Weizhou Island Research Articles

Phosphorus dynamics in volcanic soils of Weizhou Island, China: implications for environmental and agricultural applications

The dynamics of phosphorus are intricately governed by geological and ecological processes. Examining phosphorus dynamics in volcanic islands can enhance our comprehension of its behavior within such unique geological systems. However, research on phosphorus dynamics in volcanic islands remains limited. We investigated the phosphorus content of volcaniclastic rocks and basalt soils from Weizhou Island, China, to understand the influencing factors on phosphorus dynamics. The results indicate that in the volcaniclastic profile, phosphorus concentrates at 20–40 cm (17 mg/kg), decreases at 40–60 cm (11.9 mg/kg), and increases at 80–200 cm up to 46.4 mg/kg proximate to the bedrock, for the basalt profile, phosphorus content increases from the surface (80.2 mg/kg) towards the bedrock (83.9 mg/kg). The differences in phosphorus distribution between volcaniclastic rocks and basalts reflect the influence of parent material, rock weathering degree, carbonate content, topographic elevation, sea level changes, and geological activities. A strong positive correlation (R = 0.96907) between total and available phosphorus has been observed, suggesting that total phosphorus content effectively predicts available phosphorus content. Volcaniclastic rocks in wharves and high-elevation areas show low total phosphorus, while forest land with dense vegetation and neutral to alkaline soil supports higher total phosphorus due to enhanced bioavailability for plant absorption and utilization. Overall, the basalt soil of the volcanic island Weizhou Island demonstrates superior long-term fertility compared to the volcaniclastic soil. Despite its low total phosphorus content, it mainly exists in a highly bioavailable form, facilitating plant absorption, which is crucial for enhancing agricultural yields and ecosystem restoration on volcanic islands.

Late-Holocene ecosystem dynamics on Weizhou Island, China: A pollen and historical record of climate change and anthropogenic disturbances

Understanding the mechanisms behind landscape diversity changes on islands, particularly due to historical human interventions, remains a critical challenge in paleoecology. This study addresses this gap by utilizing over 160 pollen samples combined with multi-proxy data and historical records to reconstruct the late-Holocene ecological and environmental dynamics of Weizhou Island, China, over the last 1400 years. Our analyses reveal the evolution of ecosystem diversity and vegetation succession amid climatic fluctuations and anthropogenic pressures, identifying four distinct phases of transformation: (1) A warm and dry climate from 1400 to 850 cal yr BP fostering a savanna ecosystem; (2) A shift to a North subtropical seasonal rainforest under a more humid climate between 850 and 210 cal yr BP, with increased vegetation diversity; (3) The initiation of agriculture and aquaculture, along with a cooler climate from 210 cal yr BP to 1970 CE, marked by human-induced landscape alterations; and (4) A significant transformation from a once-diverse ecosystem to artificial protective forests from 1970 CE to the present. By correlating environmental indicators with historical accounts across eight Chinese dynasties, our study provides detailed insights into the climatic and human factors shaping the island's history. The findings demonstrate that while climatic shifts are primary drivers of biodiversity changes, anthropogenic disturbances also play a significant role. This research underscores the resilience of ecosystems to both climatic and human pressures and emphasizes the importance of integrating historical context into environmental studies.

Ultrasound-assisted extraction of phenolics from Sargassum carpophyllum - A kinetics study.

