2023 Vol. 45, No. 8
Display Method:
2023, 45(8): 1-10.
doi: 10.12284/hyxb2023096
Abstract:
Using tide gauge observation, satellite altimeter data, and the result of 10 CMIP6 Earth System Models with good simulation performance, the long-term trend of sea level change in China, and predicts the range of sea level rise in the future are analyzed in this study. The results show that: (1) from 1960 to 2021, the sea level in China’s coastal areas showed an accelerated rising trend, with a rise rate of 2.5 mm/a and an acceleration of 0.06 mm/a2. From 1993 to 2021, the rise rate was 4.0 mm/a, higher than the global rate of 3.3 mm/a in the same period. (2) From 1980 to 2021, the sea level rise rates of the Bohai Sea and the Yellow Sea, the East China Sea and the South China Sea were 3.5 mm/a, 3.3 mm/a and 3.6 mm/a, respectively. The sea level rise rates of the Bohai Sea and the Yellow Sea, the South China Sea were relatively fast, while the sea level rise rates of East China Sea was slow. The coastal sea level rose slowly from 1960s to 1970s, and accelerated after 1980s in the Bohai Sea and the Yellow Sea. (3) Under the medium (SSP2-4.5) and high (SSP5-8.5) scenarios, China’s offshore sea level will rise by 0.22 m (0.19−0.28 m) and 0.24 m (0.21−0.33 m) respectively in 2050, and will rise by 0.59 m (0.47−0.80 m) and 0.83 m (0.64−1.09 m) respectively in 2100. (4) During 2021−2040, the median value of sea level rise predicted by statistics is close to the predicted value under the low, medium and high scenarios of the numerical model. During 2041−2060, the predicted values of the low, medium and high scenarios of the numerical model are between the middle and high values of the statistical prediction. During 2081−2100, the high value of sea level rise predicted by statistics is close to that predicted by the medium scenario of the numerical model, the absolute deviation is 0.017 m, and the relative deviation is 3.4%. (5) Under the high scenario, the existing once-in-a-century extreme high sea level in 2100 will become less than 10 year return period, in which more than 50% of the stations will become less than 2 year return period, the defense capacity of coastal protection works and other infrastructure will be reduced, and the risk of flood and other disaster events in complex coastal cities will increase.
Using tide gauge observation, satellite altimeter data, and the result of 10 CMIP6 Earth System Models with good simulation performance, the long-term trend of sea level change in China, and predicts the range of sea level rise in the future are analyzed in this study. The results show that: (1) from 1960 to 2021, the sea level in China’s coastal areas showed an accelerated rising trend, with a rise rate of 2.5 mm/a and an acceleration of 0.06 mm/a2. From 1993 to 2021, the rise rate was 4.0 mm/a, higher than the global rate of 3.3 mm/a in the same period. (2) From 1980 to 2021, the sea level rise rates of the Bohai Sea and the Yellow Sea, the East China Sea and the South China Sea were 3.5 mm/a, 3.3 mm/a and 3.6 mm/a, respectively. The sea level rise rates of the Bohai Sea and the Yellow Sea, the South China Sea were relatively fast, while the sea level rise rates of East China Sea was slow. The coastal sea level rose slowly from 1960s to 1970s, and accelerated after 1980s in the Bohai Sea and the Yellow Sea. (3) Under the medium (SSP2-4.5) and high (SSP5-8.5) scenarios, China’s offshore sea level will rise by 0.22 m (0.19−0.28 m) and 0.24 m (0.21−0.33 m) respectively in 2050, and will rise by 0.59 m (0.47−0.80 m) and 0.83 m (0.64−1.09 m) respectively in 2100. (4) During 2021−2040, the median value of sea level rise predicted by statistics is close to the predicted value under the low, medium and high scenarios of the numerical model. During 2041−2060, the predicted values of the low, medium and high scenarios of the numerical model are between the middle and high values of the statistical prediction. During 2081−2100, the high value of sea level rise predicted by statistics is close to that predicted by the medium scenario of the numerical model, the absolute deviation is 0.017 m, and the relative deviation is 3.4%. (5) Under the high scenario, the existing once-in-a-century extreme high sea level in 2100 will become less than 10 year return period, in which more than 50% of the stations will become less than 2 year return period, the defense capacity of coastal protection works and other infrastructure will be reduced, and the risk of flood and other disaster events in complex coastal cities will increase.
2023, 45(8): 11-23.
doi: 10.12284/hyxb2023100
Abstract:
Multiple studies have confirmed the long-term property modification of water columns from the bottom to the sea surface at the Southern Ocean and pointed out that it is closely related to the changes of large-scale external forcing. However, the higher frequency interannual variability of the water masses and its causes are still poorly understood, including the winter water (WW), which is the most vulnerable to external forcing near the sea surface. Based on repeated hydrographic observations along 110°E in Januaries 2011 to 2020 and meteorological reanalysis datasets, this study estimated interannual variability of the WW layer in the seasonal ice zone (SIZ) and its possible causes over ten years. Results show that WW properties have significant temporal and spatial variability in this region. A significant positive correlation between the WW core temperature anomaly and the previous-year Antarctic Oscillation (AAO) index anomaly (R = 0.69) and a negative correlation between the AAO index and the turning latitude of the local zonal wind component (R = −0.61), indicate that a larger (smaller) AAO index corresponds to a southward (northward) shift of the divergence zone, and the increase (decrease) of the WW core temperature in the SIZ. A negative correspondence between the local net precipitation anomaly and the WW core salinity anomaly indicates the negative net precipitation anomaly (less freshwater transport to the ocean) after 2016 contributes to an increase in the WW core salinity anomaly. Meanwhile, the local eddy kinetic energy anomaly is negatively correlated with the WW thickness anomaly (R = −0.70), which supports the idea that the enhancement (decrease) in the intensity of persistent cyclonic eddies in this region may strengthen (weaken) the upward pumping to shoal the depth of the circumpolar deep water, and further affect the WW thickness. This study contributes to an in-depth understanding of the specific response of water columns in the Southern Ocean to the high-frequency variability of external forcing.
