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Using satellite-observed data and reanalysis data, we studied the spatiotemporal variation characteristics and dynamic mechanisms of thermal fronts in the Beibu Gulf (TFIBG). TFIBG occur in December, reach their strongest point in January in the following year, and then gradually weaken until they completely disappear in May. Their formation is related to the bathymetry of the Beibu Gulf. In winter, the seawater in shallow-water areas (deep-water areas) cools down more (less), and Ekman currents concurrently transport warm water from the central basin of the Beibu Gulf to the west coast, which results in the formation of a thermal front at the junction of cold and warm water. The interannual variation in TFIBG intensity is related to the northeast monsoon. The strengthened (weakened) Ekman current caused by the northeast monsoon transports more (less) warm water from the central basin of the Beibu Gulf to the west coast, forming a strong (weak) thermal front at the junction of cold and warm water on an interannual scale. The upward trend of TFIBG intensity may be related to the regional heterogeneity of climate warming. This research systematically studied TFIBG, which will help improve people's understanding of the thermal front in the South China Sea (SCS). [ABSTRACT FROM AUTHOR]

Background: Laji-He is a traditional rice-based snack from the Beibu Gulf region in southern China. In the Beibu Gulf region, "Laji-He" (literally "garbage He") signifies the removal of toxins from the body, making it a truly "green" food. Laji-He holds essential cultural and medicinal value, incorporating various medicinal plants into its preparation. Despite its local importance, there is limited scientific documentation on the ethnobotanical properties and cultural relevance of the plants used. This study aims to analyze the medicinal plant used in Laji-He and its implication in human medicine. Methods: Ethnobotanical surveys and interviews were conducted in the Beibu Gulf region, covering local markets and communities. Voucher specimens were collected and identified for each plant collected, using botanical references, while the relative frequency of citation index was used to assess the cultural importance of each plant. Additionally, the medicinal properties of these plants were categorized based on traditional Chinese medicinal theory and modern pharmacological literature. A detailed review of historical texts and local chronicles was also performed to trace the historical development and cultural changes of Laji-He. Results: A total of 63 medicinal plants from 36 families and 53 genera were documented, with Rubiaceae, Fabaceae, and Lamiaceae being the most frequently represented families. The most commonly used plants, such as Paederia foetida, Piper sarmentosum, Houttuynia cordata, Centella asiatica, and Morus alba, were primarily utilized for their heat-clearing, detoxifying, and wind-dampness expelling properties. Laji-He serves as a symbol of cultural identity and community cohesion, particularly during traditional festivals and family gatherings, reinforcing collective memory and local heritage. Conclusions: Laji-He is a traditional functional snack, with the plants used in its preparation serving as both food and medicine. Preserving and promoting the culture of Laji-He can contribute to enhancing food security and sovereignty at both the local and national levels. [ABSTRACT FROM AUTHOR]

To enhance urban resilience to climate change in the future, this study quantitatively assesses the climate carrying capacity of the Beibu Gulf Urban Agglomeration (BGUA) in the Guangxi Zhuang Autonomous Region from 2000 to 2020 and in a future projected study from 2021 to 2060. The data used includes real-time data from the National Meteorological Observatory, prediction data from the National Climate Center's global climate model BCC-CSM2-MR under different Shared Socioeconomic Pathways (SSP2-4.5 and SSP5-8.5), and socio-economic development data. The assessment is conducted using four criteria dimensions: climate natural capacity (CNC), extreme climate event pressure (ECP), urban climate pressure (UCP), and urban coordinated development capacity (UCC). The results indicate that from 2000 to 2020, there was a significant interannual fluctuation in the CNC and ECP in the BGUA. The UCP and the UCC showed an increasing trend, while the overall climate-carrying capacity of the BGUA showed a fluctuating decrease. It is estimated that the climate carrying capacity will exhibit a non-significant decreasing trend from 2021 to 2060, with the capacity in the period from 2021 to 2040 generally higher than that in the period from 2041 to 2060 and the SSP2-4.5 scenario higher than the SSP5-8.5 scenario overall. Currently and in the future, the climate-carrying capacity of the BGUA is primarily influenced by normal climate conditions and extreme events such as strong winds and temperature extremes. With the passage of time, climate instability will increase. Under the planned implementation of China's carbon peak and carbon neutrality pathway, the rate of increase in the capacity for coordinated urban development is expected to surpass the rate of increase in urban climate pressure. Industrial production and energy consumption are the main drivers of future urban climate pressure growth. [ABSTRACT FROM AUTHOR]

Copyright of South China Fisheries Science is the property of South China Fisheries Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Based on the observation data from the coastal island stations in Beibu Gulf and the fifth generation ECMWF reanalysis (ERA5) data, the probability of occurrence of mixed-type (that is, high-pressure rear type to southwest inverted trough type) sea fog processes in Beibu Gulf is analyzed. Furthermore, the typical mixed-type sea fog process from 15 March to 23 March 2016 is selected for in-depth analysis. The results show the following: (1) Compared with other types of sea fog processes, the probability of occurrence of the mixed-type sea fog processes was the highest during 2015-2020, with a cumulative number of 15 times (58 days), accounting for 34.9% (39.5%). (2) The typical mixed-type sea fog process from 15 March to 23 March 2016 was characterised by long duration and wide range. In the early stage, the Beibu Gulf was influenced by the easterly flow behind the high pressure entering the sea. In the later period, the plateau trough developed and moved eastward, which guided the warm and humid south-western airflow to expand inland, and the easterly airflow gradually turned to the southerly airflow at the edge of the south-west inverted trough in Beibu Gulf. (3) In terms of thermal conditions, the strong warm and humid transport of the low-level jet stream increased the specific humidity over the Beibu Gulf, and then the water vapour saturated layer extended from the near-surface layer to 800 hPa on the one hand. It also contributed to the establishment of the temperature inversion layer on the other hand. And the inversion layer cooperated with the high humidity region below to reach a stable state. As for the dynamical conditions, the wind shear in the vertical direction maintained a certain intensity, which was favourable to the turbulent mixing in the boundary layer. The cooperation of the wind shear with the baroclinic atmosphere was the configuration that favoured the maintenance of a stable layer in the low-layer. In addition, the weak upward motion below 800 hPa was conducive to water vapour uplift and condensation in the low-layer, which promoted the development and maintenance of the sea fog. (4) During the occurrence of the typical mixed-type sea fog, the air temperature was mostly higher than the sea surface temperature in each sea area. And the difference between the air temperature and sea surface temperature in the early stage (late stage) was between 0 and 1.5 ℃ (1.5 and 2.5 ℃).