The species of the brown macroalgal genus Sargassum are distributed globally and contain many bioactive compounds. In this study, ultrasound-assisted extraction (UAE) was applied to obtain phenolic compounds with strong antioxidant activity from Sargassum carpophyllum collected along the coastline of Weizhou Island in the South China Sea. The influence of different variables such as the solid-liquid ratio (1:5-1:30 g · mL-1), ultrasonic power (160-280 W), duty circle ratio (DCR, 1/3-1/1), and ethanol concentration (30% to ~90%) were studied using a single factor design. The extraction kinetics were investigated using the Peleg model and second-order kinetics model, and the second-order model described the extraction procedure better than the Peleg model. Total phenol content (TPC) values of 3.316, 2.964, 2.741, and 3.665 mg phloroglucinol (PHG) · g-1 algae were achieved at a higher solid-liquid ratio (1:30 g · mL-1), higher ultrasonic power (280 W), a higher DCR (1/1), and a moderate ethanol concentration (50%), respectively. However, a slightly different result was observed in the extract obtained, with total phenol contents (TPCextract) of 52.99, 65.00, 46.22, and 55.10 mg PHG · g-1 extract and DPPH radical scavenging activity (IC50) of 0.096, 0.066, 0.131, and 0.136 mg extract · mL-1 observed at 50% ethanol, 1:5 g m· mL-1, 2/3 DCR, and 200 W respectively. All variables studied influenced the extraction kinetics by altering the extraction rate and the TPC at equilibrium. As for the bioactivities in the extract, a larger solid-liquid ratio and greater ultrasonic power may not contribute because of their ability to extract non-phenolic components simultaneously, leading to reduced overall bioactivities. The results of the present study provide essential information for future UAE process design and optimization for extracting phenolics from S. carpophyllum through mathematical modeling and could be regarded as important reference for obtaining value-added products from other macroalgae species.

Splendidivirga corallicola gen. nov., sp. nov. and Agaribacillus aureus gen. nov., sp. nov., two bacteria isolated from coral Porites lutea, and proposal of Splendidivirgaceae fam. nov.

The Bacteroidota is one of the dominant bacterial phyla in corals. However, the exact taxa of those coral bacteria under the Bacteroidota are still unclear. Two aerobic, Gram-stain-negative, non-motile rods, designated strains BMA10T and BMA12T, were isolated from stony coral Porites lutea collected from Weizhou Island, PR China. Global alignment of 16S rRNA gene sequences indicated that both strains are closest to species of Fulvivirga with the highest identities being lower than 93 %, and the similarity value between these two strains was 92.3 %. Phylogenetic analysis based on 16S rRNA gene and genome sequences indicated that these two strains form an monophylogenetic lineage alongside the families Fulvivirgaceae, Reichenbachiellaceae, Roseivirgaceae, Marivirgaceae, Cyclobacteriaceae, and Cesiribacteraceae in the order Cytophagales, phylum Bacteroidota. The genomic DNA G+C contents of BMA10T and BMA12T were 38.4 and 41.9 mol%, respectively. The major polar lipids of BMA10T were phosphatidylethanolamine, unidentified aminophospholipid, four unidentified aminolipids, and five unidentified lipids. While those of BMA12T were phosphatidylethanolamine, two unidentified aminolipids, and five unidentified lipids. The major cellular fatty acids detected in both isolates were iso-C15 : 0 and C16 : 1 ω5c. Carbohydrate-active enzyme analysis indicated these two strains may utilize coral mucus or chitin. Based on above characteristics, these two strains are suggested to represent two new species in two new genera of a new family in the order Cytophagales, for which the name Splendidivirga corallicola gen. nov., sp. nov., Agaribacillus aureus gen. nov., sp. nov. and Splendidivirgaceae fam. nov. are proposed. The type strain of S. corallicola is BMA10T (=MCCC 1K08300T=KCTC 102045T), and that for A. aureus is BMA12T (=MCCC 1K08309T=KCTC 102046T).

Organophosphate esters (OPEs) in corals of the South China Sea: Occurrence, distribution, and bioaccumulation

Organophosphate esters (OPEs) have garnered significant attention in recent years. In view of the enormous ecosystem services value and severe degradation of coral reefs in the South China Sea, this study investigated the occurrence, distribution, and bioaccumulation of 11 OPEs in five coral regions: Daya Bay (DY), Weizhou Island (WZ), Sanya Luhuitou (LHT), Xisha (XS) Islands, and Nansha (NS) Islands. Although OPEs were detected at a high rate, their concentration in South China Sea seawater (1.56 ± 0.89 ng L−1) remained relatively low compared to global levels. All OPEs were identified in coral tissues, with Luhuitou (575 ± 242 ng g−1 dw) showing the highest pollution levels, attributed to intense human activities. Coral mucus, acting as a defense against environmental stresses, accumulated higher ∑11OPEs (414 ± 461 ng g−1 dw) than coral tissues (412 ± 197 ng g−1 dw) (nonparametric test, p < 0.05), and their compositional characteristics varied greatly. In the case of harsh aquatic environments, corals increase mucus secretion and then accumulate organic pollutants. Tissue-mucus partitioning varied among coral species. Most OPEs were found to be bioaccumulative (BAFs >5000 L kg−1) in a few coral tissue samples besides Triphenyl phosphate (TPHP). Mucus' role in the bioaccumulation of OPEs in coral shouldn't be ignored.