Multiple studies have confirmed the long-term property modification of water columns from the bottom to the sea surface at the Southern Ocean and pointed out that it is closely related to the changes of large-scale external forcing. However, the higher frequency interannual variability of the water masses and its causes are still poorly understood, including the winter water (WW), which is the most vulnerable to external forcing near the sea surface. Based on repeated hydrographic observations along 110°E in Januaries 2011 to 2020 and meteorological reanalysis datasets, this study estimated interannual variability of the WW layer in the seasonal ice zone (SIZ) and its possible causes over ten years. Results show that WW properties have significant temporal and spatial variability in this region. A significant positive correlation between the WW core temperature anomaly and the previous-year Antarctic Oscillation (AAO) index anomaly (R = 0.69) and a negative correlation between the AAO index and the turning latitude of the local zonal wind component (R = −0.61), indicate that a larger (smaller) AAO index corresponds to a southward (northward) shift of the divergence zone, and the increase (decrease) of the WW core temperature in the SIZ. A negative correspondence between the local net precipitation anomaly and the WW core salinity anomaly indicates the negative net precipitation anomaly (less freshwater transport to the ocean) after 2016 contributes to an increase in the WW core salinity anomaly. Meanwhile, the local eddy kinetic energy anomaly is negatively correlated with the WW thickness anomaly (R = −0.70), which supports the idea that the enhancement (decrease) in the intensity of persistent cyclonic eddies in this region may strengthen (weaken) the upward pumping to shoal the depth of the circumpolar deep water, and further affect the WW thickness. This study contributes to an in-depth understanding of the specific response of water columns in the Southern Ocean to the high-frequency variability of external forcing.
2023, 45(8): 24-30.
doi: 10.12284/hyxb2023094
Abstract:
Two single-scene SAR images observed by Radarsat-2 and Sentinel-1A were decomposed to obtain a pair of SAR sub-aperture images at different azimuth-angles, respectively. Doppler centroid anomaly method was used to invert the sea surface current of two sub-aperture images with different azimuth angles. The current field was obtained by vector synthesis. The inversion results were verified by the HYCOM model data with spatio-temporal matching. The results show that the root mean square (RMS) of the current velocity between the synthesized result by two sub-aperture images of Radarsat-2 and the HYCOM model data is 0.09 m/s, and the correlation coefficient is 0.64. The RMS of current direction is 10.49° and the correlation coefficient is 0.78 of this group data. As for the results of the Sentinel-1A image, the RMS of the current velocity is 0.06 m/s, and the correlation coefficient is 0.82. The RMS of the current direction is 2.85°, and the correlation coefficient is 0.86. It can be seen that the two-dimensional ocean currents field can be effectively inverted based on the two sub-aperture SAR images that decomposed from single-scene SAR image. The inversion accuracy is related to the relative direction of the radar’s looking direction and the real current vector. The inversion accuracy of the sea surface current field can be higher when the relative angle is small.
Two single-scene SAR images observed by Radarsat-2 and Sentinel-1A were decomposed to obtain a pair of SAR sub-aperture images at different azimuth-angles, respectively. Doppler centroid anomaly method was used to invert the sea surface current of two sub-aperture images with different azimuth angles. The current field was obtained by vector synthesis. The inversion results were verified by the HYCOM model data with spatio-temporal matching. The results show that the root mean square (RMS) of the current velocity between the synthesized result by two sub-aperture images of Radarsat-2 and the HYCOM model data is 0.09 m/s, and the correlation coefficient is 0.64. The RMS of current direction is 10.49° and the correlation coefficient is 0.78 of this group data. As for the results of the Sentinel-1A image, the RMS of the current velocity is 0.06 m/s, and the correlation coefficient is 0.82. The RMS of the current direction is 2.85°, and the correlation coefficient is 0.86. It can be seen that the two-dimensional ocean currents field can be effectively inverted based on the two sub-aperture SAR images that decomposed from single-scene SAR image. The inversion accuracy is related to the relative direction of the radar’s looking direction and the real current vector. The inversion accuracy of the sea surface current field can be higher when the relative angle is small.
2023, 45(8): 31-45.
doi: 10.12284/hyxb2023086
Abstract:
Sea ice motion is an important factor affecting Arctic sea ice advection and spatial redistribution of mass balance. Based on the data collected by 66 ice-based drifting buoys deployed in the Arctic Ocean from September 2018 to August 2019, combined with atmospheric reanalysis data and passive microwave sea ice concentration product, we calculated the sea ice drifting speed, the ice-wind speed ratio and the inertial intensity of sea ice motion, so as to characterize the temporal and spatial changes of Arctic sea ice kinematic parameters over a full ice season, and analyse the correlation between ice-wind speed ratio and sea ice concentration. Seasonally, the sea ice drift speed in the Beaufort-Chukchi Sea, the central eastern Arctic Ocean and the central western Arctic Ocean showed a decreasing trend in autumn and winter and an increasing trend in spring and summer. Spatially, the Greenland Sea ((0.32 ± 0.06) m/s) had the highest sea ice drift speed, followed by the Fram Strait ((0.17 ± 0.07) m/s), and those in the Beaufort-Chukchi Sea ((0.14 ± 0.05) m/s), the central eastern Arctic Ocean ((0.09 ± 0.02) m/s) and the central western Arctic Ocean ((0.07 ± 0.03) m/s) were relatively low. On the monthly scale, the ice-wind speed ratio was mainly dominated by sea ice drift speed. The ice-wind speed ratio in the Fram Strait and the Greenland Sea was relatively larger, due to the strong ocean surface current. While the ice-wind speed ratio in the central western Arctic Ocean, the central eastern Arctic Ocean, and the Beaufort-Chukchi Sea was relative low and tended to be distributed between 0−0.02 with the increase in sea ice concentration. The monthly averaged IMI for all buoys was 0.158 ± 0.144, and the response of ice to wind and the inertial signal of ice motion gradually weakened during the autumn-winter transition and started to strengthen again in spring and summer. Therefore, both of the above parameters can be used as important indicators to indicate the consolidation of ice field.
