2023 Vol. 45, No. 11
Display Method:
2023, 45(11): 1-9.
doi: 10.12284/hyxb2023148
Abstract:
The ocean contains various spatiotemporal scales of motion processes, and ocean striations are a newly discovered form of flow in recent years. This flow phenomenon lies between geostrophic turbulence and quasi-steady flow. Due to the dominance of large-scale motion in the upper ocean, ocean striations are masked and need to be extracted using filtering methods. In this study, the three-dimensional structure of ocean striations in the North Pacific was extracted based on zonal velocity data using Chebyshev high-pass filtering. The “flow stability” index was defined to quantitatively analyze the barotropic feature of ocean striations in the North Pacific, thereby deepening the understanding of the structural characteristics of ocean striations in the North Pacific.
The ocean contains various spatiotemporal scales of motion processes, and ocean striations are a newly discovered form of flow in recent years. This flow phenomenon lies between geostrophic turbulence and quasi-steady flow. Due to the dominance of large-scale motion in the upper ocean, ocean striations are masked and need to be extracted using filtering methods. In this study, the three-dimensional structure of ocean striations in the North Pacific was extracted based on zonal velocity data using Chebyshev high-pass filtering. The “flow stability” index was defined to quantitatively analyze the barotropic feature of ocean striations in the North Pacific, thereby deepening the understanding of the structural characteristics of ocean striations in the North Pacific.
2023, 45(11): 10-19.
doi: 10.12284/hyxb2023154
Abstract:
Combining satellite altimetry and drifter data, the method of sea surface height to discover and track an anticyclonic eddy merger event that occurred near the southeastern Gulf of Mexico was used in this study. By studying this typical anticyclonic eddy merger process, the mode of eddy merging is preliminarily revealed, which helps to further understand the complex eddy mechanism. The Eulerian eddy results show that pairs of anticyclonic eddies attract each other and propagate together for more than three weeks before merging into a unified eddy structure and continuing to propagate westward. The Lagrangian vortex trajectories captured by drifters provide evidence of water exchange between the vortices before the merger, as one drifter exchanged its original anticyclonic eddy on November 15, indicating significant water exchange between the vortices before being observed by the altimeter. Before and after the merger, the radii of the Eulerian and Lagrangian vortices both increased significantly with the Eulerian radius improving by 96.2% and the Lagrangian radius of the drifting buoys pulled by two anticyclonic eddies improving by 49.1% and 115.6%, respectively. The sea surface temperature field also exhibited different environmental responses due to the merging effect, further verifying the occurrence of the merger process. Finally, the analysis of the dynamic evolution of kinematics such as kinetic energy, vorticity, and divergence before and after the merger, as well as the morphological changes such as radius, amplitude, and shape, showes that the merger roughly experienced processes such as vortex asymptote, water exchange, contour compression and deformation, elongated elliptical vortex generation, and boundary reshaping. The vertical structure of the plane where the vortex is located mainly shows evolution from bimodal to unimodal. After the vortex merger, energy is transferred to the mesoscale through inverse cascade. Due to the single-core vortex structure, some statistical properties are biased during the merging process, which may have led to abrupt changes before and after the event.
Combining satellite altimetry and drifter data, the method of sea surface height to discover and track an anticyclonic eddy merger event that occurred near the southeastern Gulf of Mexico was used in this study. By studying this typical anticyclonic eddy merger process, the mode of eddy merging is preliminarily revealed, which helps to further understand the complex eddy mechanism. The Eulerian eddy results show that pairs of anticyclonic eddies attract each other and propagate together for more than three weeks before merging into a unified eddy structure and continuing to propagate westward. The Lagrangian vortex trajectories captured by drifters provide evidence of water exchange between the vortices before the merger, as one drifter exchanged its original anticyclonic eddy on November 15, indicating significant water exchange between the vortices before being observed by the altimeter. Before and after the merger, the radii of the Eulerian and Lagrangian vortices both increased significantly with the Eulerian radius improving by 96.2% and the Lagrangian radius of the drifting buoys pulled by two anticyclonic eddies improving by 49.1% and 115.6%, respectively. The sea surface temperature field also exhibited different environmental responses due to the merging effect, further verifying the occurrence of the merger process. Finally, the analysis of the dynamic evolution of kinematics such as kinetic energy, vorticity, and divergence before and after the merger, as well as the morphological changes such as radius, amplitude, and shape, showes that the merger roughly experienced processes such as vortex asymptote, water exchange, contour compression and deformation, elongated elliptical vortex generation, and boundary reshaping. The vertical structure of the plane where the vortex is located mainly shows evolution from bimodal to unimodal. After the vortex merger, energy is transferred to the mesoscale through inverse cascade. Due to the single-core vortex structure, some statistical properties are biased during the merging process, which may have led to abrupt changes before and after the event.
2023, 45(11): 20-33.
doi: 10.12284/hyxb2023170
Abstract:
Liaodong Bay is the most severely ice-covered sea waters in China during winter. The large area of sea ice on the sea surface has significant impacts on maritime economic activities. This study focuses on reconstructing a time series of sea ice extent from 2001 to 2021 for Liaodong Bay based on MODIS satellite images. Meanwhile, a nonlinear relation between the floe ice distance and sea ice extent in Liaodong Bay is figured out, which is used to extend the historical maximum sea ice extent of Liaodong Bay back to 1953. Then, the interannual variation of the maximum sea ice extent is researched to obtain the sea ice extent in Liaodong Bay in the return period of engineering design. The impact factors of the maximum sea ice extent in Liaodong Bay are analyzed, and the results show that the correlation coefficient between the maximum sea ice extent and the freezing degree-days, as well as northerly wind component, reached 0.96. Furthermore, the correlation between the sea ice concentration in some regions of the Arctic during autumn and the winter sea ice extent in the Liaodong Bay is analyzed. Our results provide valuable insights for understanding the trend of sea ice extent in Liaodong Bay and formulating measures for sea ice disaster prevention.