섬 관광의 지속가능성에 관한 연구

Purpose: Achieving a balance between development and conservation for sustainability in island tourism destinations necessitates a profound understanding of tourists' perspectives. This research aims to assess how tourists perceive the social, environmental, and economic sustainability aspects, often referred to as the Triple Bottom Line.&#x0D; Methods: Utilizing the Martilla &amp; James Importance-Performance Analysis (IPA), with Deng's modifications, this study focuses on Chinese domestic tourists with experience in Weizhou Island in China. Through convenience sampling, data were collected via online surveys from November 1 to November 7, 2023, resulting in 300 valid responses for final analysis.&#x0D; Results: The revised IPA technique revealed that, from the tourist's standpoint, effective management of tourism products and services, especially souvenir prices and transportation costs, at an appropriate level is crucial. Tourists emphasize the need for prioritized attention to achieve this. Furthermore, while tourists generally rate the economic value creation through dominant island tourism positively, concerns arise regarding excessive dependence on tourism in both industry and regional economies.&#x0D; Conclusion: This study highlights two key academic implications. Firstly, it emphasizes that although similar factors contribute to the pursuit of sustainability, tourists' evaluations may vary depending on specific attributes. Secondly, evaluating sustainability from the perspective of external stakeholders, such as tourists, holds significance.

Molecular phylogenetic classification of scleractinian corals from Weizhou Island, China

Abstract Scleractinian corals play important roles in the maintenance and restoration of coral systems. However, the evolutionary relationships among species remain unclear, mostly due to the limitations of traditional coral classifications because of their ecophenotypic variation and morphological plasticity. Thus, here we aimed to reconstruct the phylogenetic relationships of corals through single- and multi-gene analyses based on 116 colonies (14 families and 49 species) from Weizhou Island, China, and five molecular markers (CO1, 16S rRNA, 12S rRNA, H3, and ITS). The results reveal four cryptic species (Platygyra pini, Platygyra verweyi, Psammocora nierstraszi, and Coscinaraea columna). In single-gene analyses, mitochondrial genes can classify taxa at the family but not genus level, and vice versa for nuclear genes. Species are divided into complex and robust corals based on multi-gene analysis. Within robust corals, Merulinidae (Group XVII) is classified into eight subclades, and Dipsastraea, Favites, and Goniastrea are polyphyletic. Complex corals comprise the monophyletic Acroporidae (VI), Agariciidae (VII), Euphylliidae (V), Porites (III), and Dendrophylliidae (II). Notably, Turbinaria peltata is highly divergent from its congeners and clusters. Multi-gene analysis proved to be more accurate than single-gene analysis in elucidating phylogenetic relationships among corals. This study enhances our understanding of the diversity, evolution, and conservation of corals from Weizhou Island.

Microbulbifer litoralis sp. nov., Isolated from Seashore of Weizhou Island.

A bacterium designated GXH0434T was isolated from sea shore samples collected from Weizhou Island, Beihai, Guangxi, China. The organism is motile, strictly aerobic, and possesses a rod-coccus cell cycle in association with the growth phase. It can grow at 15-45°C (optimum 37°C), at pH 6.0-11.0 (optimum 6.0), and at 0-20% (w/v) NaCl (optimum 5.0-8.0%). The strain is positive for peroxidase and oxidase activity, negative for Voges-Proskauer test, can hydrolyze Tween 20, Tween 60, Tween 80, casein, and is able to produce siderophore and has the function of nitrogen fixation. Molecular phylogenetic analysis based on 16S rRNA gene sequences indicated that GXH0434T was most closely related to Microbulbifer halophilus KCTC 12848T with the similarity of 97.2%, followed by Microbulbifer chitinilyticus JCM 16148T (97.1%) and Microbulbifer taiwanensis LMG 26125T (96.5%). The digital DNA-DNA hybridization and the average nucleotide identity values between GXH0434T and Microbulbifer halophilus KCTC 12848T were 28.90% and 83.38%, respectively, which were below thresholds of species delineation. The genomic DNA G+C content of the strain was 61.9%. The major fatty acids were iso-C15:0, C16:0, iso-C11:0 3-OH, iso-C11:0 and Summed features 8 (C18:0 ω7c and/or C18:0 ω6c). The major polar lipids detected in GXH0434T were diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), phosphatidylcholine (PC). The major respiratory quinone was ubiquinone Q-8. Based on the above polyphasic classification indicated strain GXH0434T represents a novel species of the genus Microbulbifer, for which the name Microbulbifer litoralis sp. nov. is proposed. The type strain is GXH0434T (= MCCC 1K07158T = KCTC 92169T).