Sea ice motion is an important factor affecting Arctic sea ice advection and spatial redistribution of mass balance. Based on the data collected by 66 ice-based drifting buoys deployed in the Arctic Ocean from September 2018 to August 2019, combined with atmospheric reanalysis data and passive microwave sea ice concentration product, we calculated the sea ice drifting speed, the ice-wind speed ratio and the inertial intensity of sea ice motion, so as to characterize the temporal and spatial changes of Arctic sea ice kinematic parameters over a full ice season, and analyse the correlation between ice-wind speed ratio and sea ice concentration. Seasonally, the sea ice drift speed in the Beaufort-Chukchi Sea, the central eastern Arctic Ocean and the central western Arctic Ocean showed a decreasing trend in autumn and winter and an increasing trend in spring and summer. Spatially, the Greenland Sea ((0.32 ± 0.06) m/s) had the highest sea ice drift speed, followed by the Fram Strait ((0.17 ± 0.07) m/s), and those in the Beaufort-Chukchi Sea ((0.14 ± 0.05) m/s), the central eastern Arctic Ocean ((0.09 ± 0.02) m/s) and the central western Arctic Ocean ((0.07 ± 0.03) m/s) were relatively low. On the monthly scale, the ice-wind speed ratio was mainly dominated by sea ice drift speed. The ice-wind speed ratio in the Fram Strait and the Greenland Sea was relatively larger, due to the strong ocean surface current. While the ice-wind speed ratio in the central western Arctic Ocean, the central eastern Arctic Ocean, and the Beaufort-Chukchi Sea was relative low and tended to be distributed between 0−0.02 with the increase in sea ice concentration. The monthly averaged IMI for all buoys was 0.158 ± 0.144, and the response of ice to wind and the inertial signal of ice motion gradually weakened during the autumn-winter transition and started to strengthen again in spring and summer. Therefore, both of the above parameters can be used as important indicators to indicate the consolidation of ice field.
2023, 45(8): 46-61.
doi: 10.12284/hyxb2023092
Abstract:
Sea ice numerical model is an effective way to study the dynamical and thermal state parameters of sea ice and the connections between them. The current assessment of the results of numerical ice thickness simulation is much less than the sea ice extent/area and concentration, and the study of the influence of ice velocity and sea ice deformation on ice thickness distribution is still lacking. We simulated the Arctic sea ice variability from 1980 to 2018 using the Los Alamos sea ice model (CICE), and validated and comparison the CICE simulation results using remote sensing and assimilated ice thickness data. We further analyzed the effects of simulated ice velocity and sea ice deformation on ice thickness, and calculated the contributions of ice velocity divergence and shear bias to ice thickness bias. The results show that the interannual variability of the mean ice thickness and ice speed in the Arctic north of 70°N is reasonable, but the multi-year trends of the simulated mean ice thickness and ice speed are smaller than the variability of the assimilated data; the differences in the spatial distribution of the simulated and observed ice thickness are closely related to the deviations of the ice speed and deformation rate, mainly in the positive deviation in the Beaufort Sea and the negative deviation in the Arctic central zone to Fram Strait. The contribution of divergence and shear deviation to ice thickness deviation in the pan-Arctic region fluctuates between 13% and 16% before March, and jumps from 16% to 27% in March-April. The divergence bias dominates the positive bias of ice thickness in the Beaufort Sea region in November and December, while the shear bias dominates the negative ice thickness bias in the winter in the ocean north of the Canadian archipelago and in the region of the Arctic transpolar drift.
Sea ice numerical model is an effective way to study the dynamical and thermal state parameters of sea ice and the connections between them. The current assessment of the results of numerical ice thickness simulation is much less than the sea ice extent/area and concentration, and the study of the influence of ice velocity and sea ice deformation on ice thickness distribution is still lacking. We simulated the Arctic sea ice variability from 1980 to 2018 using the Los Alamos sea ice model (CICE), and validated and comparison the CICE simulation results using remote sensing and assimilated ice thickness data. We further analyzed the effects of simulated ice velocity and sea ice deformation on ice thickness, and calculated the contributions of ice velocity divergence and shear bias to ice thickness bias. The results show that the interannual variability of the mean ice thickness and ice speed in the Arctic north of 70°N is reasonable, but the multi-year trends of the simulated mean ice thickness and ice speed are smaller than the variability of the assimilated data; the differences in the spatial distribution of the simulated and observed ice thickness are closely related to the deviations of the ice speed and deformation rate, mainly in the positive deviation in the Beaufort Sea and the negative deviation in the Arctic central zone to Fram Strait. The contribution of divergence and shear deviation to ice thickness deviation in the pan-Arctic region fluctuates between 13% and 16% before March, and jumps from 16% to 27% in March-April. The divergence bias dominates the positive bias of ice thickness in the Beaufort Sea region in November and December, while the shear bias dominates the negative ice thickness bias in the winter in the ocean north of the Canadian archipelago and in the region of the Arctic transpolar drift.
