reef limestone tended to intensify mechanical anisotropy. With the integration of the fracture initiation and propagation features of reef limestones, it is supposed that the intrinsic mechanism of anisotropy was probably attributed to the differences in coral growth direction and dissolution. Furthermore, the quantified fracture surface roughness was revealed to have a good consistency with density and UCS for the reef limestones from the South China Sea. The findings are helpful for providing theoretical and experimental references for engineering construction in coral reef areas.
文摘Coral reefs of Ku Lao Cham Islands in the Central Vietnam were studied over a quarter of a century. It was established that the reefs of these Islands were lost after the Sangshen typhoon and a heavy flood, which happened in 2006. As a result of these natural phenomena a significant part of coral populations was physically destroyed, and a powerful export of clay substances from the nearest Vietnamese coast and from the Bung River, flowing into the sea opposite the Islands, causing abundant sedimentation and death of almost all the remaining scleractinian corals. At present, where formerly there were coral reefs, now there is algal-alcyonarian stage of succession of reef communities. This is typical, as a rule, for restoration of reefs after a destructive typhoon effect.
文摘Fringing the reefs of the island Tho Chu explored a quarter century later now reexamined in the Gulf of Thailand of the South China Sea. It was found that most of the reefs of the island were lost after the passage of typhoon “Ketsana” accompanied by heavy rains and strong sea waves higher than 2 meters in October 2009. Because of these natural phenomena, physical destruction of much of the coral communities occurred. Removal of terrigenous sediments from the islands in the water has led to increased sedimentation and loss of almost all the scleractinian family Acroporidae, the main building corals on the reefs of the Indo-Pacific. At present, in places where once there was full-reef community succession is restoring the reef due to the survivors of the typhoon colonies of coral genera Pocillopora and Acropora.
