2025 Vol. 47, No. 5
Display Method:
2025, 47(5): 1-11.
doi: 10.12284/hyxb2025056
Abstract:
Mangrove wetlands are efficient coastal blue carbon sinks and play an important role in regulating the global carbon cycle. In this study, using grain size distribution, total organic carbon / total nitrogen (TOC/TN) ratio, δ13C values, and 210Pb chronological parameter, we investigated the sources of organic carbon (OC) and the temporal trends in sediment deposition and OC burial fluxes in the mangrove wetland of Tieshangang Bay, Guangxi. The results indicated that the sediment grain size was dominated by silt and sand, with TOC content and δ13C ranging from 0.26% to 3.96% and from −27.4‰ to −21.4‰, respectively. There was a strong correlation between TOC, TN, and δ13C values. The sedimentary organic matter in Tieshangang Bay had mainly a mixed signature with an average terrigenous contribution of 35.0%, marine sources 30.5% and mangrove contributions 34.5%, respectively. The average sediment OC flux over the past 100 years is 87.6 g/(m2·a), and the carbon storage in sediments over the upper 50 cm can account for 65.3% of the total storage over the 95 cm depth. After 1961, there was a general decrease in sediment flux due to the construction of reservoir dams. Between 1961 and 1999, more terrestrial sources of OC were imported and buried due to climate and human disturbances around the watershed. Between 1999 and 2020, mangrove wetlands were destroyed and degraded due to extreme weather and natural factors. Degradation of mangrove wetlands under extreme weather and natural factors reduced the TOC content and OC burial fluxes. Since 2010, TOC content in the sediments has increased, probably due to higher water content, accumulation of litter and root growth. The OC source is dominated by the contribution from mangrove sources.
Mangrove wetlands are efficient coastal blue carbon sinks and play an important role in regulating the global carbon cycle. In this study, using grain size distribution, total organic carbon / total nitrogen (TOC/TN) ratio, δ13C values, and 210Pb chronological parameter, we investigated the sources of organic carbon (OC) and the temporal trends in sediment deposition and OC burial fluxes in the mangrove wetland of Tieshangang Bay, Guangxi. The results indicated that the sediment grain size was dominated by silt and sand, with TOC content and δ13C ranging from 0.26% to 3.96% and from −27.4‰ to −21.4‰, respectively. There was a strong correlation between TOC, TN, and δ13C values. The sedimentary organic matter in Tieshangang Bay had mainly a mixed signature with an average terrigenous contribution of 35.0%, marine sources 30.5% and mangrove contributions 34.5%, respectively. The average sediment OC flux over the past 100 years is 87.6 g/(m2·a), and the carbon storage in sediments over the upper 50 cm can account for 65.3% of the total storage over the 95 cm depth. After 1961, there was a general decrease in sediment flux due to the construction of reservoir dams. Between 1961 and 1999, more terrestrial sources of OC were imported and buried due to climate and human disturbances around the watershed. Between 1999 and 2020, mangrove wetlands were destroyed and degraded due to extreme weather and natural factors. Degradation of mangrove wetlands under extreme weather and natural factors reduced the TOC content and OC burial fluxes. Since 2010, TOC content in the sediments has increased, probably due to higher water content, accumulation of litter and root growth. The OC source is dominated by the contribution from mangrove sources.
2025, 47(5): 141-149.
doi: 10.12284/hyxb2025066
Abstract:
Sediment oxygen consumption (SOC) is a key parameter for quantifying organic carbon mineralization in sediments, crucial for understanding the marine carbon cycle. The oxygen consumption of sediments in marginal seas account for approximately 60% of global marine sediments. Temperature is a major factor influencing microbial respiration in sediments. However, there is a lack of research on the differences in temperature responses of sediment oxygen consumption across various estuaries and nearshore areas, which may lead to inaccuracies in our understanding of sediment oxygen consumption and mineralization, especially in the context of global warming and rising sea temperatures. This study examined sediment from the Changjiang River Estuary, the Huanghe River Estuary, and the Yellow Sea nearshore, measuring sediment oxygen consumption across a temperature range of 2−45℃ with 2−3℃ increments. Results showed an exponential increase in sediment oxygen consumption with temperature in all three regions. The apparent activation energy (Eaʹ) of sediment oxygen consumption in the Changjiang River Estuary is in the range of 69−77 kJ/mol, and the temperature coefficient (Q10 (15−25℃)) is 2.6−3.0, similar to sediments in the Weser Estuary of Germany. In the Huanghe River Estuary and the coastal area of the Yellow Sea, the Eaʹ is 51−58 kJ/mol, and the Q10 (15−25℃) value is 2.0−2.3, comparable to data from shallow sediments in the Canada Bay. The Eaʹ and Q10 (15−25℃) of sediment oxygen consumption in the Changjiang River Estuary are significantly higher than those in the Huanghe River Estuary and the Yellow Sea nearshore (AVONA, P<0.01), likely due to higher labile organic carbon content. The range of sediment oxygen consumption Q10 (15−25℃) is 2.5 ± 0.3, basically in line with that of sediment oxygen consumption on a global scale (2.4 ± 0.4), consistent with the range of Q10 being 2−3 for most biological reactions. This study provides critical data on the temperature response and differences in SOC, offering insights into the feedback between carbon mineralization in estuarine and nearshore sediments and global climate change.