Heat-tolerant intertidal rock pool coral Porites lutea can potentially adapt to future warming.

The growing threat of global warming on coral reefs underscores the urgency of identifying heat-tolerant corals and discovering their adaptation mechanisms to high temperatures. Corals growing in intertidal rock pools that vary markedly in daily temperature may have improved heat tolerance. In this study, heat stress experiments were performed on scleractinian coral Porites lutea from subtidal habitat and intertidal rock pool of Weizhou Island in the northern South China Sea. Thermotolerance differences in corals from the two habitats and their mechanisms were explored through phenotype, physiological indicators, ITS2, 16S rRNA, and RNA sequencing. At the extremely high temperature of 34°C, rock pool P. lutea had a stronger heat tolerance than those in the subtidal habitat. The strong antioxidant capacity of the coral host and its microbial partners was important in the resistance of rock pool corals to high temperatures. The host of rock pool corals at 34°C had stronger immune and apoptotic regulation, downregulated host metabolism and disease-infection-related pathways compared to the subtidal habitat. P. lutea, in this habitat, upregulated Cladocopium C15 (Symbiodiniaceae) photosynthetic efficiency and photoprotection, and significantly increased bacterial diversity and coral probiotics, including ABY1, Ruegeria, and Alteromonas. These findings indicate that rock pool corals can tolerate high temperatures through the integrated response of coral holobionts. These corals may be 'touchstones' for future warming. Our research provides new insights into the complex mechanisms by which corals resist global warming and the theoretical basis for coral reef ecosystem restoration and selection of stress-resistant coral populations.

Pelagibacterium flavum sp. nov., Isolated from Soil Sample.

A Gram-stain-negative, yellow, moist and circular, aerobic, motile, and rod-shaped bacterium, designated YIM 151497T, was isolated from soil sample collected from Blue-Bridge, Weizhou Island, Guangxi province, China. Classification using a polyphasic approach suggested that strain YIM 151497T belonged to the genus Pelagibacterium, and was closely relevant to Pelagibacterium nitratireducens JLT2005T (98.8%), Pelagibacterium halotolerans CGMCC 1.7692T (98.7%), Pelagibacterium lixinzhangensis H64T (98.1%), and Pelagibacterium luteolum CGMCC 1.10267T (97.1%). The growth ranges of temperature, pH, and NaCl were 4-40℃, pH 4.0-10.0, and 0-7% NaCl, respectively. It was positive for catalase and oxidase. The primary respiratory quinone was Q-10. The elemental fatty acids were Summed Feature 8 (constituting C18:1ω7c and/or C18:1ω6c), C19:0 cyclo ω8c, C16:0, and C18:1ω7c 11-methyl. The major polar lipids were phosphatidylglycerol, diphosphatidylglycerol, and three unidentified glycolipids. The DNA G+C content based on the complete genome sequence was 60.7mol%. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) between strain YIM 151497T and species of Pelagibacterium were in the ranges of 73.9-86.3% and 19.7-31.3%, respectively. The Average Amino Acid Identity (AAI) between strain YIM 151497T and species of Pelagibacterium were in the ranges of 68.8-88.8%. On the basis of these data, strain YIM 151497T is considered to represent a novel species of the genus Pelagibacterium with the name of Pelagibacterium flavum sp. nov. Type strain is strain YIM 151497T (= KCTC 49826T = CGMCC 1.61521T = MCCC 1K08053T).