Liaodong Bay is the most severely ice-covered sea waters in China during winter. The large area of sea ice on the sea surface has significant impacts on maritime economic activities. This study focuses on reconstructing a time series of sea ice extent from 2001 to 2021 for Liaodong Bay based on MODIS satellite images. Meanwhile, a nonlinear relation between the floe ice distance and sea ice extent in Liaodong Bay is figured out, which is used to extend the historical maximum sea ice extent of Liaodong Bay back to 1953. Then, the interannual variation of the maximum sea ice extent is researched to obtain the sea ice extent in Liaodong Bay in the return period of engineering design. The impact factors of the maximum sea ice extent in Liaodong Bay are analyzed, and the results show that the correlation coefficient between the maximum sea ice extent and the freezing degree-days, as well as northerly wind component, reached 0.96. Furthermore, the correlation between the sea ice concentration in some regions of the Arctic during autumn and the winter sea ice extent in the Liaodong Bay is analyzed. Our results provide valuable insights for understanding the trend of sea ice extent in Liaodong Bay and formulating measures for sea ice disaster prevention.
2023, 45(11): 34-44.
doi: 10.12284/hyxb2023156
Abstract:
Empirical Orthogonal Functions (EOFs) are usually used for sparse representation of the sound speed profile (SSP). However, due to the restriction of data completeness and measurement time, the representative error of the EOF will lead to limited accuracy of SSP reconstruction. In order to improve the reconstruction accuracy of SSP, the fuzzy C-means clustering algorithm is used to analyze the BOA_Argo historical data set and the reconstruction accuracy of the measured SSP based on different clustering spaces of data samples is discussed. The results shows that the SSPs are significant temporal-spatial clustering. The EOF and mean SSP generated by the clustered historical SSPs have the best reconstruction performance. The results of this paper are helpful to provide practical guidance for the selection of historical SSP training data and can improve the accuracy of SSP reconstruction.
Empirical Orthogonal Functions (EOFs) are usually used for sparse representation of the sound speed profile (SSP). However, due to the restriction of data completeness and measurement time, the representative error of the EOF will lead to limited accuracy of SSP reconstruction. In order to improve the reconstruction accuracy of SSP, the fuzzy C-means clustering algorithm is used to analyze the BOA_Argo historical data set and the reconstruction accuracy of the measured SSP based on different clustering spaces of data samples is discussed. The results shows that the SSPs are significant temporal-spatial clustering. The EOF and mean SSP generated by the clustered historical SSPs have the best reconstruction performance. The results of this paper are helpful to provide practical guidance for the selection of historical SSP training data and can improve the accuracy of SSP reconstruction.
2023, 45(11): 45-61.
doi: 10.12284/hyxb2023124
Abstract:
It has been an important research topic in oceanography and climatology to understand the evolution of marine environment in the context of anathroprogenic warming. In the geological past, the Earth has experienced several warming periods (including the early Holocene), which provide natural analogs for future climate. The global climate experienced rapid warming during the early Holocene, accompanied by ice sheet melting and rapid sea level rise, which have significantly impacted sedimentary processes and marine environment in high-latitude marginal seas, including the Bering Sea. The Bering Sea consists of a broad continental shelf, adjacent to the North American continent, and receives material supplies from the Yukon River, Anadyr River and Kuskokwim River. There are still significant gaps in our understanding of how the Bering Sea responds to the early Holocene climate. In this study, high-resolution analysis of major and minor elements in bulk sediments of Core LV63-19-3 retrieved from the northern slope of the Bering Sea, in combination with a well-constrained sedimentary age model to investigate the sedimentary environment changes on the northern Bering Sea slope during the early to middle Holocene (11.7–5.5 ka BP). The results show that the sedimentation rate on the northern continental slope of Bering Sea was as high as 392.9 cm/ka during 11.5–11 ka BP, and decreased rapidly to 17.2 cm/ka after 9.7 ka BP. At 11–10.7 ka BP, a dark laminated sediment layer about of 40 cm thick was found. In the period of high sedimentation rate, the average grain size of sediments was finer, and increased gradually after 9 kaBP. Both major and minor element concentrations indicate that the lithological properties of terrigenous clastic sediments were mainly felsic sediments with a small amount of pyroclastic contributions. The high sediment rate corresponds to the Meltwater Pulse-1B event (11.4–11.1 ka BP) and resulted in a blooming of siliceous productivity on the Bering Sea continental slope. In the study area from 11 ka BP to 10.7 ka BP, the increase in seasonal sea ice coverage inhibited the oxygen supply from the atmosphere to surface water and subsequent transport to the bottom water, while the glacial meltwater and the persistent high productivity in summer and autumn further exacerbated the surface water stratification and ocean interior oxygen consumption on the continental slope of the Bering Sea, both of which together triggered the formation of laminated sediment. After 9 ka BP, the seasonal sea ice activity in the Bering Sea increased gradually, but the mass accumulation rate of terrigenous detrital materials decreased, indicateing a decrease in the supply of terrigenous materials to the study area along with sea level rise. We suggest that the rapid shift in early Holocene sedimentary environment on the northern Bering Sea continental slope is the result of a combination of sea level, Meltwater Pulse 1B event and seasonal sea ice activity, which is actually controlled by high-latitude solar insolation, North American ice sheet melting, and global climate.