Sediment oxygen consumption (SOC) is a key parameter for quantifying organic carbon mineralization in sediments, crucial for understanding the marine carbon cycle. The oxygen consumption of sediments in marginal seas account for approximately 60% of global marine sediments. Temperature is a major factor influencing microbial respiration in sediments. However, there is a lack of research on the differences in temperature responses of sediment oxygen consumption across various estuaries and nearshore areas, which may lead to inaccuracies in our understanding of sediment oxygen consumption and mineralization, especially in the context of global warming and rising sea temperatures. This study examined sediment from the Changjiang River Estuary, the Huanghe River Estuary, and the Yellow Sea nearshore, measuring sediment oxygen consumption across a temperature range of 2−45℃ with 2−3℃ increments. Results showed an exponential increase in sediment oxygen consumption with temperature in all three regions. The apparent activation energy (Eaʹ) of sediment oxygen consumption in the Changjiang River Estuary is in the range of 69−77 kJ/mol, and the temperature coefficient (Q10 (15−25℃)) is 2.6−3.0, similar to sediments in the Weser Estuary of Germany. In the Huanghe River Estuary and the coastal area of the Yellow Sea, the Eaʹ is 51−58 kJ/mol, and the Q10 (15−25℃) value is 2.0−2.3, comparable to data from shallow sediments in the Canada Bay. The Eaʹ and Q10 (15−25℃) of sediment oxygen consumption in the Changjiang River Estuary are significantly higher than those in the Huanghe River Estuary and the Yellow Sea nearshore (AVONA, P<0.01), likely due to higher labile organic carbon content. The range of sediment oxygen consumption Q10 (15−25℃) is 2.5 ± 0.3, basically in line with that of sediment oxygen consumption on a global scale (2.4 ± 0.4), consistent with the range of Q10 being 2−3 for most biological reactions. This study provides critical data on the temperature response and differences in SOC, offering insights into the feedback between carbon mineralization in estuarine and nearshore sediments and global climate change.
2025, 47(5): 150-166.
doi: 10.12284/hyxb2025054
Abstract:
We conducted two surveys on the carbonate system in Xiaohai, the largest lagoon on Hainan Island, during April and October 2023. The aims were to evaluate the seasonal differences in riverine inorganic carbon export flux, air-sea carbon dioxide (CO2) flux, and coastal acidification as well as their controlling mechanisms. The results indicate that the surrounding major rivers deliver 0.682 × 109 mol dissolved inorganic carbon (DIC), 0.571×109 mol total alkalinity, and 0.195×109 mol calcium ions to Xiaohai Lagoon annually, and multiple factors result in a high DIC areal yield among other estuaries around the world (47/134). The lagoon water was a CO2 source in April, but turned into a sink in October, with an annual mean CO2 flux [0.9 mol/(m2·a)] significantly lower than most tropical lagoons worldwide. In April, some acidification events occurred in the southeastern lagoon and the northern tidal channel. In October, strong photosynthesis by benthic seagrass, macroalgae, and phytoplankton alleviated estuarine acidification, resulting in a supersaturation of dissolved oxygen (107%−136%), a deficit of partial pressure of CO2 as low as 116 μatm, and an elevated pH (8.41 ± 0.14) significantly higher than the offshore seawater. Our study will provide scientific support for the carbon cycle in tropical lagoons and ecological environment management in Xiaohai Lagoon.