Creating Sustainable Artistic Homestay: Approaches to Design Weizhou Island into an Ideal Tourist Attraction Homestay

This article explores the development of sustainable artistic homestays in Weizhou Island, China, a burgeoning tourist destination rich in cultural and ecological heritage. In this study, a narrative review method is employed, which involves a comprehensive examination of existing literature, focusing on several key themes: sustainable tourism, homestay development, infrastructure challenges, and ecological conservation. By synthesizing insights from a wide range of scholarly articles, books, and reports, this narrative review aims to provide a holistic understanding of the factors influencing the development of sustainable artistic homestays in the context of Weizhou Island. It assesses the current state of homestays, identifying key challenges such as environmental sustainability, cultural erosion, and economic viability. The article proposes innovative strategies for sustainable development, emphasizing ecological conservation, cultural preservation, and community involvement. It also discusses the potential benefits of these homestays, including promoting local arts, fostering cultural exchange, and generating economic opportunities for residents. The findings suggest that a balanced approach, combining sustainable practices with cultural authenticity, can transform Weizhou Island into an exemplary sustainable tourist attraction, setting a benchmark for similar destinations worldwide.

Study on the Community of Extant Microgastropod Mollusks among Different Types of the Coast of Weizhou Island, China

Study on the Community of Extant Microgastropod Mollusks among Different Types of the Coast of Weizhou Island, China

Thermal bleaching in the northern South China Sea: impact of abnormal environment and climate on high-latitude coral reefs.

Extensive coral bleaching events can result in catastrophic degradation of coral reefs and reorganization of coral communities. In the present study, we analyzed the spatial differences in coral bleaching and possible reasons of large-scale coral bleaching, based on the results of a survey carried out in the northern South China Sea in 2020. In addition, we have continuously monitored the sea surface temperature (SST) of the northernmost Weizhou Island for more than six years. The living coral cover at Weizhou Island (W), Xuwen Nature Reserve (X), and Haihua Island (H) was relatively high at 24.6% ± 4.8%, 12.1% ± 3.8%, and 8.1% ± 2.6%, respectively, whereas their bleaching rates were 9.7% ± 2.6%, 9.7% ± 3.3%, and 6.9% ± 2.1%, respectively. Among them, the living coral cover of W was significantly different from those of X and H, whereas the bleaching rate was not significantly different among the three areas. In all three areas, the massive and encrusting corals predominate and exhibit relatively high bleaching rates, with Porites lutea and Bernardpora stutchburyi being the dominant species. In addition, the temperature monitoring results of Weizhou Island for six consecutive years showed that the critical SST of coral bleaching was 31.5 ℃. The monitoring results also showed that the average SST of Weizhou Island was 32.1 ℃, exceeding 32 ℃ in July 2020 for up to 533h. The longest continuous time when the SST exceeded 32 ℃ was 97h. These findings indicated that the coral bleaching event that occurred in the Beibu Gulf during 2020 was a large-scale and high-temperature transient event that presented a relatively homogeneous threat to the coral communities. We inferred that this sudden heat stress event was caused by the enclosed tidal current in the Beibu Gulf, which prevented the southern upwelling from reaching the north, as well as by the inability of the SST to decrease without rainfall caused by typhoon cyclones. Our findings suggested that abnormal heat waves can result in coral bleaching at high latitudes and even coral reef degradation. Furthermore, our study provides a new perspective for investigating the self-recovery and reorganization of coral communities following accumulated coral bleaching.

The first baleen whale marine protected area proposed for Bryde's whales in the Beibu Gulf, China

AbstractThe establishment of marine protected areas (MPAs) for cetaceans is an important strategy to mitigate human disturbance and protect biodiversity. Despite abundant cetacean species, there are only a few MPAs dedicated to cetacean conservation in China, all of which are for inshore dolphins. Bryde's whales, the only nearshore baleen whale population in mainland China, are conflicting with intensive human activities, yet an effective conservation strategy is lacking. This study used species distribution models to analyze distribution patterns and suitable habitats of Bryde's whales in the Beibu Gulf and proposes the first baleen whale MPA in China. Our results showed Bryde's whales have a seasonal distribution pattern in the Beibu Gulf, and that the waters around Weizhou Island and the southeastern coast of Vietnam were their core habitats. The seasonal nighttime light data indicated a negative relationship between the number of ship lights and Bryde's whale sightings and suggest that Bryde's whales might be threatened by fisheries. We proposed an MPA based on the results, suggesting that the waters within 20 km around Weizhou Island should be declared a protected area. Furthermore, we recommend that anthropogenic activities in the waters around Weizhou Island are better managed to reduce negative impacts on marine life.