It has been an important research topic in oceanography and climatology to understand the evolution of marine environment in the context of anathroprogenic warming. In the geological past, the Earth has experienced several warming periods (including the early Holocene), which provide natural analogs for future climate. The global climate experienced rapid warming during the early Holocene, accompanied by ice sheet melting and rapid sea level rise, which have significantly impacted sedimentary processes and marine environment in high-latitude marginal seas, including the Bering Sea. The Bering Sea consists of a broad continental shelf, adjacent to the North American continent, and receives material supplies from the Yukon River, Anadyr River and Kuskokwim River. There are still significant gaps in our understanding of how the Bering Sea responds to the early Holocene climate. In this study, high-resolution analysis of major and minor elements in bulk sediments of Core LV63-19-3 retrieved from the northern slope of the Bering Sea, in combination with a well-constrained sedimentary age model to investigate the sedimentary environment changes on the northern Bering Sea slope during the early to middle Holocene (11.7–5.5 ka BP). The results show that the sedimentation rate on the northern continental slope of Bering Sea was as high as 392.9 cm/ka during 11.5–11 ka BP, and decreased rapidly to 17.2 cm/ka after 9.7 ka BP. At 11–10.7 ka BP, a dark laminated sediment layer about of 40 cm thick was found. In the period of high sedimentation rate, the average grain size of sediments was finer, and increased gradually after 9 kaBP. Both major and minor element concentrations indicate that the lithological properties of terrigenous clastic sediments were mainly felsic sediments with a small amount of pyroclastic contributions. The high sediment rate corresponds to the Meltwater Pulse-1B event (11.4–11.1 ka BP) and resulted in a blooming of siliceous productivity on the Bering Sea continental slope. In the study area from 11 ka BP to 10.7 ka BP, the increase in seasonal sea ice coverage inhibited the oxygen supply from the atmosphere to surface water and subsequent transport to the bottom water, while the glacial meltwater and the persistent high productivity in summer and autumn further exacerbated the surface water stratification and ocean interior oxygen consumption on the continental slope of the Bering Sea, both of which together triggered the formation of laminated sediment. After 9 ka BP, the seasonal sea ice activity in the Bering Sea increased gradually, but the mass accumulation rate of terrigenous detrital materials decreased, indicateing a decrease in the supply of terrigenous materials to the study area along with sea level rise. We suggest that the rapid shift in early Holocene sedimentary environment on the northern Bering Sea continental slope is the result of a combination of sea level, Meltwater Pulse 1B event and seasonal sea ice activity, which is actually controlled by high-latitude solar insolation, North American ice sheet melting, and global climate.
2023, 45(11): 62-75.
doi: 10.12284/hyxb2023152
Abstract:
The composition and texture characteristics of plagioclase in basalt from the 26°S hydrothermal field of the Southern Mid-Atlantic Ridge provide an important basis for the study of magmatic evolution characteristics. On the basis of observing the petrography of basalt and analyzing the composition of plagioclase, the structure and composition of plagioclase at different stages are compared to explore the process of magma evolution. The results show that the study area is mainly composed of porphyritic basalt, and plagioclase porphyries are commonly characterized by glomerocryst structures, oscillatory-zoned, dissolved and resorbed rim, and growth structures. The plagioclase in the matrix is mainly acicular and swallow-tailed crystals; the basalts in the SMAR-26°S hydrothermal zone are mainly sodium tholeiitic basalts. In the early stage of magma evolution, bytownite was mainly formed, while in the late stage, labradorite was mainly formed. Throughout the entire evolution process, the content of CaO and Al2O3 decreases, while the content of SiO2, Na2O, FeO, and MgO increases; from the core to rim of plagioclase phenocrysts and then to plagioclase microcrystalline in the matrix, the An values decreases overall. The An values in the rim of plagioclase phenocryst partially overlaps with the An values of plagioclase microlites in the matrix, resulting in a gradual decrease in temperature. These represent the changes from the magma origin area to magma eruption. After the formation of mantle magma, it rapidly rises and erupts to form basalt. During the upwelling process, it may undergo the process of decompression accompanied by volatiles escaping, dissolving in the deep, supersaturated crystallizing of the melt, mixing of low-Si same sourced magma, and syn-eruptive fast decompression of degassed magma.
The composition and texture characteristics of plagioclase in basalt from the 26°S hydrothermal field of the Southern Mid-Atlantic Ridge provide an important basis for the study of magmatic evolution characteristics. On the basis of observing the petrography of basalt and analyzing the composition of plagioclase, the structure and composition of plagioclase at different stages are compared to explore the process of magma evolution. The results show that the study area is mainly composed of porphyritic basalt, and plagioclase porphyries are commonly characterized by glomerocryst structures, oscillatory-zoned, dissolved and resorbed rim, and growth structures. The plagioclase in the matrix is mainly acicular and swallow-tailed crystals; the basalts in the SMAR-26°S hydrothermal zone are mainly sodium tholeiitic basalts. In the early stage of magma evolution, bytownite was mainly formed, while in the late stage, labradorite was mainly formed. Throughout the entire evolution process, the content of CaO and Al2O3 decreases, while the content of SiO2, Na2O, FeO, and MgO increases; from the core to rim of plagioclase phenocrysts and then to plagioclase microcrystalline in the matrix, the An values decreases overall. The An values in the rim of plagioclase phenocryst partially overlaps with the An values of plagioclase microlites in the matrix, resulting in a gradual decrease in temperature. These represent the changes from the magma origin area to magma eruption. After the formation of mantle magma, it rapidly rises and erupts to form basalt. During the upwelling process, it may undergo the process of decompression accompanied by volatiles escaping, dissolving in the deep, supersaturated crystallizing of the melt, mixing of low-Si same sourced magma, and syn-eruptive fast decompression of degassed magma.