We conducted two surveys on the carbonate system in Xiaohai, the largest lagoon on Hainan Island, during April and October 2023. The aims were to evaluate the seasonal differences in riverine inorganic carbon export flux, air-sea carbon dioxide (CO2) flux, and coastal acidification as well as their controlling mechanisms. The results indicate that the surrounding major rivers deliver 0.682 × 109 mol dissolved inorganic carbon (DIC), 0.571×109 mol total alkalinity, and 0.195×109 mol calcium ions to Xiaohai Lagoon annually, and multiple factors result in a high DIC areal yield among other estuaries around the world (47/134). The lagoon water was a CO2 source in April, but turned into a sink in October, with an annual mean CO2 flux [0.9 mol/(m2·a)] significantly lower than most tropical lagoons worldwide. In April, some acidification events occurred in the southeastern lagoon and the northern tidal channel. In October, strong photosynthesis by benthic seagrass, macroalgae, and phytoplankton alleviated estuarine acidification, resulting in a supersaturation of dissolved oxygen (107%−136%), a deficit of partial pressure of CO2 as low as 116 μatm, and an elevated pH (8.41 ± 0.14) significantly higher than the offshore seawater. Our study will provide scientific support for the carbon cycle in tropical lagoons and ecological environment management in Xiaohai Lagoon.
2025, 47(5): 12-39.
doi: 10.12284/hyxb2025060
Abstract:
The relationship between the marine biological carbon pump(BCP) and paleoclimate is a central scientific issue in carbon cycle research. This study utilizes the ecological characteristics implied by total organic carbon (TOC) and key lipid compounds in Ross Sea sediments, specifically molecular biomarkers that can influence the composition of the seabed carbon reservoir and the efficiency of the marine BCP (including the biological pump BP and the microbial carbon pump MCP), tracing the evolution of the ancient marine biological carbon pump (with a focus on BP and MCP) since the Last Glacial Maximum (27−0.6 ka BP) and its connection to significant geological events. The research findings indicate: (1) the relatively high TOC and low C/N ratios in surface sediments of the Ross Sea, along with characteristics such as normal alkane chromatographic peak shapes, dominant carbon, molecular composition features with low to high carbon number ratios (L/H) and(nC21 + nC22)/(nC28 + nC29)ratios, low n-alkanes(nC15 + nC17 + nC19), mid-chain alkanes(nC21 + nC23 + nC25), high-chain alkanes (nC27 + nC29 + nC31), bacterial (BrGDGT), and lower terrigenous input index (BIT), collectively indicate a predominance of marine-derived organic matter contributing to the seabed through the effects of the marine BP and MCP, facilitating long-term carbon storage. The Pr/Ph ratio combined with Ph/nC18 and Ph/nC17 ratios suggest that surface sediments represent a reducing to strongly reducing anoxic environment conducive to organic carbon sequestration on the seafloor, closely linked to sea ice melt. (2) By employing a low-temperature correction formula\begin{document}$ {\mathrm{T}\mathrm{E}\mathrm{X}}_{86}^{\mathrm{L}} $\end{document} ![]()
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The relationship between the marine biological carbon pump(BCP) and paleoclimate is a central scientific issue in carbon cycle research. This study utilizes the ecological characteristics implied by total organic carbon (TOC) and key lipid compounds in Ross Sea sediments, specifically molecular biomarkers that can influence the composition of the seabed carbon reservoir and the efficiency of the marine BCP (including the biological pump BP and the microbial carbon pump MCP), tracing the evolution of the ancient marine biological carbon pump (with a focus on BP and MCP) since the Last Glacial Maximum (27−0.6 ka BP) and its connection to significant geological events. The research findings indicate: (1) the relatively high TOC and low C/N ratios in surface sediments of the Ross Sea, along with characteristics such as normal alkane chromatographic peak shapes, dominant carbon, molecular composition features with low to high carbon number ratios (L/H) and(nC21 + nC22)/(nC28 + nC29)ratios, low n-alkanes(nC15 + nC17 + nC19), mid-chain alkanes(nC21 + nC23 + nC25), high-chain alkanes (nC27 + nC29 + nC31), bacterial (BrGDGT), and lower terrigenous input index (BIT), collectively indicate a predominance of marine-derived organic matter contributing to the seabed through the effects of the marine BP and MCP, facilitating long-term carbon storage. The Pr/Ph ratio combined with Ph/nC18 and Ph/nC17 ratios suggest that surface sediments represent a reducing to strongly reducing anoxic environment conducive to organic carbon sequestration on the seafloor, closely linked to sea ice melt. (2) By employing a low-temperature correction formula
2025, 47(5): 40-47.