2023, 45(8): 62-72.
doi: 10.12284/hyxb2023098
Abstract:
The distribution process of trace elements between coral aragonite skeletons and seawater is a key link to control the incorporating of trace elements in seawater into coral skeletons. The distribution coefficient (KD) characterizing this distribution process is often used to reconstruct the contents of trace elements in seawater in time series. Lacking of in situ research on corals and seawater, the limited knowledge related to the distribution behavior of trace elements between coral aragonite skeletons and seawater seriously hindered our acquisition of accurate chemical quantitative data on seawater. In this study we selected two typical reef-building coral species (Goniastrea retiformis and Platygyra yaeyamaensis) and five trace elements (Cu, Zn, Pb, Cd and Cr) in the surrounding in-situ surface seawater of Weizhou Island in the northern South China Sea, and estimated the distribution coefficients of these trace elements between the coral aragonite skeleton and seawater. Results revealed that the KD value of G. retiformis for Cu, Zn, Pb, Cd, Cr was 3.65, 0.57, 1.06, 0.88, 0.66 respectively; the KD value of P. yaeyamaensis was 3.49, 0.97, 1.42, 1.01, 0.60 respectively. We found a significant difference among different coral species in the KD values of Cu, Zn, Pb and Cd, but no significant difference for Cr. The results indicate that the KD values of trace elements are affected by the Rayleigh fractionation, which is related to the numerical values of KD. The study provided relatively accurate KD values for coral aragonite skeleton and seawater, represented important basic data for future research on coral reefs, and expanded our knowledge of chemical signature in biogenic lattices associated with marine organism.
The distribution process of trace elements between coral aragonite skeletons and seawater is a key link to control the incorporating of trace elements in seawater into coral skeletons. The distribution coefficient (KD) characterizing this distribution process is often used to reconstruct the contents of trace elements in seawater in time series. Lacking of in situ research on corals and seawater, the limited knowledge related to the distribution behavior of trace elements between coral aragonite skeletons and seawater seriously hindered our acquisition of accurate chemical quantitative data on seawater. In this study we selected two typical reef-building coral species (Goniastrea retiformis and Platygyra yaeyamaensis) and five trace elements (Cu, Zn, Pb, Cd and Cr) in the surrounding in-situ surface seawater of Weizhou Island in the northern South China Sea, and estimated the distribution coefficients of these trace elements between the coral aragonite skeleton and seawater. Results revealed that the KD value of G. retiformis for Cu, Zn, Pb, Cd, Cr was 3.65, 0.57, 1.06, 0.88, 0.66 respectively; the KD value of P. yaeyamaensis was 3.49, 0.97, 1.42, 1.01, 0.60 respectively. We found a significant difference among different coral species in the KD values of Cu, Zn, Pb and Cd, but no significant difference for Cr. The results indicate that the KD values of trace elements are affected by the Rayleigh fractionation, which is related to the numerical values of KD. The study provided relatively accurate KD values for coral aragonite skeleton and seawater, represented important basic data for future research on coral reefs, and expanded our knowledge of chemical signature in biogenic lattices associated with marine organism.
2023, 45(8): 73-85.
doi: 10.12284/hyxb2023127
Abstract:
Early diagenesis in marginal sea sediments is an important process that affects carbon cycling and burial. Early diagenetic processes and influencing factors, however, remains poorly constrained. Dissolved inorganic carbon (DIC), dissolved inorganic nitrogen (DIN), Fe2+, Mn2+, sulfate and other parameters in sediment porewaters of five short cores collected in August 2018 from the Changjiang River Estuary and East China Sea inner-shelf were analyzed. In combination with grain size composition, specific surface area, organic carbon concentrations and stable carbon isotopic composition in surface sediments and bottom water parameters, the early diagenetic processes and influencing factors in sediments under different sedimentary regimes were studied. Concentrations of DIC and\begin{document}${{\rm {NH}}_4^+} $\end{document} ![]()
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Early diagenesis in marginal sea sediments is an important process that affects carbon cycling and burial. Early diagenetic processes and influencing factors, however, remains poorly constrained. Dissolved inorganic carbon (DIC), dissolved inorganic nitrogen (DIN), Fe2+, Mn2+, sulfate and other parameters in sediment porewaters of five short cores collected in August 2018 from the Changjiang River Estuary and East China Sea inner-shelf were analyzed. In combination with grain size composition, specific surface area, organic carbon concentrations and stable carbon isotopic composition in surface sediments and bottom water parameters, the early diagenetic processes and influencing factors in sediments under different sedimentary regimes were studied. Concentrations of DIC and
2023, 45(8): 86-95.
doi: 10.12284/hyxb2023106
Abstract:
Traditional species distribution models rarely incorporate interspecific relationships into the modeling framework, which hinders their predictions of habitat distributions. In recent years, joint species distribution models (JSDMs) have drawn increasing attentions, but their practical applications remain rare in the marine realm. In this study, we used the HMSC (hierarchical modelling of species communities) method to study their relationships between 17 demersal fish species and environmental factors and the interspecific correlation. The model was built on the basis of bottom trawling data collected in the coastal waters of Shandong in summer, 2017, including the environmental data of water depth, bottom water temperature and bottom water salinity. Five variants of HMSC models were developed with respect to the linear or nonlinear relationships between species and the environmental variables and the exists of random effects, and WAIC and other indicators as well as cross-validation were used to evaluate the performances of fitting and prediction of these models. The results showed that the optimal model was the one incorporating nonlinear relationships and random effects (Model 5). The nonlinear models were generally superior to the linear models, and including the interspecific relationships in the model could improve model fitting performances. Temperature was the main factor influencing the distribution of demersal fishes in the coastal waters of Shandong, accounting for 51.4% of the mean explained variance, followed by water depth and random effects, which accounted for 35.7% and 12.8% explained variance, respectively. There were significant linear positive correlations between most demersal fishes and water depth, and significant nonlinear relationships with water temperature. There were significant interspecific correlations among the demersal fishes, which could be roughly divided into three groups according to the sign of the correlations, indicating that the interspecies relationships played an important role in shaping species distributions. This study suggested that the abiotic factors and biotic factors should be integrated in species distribution modeling, and our results might provide a guideline for the prediction of habitat distribution of fishery resources.