The dinoflagellate genus Heterocapsa includes several widely distributed and potentially toxic species associated with Harmful Algal Blooms (HABs), particularly affecting the Western Pacific Ocean. To reveal the biodiversity of Heterocapsa in Beibu Gulf, six strains were morphologically characterized using light and scanning electron microscopy, while large subunit rDNA (LSU rDNA) and internal transcribed spacer (ITS) were sequenced for phylogenetic analysis through maximum likelihood and Bayesian inferences. Two strains (BGERL169, BGERL170) were identified as Heterocapsa philippinensis ribotype I, three (BGERL171-BGERL173) as a new Heterocapsa philippinensis ribotype II, and one strain (BGERL174) as Heterocapsa pseudotriquetra. Cells of H. philippinensis were ovoid to spherical, yellowish-brown, with reticulate chloroplasts, and had a sausage-shaped nucleus positioned longitudinally along the dorsal side of the cell, and the theca was arranged in Po, cp, X, 5′, 3a, 7″, 6c, 5s, 5‴, 2⁗. Additionally, BGERL169 and BGERL171 showed no hemolytic toxicity in rabbit erythrocyte lysis assays. To the best of our knowledge, this research provides the first morphological and phylogenetic analysis of H. philippinensis, including the identification of a new ribotype, as well as the discovery of H. pseudotriquetra in Chinese waters. The findings contribute to the understanding of Heterocapsa species biogeography and toxicity in Chinese waters, offering valuable data for future HAB monitoring in Beibu Gulf. [ABSTRACT FROM AUTHOR]

The ecological function of land use is the basis for developing an ecological civilization and realizing sustainable development. This paper may help guide the coordination of economic development and ecological development in China's coastal border areas. Based on theoretical analysis, this paper studies the spatiotemporal evolution of the functional spaces and the ecological function transitions of land use in the Beibu Gulf Economic Zone (BGEZ) by analyzing patterns, processes, and factors by applying eco-environmental quality index, grid subdivision, kriging interpolation, barycenter model, and Geodetector. This paper constructs a theoretical framework of ecological function transitions of land use based on the research idea of "system-pattern-process-factor", and carries out empirical research. Some conclusions can be drawn as follows: (1) The ecological space in the BGEZ has continuously decreased, converting mainly into agricultural production space and industrial-mining production space. The production space has expanded slowly. The area of living space in the BGEZ has increased rapidly. (2) The ecological function of land use in the BGEZ has continued to weaken, especially in the southern part of the BGEZ. The "high - sub-high" quality zones of ecological function are retreating to the north. (3) There were more deterioration transition areas than optimization transition areas of ecological function in the BGEZ. The former were mostly located in the central and southern urbanized areas of the BGEZ, whereas the latter were mostly located in the edge zones of district and county units. (4) As for the driving factors of the deterioration transitions of land use ecological function in the BGEZ, the significant trend of "de-ecologization" of the land cover/land use structure was the dominant driving factor; the interactions among the "natural-socioeconomic-managerial" systems were the main recessive factor. The natural system played a fundamental role, and the driving force of natural factors was the strongest. The industrialization, urbanization, and GDP increment in the socioeconomic system and the policy positioning of development intensity in the managerial system played a significant role. The interactions among natural factors, road construction, and industrial non-agricultural transformation had a "fuze" effect on stimulating driving forces. [ABSTRACT FROM AUTHOR]

This study analyzed the horizontal and vertical distribution characteristics of temperature and salinity in the central and eastern regions of the Beibu Gulf, based on conductivity measurements in summer 2022, temperature, and depth (CTD) measurement data from the Sino–Vietnamese cooperative project "Demonstration Study on Ecological Protection and Management in Typical Bays: Seasonal Survey of the Beibu Gulf". Furthermore, the study utilized the computational results from the numerical Finite-Volume Coastal Ocean Model (FVCOM) to elucidate the intrinsic patterns that formed the temperature and salinity distribution characteristics in August 2022 from both thermodynamic and dynamic perspectives. The circulation in the Beibu Gulf drives external seawater to move northward from the bay mouth. During this movement, numerous upwelling areas are created by lateral Ekman transport. The formation of different scales of cyclonic and anticyclonic vortices and current convergence zones is influenced by topography, runoff, and the water flux from the Qiongzhou Strait, which are key factors in the formation of upwelling and downwelling. The surface circulation in August 2022 significantly differed from the 20-year average surface circulation, with an influx of 1.15 × 104 m3/s more water entering the Beibu Gulf compared to the multi-year average. The water flux from the Qiongzhou Strait is a critical factor affecting the circulation patterns in the Beibu Gulf. The northeastern waters of the Beibu Gulf are characterized by current convergence zones, where extensive upwelling occurs. The rich nutrient salts in these areas promote the reproduction and growth of phytoplankton and zooplankton, making this the most favorable ecological environment in the Beibu Gulf and serving as a natural reserve for fisheries, coral reefs, dugongs, and Bryde's whales. [ABSTRACT FROM AUTHOR]