2023, 45(11): 76-87.
doi: 10.12284/hyxb2023158
Abstract:
The Zhujiang River Estuary is located in the northern South China Sea. It has a wide intertidal zone and a high diversity of intertidal macrobenthos. However, most of the previous intertidal-related studies and intertidal species records were carried out on the east coast of the Zhujiang River Estuary, while studies on the west coast of the Zhujiang River Estuary were relatively scarce. From 2021 to 2023, a comprehensive survey focus on Brachyura (crabs), one of the main groups of intertidal macrobenthos, was conducted in the intertidal zone of Qi’ao Island, Zhuhai City, western Zhujiang River Estuary. Combined with the collection and revision of species recorded in previous studies, an updated checklist of intertidal crabs in Qi’ao Island was created, and the ecological and geographical distribution of these crab species were described. A total of 90 specimens were colleted and 31 species from 10 families and 21 genera were identified. Seventeen species (e.g. Orisarma patshuni and Anomalifrons lightana) were new to the Qi’ao Island, and one species (Hemigrapsus takanoi) were new to the Zhujiang River Estuary. The updated checklist includes 48 intertidal crab species belonging to 13 families and 29 genera, among which Sesarmidae (10 species), Varunidae (10) and Ocypodidae (8) are the three most species-rich families. The crab fauna composition of the island is mainly composed of East Asian endemic taxa and Indo-West Pacific/West Pacific widespread taxa, showing overwhelming East Asian warm water characteristics. Mudflats and mangroves are the most abundant habitat types for crab species on the island. Our results has increased the number of intertidal crab species on the west coast of the Zhujiang River Estuary from 31 to 55 species, which is the same as the number of species recorded in Shenzhen Bay on the east coast of the Zhujiang River Estuary. The total number of intertidal crab species recorded in the Zhujiang River Estuary has reached 77 species in 14 families and 38 genera, of which 33 species (42.9%) has been reported on both the east and west coasts.
The Zhujiang River Estuary is located in the northern South China Sea. It has a wide intertidal zone and a high diversity of intertidal macrobenthos. However, most of the previous intertidal-related studies and intertidal species records were carried out on the east coast of the Zhujiang River Estuary, while studies on the west coast of the Zhujiang River Estuary were relatively scarce. From 2021 to 2023, a comprehensive survey focus on Brachyura (crabs), one of the main groups of intertidal macrobenthos, was conducted in the intertidal zone of Qi’ao Island, Zhuhai City, western Zhujiang River Estuary. Combined with the collection and revision of species recorded in previous studies, an updated checklist of intertidal crabs in Qi’ao Island was created, and the ecological and geographical distribution of these crab species were described. A total of 90 specimens were colleted and 31 species from 10 families and 21 genera were identified. Seventeen species (e.g. Orisarma patshuni and Anomalifrons lightana) were new to the Qi’ao Island, and one species (Hemigrapsus takanoi) were new to the Zhujiang River Estuary. The updated checklist includes 48 intertidal crab species belonging to 13 families and 29 genera, among which Sesarmidae (10 species), Varunidae (10) and Ocypodidae (8) are the three most species-rich families. The crab fauna composition of the island is mainly composed of East Asian endemic taxa and Indo-West Pacific/West Pacific widespread taxa, showing overwhelming East Asian warm water characteristics. Mudflats and mangroves are the most abundant habitat types for crab species on the island. Our results has increased the number of intertidal crab species on the west coast of the Zhujiang River Estuary from 31 to 55 species, which is the same as the number of species recorded in Shenzhen Bay on the east coast of the Zhujiang River Estuary. The total number of intertidal crab species recorded in the Zhujiang River Estuary has reached 77 species in 14 families and 38 genera, of which 33 species (42.9%) has been reported on both the east and west coasts.
2023, 45(11): 88-100.
doi: 10.12284/hyxb2023160
Abstract:
Habitat environment provides necessary condition for the survival of marine organisms. Biological and abiotic component jointly affect the spatial distribution of marine organisms. This study used three Bayesian models to analyze the bottom trawl survey data and environmental monitoring data during spring and autumn of 2013−2022 in Haizhou Bay, in order to explore the habitat distribution characteristics of Amblychaetorichthys hexanema and main influencing factors. It was found that the Bayesian regularized neural network (BRNN) model had good performance. Therefore, this study applied this model for analysis. The research results showed that there was a positive correlation between the relative resource density of A. hexanema and the relative density of its prey organisms. With the increase of bottom temperature, bottom salinity, water depth, predators and competitors, the relative density of A. hexanema rose firstly, and then declined. The relative density of A. hexanema in Haizhou Bay in spring and autumn showed a decreasing trend from southwest to northeast, and the density in the southwest coastal shallow area was relatively high. Among them, the density in autumn was higher than that in spring. At the same time, the A. hexanema in autumn of 2018, 2021, and 2022 showed higher resource density in offshore waters between 34.7°−36°N and 121°−121.6°E. This study will contribute to the understanding of habitat distribution characteristics of A. hexanema and main influencing factors, providing a theoretical basis for the conservation and management of its resource.