Traditional species distribution models rarely incorporate interspecific relationships into the modeling framework, which hinders their predictions of habitat distributions. In recent years, joint species distribution models (JSDMs) have drawn increasing attentions, but their practical applications remain rare in the marine realm. In this study, we used the HMSC (hierarchical modelling of species communities) method to study their relationships between 17 demersal fish species and environmental factors and the interspecific correlation. The model was built on the basis of bottom trawling data collected in the coastal waters of Shandong in summer, 2017, including the environmental data of water depth, bottom water temperature and bottom water salinity. Five variants of HMSC models were developed with respect to the linear or nonlinear relationships between species and the environmental variables and the exists of random effects, and WAIC and other indicators as well as cross-validation were used to evaluate the performances of fitting and prediction of these models. The results showed that the optimal model was the one incorporating nonlinear relationships and random effects (Model 5). The nonlinear models were generally superior to the linear models, and including the interspecific relationships in the model could improve model fitting performances. Temperature was the main factor influencing the distribution of demersal fishes in the coastal waters of Shandong, accounting for 51.4% of the mean explained variance, followed by water depth and random effects, which accounted for 35.7% and 12.8% explained variance, respectively. There were significant linear positive correlations between most demersal fishes and water depth, and significant nonlinear relationships with water temperature. There were significant interspecific correlations among the demersal fishes, which could be roughly divided into three groups according to the sign of the correlations, indicating that the interspecies relationships played an important role in shaping species distributions. This study suggested that the abiotic factors and biotic factors should be integrated in species distribution modeling, and our results might provide a guideline for the prediction of habitat distribution of fishery resources.
2023, 45(8): 96-107.
doi: 10.12284/hyxb2023104
Abstract:
Colanic acid is one of the vital exopolysaccharides in biofilms, yet the effect of marine bacterial colanic acid on the settlement of invertebrates is still rarely covered. In this study, eight strains of marine bacteria isolated from natural biofilms were identified and the phylogenetic analysis was carried out, the colanic acid content and inducing ability of biofilms were also determined. Before that, the biofilm formation capacity and the extracellular products of the screened bacteria were detected. It was found that β-polysaccharide had a significant positive correlation with the settlement rate of Mytilus coruscus plantigrades (p < 0.05). The quantitative results of colanic acid content showed that among the five Gram-negative bacteria which could produce colanic acid, Shewanella marisflavi had the highest colanic acid yield of 1076.43 μg/mL, and three Gram-positive bacteria could not generate it. The results of plantigrade settlement induced by different biofilms showed that the inducing activity of marine bacterial biofilms on the settlement rate of M. coruscus was positively correlated with the content of colanic acid (p < 0.05). These findings prove that the Gram-negative bacteria with colanic acid can positively regulate the settlement of M. coruscus plantigrades, while the Gram-positive bacteria without colanic acid have no inducing activity. This study provides further insights to figure out the interaction between the chemical cues of biofilms and marine molluscs.
Colanic acid is one of the vital exopolysaccharides in biofilms, yet the effect of marine bacterial colanic acid on the settlement of invertebrates is still rarely covered. In this study, eight strains of marine bacteria isolated from natural biofilms were identified and the phylogenetic analysis was carried out, the colanic acid content and inducing ability of biofilms were also determined. Before that, the biofilm formation capacity and the extracellular products of the screened bacteria were detected. It was found that β-polysaccharide had a significant positive correlation with the settlement rate of Mytilus coruscus plantigrades (p < 0.05). The quantitative results of colanic acid content showed that among the five Gram-negative bacteria which could produce colanic acid, Shewanella marisflavi had the highest colanic acid yield of 1076.43 μg/mL, and three Gram-positive bacteria could not generate it. The results of plantigrade settlement induced by different biofilms showed that the inducing activity of marine bacterial biofilms on the settlement rate of M. coruscus was positively correlated with the content of colanic acid (p < 0.05). These findings prove that the Gram-negative bacteria with colanic acid can positively regulate the settlement of M. coruscus plantigrades, while the Gram-positive bacteria without colanic acid have no inducing activity. This study provides further insights to figure out the interaction between the chemical cues of biofilms and marine molluscs.
2023, 45(8): 108-119.
doi: 10.12284/hyxb2023088
Abstract:
As one of the vegetation types with the highest carbon storage in tropical regions, the area of mangrove forest shows a trend of fragmentation and reduction. The spatial distribution and dynamic information of mangrove biomass are crucial to the estimation of greenhouse gas flux and carbon storage, as well as policy formulation and implementation. However, both optical data and SAR data commonly used for biomass estimation have signal saturation phenomenon, and traditional estimation algorithms for mangrove biomass estimation have high data requirements and relatively low estimation accuracy. In order to solve this problem, this study compared the accuracy of four gradient enhanced decision tree algorithms for estimating aboveground biomass (AGB) of invasive mangrove species Sonneria apetala used UAV-LiDAR data, and discussed the importance of variables in the modeling process. The results indicate that: (1) XGBR had a high fitting ability for the estimation of mangrove AGB, reaching R² = 0.833 8, RMSE = 1.55 Mg/hm2. (2) The predicted AGB in the study area ranged from 73.10 Mg/hm2 to 190.00 Mg/hm2, with an average of 109.10 Mg/hm2. (3) LiDAR index describing canopy height characteristics is an important variable for estimating mangrove AGB. Conclusion: This study proved the feasibility of UAV-LiDAR data and XGBR model for estimating the AGB of mangrove forests, in order to provide data support for the blue carbon research of mangrove ecosystems.