Based on observation analysis and numerical simulation, this study reveals that the spring land-sea thermal contrast between Yun-Gui Plateau and Beibu Gulf has a significant triggering impact on the variations of South China Sea summer monsoon onset dates (SCSSMOD) at the interannual timescale. The March–April thermal contrast with warm Yun-Gui Plateau and cold Beibu Gulf results in an anomalous low-level anticyclone over the western North Pacific, which in turn causes the active convection in the tropical western Pacific via the friction convergence. This active convection persists into May and moves northward towards the South China Sea. It subsequently excites an anomalous low-level cyclone in situ via the Matsuno-Gill mechanism. Then, the western Pacific subtropical high is tending to retreat eastward and the westerly wind anomalies occupy the South China Sea, promoting an early SCSSMOD. When the thermal contrast reverses, the SCSSMOD is inclined to be late. The effects mentioned above are independent of ENSO, indicating an effective indicator for monitoring and predicting the SCSSMOD at the interannual timescale. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of Soil & Water Conservation is the property of Bulletin of Soil & Water Conservation Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Invertebrates can store carbon (C), nitrogen (N), phosphorus (P), and other elements in their body tissues at theoretically homeostatic rates, thus playing an important role in the biogeochemical cycle of aquatic ecosystems. To sustain homeostasis, consumers must either balance their resource supply or adjust their stoichiometric features in response to environmental changes. However, there is limited understanding regarding potential differences in the ecological stoichiometric characteristics of marine invertebrates. To explore the ecological stoichiometric characteristics of marine invertebrates, the C, N, P, calcium (Ca), d13C, and d15N contents of 18 invertebrate species were analyzed from the Beibu Gulf. The results revealed that the ranges of elemental variations (C, N, and P) in invertebrates were 25.17%-47.34%, 6.14%-14.13%, and 0.26%- 1.31%, respectively. The content of P in invertebrates exhibited the most significant variation, leading to alterations in C:P and N:P ratios. A significant negative correlation was observed between P content and body weight in invertebrates (p < 0.01). Furthermore, the C and N content of invertebrates were significantly negatively correlated with d13C (p < 0.01), suggesting that the variations in C content and N content in invertebrates are influenced by different food sources, while P content varies according to body size. Our results also indicated significant interspecific differences in the ecological stoichiometry of invertebrates from the Beibu Gulf (p < 0.05). Invertebrate growth may be inhibited by P, and they do not maintain strict homeostasis, with stable homeostasis observed in higher trophic levels. [ABSTRACT FROM AUTHOR]

Spring circulation in the Beibu Gulf remains an underinvestigated research topic. Model results validated by observations reveal that the northern and southern parts of the Beibu Gulf are controlled by an enclosed cyclonic gyre and a cyclonic gyre, respectively, while in the vertical, the circulation at the surface differs from those in the middle and deep layers. Contrary to that of the classical view, the modeled Qiongzhou Strait (QS) current flows eastward during some days in spring. This eastward current has an occurrence proportion of 29.3-55.4%, and its longest duration period is 7~18 d. The average current in the QS in spring is approximately westward except in some typical years. In spring, the northern Beibu Gulf is affected by the cold water mass (CWM), which is depicted by the 12°C and 10°C isolines in strong and weak years, respectively. Sensitivity experiments show that the heat flux is dominant in the northern Beibu Gulf via the effect of the CWM, and the monsoon wind favors the formation of the cyclonic gyre. Conversely, the cyclonic gyre in the southern Beibu Gulf is jointly driven by the monsoon wind and heat flux, with the effect of the monsoon wind being more significant. The current off the northern coast of Vietnam (VNC) can be either northeastward or southwestward in spring in different years. The VNC is mainly controlled by the elevation gradient along the northern coast of Vietnam, and the Coriolis force, horizontal advection, and vertical diffusion also play significant roles. Additionally, the CWM is mainly controlled by the heat flux whereas the monsoon wind plays a secondary role. And the VNC, current in the QS, CWM, and cyclonic gyre jointly affect nutrient distributions in the northern Beibu Gulf. [ABSTRACT FROM AUTHOR]

Beibu Gulf is an important semi-enclosed bay located in the northwestern South China Sea, and is famous for its high bio-productivity and rich bio-diversity. The fast development along the Beibu Gulf Economical Rim has brought pressure to the environment, and algal blooms occurred frequently in the gulf. In this study, surface water samples and micro-plankton samples (20-200 µm) were collected in the northern Beibu Gulf coast. Diversity and distribution of eukaryotic planktonic microalgae were analyzed by both metabarcoding and microscopic analyses. Metabarcoding revealed much higher diversity and species richness of microalgae than morphological observation, especially for dinoflagellates. Metabarcoding detected 144 microalgal genera in 8 phyla, while microscopy only detected 40 genera in 2 phyla. The two methods revealed different microalgal community structures. Dinoflagellates dominated in microalgal community based on metabarcoding due to their high copies of 18 s rRNA gene, and diatoms dominated under microscopy. Altogether 48 algal bloom and/or toxic species were detected in this study, 34 species by metabarcoding and 19 species by microscopy. Our result suggested a high potential risk of HABs in the Beibu Gulf. Microalgal community in the surface water samples demonstrated significantly higher OTU/species richness, alpha diversity, and abundance than those in the micro-plankton samples, although more HAB taxa were detected by microscopic observations in the micro-plankton samples. Furthermore, nano-sized taxa, such as those in chlorophytes, haptophytes, and chrysophyceans, occurred more abundantly in the surface water samples. This study provided a comprehensive morphological and molecular description of microalgal community in the northern Beibu Gulf. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) in semi-enclosed gulfs are influenced by physical and biochemical processes, which haven’t been well understood. This study aims to investigate the spatial distribution and vertical profiles of dissolved PAHs in the Beibu Gulf (BG) and adjacent waters of the South China Sea, along with hydrological, meteorological, and biochemical variables. Particularly relevant are the effects of atmospheric pressure, salinity, ammonium, chlorophyll-a, as well as riverine inputs (RI), sea currents, and upwelling. In surface seawater, the total concentrations of eight dissolved PAHs (∑8PAHs) were 7.76 ± 2.16 ng/L, with a distribution pattern of western Guangdong waters (WGWs) > BG > Qiongzhou Strait (QS). ∑8PAHs in the northern BG (9.10 ± 2.00 ng/L) was significantly higher than that in the southern BG (6.65 ± 1.54 ng/L) (p < 0.01), suggesting that local anthropogenic activities and unique environmental characteristics significantly influenced PAHs distribution. In water column, PAHs in BG displayed enrichment in surface and bottom but decreased in medium water, while those in WGWs and QS decreased with increasing depth. Source apportionment concluded that PAHs in QS and WGWs were primarily from petroleum sources, and PAHs in BG were mainly from coal combustion. RI, combined with circulation, coastal current, and intrusion of SCS water influenced the surface PAHs distribution in BG, with eddy impacts observed. Specifically, regarding the surface PAHs distribution, differences in atmospheric pressure may influence the air-sea exchange of PAHs, especially positively affecting 4-ring PAHs. Salinity factors further corroborated the contribution of RI to 3-ring PAHs, followed by the regulation of PAHs through biological pumps (ammonia and chlorophyll-a). Moreover, upwelling-induced biodegradation and resuspension affected the vertical distribution of PAHs. While most PAHs posed a negligible risk, coking-generated fluorene posed a moderate risk to ecosystems due to changes in the energy structure, warranting further investigation into its toxicological impacts.