doi: 10.12284/hyxb2025016
Abstract:
To investigate the feeding effects of Acanthaster cf. solaris on Pocillopora damicornis and its molecular regulatory mechanisms, this study focused on the typical P. damicornis in the South China Sea, combining behavioral experiments, transcriptome sequencing, and enzyme activity assays of stomach tissue to systematically analyze the role of olfactory receptors in the feeding behavior of A. cf. solaris. The results showed that the expression of chemical receptor genes in the A. cf. solaris significantly changed during the feeding process on P. damicornis, with 89 genes being significantly upregulated and 335 genes being significantly downregulated. Further exploration of the upregulated genes revealed that five olfactory receptor genes suggested by the transcriptome, including gamma-aminobutyric acid type B receptor subunit 1-like and olfactory receptor 13-like, may play crucial roles in the recognition and feeding on P. damicornis. Meanwhile, feeding behavior significantly activated cellulase activity in the stomach tissues (p < 0.05), whereas the activities of phosphoenolpyruvate carboxykinase and lipase showed an increasing trend but did not reach statistical significance. This suggests that cellulase may be involved in the digestive process by enhancing the degradation of coral skeletons and zooxanthella cell walls. This study provides preliminary insights into the mediation of feeding behavior by key olfactory receptors in Acanthaster cf. solaris and offers important scientific references for further understanding the mechanisms behind population outbreaks.
To investigate the feeding effects of Acanthaster cf. solaris on Pocillopora damicornis and its molecular regulatory mechanisms, this study focused on the typical P. damicornis in the South China Sea, combining behavioral experiments, transcriptome sequencing, and enzyme activity assays of stomach tissue to systematically analyze the role of olfactory receptors in the feeding behavior of A. cf. solaris. The results showed that the expression of chemical receptor genes in the A. cf. solaris significantly changed during the feeding process on P. damicornis, with 89 genes being significantly upregulated and 335 genes being significantly downregulated. Further exploration of the upregulated genes revealed that five olfactory receptor genes suggested by the transcriptome, including gamma-aminobutyric acid type B receptor subunit 1-like and olfactory receptor 13-like, may play crucial roles in the recognition and feeding on P. damicornis. Meanwhile, feeding behavior significantly activated cellulase activity in the stomach tissues (p < 0.05), whereas the activities of phosphoenolpyruvate carboxykinase and lipase showed an increasing trend but did not reach statistical significance. This suggests that cellulase may be involved in the digestive process by enhancing the degradation of coral skeletons and zooxanthella cell walls. This study provides preliminary insights into the mediation of feeding behavior by key olfactory receptors in Acanthaster cf. solaris and offers important scientific references for further understanding the mechanisms behind population outbreaks.
2025, 47(5): 48-63.
doi: 10.12284/hyxb2025048
Abstract:
Global coral bleaching under heat stress has been identified as a major driver of coral reef degradation. The composition, metabolism and functional characteristics of microbial communities in coral holosomes under heat stress has been reported. However, the changes in microbial structure and composition throughout the entire process of coral health-bleaching-recovery have not been studied so far. In this study, Porites lutea in Shenzhen Sea area was selected as the research object. The process of coral health-bleaching-recovery under heat stress was simulated in the laboratory. High-throughput sequencing and macro-genome sequencing technologies were used to analyse the differences in coral microbial communities and functional gene changes during five characteristic phases of coral bleaching and restoration: healthy, beginning of bleaching, continued bleaching, beginning of recover, and recovered. With the increase of temperature, Proteobacteria increased significantly during the bleaching process and decreased during recovery; Bacteroidota etc. decreased during bleaching and increased during recovery. During the coral bleaching process, the abundance of bacteria associated with stress tolerance, biofilm formation, mobile elements, and potential pathogenicity significantly increases. Conversely, the abundance of bacteria involved in quorum sensing decreases. Notably, four kinds of microbes play a crucial role in coral bleaching: Acinetobacter, Rhodobacter, and Burkholderia are key differential taxa in warming-induced coral bleaching, while Delftia may modulate other bacterial assemblages via quorum sensing mechanisms to maintain the stability of coral microbial communities.This study revealed the changes of microbes and their functions in coral tissues under high temperature stress, which provided molecular basis for elucidating the interaction mechanism between microbes and hosts during coral bleaching.