As one of the vegetation types with the highest carbon storage in tropical regions, the area of mangrove forest shows a trend of fragmentation and reduction. The spatial distribution and dynamic information of mangrove biomass are crucial to the estimation of greenhouse gas flux and carbon storage, as well as policy formulation and implementation. However, both optical data and SAR data commonly used for biomass estimation have signal saturation phenomenon, and traditional estimation algorithms for mangrove biomass estimation have high data requirements and relatively low estimation accuracy. In order to solve this problem, this study compared the accuracy of four gradient enhanced decision tree algorithms for estimating aboveground biomass (AGB) of invasive mangrove species Sonneria apetala used UAV-LiDAR data, and discussed the importance of variables in the modeling process. The results indicate that: (1) XGBR had a high fitting ability for the estimation of mangrove AGB, reaching R² = 0.833 8, RMSE = 1.55 Mg/hm2. (2) The predicted AGB in the study area ranged from 73.10 Mg/hm2 to 190.00 Mg/hm2, with an average of 109.10 Mg/hm2. (3) LiDAR index describing canopy height characteristics is an important variable for estimating mangrove AGB. Conclusion: This study proved the feasibility of UAV-LiDAR data and XGBR model for estimating the AGB of mangrove forests, in order to provide data support for the blue carbon research of mangrove ecosystems.
2023, 45(8): 120-129.
doi: 10.12284/hyxb2023108
Abstract:
Coccolithophores can produce particulate organic carbon (POC) via photosynthesis and synthesize particulate inorganic carbon (PIC) via calcification; they also make an important contribution to marine carbon cycle. Some studies have reported that ocean acidification generally increases POC content and decreases PIC content of coccolithophores, however, most of the studies show these results under nutrient replete conditions, and a few studies focus on the combined effects of nutrient limitation and ocean acidification on coccolithophores. In this study, we investigated the physiological responses of the coccolithophore Emiliania huxleyi to ocean acidification under dissolved inorganic phosphorus (DIP) limitation. Our data show that ocean acidification and DIP limitation act synergistically to reduce growth rate, relative photosynthetic electron transport rate and light use efficiency of photosynthetic system II of E. huxleyi. Dissolved inorganic phosphorus limitation dominantly increases cellular POC content and offsets the negative effect of ocean acidification on cellular PIC content and the ratio of PIC : POC. Our results suggest that DIP limitation changed the response trends of POC and PIC contents to ocean acidification, which indicates that the contributions of coccolithophores to marine carbon cycle are different in these ocean areas with different DIP concentrations.
Coccolithophores can produce particulate organic carbon (POC) via photosynthesis and synthesize particulate inorganic carbon (PIC) via calcification; they also make an important contribution to marine carbon cycle. Some studies have reported that ocean acidification generally increases POC content and decreases PIC content of coccolithophores, however, most of the studies show these results under nutrient replete conditions, and a few studies focus on the combined effects of nutrient limitation and ocean acidification on coccolithophores. In this study, we investigated the physiological responses of the coccolithophore Emiliania huxleyi to ocean acidification under dissolved inorganic phosphorus (DIP) limitation. Our data show that ocean acidification and DIP limitation act synergistically to reduce growth rate, relative photosynthetic electron transport rate and light use efficiency of photosynthetic system II of E. huxleyi. Dissolved inorganic phosphorus limitation dominantly increases cellular POC content and offsets the negative effect of ocean acidification on cellular PIC content and the ratio of PIC : POC. Our results suggest that DIP limitation changed the response trends of POC and PIC contents to ocean acidification, which indicates that the contributions of coccolithophores to marine carbon cycle are different in these ocean areas with different DIP concentrations.
2023, 45(8): 130-142.
doi: 10.12284/hyxb2023102
Abstract:
In order to clarify the effects of litter decomposition of Gracilaria lemaneiformis segments on environment and the succession of bacterial community, the characteristics of nutrient content in seaweed, water and sediment, and succession characteristics of bacterial community attached to the seaweed, water and sediment were carried out by the simulation experiment. The results showed that its decomposition rate reached 83.5% after 50 d. The content of total organic carbon (TOC), total nitrogen (TN) and total phosphorus (TP) in water increased by 241.2%, 229.8% and 101.3%, respectively, compared with the initial period. The content of dissolved oxygen (DO) in water decreased by 82.9%, which from 1.87 mg/L to 0.32 mg/L. In addition, the number of bacteria attached to G. lemanei-formis remained at 107 copy/g, while the richness and diversity of bacteria continued to increase during the decomposition processes. The bacteria community structure was significantly affected by total organic carbon, total nitrogen, total phosphorus and DO in water. The relative abundances of Planctomycetes, Spirochaetae, Firmicutes and δ-Proteobacteria increased, while that of Bacteroidetes, α-Proteobacteria and γ-Proteobacteria decreased. During the process of decomposition, the functional gene abundance of metabolism attached to G. lemaneiformis continued to decline. Briefly, the results indicated that decomposition of G. lemaneiformis segments would lead to the increasing of nutrient concentration in water. And Planctomycetes, Spirochaetae, Firmicutes and δ-Proteobacteria played important roles in the process of decomposing of G. lemaneiformis.
In order to clarify the effects of litter decomposition of Gracilaria lemaneiformis segments on environment and the succession of bacterial community, the characteristics of nutrient content in seaweed, water and sediment, and succession characteristics of bacterial community attached to the seaweed, water and sediment were carried out by the simulation experiment. The results showed that its decomposition rate reached 83.5% after 50 d. The content of total organic carbon (TOC), total nitrogen (TN) and total phosphorus (TP) in water increased by 241.2%, 229.8% and 101.3%, respectively, compared with the initial period. The content of dissolved oxygen (DO) in water decreased by 82.9%, which from 1.87 mg/L to 0.32 mg/L. In addition, the number of bacteria attached to G. lemanei-formis remained at 107 copy/g, while the richness and diversity of bacteria continued to increase during the decomposition processes. The bacteria community structure was significantly affected by total organic carbon, total nitrogen, total phosphorus and DO in water. The relative abundances of Planctomycetes, Spirochaetae, Firmicutes and δ-Proteobacteria increased, while that of Bacteroidetes, α-Proteobacteria and γ-Proteobacteria decreased. During the process of decomposition, the functional gene abundance of metabolism attached to G. lemaneiformis continued to decline. Briefly, the results indicated that decomposition of G. lemaneiformis segments would lead to the increasing of nutrient concentration in water. And Planctomycetes, Spirochaetae, Firmicutes and δ-Proteobacteria played important roles in the process of decomposing of G. lemaneiformis.