Simple Summary: A new interspecific backcross ([(Crassostrea hongkongensis ♀ × C. gigas ♂) ♂ × C. hongkongensis ♀]) variety was bred by the South China Sea Institute of Oceanology and named "South China No. 1". This study aims to explore the effects of stocking density on the growth performance of "South China No. 1", and compare the growth performance and genetic diversity to that of C. hongkongensis in Beibu Gulf. The results showed that oysters bred under a stocking density of 20 oysters/substrate had better growth manifestation. It was found that the shell height and total weight of "South China No. 1" cultured in Fangchenggang were significantly higher than that of those in Beihai and Qinzhou from September 2018 to November 2018. In addition, the shell height and shell width of "South China No. 1" were significantly higher than that of C. hongkongensis. In the Hardy–Weinberg equilibrium test, for the seven populations and ten microsatellites, in 10 of the 70 groups, the segregation distortion was significant. These results suggest that a stocking density of 20 oysters/substrate can promote the shell height, shell width and total weight of "South China No. 1". Fangchenggang is a suitable place to cultivate the "South China No. 1" breed according to the total weight and sum of all algal genus abundances. Crassostrea hongkongensis is an economically important bivalve found in various parts of the South China Sea. A new interspecific backcross ([(Crassostrea hongkongensis ♀ × C. gigas ♂) ♂ × C. hongkongensis ♀]) variety was bred by the South China Sea Institute of Oceanology which named "South China No. 1". This study aims to explore the effects of stocking density on the growth performance of "South China No. 1", compared their growth performance and genetic diversity to C. hongkongensis, and found the best place breeding site for "South China No. 1" in Beibu Gulf. The results showed that stocking a density of 20 oysters/substrate can significantly increase the shell height, shell width, total weight, survival rate, daily shell height gain and daily body mass gain. It was found that the shell height and total weight of "South China No. 1" cultured in Fangchenggang were significantly higher than that of those in Beihai and Qinzhou from September 2018 to November 2018. Similarly, the shell width of oysters in Fangchenggang and Qinzhou was also significantly higher in September 2018, and the interaction between site and stocking density had significant effects on the shell width in March 2018 and November 2018. In addition, the shell height and shell width of "South China No. 1" were significantly higher than that of C. hongkongensis in all three sites. At all three sites, the phytoplankton community structure was mostly dominated by Bacillariophyta. In the Hardy–Weinberg equilibrium test, for the seven populations and ten microsatellites, in 10 of the 70 groups, the segregation distortion was significant. These results suggest that a stocking density of 20 oysters/substrate can promote the shell height, shell width and total weight of "South China No. 1" in Beibu Gulf, China. "South China No. 1" has better growth performance compared with C. hongkongensis. Fangchenggang is a suitable place to cultivate the "South China No. 1" breed according to the total weight and sum of all algal genus abundances. The results of this study can be used as a reference to further understand the stocking density and genetic diversity of the "South China No. 1" breed in Beibu Gulf, China. [ABSTRACT FROM AUTHOR]

Using shallow-water buoy observations, reanalysis data, and numerical models, this study analyzes the variations in sea temperature and significant wave height (SWH) caused by two sequential tropical cyclones (TCs) 'Lionrock' and 'Kompasu' in October 2021 in the northeast Beibu Gulf, South China Sea. The results show that the sea surface temperature (SST) cooling of the nearshore waters was larger than the offshore water in the basin of the gulf, with the cooling amplitude and rate decreasing and the cooling time lagging behind wind increasing from coast to offshore. The near-surface temperature at the buoy station had a maximum decrease of 2.8 °C after 'Lionrock', and the decrease increased slightly to 3 °C after the stronger wind of 'Kompasu'. The total decrease of 4.6 °C indicates that the sequential TCs had a superimposed effect on the cooling of the Beibu Gulf. The heat budget analysis revealed that the sea surface heat loss and the Ekman pumping rate in the nearshore waters during 'Kompasu' (−535 W/m2 and 5.8 × 10−4 m/s, respectively) were significantly higher than that (−418 W/m2 and 4 × 10−4 m/s) during 'Lionrock'. On the other hand, the SST cooling (−1.2 °C) during the second TC is smaller than (−1.6 °C) the first weaker TC in the gulf basin, probably due to the deepening of the mixed layer. During the observation period, the waves in the Beibu Gulf were predominantly wind-driven. The maximum SWHs reached 1.58 m and 2.3 m at the bouy station near shore during the two TCs, and the SWH variation was highly correlated to the wind variation with a correlation of 0.95. The SWH increases from the nearshore to offshore waters during the TCs. The SAWN and ARCIRC coupled model results suggest that wave variations in the Beibu Gulf are primarily influenced by water depth, bottom friction, and whitecapping. Two days after the TCs, sea surface cooling and high waves appeared again due to a cold air event. [ABSTRACT FROM AUTHOR]

Marine water quality significantly impacts human livelihoods and production such as fisheries, aquaculture, and tourism. Satellite remote sensing facilitates the predictions of large-area marine water quality without the need for frequent field work and sampling. Prediction of diffuse attenuation coefficient (Kd), which describes the speed at which light decays as it travels through water, obtained from satellite-derived ocean color products can reflect the overall water quality trends. However, current models inadequately explore the complex nonlinear features of Kd, and there are difficulties in achieving accurate long-term predictions and optimal computational efficiency. This study innovatively proposes a model called Remote Sensing-Informer-based Kd Prediction (RSIKP). The proposed RSIKP is characterized by a distinctive Multi-head ProbSparse self-attention mechanism and generative decoding structure. It is designed to comprehensively and accurately capture the long-term variation characteristics of Kd in complex water environments while avoiding error accumulation, which has a significant advantage in multi-dataset experiments due to its high efficiency in long-term prediction. A multi-dataset experiment is conducted at different prediction steps, using 70 datasets corresponding to 70 study areas in Hangzhou Bay and Beibu Gulf. The results show that RSIKP outperforms the five prediction models based on Artificial Neural Networks (ANN, Convolutional Neural Networks (CNN), Gated Recurrent Unit (GRU), Long Short-Term Memory Recurrent Neural Networks (LSTM-RNN), and Long Short-Term Memory Networks (LSTM)). RSIKP captures the complex influences on Kd more effectively to achieve higher prediction accuracy compared to other models. It shows a mean improvement of 20.6%, 31.1%, and 22.9% on Mean Absolute Error (MAE), Mean Square Error (MSE), and Mean Absolute Percentage Error (MAPE). Particularly notable is its outstanding performance in the long time-series predictions of 60 days. This study develops a cost-effective and accurate method of marine water quality prediction, providing an effective prediction tool for marine water quality management. [ABSTRACT FROM AUTHOR]