Exposure to pentachlorophenol destructs the symbiotic relationship between zooxanthellae and host and induces pathema in coral Porites lutea

Stress from chemical pollutants is among the key issues that have adverse impacts on coral reefs. As a persistent organic pollutant, pentachlorophenol (PCP) has been detected in the seawater of Weizhou Island and was proved to have significant adverse effects on aquatic animals. However, little is known about its effects on scleractinian coral. Therefore, we investigated the response of the coral Porites lutea to PCP stress. Coral bleaching, photosynthesis parameters and antioxidant enzyme activities of P. lutea under PCP exposure were documented. After 96 h of exposure, significant tissue loss and bleaching occurred when the PCP concentration exceeded 100 μg/L. The density of symbiotic zooxanthellae decreased from 2.06 × 106 cells/cm2 to 0.93 × 106 cells/cm2 when the PCP concentration increased from 1 μg/L- 1000 μg/L. Long-term exposure of 120 days to PCP at 0.1 μg/L also led to coral bleaching, the maximum photochemical quantum yield of PSII in P. lutea nubbins significantly decreased to 0.482. The analysis of microbial community distribution indicated that the increase of the pathogenic bacterium Citrobacter may be one of the inducers of coral bleaching. Conjoint analysis of transcriptomics and proteomics showed that the metabolism of amino acids and carbohydrates in zooxanthellae was abnormal, leading to the destruction of its symbiotic relationship with the host. The immune system of the host was disrupted, which could be linked to the prevalence of coral pathema. The toxic responses of PCP on both zooxanthellae and its host were further confirmed by the upregulation of the differential metabolites including 1-naphthylamine and phosphatidylcholine, etc.

Cumulated influence of natural and anthropogenic drivers on surface seawater barium: Evidence from a high-resolution coral record in the northern South China Sea

Barium (Ba) plays a crucial role as a tracer element in elucidating essential marine biogeochemical processes. However, the limited knowledge regarding Ba sources and variations impedes our comprehension of the diverse array of processes occurring in the marine environment. Although coral Ba/Ca ratios have demonstrated potential as a tracer of oceanic Ba, there remains a scarcity of long-term and high-resolution records to fully utilize this technique. Here, we presented a 32-year record of monthly coral Ba/Ca ratios and δ18O from the Weizhou Island in the northern South China Sea to elucidate the sources and the influence factors on surface seawater Ba. The results indicated no significant correlation between coral Ba/Ca and sea surface temperature or growth rate, implying that coral Ba/Ca ratios could serve as a dependable proxy for surface seawater Ba concentrations. Significant increases and abrupt fluctuations in coral Ba/Ca ratios were observed during the period of oil drilling exploration and engineering construction, indicating that anthropogenic activities might lead to an elevation of surface seawater Ba levels, subsequently affecting coral Ba/Ca ratios. The winter coral Ba/Ca peaks on monthly timescales were confirmed to be caused by resuspended sediment driven by the winter monsoon. Extreme peaks of coral Ba/Ca occurring during the wet season demonstrated the potential of coral Ba/Ca to record tropical cyclones, which has not been found in low-resolution scale studies. The continuous, long-term, and high-resolution coral Ba/Ca time series provides compelling evidence for the combined influence of both natural and anthropogenic factors on seawater Ba concentrations. These findings significantly contribute to the comprehension of the intricate biogeochemical cycling of marine Ba.