Global coral bleaching under heat stress has been identified as a major driver of coral reef degradation. The composition, metabolism and functional characteristics of microbial communities in coral holosomes under heat stress has been reported. However, the changes in microbial structure and composition throughout the entire process of coral health-bleaching-recovery have not been studied so far. In this study, Porites lutea in Shenzhen Sea area was selected as the research object. The process of coral health-bleaching-recovery under heat stress was simulated in the laboratory. High-throughput sequencing and macro-genome sequencing technologies were used to analyse the differences in coral microbial communities and functional gene changes during five characteristic phases of coral bleaching and restoration: healthy, beginning of bleaching, continued bleaching, beginning of recover, and recovered. With the increase of temperature, Proteobacteria increased significantly during the bleaching process and decreased during recovery; Bacteroidota etc. decreased during bleaching and increased during recovery. During the coral bleaching process, the abundance of bacteria associated with stress tolerance, biofilm formation, mobile elements, and potential pathogenicity significantly increases. Conversely, the abundance of bacteria involved in quorum sensing decreases. Notably, four kinds of microbes play a crucial role in coral bleaching: Acinetobacter, Rhodobacter, and Burkholderia are key differential taxa in warming-induced coral bleaching, while Delftia may modulate other bacterial assemblages via quorum sensing mechanisms to maintain the stability of coral microbial communities.This study revealed the changes of microbes and their functions in coral tissues under high temperature stress, which provided molecular basis for elucidating the interaction mechanism between microbes and hosts during coral bleaching.
2025, 47(5): 64-77.
doi: 10.12284/hyxb2025064
Abstract:
In this study, we conducted comprehensive field surveys in the Bohai Sea’s seagrass beds at Caofeidian, Huanghe River mouth, and Juehua Island, gathering data on seagrass growth, water and sediment quality, plankton, benthic life, and juvenile fish. An integrated assessment index system for the nursery function of nearshore seagrass beds was constructed. The seagrass biomass at Caofeidian and Juehua Island was measured at 371.22 g/m2 and 340.05 g/m2, respectively, both of which were significantly higher than that recorded at the Huanghe River mouth (161.24 g/m2, p < 0.05). The average abundance and biomass of phytoplankton in each seagrass bed followed the order: Huanghe River mouth > Caofeidian > Juehua Island, exhibiting significant spatial differences (p < 0.05). Regarding juvenile fish density, Juehua Island exhibited the highest density, followed by the Huanghe River mouth, with Caofeidian showing the lowest density, also demonstrating significant spatial differences (p < 0.05). The nursery function of seagrass beds was best in Juehua Island seagrass bed, followed by Caofeidian seagrass bed and Huanghe River mouth seagrass bed. Environmental and biological indicators with significant contributions varied spatially. The seagrass bed in Juehua Island has a good environmental and biological status, with high water transparency, abundant dissolved oxygen, and moderate inorganic nitrogen mass concentration, and the juvenile fish community indicators all performed well, contributing significantly to the nursery function. The seagrass bed in Huanghe River Delta has relatively poor water environment and biological status, with low water transparency, high pH value, and excessive inorganic nitrogen. The biological indicators showed poor plankton diversity characteristics and low proportion of juvenile fish, which became the main negative factors for its nursery function assessment result of only average. The environmental status in Caofeidian seagrass bed is good, with factors such as temperature, inorganic nitrogen, and inorganic phosphorus mass concentration contributing significantly. However, its biological status is average, and the low number of planktonic animals and juvenile fish is the main negative factor in the nursery function assessment of this area. This study helps to deeply understand and recognize the spatial and temporal differences and driving factors of the nursery function of typical seagrass beds in the Bohai Sea area, and provides effective scientific basis and data support for the protection of seagrass bed ecosystems and the sustainable development of marine fishery resources in China.
In this study, we conducted comprehensive field surveys in the Bohai Sea’s seagrass beds at Caofeidian, Huanghe River mouth, and Juehua Island, gathering data on seagrass growth, water and sediment quality, plankton, benthic life, and juvenile fish. An integrated assessment index system for the nursery function of nearshore seagrass beds was constructed. The seagrass biomass at Caofeidian and Juehua Island was measured at 371.22 g/m2 and 340.05 g/m2, respectively, both of which were significantly higher than that recorded at the Huanghe River mouth (161.24 g/m2, p < 0.05). The average abundance and biomass of phytoplankton in each seagrass bed followed the order: Huanghe River mouth > Caofeidian > Juehua Island, exhibiting significant spatial differences (p < 0.05). Regarding juvenile fish density, Juehua Island exhibited the highest density, followed by the Huanghe River mouth, with Caofeidian showing the lowest density, also demonstrating significant spatial differences (p < 0.05). The nursery function of seagrass beds was best in Juehua Island seagrass bed, followed by Caofeidian seagrass bed and Huanghe River mouth seagrass bed. Environmental and biological indicators with significant contributions varied spatially. The seagrass bed in Juehua Island has a good environmental and biological status, with high water transparency, abundant dissolved oxygen, and moderate inorganic nitrogen mass concentration, and the juvenile fish community indicators all performed well, contributing significantly to the nursery function. The seagrass bed in Huanghe River Delta has relatively poor water environment and biological status, with low water transparency, high pH value, and excessive inorganic nitrogen. The biological indicators showed poor plankton diversity characteristics and low proportion of juvenile fish, which became the main negative factors for its nursery function assessment result of only average. The environmental status in Caofeidian seagrass bed is good, with factors such as temperature, inorganic nitrogen, and inorganic phosphorus mass concentration contributing significantly. However, its biological status is average, and the low number of planktonic animals and juvenile fish is the main negative factor in the nursery function assessment of this area. This study helps to deeply understand and recognize the spatial and temporal differences and driving factors of the nursery function of typical seagrass beds in the Bohai Sea area, and provides effective scientific basis and data support for the protection of seagrass bed ecosystems and the sustainable development of marine fishery resources in China.