Habitat environment provides necessary condition for the survival of marine organisms. Biological and abiotic component jointly affect the spatial distribution of marine organisms. This study used three Bayesian models to analyze the bottom trawl survey data and environmental monitoring data during spring and autumn of 2013−2022 in Haizhou Bay, in order to explore the habitat distribution characteristics of Amblychaetorichthys hexanema and main influencing factors. It was found that the Bayesian regularized neural network (BRNN) model had good performance. Therefore, this study applied this model for analysis. The research results showed that there was a positive correlation between the relative resource density of A. hexanema and the relative density of its prey organisms. With the increase of bottom temperature, bottom salinity, water depth, predators and competitors, the relative density of A. hexanema rose firstly, and then declined. The relative density of A. hexanema in Haizhou Bay in spring and autumn showed a decreasing trend from southwest to northeast, and the density in the southwest coastal shallow area was relatively high. Among them, the density in autumn was higher than that in spring. At the same time, the A. hexanema in autumn of 2018, 2021, and 2022 showed higher resource density in offshore waters between 34.7°−36°N and 121°−121.6°E. This study will contribute to the understanding of habitat distribution characteristics of A. hexanema and main influencing factors, providing a theoretical basis for the conservation and management of its resource.
2023, 45(11): 101-111.
doi: 10.12284/hyxb2023150
Abstract:
Tide level and salinity are crucial environmental factors that significantly impact the growth and development of Aegiceras corniculatum seedlings and to a certain extent, determine if their embryos could land successfully and develop into seedling rapidly. In this paper, the process of A. corniculatum embryos developing to seedings was observed by the indoor controlled experiments, during which, the effects of salinity, submergence duration, as well as the interaction between salinity and submergence duration on the germination and growth of radicles were discussed. The results showed that: (1) the embryos of the A. corniculatum were unable to sprout in the treatment group that the embryos were soaked completely for 24 h/d in a simulated lower low tidal level of flooded environment. For the treatment group that the embryos were soaked completely for 6 h/d and the radicles soaked for 18 h/d in a simulated low to medium tidal level of flooded environment, the highest mean rooting rates and the longest radicle of the embryos were produced. In the treatment group that the base of embryos were soaked in a simulated higher high tide flooded environment, the rooting rates and mean rooting rates of embryos were the lowest, accompanied by the least quantities of radicles. However, in the treatment group where the vermiculites were shallowly inserted into the bottom, which simulated a scene that the base of embryo was immersed within the tidal environment, it was found that the radicle germination was the slowest with the highest rooting rates, and the radicles were the shortest, along with the largest quantities. (2) In the salinity environment of 0, the radicles were the longest after a 11 days cultivation. In the salinity environment of 10, highest levels in both the length and quantities of radicles were observed in the first 13 days of embryo culture. In contrast, the rooting rate and the mean rooting rate of the embryos, as well as the length and quantity of radicle were significantly smaller in the salinity environment of 20, which indicated the germination and growth of radicle were inhibited in such salinity environment. (3) The interaction between submergence duration and salinity had a significant impact on the growth of the radicles of A. corniculatum. If both the submergence duration and salinity were within the tolerance ranges of the radicles of A. corniculatum, its embryos could still sprout normally under the stresses of different combination of submergence duration and salinity. Hence, the optimal way to artificially cultivatethe A. corniculatum seedlings, was that the embryo was completely soaked for 6 h/d and the radicle was soaked for 18 h/d in the salinity environment of 10. The study can provide some theoretical basis for the artificial cultivation and protection of A. corniculatum seedlings in the intertidal zone.
Tide level and salinity are crucial environmental factors that significantly impact the growth and development of Aegiceras corniculatum seedlings and to a certain extent, determine if their embryos could land successfully and develop into seedling rapidly. In this paper, the process of A. corniculatum embryos developing to seedings was observed by the indoor controlled experiments, during which, the effects of salinity, submergence duration, as well as the interaction between salinity and submergence duration on the germination and growth of radicles were discussed. The results showed that: (1) the embryos of the A. corniculatum were unable to sprout in the treatment group that the embryos were soaked completely for 24 h/d in a simulated lower low tidal level of flooded environment. For the treatment group that the embryos were soaked completely for 6 h/d and the radicles soaked for 18 h/d in a simulated low to medium tidal level of flooded environment, the highest mean rooting rates and the longest radicle of the embryos were produced. In the treatment group that the base of embryos were soaked in a simulated higher high tide flooded environment, the rooting rates and mean rooting rates of embryos were the lowest, accompanied by the least quantities of radicles. However, in the treatment group where the vermiculites were shallowly inserted into the bottom, which simulated a scene that the base of embryo was immersed within the tidal environment, it was found that the radicle germination was the slowest with the highest rooting rates, and the radicles were the shortest, along with the largest quantities. (2) In the salinity environment of 0, the radicles were the longest after a 11 days cultivation. In the salinity environment of 10, highest levels in both the length and quantities of radicles were observed in the first 13 days of embryo culture. In contrast, the rooting rate and the mean rooting rate of the embryos, as well as the length and quantity of radicle were significantly smaller in the salinity environment of 20, which indicated the germination and growth of radicle were inhibited in such salinity environment. (3) The interaction between submergence duration and salinity had a significant impact on the growth of the radicles of A. corniculatum. If both the submergence duration and salinity were within the tolerance ranges of the radicles of A. corniculatum, its embryos could still sprout normally under the stresses of different combination of submergence duration and salinity. Hence, the optimal way to artificially cultivatethe A. corniculatum seedlings, was that the embryo was completely soaked for 6 h/d and the radicle was soaked for 18 h/d in the salinity environment of 10. The study can provide some theoretical basis for the artificial cultivation and protection of A. corniculatum seedlings in the intertidal zone.