2023, 45(8): 143-154.
doi: 10.12284/hyxb2023084
Abstract:
To understand the characteristics of autophagy induced by virus infection in microalgae Emiliania huxleyi, we used diverse techniques including transmission electron microscopy, fluorescence microscopy, immunolabeling and biochemical methodologies to investigate the role of autophagy in the interaction between E. huxleyi BOF92 and its specific virus EhV99B1. The results showed that virus infection induced autophagy and vacuolar acidification in host cells, concomitant with up-regulation of autophagy-related genes such as atg1, atg5, atg8 and atg12 (p < 0.01) and Vps34 protein involved in the induction and nucleation of autophagosomes (p < 0.01). The expression level of autophagy marker protein p62 was significantly down-regulated (p < 0.05) during viral infection, indicating enhanced autophagic flux and activated autophagy. The expressions levels of negative regulatory factors such as phosphatidylinositol (PI3K), phosphorylated protein kinase B (p-Akt) and phosphorylated target of rapamycin protein (p-TOR) were significantly decreased in the late stage of viral infection (p < 0.01). Moreover, the level of reactive oxygen species (ROS) increased dramatically (p < 0.01), accompanied by a significant reduction in mitochondrial membrane potential (MMP) and ATP levels (p < 0.01) during viral infection. In conclusion, EhV99B1 infection induces ROS production and mitochondrial membrane damage in host cells, and initiates autophagy by regulating the PI3K/Akt/TOR signal pathway. Therefore, autophagy, as a unique form of programmed cell death, is of great significance to the individual survival and population dynamics of phytoplankton respond to environmental and biological stress.
To understand the characteristics of autophagy induced by virus infection in microalgae Emiliania huxleyi, we used diverse techniques including transmission electron microscopy, fluorescence microscopy, immunolabeling and biochemical methodologies to investigate the role of autophagy in the interaction between E. huxleyi BOF92 and its specific virus EhV99B1. The results showed that virus infection induced autophagy and vacuolar acidification in host cells, concomitant with up-regulation of autophagy-related genes such as atg1, atg5, atg8 and atg12 (p < 0.01) and Vps34 protein involved in the induction and nucleation of autophagosomes (p < 0.01). The expression level of autophagy marker protein p62 was significantly down-regulated (p < 0.05) during viral infection, indicating enhanced autophagic flux and activated autophagy. The expressions levels of negative regulatory factors such as phosphatidylinositol (PI3K), phosphorylated protein kinase B (p-Akt) and phosphorylated target of rapamycin protein (p-TOR) were significantly decreased in the late stage of viral infection (p < 0.01). Moreover, the level of reactive oxygen species (ROS) increased dramatically (p < 0.01), accompanied by a significant reduction in mitochondrial membrane potential (MMP) and ATP levels (p < 0.01) during viral infection. In conclusion, EhV99B1 infection induces ROS production and mitochondrial membrane damage in host cells, and initiates autophagy by regulating the PI3K/Akt/TOR signal pathway. Therefore, autophagy, as a unique form of programmed cell death, is of great significance to the individual survival and population dynamics of phytoplankton respond to environmental and biological stress.
2023, 45(8): 155-165.
doi: 10.12284/hyxb2023147
Abstract:
Accurate extraction of marine raft aquaculture area information is of great significance for marine resource management and environmental monitoring. But the raft culture area is often submerged in water with weak data signal areas, resulting in low extraction accuracy based on optical images alone. Therefore, this paper takes Weihai Rongcheng Bay as the research area, and improves the U-Net neural network by adding channel attention mechanism to combine the spectral information of GF-2 optical image and the texture information of GF-3 radar image, trying to improve the extraction accuracy of raft aquaculture area. The results show that: （1) Whether it is a single optical image or a fusion image of optical and radar images, the overall accuracy of the prediction results of the U-Net neural network with channel attention mechanism will be improved, with an increase of 2.21%−4.12%. （2) Using the improved U-Net neural network to process the fusion data, the overall accuracy is 95.75%, which is 4.3% higher than that of only using GF-2 image. （3) For weak signal region, the overall accuracy and Kappa coefficient of extraction based on improved network and data fusion are 91.61% and 0.827 7, respectively. This method can effectively extract the weak signal area of marine raft aquaculture area, and can provide technical support for marine aquaculture area statistics and marine environment detection.
Accurate extraction of marine raft aquaculture area information is of great significance for marine resource management and environmental monitoring. But the raft culture area is often submerged in water with weak data signal areas, resulting in low extraction accuracy based on optical images alone. Therefore, this paper takes Weihai Rongcheng Bay as the research area, and improves the U-Net neural network by adding channel attention mechanism to combine the spectral information of GF-2 optical image and the texture information of GF-3 radar image, trying to improve the extraction accuracy of raft aquaculture area. The results show that: （1) Whether it is a single optical image or a fusion image of optical and radar images, the overall accuracy of the prediction results of the U-Net neural network with channel attention mechanism will be improved, with an increase of 2.21%−4.12%. （2) Using the improved U-Net neural network to process the fusion data, the overall accuracy is 95.75%, which is 4.3% higher than that of only using GF-2 image. （3) For weak signal region, the overall accuracy and Kappa coefficient of extraction based on improved network and data fusion are 91.61% and 0.827 7, respectively. This method can effectively extract the weak signal area of marine raft aquaculture area, and can provide technical support for marine aquaculture area statistics and marine environment detection.