2025, 47(5): 78-86.
doi: 10.12284/hyxb2025052
Abstract:
Zhoushan Fishing Ground (ZFG) is the largest fishing ground in China, with rich fishery resources. Under the effects of climate changes and anthropogenic disturbances, changes in local marine environment and selective fishing have increased spatial heterogeneity of habitat and function of the fish communities, and futher result in instability of ecosystem. Traditional studies were major focus on the spatial patterns of the fish communities based on taxonomic level in the ZFG. However, there are still knowledge gaps about the spatial patterns of the functional structure of the fish communities because of shortage in functional data of fishes. Here, we investigate the spatial patterns of the taxonomic and functional structures of the fish communities and their seasonal variations in ZFG, as well as their correlations with environmental variables. The fishery surveys were conducted in 4 seasons during 2006−2007. To measure the functional compositions of the fish communities, community-weighted mean trait values (CWMs) were calculated for each functional trait of fishes. β diversities were calculated to measure the spatial heterogeneity of the fish communities. Our results indicated that most of CWMs showed significant difference between at least two seasons. Taxonomic and functional β diversities showed high values with range from0.7423 −0.8396 and 0.7184 −0.7824 , respectively, indicating that the taxonomic and functional structures have high levels of spatial heterogeneity. In addition, the taxonomic β diversities showed significant change with seasons, and significantly related to water depth, salinity, and chemical oxygen demand (COD), while functional β diversities showed different patterns. The results contribute to a better understanding of the spatial patterns of the fish communities and their seasonal dynamics in ZFG, and guilde for biodiversity conservation and fishery resource management.
Zhoushan Fishing Ground (ZFG) is the largest fishing ground in China, with rich fishery resources. Under the effects of climate changes and anthropogenic disturbances, changes in local marine environment and selective fishing have increased spatial heterogeneity of habitat and function of the fish communities, and futher result in instability of ecosystem. Traditional studies were major focus on the spatial patterns of the fish communities based on taxonomic level in the ZFG. However, there are still knowledge gaps about the spatial patterns of the functional structure of the fish communities because of shortage in functional data of fishes. Here, we investigate the spatial patterns of the taxonomic and functional structures of the fish communities and their seasonal variations in ZFG, as well as their correlations with environmental variables. The fishery surveys were conducted in 4 seasons during 2006−2007. To measure the functional compositions of the fish communities, community-weighted mean trait values (CWMs) were calculated for each functional trait of fishes. β diversities were calculated to measure the spatial heterogeneity of the fish communities. Our results indicated that most of CWMs showed significant difference between at least two seasons. Taxonomic and functional β diversities showed high values with range from
2025, 47(5): 87-98.
doi: 10.12284/hyxb2025050
Abstract:
To understand the characteristics of fish communities in the upwelling waters of the west-central South China Sea, data from the 2014 summer light falling-net fishery resources survey were utilized to study the species composition, biodiversity, and community structure of phototropic pelagic fish communities. There are 13 fish species in the upwelling core region, belonging to 11 genera in 3 orders and 8 families, with the dominant species being the Cubiceps squamiceps; 11 species of fish were collected from the upwelling periphery region, belonging to 10 genera in 2 orders and 8 families, with the dominant species being the Auxis thazard and Thunnus obesus. The fish diversity index, richness index, and evenness index were lower in the upwelling core region than in the periphery waters. The average catch rate in the upwelling core region was 45.9 kg/h, 1.63 times higher than that in the periphery region. PERMANOVA analysis showed that the fish communities in the upwelling core region and the periphery region had marginally significant differences in fish communities, with the main divergent species being Cubiceps squamiceps, Auxis thazard, Decapterus macrosoma, Thunnus obesus, and Auxis rochei. Correlation analysis showed that sea surface chlorophyll a mass concentration was the most important environmental factor influencing the spatial distribution of fish abundance.