Ecological challenges on small tourist islands: A case from Chinese rural island

AbstractThe expansion of the global tourism market has accelerated the development of small tourist islands. The rapid growth of tourist scale and activity intensity poses a potential threat to the fragile ecosystems of small islands. This article focuses on the ecological stresses small tourism islands face in their development. Compared with similar studies, we found a more flexible way to measure ecological stress of current activities. We show a framework for ecological stress assessment on small rural islands and illustrate it with Weizhou Island, China. It reveals a new approach to combining ecological footprint, geographic data, and visitor activity data. This combination enables a spatial linkage between biophysical and social surveys. To verify the validity of the assessment framework, we assessed the spatial distribution of ecosystem loss on the island using habitat quality. A multi‐scale geographically weighted model describes the spatial correlation between ecological stress and habitat quality. Real‐world application cases were used to test the usability and practical use of the policy assessment framework. We provide methodological and application‐based contributions to support the sustainable development of small tourist islands. Overall, the assessment framework offers a reliable solution for systematically collecting, analyzing, and reporting ecological stresses faced by small tourist islands.

Applications of Environmental DNA (eDNA) in Monitoring the Endangered Status and Evaluating the Stock Enhancement Effect of Tropical Sea Cucumber Holothuria Scabra.

The tropical sea cucumber Holothuria scabra is naturally found in the Indo-West Pacific. However, due to their commercial value, natural H. scabra populations have declined significantly in recent years, resulting in its status as an endangered species. Surveys of H. scabra resource pose a challenge due to its specific characteristics, such as sand-burrowing behavior. To overcome this problem, our study established a convenient and feasible method for assessing H. scabra resources using environmental DNA (eDNA) monitoring technology. First, H. scabra-specific TaqMan primers and probe were designed based on its cox1 gene, followed by the development of an eDNA monitoring method for H. scabra in two separate sea areas (Xuwen and Daya Bay). The method was subsequently employed to investigate the distribution of H. scabra and assess the effects of aquaculture stock enhancement through juvenile releasing in the Weizhou Island sea area. The H. scabra eDNA monitoring approach was found to be more appropriate and credible than traditional methods, and a positive impact of stocking on H. scabra populations was observed. In summary, this is the first report to quantify eDNA concentration in a Holothuroidea species, and it provides a convenient and accurate method for surveying H. scabra resources. This study introduces novel concepts for eDNA-based detection of endangered marine benthic animals and monitoring their population distribution and abundance.

Optimized spatial and temporal pattern for coral bleaching heat stress alerts for China's coral reefs

Most studies on coral bleaching alerts use common Degree Heating Week (DHW) thresholds; however, these may underestimate historical patterns of heat stress for coral reef ecosystems. Taking an optimized DHW threshold for coral bleaching alerts for Coral Reef Watch (CRW) and Coral Reef Temperature Anomaly Database (CoRTAD) products, we analyzed the precise spatial and temporal pattern of heat stress on China's coral reefs from 2010 to 2021 in the South China Sea (SCS) and the Beibu Gulf (BG). We compared acute heat stress using common and optimized thresholds. Results indicated that the ocean warming rate in 2010–2021 was approximately 0.43 ± 0.22 °C/10a, showing a significant increase in the northern SCS and the BG. More severe bleaching events were predicted by the optimized thresholds and the high-frequency areas were mainly in the northern SCS. The number and intensity of years with severe heat stress anomalies was in the order 2020 > 2014 > 2010 > 2015. Heat stress duration was the longest in the Xisha Islands among offshore archipelagos, and longest in 2020–2021 in Weizhou Island in BG in the relative high-latitude inshore reefs. These abnormal events were mainly caused by El Niño, but La Niña was also involved in 2020.

Two New Cembranoids from the Chinese Soft CoralSarcophyton boettgeri.

Two new cembranoids, namely sarcoboettgerols D and E, together with four known related ones, have been isolated from the soft coral Sarcophyton boettgeri collected from Weizhou Island in the South China Sea. Their structures including absolute configurations were elucidated by extensive spectroscopic analysis, quantum mechanical nuclear magnetic resonance methods, time-dependent density functional theory-electronic circular dichroism calculations, as well as comparison with the reported data in the literature. A plausible biogenetic relationship of four cembranoids was proposed. In bioassays, sarcomililatin B exhibited cytotoxic activity against H1299 cell (IC50 = 35.0 μM), whereas sarcomililatin B and sarcomililatin A displayed moderate antibacterial activities (MIC 17.4-34.8 µg/mL).