Highlights: What are the main findings? The commercial small pelagic fishes (Decapterus maruadsi and Trachurus japonicus) in the Beibu Gulf were still miniaturizing. Fisheries management, characterized by reduced fishing efforts, cannot completely restore population structure in a short period. What are the suggestions for the future fisheries development in the Beibu Gulf? Continuing to maintain low fishing mortality and increasing the catchable length should be the key ways to achieve fishery resource conservation and recovery. Simple Summary: Decapterus maruadsi and Trachurus japonicus, as the main commercial small pelagic fish in the coastal fisheries of China, have been facing the threat of population decline due to overfishing. In this work, we assessed the population status of two commercial small pelagic fish stocks in the Beibu Gulf (in the South China Sea) over the past 15 years (2006–2020). The analysis results show that the commercial small pelagic fishes in the Beibu Gulf were still miniaturizing, and fisheries management characterized by reduced fishing efforts cannot completely restore population structure in a short period. Continuing to maintain low fishing mortality and increasing the catchable length should be the key ways to achieve fishery resource conservation and recovery. Our findings will provide a key scientific basis for future improvements in offshore fisheries management. Long-term variations in population structure, growth, mortality, exploitation rate, and recruitment pattern of two major commercial small pelagic fishes (CSPFs) (Decapterus maruadsi and Trachurus japonicus) are reported based on bottom trawl survey data collected during 2006–2020 in the Beibu Gulf, South China Sea. All individuals collected during each sampling quarter over a period of 15 years were subjected to laboratory-based analysis. In this study, the stock of D. maruadsi and T. japonicus inhabiting the Beibu Gulf was assessed using length-based methods (bootstrapped electronic length frequency analysis (ELEFAN)) to complete stock assessment in different fishery management periods (the division of fisheries management periods was based on China's input and output in the South China Sea offshore fisheries over 15 years, specifically divided into period I (2006–2010), period II (2011–2015), and period III (2016–2020)). The results showed that the mean body length, dominant body size, and estimated asymptotic length of two CSPFs decreased, whereas their growth coefficient decreased, indicating miniaturization and slower growth, respectively. Estimated exploitation rates and catching body length for two CSPFs indicated that both stocks in the Beibu Gulf were overexploited in period I and moderately exploited after 2011. These stocks were taking a good turn in status in period III, with the exploitation rate much lower than the initial period and reversing the downward trend in catching body length. Furthermore, the variations in the spawning season of the two CSPF stocks and their barely satisfactory expected yield indicated the complexity of the current fishery management in the Beibu Gulf. These results suggest that management measures to reduce fishing pressure may have a positive influence on the biological characteristics of those CSPFs in the Beibu Gulf; however, the stock structure already affected by overfishing will be a huge challenge for the conservation and restoration of fisheries resources in the future. Given that the current stocks of D. maruadsi and T. japonicus in the Beibu Gulf still have low first-capture body length (Lc) and high fishing mortality (F) (compared to F0.1), we identify a need to refine population structure by controlling fishing efforts and increasing catchable size, and more consideration should be given to the local fishery resource status in fisheries management. [ABSTRACT FROM AUTHOR]

The 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. [ABSTRACT FROM AUTHOR]

The geochemical characteristics of a 2.1 m BBW25 core, collected from the Beibu Gulf, have been investigated in terms of the major and trace elements, organic matter, and CaCO3 and AMS 14C dating by XRF, ICP-OES, ICP-MS, and more. We have found through previous research that there are issues with unclear delineation of sedimentary evolution environments and inexact responses between chemical weathering intensity and major paleoclimate events in the Beibu Gulf. The AMS 14C dating results indicate that the sedimentary age at the bottom was 19.24 ky b.p. CaCO3, δ13C, C/N, and Sr/Ba indexes show a sedimentary environment change from terrestrial to marine environments and a "jump" of ~4000 years in continent–ocean changes. The evolution of the sedimentary environment of Beibu Gulf was divided into three environments and five sub-environments. The changes in chemical weathering intensity indicators recorded by the CIX and the Fe/Al ratio respond well to the East Asian monsoon cycle, the meltwater events, and the alternation of cold and warm events. This study explains the chemical weathering intensity and sedimentary environment in the BBW25 core by geochemical characteristics and further reveals the paleoenvironmental characteristics and possible driving mechanisms over the past ~20,000 years. [ABSTRACT FROM AUTHOR]

Mangrove forest is a critical primary producer, biological habitat, and carbon sink in the subtropical-tropical coast zone, and the natural variation of mangrove coverage deserves study for a better understanding of the dynamics of mangrove coastal evolution. In this study, multispectral Landsat images from 1985 to 2018 are used to reconstruct the change in the coverage of mangrove (dominant species is Aegiceras corniculatum) and salt marsh (dominant species is Cyperus malaccensis) in the Nanliu River estuary. Tidal flat elevation measuring and 210Pb dating is used to study the substrate elevation when mangroves first colonize salt marsh. Historical temperature records, river discharge records, and the time series N/P concentration in sediment are analyzed. It is found that the mangrove forests have expanded rapidly in salt marsh since the mid-1980s. The change in factors such as accommodation space, cold event frequency, and nutrient supply cannot explain the origin of mangrove expansion. A low river discharge episode lasting for 8 years since 1986 is considered to have triggered the mangrove expansion in this area, as previously established salt marsh plants died due to germination restriction caused by high salinity and mangroves colonized the salt marsh habitat during this period. This case proves again that estuarine wetlands are very sensitive to salinity variation. [ABSTRACT FROM AUTHOR]