To understand the characteristics of fish communities in the upwelling waters of the west-central South China Sea, data from the 2014 summer light falling-net fishery resources survey were utilized to study the species composition, biodiversity, and community structure of phototropic pelagic fish communities. There are 13 fish species in the upwelling core region, belonging to 11 genera in 3 orders and 8 families, with the dominant species being the Cubiceps squamiceps; 11 species of fish were collected from the upwelling periphery region, belonging to 10 genera in 2 orders and 8 families, with the dominant species being the Auxis thazard and Thunnus obesus. The fish diversity index, richness index, and evenness index were lower in the upwelling core region than in the periphery waters. The average catch rate in the upwelling core region was 45.9 kg/h, 1.63 times higher than that in the periphery region. PERMANOVA analysis showed that the fish communities in the upwelling core region and the periphery region had marginally significant differences in fish communities, with the main divergent species being Cubiceps squamiceps, Auxis thazard, Decapterus macrosoma, Thunnus obesus, and Auxis rochei. Correlation analysis showed that sea surface chlorophyll a mass concentration was the most important environmental factor influencing the spatial distribution of fish abundance.
2025, 47(5): 99-111.
doi: 10.12284/hyxb2025062
Abstract:
To study the community characteristics of meiofauna in the mangrove wetland of Beihai, Guangxi, quantitative sampling of meiofauna and environmental factors was conducted in January (winter) and July (summer) of 2021. Three sections with nine stations were set up in the mangrove wetland. The results showed that the average abundance of meiofauna in winter and summer were (2617.17 ± 973.13) ind./(10 cm2) and (1173.69 ± 535.75) ind./(10 cm2). The average abundance of meiofauna in mangrove section was the highest (2398.23 ± 1502.71 ) ind./(10 cm2), and the section of the bare section is the lowest, which is (1539.55 ± 731.04) ind./(10 cm2), and the cultivation section is (1748.50 ± 469.20) ind./(10 cm2). The average (dry weight, the same below) biomass of meiofauna was (3686.93 ± 1096.40 ) μg/(10 cm2) in winter and (2258.18 ± 1019.48 ) μg/(10 cm2) in summer. The average biomass of meiofauna in bare section was the highest, which was (3650.13 ± 1188.95 ) μg/(10 cm2). The lowest cultivation section was (272.32 ± 531.48) μg/(10 cm2). The mangrove section is (2995.21 ± 1499.03 ) μg/(10 cm2). Ten groups of meiofauna were identified in each season and each section. Marine nematodes were the most dominant group. The composition of groups in the bare section was more uniform. The meiofauna community in bare section was the most unique, characterized by its lowest abundance, highest biomass, higher uniformity in group composition and greater difference in overall community structure than the other two sections. This is related to the unique environmental characteristics of bare section, especially the influence of larger sediment particles, higher temperature and lower water content, and the overall environmental condition is the best. According to the evaluation results of N/C ratio, the environmental condition of the study area is generally good.
To study the community characteristics of meiofauna in the mangrove wetland of Beihai, Guangxi, quantitative sampling of meiofauna and environmental factors was conducted in January (winter) and July (summer) of 2021. Three sections with nine stations were set up in the mangrove wetland. The results showed that the average abundance of meiofauna in winter and summer were (
2025, 47(5): 112-127.
doi: 10.12284/hyxb2025058
Abstract:
To explore the characteristics and changes of zooplankton community structure in Tieshan Bay area of the Beibu Gulf, the abundance, biomass, species composition, dominant species and their relationship with environmental factors were analyzed based on the investigation conducted during April 2018 (spring), July 2018 (summer), October 2018 (autumn) and July 2022 (summer). A total of 162 species (classes) of zooplankton were identified. In 2018, the abundance and biomass of zooplankton were higher in summer [(274.58 ± 221.15) ind./m3, (152.09 ± 142.97) mg/m3], higher than in autumn [(215.72 ± 114.81) ind./m3, (87.65 ± 46.70) mg/m3], and higher than in spring [(193.75 ± 185.81) ind./m3, (60.95 ± 47.96) mg/m3]. There were 15 dominant species. The dominant species had obvious seasonal variation. In spring, the dominant species were offshore species such as Muggiaea atlantica and Dolioletta gegenbauri. Pleurobrachia globosa was dominant species only in summer. Nearshore warm-water species such as Acartia pacifica and Temora turbinata dominated in autumn. Compared with the summer of 2018, the temperature and chlorophyll a mass concentration in the summer of 2022 increased, which increased the proportion of jellyfish in the zooplankton community structure. The seasonal and interannual differences of zooplankton community structure in Tieshan Bay were mainly affected by temperature, salinity and Chl a concentration. The study also shows that the community structure of zooplankton tends to be miniaturized and the community stability is poor.