2023, 45(8): 166-177.
doi: 10.12284/hyxb2023082
Abstract:
The virtual ocean platform constructed by digital twin technology can further realize the 3D visualization and analysis of seabed environmental monitoring data. Based on the long-term in-situ monitoring data of the deep seabed, this paper uses Unity3D technology to build a virtual marine environment with multi-model fusion, and initially establishes a digital twin system for marine engineering geological environment; combines MATLAB and ArcGIS data analysis technology to realize intelligent monitoring, data analysis, human-computer interaction and auxiliary decision-making; the study further constructs a virtual environment particle system to conduct a 3D visualization and analysis of the near-bottom suspended sediment concentration elevation event in the northern part of the South China Sea. The results show that there are large spatial and temporal differences in suspended matter concentration, particle number and aggregation degree in the virtual environmental particle system. In particular, when the suspended matter concentration is maintained at a high level, particles are found to collide and overlap with each other, and the denser microclusters are derived in space. When the suspended matter concentration rises further to the peak, the number of microclusters increases and occupies most of the volume of space, forming a highly aggregated suspended matter aggregate with a wider coverage of suspended particles. This paper is based on image analysis techniques and compares the visualization results with real seafloor cameras with relative errors in the range of 0.16%–2.80%, which is highly feasible.
The virtual ocean platform constructed by digital twin technology can further realize the 3D visualization and analysis of seabed environmental monitoring data. Based on the long-term in-situ monitoring data of the deep seabed, this paper uses Unity3D technology to build a virtual marine environment with multi-model fusion, and initially establishes a digital twin system for marine engineering geological environment; combines MATLAB and ArcGIS data analysis technology to realize intelligent monitoring, data analysis, human-computer interaction and auxiliary decision-making; the study further constructs a virtual environment particle system to conduct a 3D visualization and analysis of the near-bottom suspended sediment concentration elevation event in the northern part of the South China Sea. The results show that there are large spatial and temporal differences in suspended matter concentration, particle number and aggregation degree in the virtual environmental particle system. In particular, when the suspended matter concentration is maintained at a high level, particles are found to collide and overlap with each other, and the denser microclusters are derived in space. When the suspended matter concentration rises further to the peak, the number of microclusters increases and occupies most of the volume of space, forming a highly aggregated suspended matter aggregate with a wider coverage of suspended particles. This paper is based on image analysis techniques and compares the visualization results with real seafloor cameras with relative errors in the range of 0.16%–2.80%, which is highly feasible.
2023, 45(8): 178-190.
doi: 10.12284/hyxb2023090
Abstract:
The Huanghe River Delta is an important ecological function area in China. It is of guiding significance to explore the distribution of suspended sediment concentration (SSC) at the estuary and its influencing factors for sediment erosion and re-suspension, and the ecological process in the estuary and coastal zone. Based on the relationship between chromaticity angle and SSC, an SSC inversion model (R2 = 0.80, MRE = 11.0%, RMSE = 1.35 mg/L) suitable for the Huanghe River Estuary and its adjacent sea areas is established in this paper. With the help of the GEE (Google Earth Engine) platform, the spatial and temporal distribution characteristics and changing rules of SSC in the Huanghe River Estuary and its adjacent sea area during the 22 years from 2000 to 2021 were studied, and the influencing factors were analyzed from two aspects of nature and human activities. The annual average value of SSC in the study area showed a downward trend (−1.83 mg/(L·a)). The spatial distribution shows that SSC gradually decreases from near shore to far shore; the diffusion interval (SSC > 20 mg/(L·a)) is only 4.8−14.6 km away from the estuary, and the influence of sediment from the Yellow River on the current sediment diffusion at the estuary is limited. The wave and suspended sediment concentration have the same seasonal characteristics. During the non-water and sediment regulation period, there is a positive correlation between the effective wave height and the SSC interdecadal monthly average (r = 0.66, p < 0.01). During the period of water and sediment regulation, the current SSC at the mouth of the Huanghe River and Laizhou Bay is limited by wind speed and effective wave height, and water and sediment regulation is dominant. During the period of water and sediment regulation, there is a positive correlation between the incoming sediment coefficient and the area change rate of high-concentration areas. After the water and sediment regulation (within 16 days), the boundary of the high concentration area (SSC > 200 mg/L) is expanded from about 1.3 km to about 2.5 km from the coast.
The Huanghe River Delta is an important ecological function area in China. It is of guiding significance to explore the distribution of suspended sediment concentration (SSC) at the estuary and its influencing factors for sediment erosion and re-suspension, and the ecological process in the estuary and coastal zone. Based on the relationship between chromaticity angle and SSC, an SSC inversion model (R2 = 0.80, MRE = 11.0%, RMSE = 1.35 mg/L) suitable for the Huanghe River Estuary and its adjacent sea areas is established in this paper. With the help of the GEE (Google Earth Engine) platform, the spatial and temporal distribution characteristics and changing rules of SSC in the Huanghe River Estuary and its adjacent sea area during the 22 years from 2000 to 2021 were studied, and the influencing factors were analyzed from two aspects of nature and human activities. The annual average value of SSC in the study area showed a downward trend (−1.83 mg/(L·a)). The spatial distribution shows that SSC gradually decreases from near shore to far shore; the diffusion interval (SSC > 20 mg/(L·a)) is only 4.8−14.6 km away from the estuary, and the influence of sediment from the Yellow River on the current sediment diffusion at the estuary is limited. The wave and suspended sediment concentration have the same seasonal characteristics. During the non-water and sediment regulation period, there is a positive correlation between the effective wave height and the SSC interdecadal monthly average (r = 0.66, p < 0.01). During the period of water and sediment regulation, the current SSC at the mouth of the Huanghe River and Laizhou Bay is limited by wind speed and effective wave height, and water and sediment regulation is dominant. During the period of water and sediment regulation, there is a positive correlation between the incoming sediment coefficient and the area change rate of high-concentration areas. After the water and sediment regulation (within 16 days), the boundary of the high concentration area (SSC > 200 mg/L) is expanded from about 1.3 km to about 2.5 km from the coast.
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