2023, 45(11): 112-130.
doi: 10.12284/hyxb2023166
Abstract:
In order to disclose the changes of coral communities in the Daya Bay, literature analysis, field investigation and laboratory simulating experiments were performed. A total of 39 scleractinian coral species were detected in the 2020 field investigation, and massive coral Platygyra, Favia and Favites were dominant in the bay. The inlet coral community change was featured by the near completely lost of once dominant coral Acropora and Montipora during 1983/1984−2020. Analysis based on the background of global coral degradation and the specialty of the seawater environment in the Daya Bay indicated that the coral community degradation in the Daya Bay is a result of multiple stressors, and the susceptibility of Acropora and the frequent occurrence of high temperature and low content oxygen may be the main cause of inlet A. pruinosa lost. At last, as a potential larva source of inlet coral restoration, coral community of Shuazhou East Island should be protected seriously.
In order to disclose the changes of coral communities in the Daya Bay, literature analysis, field investigation and laboratory simulating experiments were performed. A total of 39 scleractinian coral species were detected in the 2020 field investigation, and massive coral Platygyra, Favia and Favites were dominant in the bay. The inlet coral community change was featured by the near completely lost of once dominant coral Acropora and Montipora during 1983/1984−2020. Analysis based on the background of global coral degradation and the specialty of the seawater environment in the Daya Bay indicated that the coral community degradation in the Daya Bay is a result of multiple stressors, and the susceptibility of Acropora and the frequent occurrence of high temperature and low content oxygen may be the main cause of inlet A. pruinosa lost. At last, as a potential larva source of inlet coral restoration, coral community of Shuazhou East Island should be protected seriously.
2023, 45(11): 131-141.
doi: 10.12284/hyxb2023146
Abstract:
Salinity is a crucial factor affecting the gut microbial homeostasis of aquatic animals, which has a significant impact on their growth and health. Sinonovacula constricta, a buried cultivated bivalve in mudflat, is frequently affected by salinity fluctuation. However, it remains unclear whether salinity has undesirable effects on the gut tissue and microbial community of S. constricta. To address these concerns, this study set up three different salinity stress groups: low salinity (5), normal salinity (20) and high salinity (35), with normal salinity 20 at 0 day as the control. Samples of S. constricta were collected before stress (i.e., normal salinity 20, 0 day) and after stress for 15 days, and were analyzed the differences in gut tissue structure, gut microbial compositions and potential functions via using the histopathology, 16S rRNA high-throughput sequencing technology and PICRUSt2. Simultaneously, the guts from S. constricta under normal salinity at 0 day were taken for comparative analysis. The results showed that the acute salinity stress for 15 days caused varying degrees of damage to the gut tissue structure of S. constricta, as observed by the cell vacuolation, tissue necrosis and villi clutter. A total of 712 bacterial OTUs were identified across all groups, among which the number of shared OTUs accounted for 6.2% of total OTUs. The dominant bacteria in the gut of S. constricta under low- and high- salinity stress belonged to γ-Proteobacteria and α-Proteobacteria, respectively. Acute salinity stress altered the α-diversity of gut bacterial community, with the lowest species richness under low salinity stress. The gut bacterial community structure of S. constricta changed significantly (p < 0.002) under both low- and high- salinity stress, accompanied by a decrease in the interspecific interactions of gut bacterial community. The ecological processes governing gut bacterial assembly of S. constricta was mainly deterministic under three salinity stresses, and this process decreased under the low salinity stress. Functional prediction results showed that acute salinity stress significantly varied the abundance of S. constricta gut bacterial-mediated nutrient and energy metabolism-related functional pathways, whereas the abundance of immune-related functional pathways significantly increased under high salinity stress. These findings suggest that acute salinity stress can cause pathological damage to the gut of S. constricta, accompanied by obvious change in gut bacterial communities and functional potentials, which could affect the health of S. constricta.