To explore the characteristics and changes of zooplankton community structure in Tieshan Bay area of the Beibu Gulf, the abundance, biomass, species composition, dominant species and their relationship with environmental factors were analyzed based on the investigation conducted during April 2018 (spring), July 2018 (summer), October 2018 (autumn) and July 2022 (summer). A total of 162 species (classes) of zooplankton were identified. In 2018, the abundance and biomass of zooplankton were higher in summer [(274.58 ± 221.15) ind./m3, (152.09 ± 142.97) mg/m3], higher than in autumn [(215.72 ± 114.81) ind./m3, (87.65 ± 46.70) mg/m3], and higher than in spring [(193.75 ± 185.81) ind./m3, (60.95 ± 47.96) mg/m3]. There were 15 dominant species. The dominant species had obvious seasonal variation. In spring, the dominant species were offshore species such as Muggiaea atlantica and Dolioletta gegenbauri. Pleurobrachia globosa was dominant species only in summer. Nearshore warm-water species such as Acartia pacifica and Temora turbinata dominated in autumn. Compared with the summer of 2018, the temperature and chlorophyll a mass concentration in the summer of 2022 increased, which increased the proportion of jellyfish in the zooplankton community structure. The seasonal and interannual differences of zooplankton community structure in Tieshan Bay were mainly affected by temperature, salinity and Chl a concentration. The study also shows that the community structure of zooplankton tends to be miniaturized and the community stability is poor.
2025, 47(5): 128-140.
doi: 10.12284/hyxb2025046
Abstract:
Chemical oxygen demand (COD) is an critical parameter for measuring the degree of organic pollution in water bodies. Using remote sensing inversion to quickly obtain the spatiotemporal distribution of COD concentration is essential for aquaculture pollution control and nearshore ecological environment protection. This study used Sentinel-2 extracted single band, vegetation index (NDVI), and water index (NDWI) to evaluate the performance of six models, including catboost regression (CBR), gradient boost regression (GBR), K-nearest neighbor regression (KNNR), light generalized boosted regression (LGBM), random forest (RF), and extreme gradient boosting regression (XGBR). The performance of each model was evaluated with the coefficient of determination (R2) and root mean square error (RMSE). The spatiotemporal distribution characteristics of COD concentration Maowei Sea and its coastal aquaculture ponds were analyzed. The results showed that: (1) The XGBR model had the best predictive performance, with a test set R2 of0.9432 and an RMSE of 1.4033 mg/L. (2) B8a, B2, and NDVI contributed significantly to the XGBR inversion model. (3) During the period of 2019−2023, the annual average concentration of COD in the aquaculture pond water ranged from 16.23 to 17.39 mg/L, with a relatively uniform spatial distribution pattern; The annual average concentration of COD in Maowei Sea ranged from 2.30 mg/L to 2.88 mg/L, showing a distribution pattern of decreasing from the inner bay to the outer bay and higher near the shore than far shore. This study has validated the remarkable universal applicability of the XGBR model when applied simultaneously to COD inversion in two specific aquatic environments: aquaculture waters and their coastal seas. The relevant findings not only provide valuable insights for COD inversion under various complex water quality conditions but also offer robust technical support and a solid theoretical foundation for aquaculture activities and environmental management in coastal areas.
Chemical oxygen demand (COD) is an critical parameter for measuring the degree of organic pollution in water bodies. Using remote sensing inversion to quickly obtain the spatiotemporal distribution of COD concentration is essential for aquaculture pollution control and nearshore ecological environment protection. This study used Sentinel-2 extracted single band, vegetation index (NDVI), and water index (NDWI) to evaluate the performance of six models, including catboost regression (CBR), gradient boost regression (GBR), K-nearest neighbor regression (KNNR), light generalized boosted regression (LGBM), random forest (RF), and extreme gradient boosting regression (XGBR). The performance of each model was evaluated with the coefficient of determination (R2) and root mean square error (RMSE). The spatiotemporal distribution characteristics of COD concentration Maowei Sea and its coastal aquaculture ponds were analyzed. The results showed that: (1) The XGBR model had the best predictive performance, with a test set R2 of
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