Tidal flats are an important part of coastal wetland systems and play an irreplaceable role in maintaining the health of global coastal ecosystems, resisting natural coastal disasters, and sequestering blue carbon. For the coastal zone around Beibu Gulf, where tidal flats are densely distributed, the spatiotemporal characteristics of tidal flats evolution and its key driving factors remain unclear. This article took the Beibu Gulf as the study area, and constructed an integrated tidal flats extraction algorithm of “maximum spectral index composite (MSIC) + Otsu algorithm (OTSU) + DEM correction” based on the cloud computing platform of Google Earth Engine to realize a large-scope and high-accuracy automatic extraction of tidal flats. The results discovered that 1) the tidal flats extraction method proposed in this study has high accuracy, with the overall accuracy of the confusion matrix reaching 93.9%, and the Kappa coefficient reaching 0.82. The user accuracy and mapping accuracy of the tidal flats are both greater than 85%. 2) In 35 years, the total tidal flats area of the Beibu Gulf has decreased by 683.9 km2, a reduction of 29%, and the average annual rate of change was −19.5 km2/a. 3) The fragmentation state of the tidal flats in Beibu Gulf intensified with time, and the natural driving forces of the tidal flats were mainly the rise in sea level, decrease in the amount of sediment in the river entering the sea, and expansion of mangrove trees. Human-driven forces were mainly coastal economic development and offshore aquaculture.

Small and medium-sized mountain rivers have characteristics of short processes, rapid flow rates, and quick responses to extreme weather, thereby playing an important role in the global marine geochemical cycle. Understanding the changes in water and sediment characteristics of small and medium-sized rivers in response to extreme weather can provide scientific support for disaster prevention and mitigation and channel management of river basins. This study analyzed data from the past 60 years to understand the variations in the characteristics of water and sediment in the Qinjiang River of the Beibu Gulf under extreme weather conditions by estimating their variation coefficients and contribution rates. The results of the analyses show the following: (1) The Qinjiang River has an average discharge of 32 and 290 m3/s in normal and tropical cyclone weather conditions, respectively. During a tropical cyclone year, the average flow rate is 9.06 times that during normal weather. The average sediment transport rates during normal weather and tropical cyclones are 0.05 × 104 and 1.15 × 104 t, respectively, wherein the latter is 23 times higher. (2) The average flow rates during normal weather and flood periods are 375 and 2,725 m3/s, respectively; the latter is 7.27 times higher. The average sediment transport rates in normal weather and flood period are 0.07 × 104 and 1.14 × 104 t, respectively, wherein the latter is 16.28 times higher. (3) The average annual contribution rates of tropical cyclones and floods to the runoff and sediment discharge of the Qinjiang River are 10.75% and 20.95% and 16.75% and 30.07%, respectively. Extreme weather contributes significantly to the variations in the water and sediment characteristics of the Qinjiang River. During extreme weather, the Qinjiang River exhibits a surge of water and sediment with inter-annual variations. The peaks of runoff and sediment transport during the transit of tropical cyclones tend to decrease gradually over the years, probably because of the reduction in the impact of their activities. The Qinjiang River is located in the South China Sea. The under construction western land-sea new passage grand project, namely the Pinglu Canal, will provide access to the Beibu Gulf along the Qinjiang River. The results of this study will provide scientific support for the disaster prevention and mitigation of the Pinglu Canal and the construction of the port.

The Beibu Gulf is one of the biodiversity hotspots in the global marine ecosystem, and an important fishing ground of East Asia. In the past several decade years, multiple pressures including overfishing, habitats destruction, pollution and eutrophication, and non-native species have seriously threaten the biodiversity of fish in the Beibu Gulf. However, the information about fish fauna in this region is very poorly which limiting the conservation of fish biodiversity and sustainability of the fishery. In this study, we calculated taxonomic features of fish in the Beibu Gulf based on the sampling and observational field data obtained from the competent authorities. Our results indicate that 1519 species were recorded, which belongs to 42 orders and 198 families. Compared with earlier studies, the species richness of fish in Beibu Gulf has decreased significantly, especially in large predatory fish and demersal fish. Now, overfishing, habitats destruction, pollution and eutrophication, and non-native species are important threat to native fish biodiversity. The results shed light on the importance of conservation and ecosystem-based fishery management. For better to protect fish biodiversity and fisheries resources, more international cooperation on protected areas, fishing ban, and scientific research should be implemented for effectively protecting fish biodiversity and fisheries resource sustainability. [ABSTRACT FROM AUTHOR]

Six benzophenone derivatives, carneusones A-F (1–6), along with seven known compounds (7–13) were isolated from a strain of sponge-derived marine fungus Aspergillus carneus GXIMD00543. Their chemical structures were elucidated by detailed spectroscopic data and quantum chemical calculations. Compounds 5, 6, and 8 exhibited moderate anti-inflammatory activity on NO secretion using lipopolysaccharide (LPS)-induced RAW 264.7 cells with EC50 values of 34.6 ± 0.9, 20.2 ± 1.8, and 26.8 ± 1.7 μM, while 11 showed potent effect with an EC50 value of 2.9 ± 0.1 μM. [ABSTRACT FROM AUTHOR]

Copyright of South China Fisheries Science is the property of South China Fisheries Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Mangrove ecosystems are one of the most diverse and productive marine ecosystems around the world, although losses of global mangrove area have been occurring over the past decades. Therefore, tracking spatio-temporal changes and assessing the current state are essential for mangroves conservation. To solve the issues of inaccurate detection results of single algorithms and those limited to historical change detection, this study proposes the detect–monitor–predict (DMP) framework of mangroves for detecting time-series historical changes, monitoring abrupt near-real-time events, and predicting future trends in Beibu Gulf, China, through the synergetic use of multiple detection change algorithms. This study further developed a method for extracting mangroves using multi-source inter-annual time-series spectral indices images, and evaluated the performance of twenty-one spectral indices for capturing expansion events of mangroves. Finally, this study reveals the spatio-temporal dynamics of mangroves in Beibu Gulf from 1986 to 2021. In this study, we found that our method could extract mangrove growth regions from 1986 to 2021, and achieved 0.887 overall accuracy, which proved that this method is able to rapidly extract large-scale mangroves without field-based samples. We confirmed that the normalized difference vegetation index and tasseled cap angle outperform other spectral indexes in capturing mangrove expansion changes, while enhanced vegetation index and soil-adjusted vegetation index capture the change events with a time delay. This study revealed that mangrove changes displayed historical changes in the hierarchical gradient from land to sea with an average annual expansion of 239.822 ha in the Beibu Gulf during 1986–2021, detected slight improvements and deteriorations of some contemporary mangroves, and predicted 72.778% of mangroves with good growth conditions in the future.