Salinity is a crucial factor affecting the gut microbial homeostasis of aquatic animals, which has a significant impact on their growth and health. Sinonovacula constricta, a buried cultivated bivalve in mudflat, is frequently affected by salinity fluctuation. However, it remains unclear whether salinity has undesirable effects on the gut tissue and microbial community of S. constricta. To address these concerns, this study set up three different salinity stress groups: low salinity (5), normal salinity (20) and high salinity (35), with normal salinity 20 at 0 day as the control. Samples of S. constricta were collected before stress (i.e., normal salinity 20, 0 day) and after stress for 15 days, and were analyzed the differences in gut tissue structure, gut microbial compositions and potential functions via using the histopathology, 16S rRNA high-throughput sequencing technology and PICRUSt2. Simultaneously, the guts from S. constricta under normal salinity at 0 day were taken for comparative analysis. The results showed that the acute salinity stress for 15 days caused varying degrees of damage to the gut tissue structure of S. constricta, as observed by the cell vacuolation, tissue necrosis and villi clutter. A total of 712 bacterial OTUs were identified across all groups, among which the number of shared OTUs accounted for 6.2% of total OTUs. The dominant bacteria in the gut of S. constricta under low- and high- salinity stress belonged to γ-Proteobacteria and α-Proteobacteria, respectively. Acute salinity stress altered the α-diversity of gut bacterial community, with the lowest species richness under low salinity stress. The gut bacterial community structure of S. constricta changed significantly (p < 0.002) under both low- and high- salinity stress, accompanied by a decrease in the interspecific interactions of gut bacterial community. The ecological processes governing gut bacterial assembly of S. constricta was mainly deterministic under three salinity stresses, and this process decreased under the low salinity stress. Functional prediction results showed that acute salinity stress significantly varied the abundance of S. constricta gut bacterial-mediated nutrient and energy metabolism-related functional pathways, whereas the abundance of immune-related functional pathways significantly increased under high salinity stress. These findings suggest that acute salinity stress can cause pathological damage to the gut of S. constricta, accompanied by obvious change in gut bacterial communities and functional potentials, which could affect the health of S. constricta.
2023, 45(11): 142-152.
doi: 10.12284/hyxb2023142
Abstract:
Mytilus galloprovincialis is the representative bivalve with the great ability to enrich for paralytic shellfish toxins (PSTs), however, it has been shown that exposure of Mytilus galloprovincialis to PSTs can induces an inflammatory response in the organism, while its mechanism and effects on toxin metabolism are not clear. In this study, transcriptomics and metabolomics were used to compare the differences in gene expression and metabolite content of purple mussel (M. galloprovincialis) in different periods of Alexandrium catenella bloom, in order to analyze the inflammatory response mechanism of purple mussel under the stress of PSTs. The results show that there are significantly changes in genes and metabolites expressed after exposure to PSTs, including 17 232 differentially expressed genes and 341 differentially expressed metabolites. Based on the association analysis, differentially expressed genes and metabolites are significantly enriched in the arachidonic acid and glutathione metabolic pathways, and genes PLA2G2F, ALOX5, TBXAS1 and metabolites ARA, PGH2, TXA2, LTA4, 5-HETE play important roles in the pro-inflammatory response of the mussel organism; while genes GPX4, CYP2J2 and metabolites 15-HETE and GSH regulate the regression of inflammation in the organism, constituting a complex network of inflammatory regulatory signals. This study reveals that arachidonic acid-related pathways play an important regulatory role in the inflammatory response of the mussel organism, which provides a basis for further insight into the mechanism of the inflammatory network response of the mussel organism under the stress of PSTs.
Mytilus galloprovincialis is the representative bivalve with the great ability to enrich for paralytic shellfish toxins (PSTs), however, it has been shown that exposure of Mytilus galloprovincialis to PSTs can induces an inflammatory response in the organism, while its mechanism and effects on toxin metabolism are not clear. In this study, transcriptomics and metabolomics were used to compare the differences in gene expression and metabolite content of purple mussel (M. galloprovincialis) in different periods of Alexandrium catenella bloom, in order to analyze the inflammatory response mechanism of purple mussel under the stress of PSTs. The results show that there are significantly changes in genes and metabolites expressed after exposure to PSTs, including 17 232 differentially expressed genes and 341 differentially expressed metabolites. Based on the association analysis, differentially expressed genes and metabolites are significantly enriched in the arachidonic acid and glutathione metabolic pathways, and genes PLA2G2F, ALOX5, TBXAS1 and metabolites ARA, PGH2, TXA2, LTA4, 5-HETE play important roles in the pro-inflammatory response of the mussel organism; while genes GPX4, CYP2J2 and metabolites 15-HETE and GSH regulate the regression of inflammation in the organism, constituting a complex network of inflammatory regulatory signals. This study reveals that arachidonic acid-related pathways play an important regulatory role in the inflammatory response of the mussel organism, which provides a basis for further insight into the mechanism of the inflammatory network response of the mussel organism under the stress of PSTs.
2023, 45(11): 153-163.
doi: 10.12284/hyxb2023168
Abstract:
The Analytical Four Dimensional Ensemble Variational is a “flow-dependent” and non-sequential data assimilation method without adjoint models and completely inherits the nonlinear processing ability of Four Dimensional Variational. In this study, based on the Analytical Four Dimensional Ensemble Variational, the initial field optimization of the Global Barotropic Model was carried out, the assimilation ability of Analytical Four Dimensional Ensemble Variational in the medium complex model was verified, the efficient perturbation ensemble member generation scheme was explored, and Analytical Four Dimensional Ensemble Variational was reduced to the sample space, and finally the sensitivity to the assimilation time window length and the observation sampling interval was verified. The experiments results show that the Analytical Four Dimensional Ensemble Variational can optimize the initial field of the Global Barotropic Model, and after reducing the dimensionality to the sample space, only 80 ensemble members are required to achieve good assimilation effect, and ideal assimilation can also be achieved under the conditions of a long assimilation integration window and observation sampling interval.
The Analytical Four Dimensional Ensemble Variational is a “flow-dependent” and non-sequential data assimilation method without adjoint models and completely inherits the nonlinear processing ability of Four Dimensional Variational. In this study, based on the Analytical Four Dimensional Ensemble Variational, the initial field optimization of the Global Barotropic Model was carried out, the assimilation ability of Analytical Four Dimensional Ensemble Variational in the medium complex model was verified, the efficient perturbation ensemble member generation scheme was explored, and Analytical Four Dimensional Ensemble Variational was reduced to the sample space, and finally the sensitivity to the assimilation time window length and the observation sampling interval was verified. The experiments results show that the Analytical Four Dimensional Ensemble Variational can optimize the initial field of the Global Barotropic Model, and after reducing the dimensionality to the sample space, only 80 ensemble members are required to achieve good assimilation effect, and ideal assimilation can also be achieved under the conditions of a long assimilation integration window and observation sampling interval.
2023, 45(11): 164-174.
doi: 10.12284/hyxb2023144
Abstract:
In order to master the current distribution and the restoration status of Suaeda salsa in the Red Beach, a remote sensing extraction model was constructed based on the HY-1C satellite CZI data and on-site measured spectral. Five periods of spatial distribution data of S. salsa were obtained in 2018−2022, with the extraction accuracy better than 87%; based on the extracted results, a change analysis on the spatio-temporal distribution and the class-level landscape pattern of S. salsa was conducted. The results show that: in the past 5 years, the overall distribution area of the S. salsa community has shown a significant increase trend, with indicators such as class area (CA), percentage of landscape (PLAND), largest patch index (LPI), effective mesh size (MESH), and mean patch size (AREA_MN) showing a first decreasing and then increasing trend, splitting index (SPLIT) first increasing and then decreasing, and aggregation index (AI) overall showing an upward trend. It can be seen that the proportion of S. salsa community in the landscape composition of Red Beach has been increasing year by year, the complexity of landscape shape has increased, the fragmentation trend has been reversed, and the trend of aggregation distribution is more obvious. This all indicates that the large-scale restoration project of S. salsa implemented since 2019 has achieved a significant result. The biotope of the Red Beach S. salsa continues to improve, but at the same time, it shows a spatial imbalance of the recovery level, which is generally better in the middle and east than in the west, and better in the south than in the north. The results of this paper can provide basic data for the evaluation of the effectiveness of the restoration project, and provide decision-making reference for the spatial planning in the future restoration work.
In order to master the current distribution and the restoration status of Suaeda salsa in the Red Beach, a remote sensing extraction model was constructed based on the HY-1C satellite CZI data and on-site measured spectral. Five periods of spatial distribution data of S. salsa were obtained in 2018−2022, with the extraction accuracy better than 87%; based on the extracted results, a change analysis on the spatio-temporal distribution and the class-level landscape pattern of S. salsa was conducted. The results show that: in the past 5 years, the overall distribution area of the S. salsa community has shown a significant increase trend, with indicators such as class area (CA), percentage of landscape (PLAND), largest patch index (LPI), effective mesh size (MESH), and mean patch size (AREA_MN) showing a first decreasing and then increasing trend, splitting index (SPLIT) first increasing and then decreasing, and aggregation index (AI) overall showing an upward trend. It can be seen that the proportion of S. salsa community in the landscape composition of Red Beach has been increasing year by year, the complexity of landscape shape has increased, the fragmentation trend has been reversed, and the trend of aggregation distribution is more obvious. This all indicates that the large-scale restoration project of S. salsa implemented since 2019 has achieved a significant result. The biotope of the Red Beach S. salsa continues to improve, but at the same time, it shows a spatial imbalance of the recovery level, which is generally better in the middle and east than in the west, and better in the south than in the north. The results of this paper can provide basic data for the evaluation of the effectiveness of the restoration project, and provide decision-making reference for the spatial planning in the future restoration work.
2023, 45(11): 175-184.
doi: 10.12284/hyxb2023138
Abstract:
The SWOT was successfully launched on December 16, 2022, which is a new generation of wide-swath altimetry satellite. The SWOT is expected to provide two-dimensional strip hight informations of global sea area and inland water surface. It is expected to solve the problem of traditional one-dimensional observations, which is inconsistent accuracy in solving the directional component of the vertical deflection. In this paper, we adopted SWOT simulated data to solve along-track vertical deflection by jointing multi-directions, and proposed two upgrading schemes according to the characteristics of the simulated data: one is to increase the distance of joint observations appropriately, and the other is to assign weights according to the quality of SWOT strip data separately. The vertical deflection of the SWOT simulated data solved is checked with EGM2008 model, the standard deviation of the north component and east component are 0.416 8, 0.472 9 arcsec respectively. The solution quality is better than other schemes, it proves the feasibility of improved schemes. The method is also validated using Tiangong II wide-swath data. So it can be applied to SWOT real data to solve the vertical deflection.
The SWOT was successfully launched on December 16, 2022, which is a new generation of wide-swath altimetry satellite. The SWOT is expected to provide two-dimensional strip hight informations of global sea area and inland water surface. It is expected to solve the problem of traditional one-dimensional observations, which is inconsistent accuracy in solving the directional component of the vertical deflection. In this paper, we adopted SWOT simulated data to solve along-track vertical deflection by jointing multi-directions, and proposed two upgrading schemes according to the characteristics of the simulated data: one is to increase the distance of joint observations appropriately, and the other is to assign weights according to the quality of SWOT strip data separately. The vertical deflection of the SWOT simulated data solved is checked with EGM2008 model, the standard deviation of the north component and east component are 0.416 8, 0.472 9 arcsec respectively. The solution quality is better than other schemes, it proves the feasibility of improved schemes. The method is also validated using Tiangong II wide-swath data. So it can be applied to SWOT real data to solve the vertical deflection.
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