This study focused on major fish species caught from different ecological habitats to analyze the habitat changes in economically important fish in the Beibu Gulf. The maximum entropy model was constructed based on the data from 26 voyages obtained through the otter trawl fishery stock surveys conducted in the Beibu Gulf from 2006 to 2018. A total of 10 taxa of major fish catches, belonging to 4 families, 1 genus, and 5 species, were analyzed for their distribution characteristics in potential habitats during various ecological periods, specifically the withered and high-water periods, as well as their relationships with crucial environmental factors. During both the withered and high-water periods, the average area under the curve was 0.927, and all models had values exceeding 0.9. Salinity was identified as the principal factor during both periods. The salinity niche of Acropoma japonicum and the primary productivity niche of Sciaenidae were identified as the most restricted factors. The total distribution area of potentially suitable regions for major fish catches extended between 106°30′–109°45′ E and 17°30′–20°45′ N, and the area was lesser during the withered period. During the withered period, the distribution areas of Sciaenidae, Leiognathidae, and Saurida increased, while the distribution area of Trachurus japonicus increased during the high-water period. Sciaenidae and Trachurus japonicus exhibited the highest rates of change at 6.22% and 10.92%, respectively. This indicates that the high-water period may expand the range of suitable habitats for large catches that have an ideal habitat status in the Beibu Gulf. Therefore, it is crucial to anticipate the potential fish habitats in the Beibu Gulf and clarify their spatial distribution patterns. [ABSTRACT FROM AUTHOR]

Copyright of Tropical Geography is the property of Tropical Geography Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Halobacteriovorax are predatory bacteria that have a significant ecological role in marine environments. However, understanding of dynamics of populations, driving forces, and community composition of Halobacteriovorax groups in natural marine environments is still limited. Here, we used high-throughput sequencing to study the underlying mechanisms governing the diversity and assembly of the Halobacteriovorax community at spatiotemporal scales in a subtropical estuary. Phylogenetic analysis showed that 10 of 15 known Halobacteriovorax clusters were found in the studied estuary. Halobacteriovorax α-diversity and β-diversity exhibited significant seasonal variation. Variation partitioning analysis showed that the effect of nutrients was greater than that of other measured water properties on Halobacteriovorax community distribution. The results of Spearman's and Mantel's tests indicated that the trophic pollutants dissolved inorganic phosphorus (DIP) and NH4+-N in the estuary were the key factors that significantly affected Halobacteriovorax species and community diversity. In addition, this work indicated that the biological stoichiometry (especially N/P) of nutrients exerted a significant influence on the Halobacteriovorax community. Furthermore, we found that both deterministic and stochastic processes contributed to the turnover of Halobacteriovorax communities, and environmental filtering dominated the assembly of estuarine Halobacteriovorax communities. Overall, we provide new insights into the mechanisms in the generation and maintenance of the Halobacteriovorax community in marine environments. [ABSTRACT FROM AUTHOR]

Being a biologically diversed hotspot in the global marine ecosystem, the Beibu Gulf is inhabited by a high diversity of fish and serves as a vital fishing ground in China. Due to continuous overfishing, the fishery resource has drastically declined in the Beibu Gulf. However, information about the ichthyoplankton assemblages in this area is still lacking. In this present study, ichthyoplankton diversity, spatial and temporal distribution patterns, and assemblage structures were examined using the specimens collected in the late summer–autumn and winter of 2022 in the Beibu Gulf, and the relationship between ichthyoplankton assemblage and environmental variables was studied. A total of 117 ichthyoplankton taxa, belonging to 13 orders and 42 families, were recorded. The most abundant families were Gerreidae, Leiognathidae, and Sillaginidae in late summer–autumn, accounting for 38.74%, 27.95%, and 9.94%, respectively. Sparidae, Platycephalidae, and Sillaginidae were the most abundant families in winter, accounting for 34.03%, 17.15%, and 8.20%, respectively. Cluster analysis identified five assemblages in late summer-autumn and four assemblages in winter. The most characteristic species in each cluster were Terapon jarbua, Sillago sihama, Leiognathus brevirostris, Mene maculate, and Scomberoides tol in late summer-autumn and Scomberomorus commerson, Acanthopagrus latus, Sillago sp., and Evynnis cardinalis in winter. The results of the canonical correspondence analysis indicated that pH, chlorophyll-a (Chl-a), depth, dissolved oxygen (DO), sea surface salinity (SSS), total nitrogen (TN), and total phosphorus (TP) were the major environmental variables affecting the ichthyoplankton assemblage structure in the Beibu Gulf. The finding of this study will provide valuable information in conserving fish spawning grounds and developing fishery management practices to protect fishery resources in the Beibu Gulf. [ABSTRACT FROM AUTHOR]

The Beibu Gulf is the fourth largest Chinese fishing ground, with rich fishery resources and a significant role in marine fishery production. The feeding ecology of fish is important to explain the structure and function of marine ecosystems. As one of the most important fish species in the Beibu Gulf, Nemipterus japonicus plays an essential role in energy flow and other aspects of the marine ecosystem. Understanding its feeding ecology could provide a basic theoretical basis for the rational utilization and protection of this resource. A total of 248 N. japonicus specimens were collected from Beibu Gulf from January to April and August to December in 2018. The food content composition, feeding intensity, and feeding niche of N. japonicus were analyzed using stomach contents to reflect feeding habits. Combined with carbon and nitrogen stable isotopes, the food source and trophic structure characteristics were analyzed, the trophic level was determined, and the feeding ecology of N. japonicus in the Beibu Gulf was discussed. The stomach content analysis revealed that N. japonicus is a broad-feeding benthic carnivore, which feeds on a large number of species, including eight prey groups, including fish, shrimp, and crab, among which fish and shrimp are the dominant food groups, with a relative importance index of 92.92%. The proportion of food species varied with the season and growth. Fish were an important prey group across all seasons. Moreover, N. japonicus preyed on shrimp in spring, crab in summer, shrimp and polychaetes in autumn, and shrimp and sipunculoidea in winter. With an increase in body length, the feeding habits of N. japonicus gradually change from primarily feeding on shrimp and fish to mainly feeding on fish, and the body length node of feeding transition was approximately 130 mm. There were clear seasonal variations in feeding intensity, with the highest intensity in autumn, followed by that in spring and summer, and the lowest in winter. N. japonicus had a high prey diversity; the Shannon-Wiener diversity index (H') was 1.77, and the Pielou evenness index (J') was 0.64. From spring to winter, the H' and J' values tended to increase and then decrease, and the highest value occurred in autumn, which meant that the feeding niche was the highest in autumn. The number of prey species increased with individual growth, and H' and J' showed an increasing trend with body length. The group with a body length ≥ 160 mm had the largest niche width, which suggested that the food diversity increased with individual growth, and the diet changed to broad-feeding.Based on stable isotope analysis, δ13C was positively correlated with the body length of N. japonicus (P < 0.05), indicating that the trophic source changed with growth. The span of the δ13C (CR) range was 2.86%, indicating extensive basic food sources. The span of the δ15N (NR) range was 4.23%, and the trophic span was more than one trophic level, indicating considerable differences in feeding among individuals. A significant positive correlation was found between body length and δ15N (P < 0.01), which indicated that the trophic level increased with an increasing body length. The trophic level of N. japonicus ranged from 3.21 to 4.46, with an average value of 3.97, indicating that N. japonicus species were middle-high carnivorous animals, and were at a high trophic level in the fish food web of the Beibu Gulf. The trophic level obtained in this study is higher than that obtained in other studies, which may be related to the changes in the composition of the prey, N. japonicus has shifted from feeding mainly on the low trophic level (crustaceans) to the high trophic levels (fish).In terms of trophic structure, the CR value of N. japonicus in the Beibu Gulf in spring and winter was lower than that in summer and autumn, indicating that the basic food source diversity in spring and winter is lower than that in summer and autumn, however, there are fewer prey species in summer, which might be caused by the feeding preference of N. japonicus. Simultaneously, the NR values in spring and summer were greater than those in summer and autumn, indicating that the span of the main trophic sources in the feed was higher than that in summer and autumn, consistent with the seasonal variation of dominant prey. Although the standard ellipse area (SEA) overlaps to different degrees among seasons, the total niche (TA) had clear seasonal differences, signifying that there were certain similarities and specific differences in prey resource utilization, which is beneficial for alleviating the seasonal pressure on the dominant prey. Furthermore, the CR value in different body length groups of N. japonicus showed an overall upward trend with individual growth, indicating that the food source diversity increased with growth. The NR value decreased when body length was greater than 130 mm, which indicates that the average trophic level of the population was concentrated when individuals grew to a certain stage. The SEA overlap rate was higher among length groups, implying that the trophic source components were similar at different growth stages; however, TA tended to increase and then decrease with body length, which may reduce food competition within species by niche differentiation.

Marine transgressions-regressions have profoundly shaped marginal seas following global sea-level fluctuations driven by climate change. This study on a sedimentary core profile SO219/31-4 from the Beibu Gulf, northwestern South China Sea (SCS), reveals information about paleoenvironment, paleoceanography and paleoclimate changes through fossil diatom assemblages and grain size distributions during the last ca. 12900 cal. yr. BP. Eight local diatom assemblage zones were distinguished and assigned to paleoenvironmental fluctuations recording sea-level and depositional environment changes in eight stages, ca. 12900–11700 (stage 1), ca. 11700–9500 (stage 2), ca. 9500–7200 (stage 3), ca. 7200–5800 (stage 4), ca. 5800–3800 (stage 5), ca. 3800–2400 (stage 6), ca. 2400–800 (stage 7) and ca. 800–0 (stage 8), cal. yr. BP. After the low sea level of stage 1 within the last deglaciation, rapid increases in sea level in stages 2 and 3 were recorded as meltwater events pulse-1B and pulse-1C resulting in marine transgression rates of ca. 16 m/kyr and 8 m/kyr, respectively. The high sea level, above the present level, in stages 4 and 5, in the Middle Holocene Climatic Optimum period, was clearly documented by more significant open sea/tropical diatom species and coastal planktonic species percentages, respectively. The late Holocene regression of sea levels was marked by a pronounced reversion of diatom taphocoenosis, responding to neoglacial climate. Fossil diatom assemblages outlined responded to paleoclimate of global warming in the deglacial and early Holocene. This study provides additional insights into the late Pleistocene and Post-glacial history of a tropical-subtropical shallow water gulf, in the NW-SCS.

Ligia exotica is a marine isopod that inhabits intertidal areas and exhibits transitional adaptations for the evolution to a land-based lifestyle. People in southern Chinese coastal areas use it as a traditional Chinese medicine with anti-inflammatory effects. The species is of unique value for microbiological research; however, the anti-inflammatory activities of L. exotica have lacked scientific validation, and few studies have evaluated the diversity and anti-inflammatory activity of L. exotica symbionts. In this study, 29 endosymbiotic bacteria were obtained from L. exotica that represented four bacterial phyla, 11 families, and 13 genera. Among the isolates, GXIMD07922 (Vibrio sp.), GXIMD07953 (Paracoccus sp.), and GXIMD07927 (Halomonas sp.) represent potentially new species. Six of the strains (GXIMD07836, GXIMD07913, GXIMD07918, GXIMD07884, GXIMD07904, and GXIMD07972) inhibited NO production in lipopolysaccharides (LPS)-stimulated RAW264.7 cells. The results from this study indicate that bacterial populations endosymbiotic with L. exotica are a promising and diverse resource for the discovery of novel anti-inflammatory secondary metabolites. [ABSTRACT FROM AUTHOR]

Copyright of South China Fisheries Science is the property of South China Fisheries Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of South China Fisheries Science is the property of South China Fisheries Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Bacterial communities in marine sediments of the subtropical Beibu Gulf differ significantly from those of other regions. Thus, it is of great importance to study the marine sediment characteristics comprising bacterial composition, diversity, assembly processes, and functional profile. However, such sediments characteristics in subtropical Beibu Gulf remain unclear. Therefore, we studied the diversity, assembly processes, and functional profiles of the bacterial communities in sediment samples collected from 21 sites in the Beibu Gulf. Upon analysis, Proteobacteria was determined to be the dominant phylum using 16S rRNA sequencing. Predominantly deterministic processes shaped the formation of bacterial communities. The predicted bacterial functional groups involved in the carbon cycle (59.06%) were most abundant in the FAPROTAX database, followed by nitrogen (9.25%) and sulfur (1.01%). Furthermore, the composition of the bacterial community was significantly influenced by TC, TP, and TS (p