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2024, 46(11): 1-12.
doi: 10.12284/hyxb2024130
Abstract:
The stratospheric sulfate aerosol layer formed after large volcanic eruptions can inhibit the formation and development of tropical cyclones. But relevant studies mainly focus on the Atlantic Ocean, and few involve other sea areas. The Northwest Pacific Ocean is the area where most tropical cyclones are generated. Exploring the climate influencing factors is helpful for us to deeply understand the generation and development mechanism of tropical cyclones. Based on the data of tropical cyclones in the Northwest Pacific Ocean recorded in the International Optimum Orbit Database and the China Meteorological Administration database, the changes of sea surface temperature and the number of tropical cyclones in the Northwest Pacific Ocean before and after major volcanic eruptions during 1900−2023 are compared, and the effects of major volcanic eruptions on tropical cyclones in the Northwest Pacific Ocean are discussed. By comparing the number of tropical cyclones two years before the eruption and two years after the eruption, we found that the number of tropical cyclones in the Northwest Pacific decreased significantly after a major eruption. The sea surface temperature significantly responds to low-latitude volcanic eruptions, but does not significantly respond to high-latitude volcanic eruptions. Our study shows that the increase of aerosol forcing after large volcanic eruptions is closely related to the frequency of tropical cyclones, but the decrease of sea surface temperature caused by it may not be the direct cause of the decrease of tropical cyclones, and its mechanism may be related to the migration of the intertropical convergence zone caused by aerosol forcing, which still needs further investigation.
The stratospheric sulfate aerosol layer formed after large volcanic eruptions can inhibit the formation and development of tropical cyclones. But relevant studies mainly focus on the Atlantic Ocean, and few involve other sea areas. The Northwest Pacific Ocean is the area where most tropical cyclones are generated. Exploring the climate influencing factors is helpful for us to deeply understand the generation and development mechanism of tropical cyclones. Based on the data of tropical cyclones in the Northwest Pacific Ocean recorded in the International Optimum Orbit Database and the China Meteorological Administration database, the changes of sea surface temperature and the number of tropical cyclones in the Northwest Pacific Ocean before and after major volcanic eruptions during 1900−2023 are compared, and the effects of major volcanic eruptions on tropical cyclones in the Northwest Pacific Ocean are discussed. By comparing the number of tropical cyclones two years before the eruption and two years after the eruption, we found that the number of tropical cyclones in the Northwest Pacific decreased significantly after a major eruption. The sea surface temperature significantly responds to low-latitude volcanic eruptions, but does not significantly respond to high-latitude volcanic eruptions. Our study shows that the increase of aerosol forcing after large volcanic eruptions is closely related to the frequency of tropical cyclones, but the decrease of sea surface temperature caused by it may not be the direct cause of the decrease of tropical cyclones, and its mechanism may be related to the migration of the intertropical convergence zone caused by aerosol forcing, which still needs further investigation.
The preservation of organic carbon by active iron oxides in surface sediments from Guangxi mangroves
2024, 46(11): 13-33.
doi: 10.12284/hyxb2024114
Abstract:
Iron oxides play a significant role in the global soil (sediment) organic carbon (OC) storage. Mangrove wetlands, receiving both terrestrial and marine inputs, provide a unique habitat for the preservation of organic carbon by reactive iron oxides (FeR). However, the impact of FeR in the surface sediments of mangroves on the preservation process of OC, as well as the selectivity of FeR towards different OC components, is still unclear. The surface sediments in the present work was collected in the natural mangrove areas around the estuaries of the Dafeng River and Maowei Sea in Guangxi, which are highly influenced by tides and rivers. The research was focused on the changes in the content and composition of iron-bound organic carbon (Fe-OC) in sediments. The results indicated that the average content of Fe-OC in surface sediments in the estuaries of Dafeng River and Maowei Sea was 0.16% ± 0.07% and 0.17% ± 0.07%, respectively. These values represented 16.2 ± 5.04% and 10.9 ± 5.63% of the total organic carbon (TOC) content in the respective sediments, which were primarily preserved through adsorption. Furthermore, the preservation of OC by FeR was influenced by the sediment particle size, the content and form of FeR, and the source and composition of TOC. TOC, FeR and Fe-OC were mainly distributed in the smaller grain size sediment fractions. The predominant form of iron in surface sediments was Fe3+, accounting for 87.42% of the total iron, and was relatively higher in high salinity sediments. FeR selectively preserved OC with higher δ13C (stable carbon isotope natural abundance) and aromatic OC. Compared with the Maowei Sea, the proportion of protein-like fluorescent components in Fe-OC of surface sediments from the Dafeng River estuary was higher and the proportion of protein-like fluorescent components increased as the molar ratio of Fe-OC∶Fe increased. This study helps to clarify the selective preservation mechanism of OC by FeR in mangrove surface sediments in Guangxi, and deepen our understanding of the preservation process of OC in land-sea interface sediments.
Iron oxides play a significant role in the global soil (sediment) organic carbon (OC) storage. Mangrove wetlands, receiving both terrestrial and marine inputs, provide a unique habitat for the preservation of organic carbon by reactive iron oxides (FeR). However, the impact of FeR in the surface sediments of mangroves on the preservation process of OC, as well as the selectivity of FeR towards different OC components, is still unclear. The surface sediments in the present work was collected in the natural mangrove areas around the estuaries of the Dafeng River and Maowei Sea in Guangxi, which are highly influenced by tides and rivers. The research was focused on the changes in the content and composition of iron-bound organic carbon (Fe-OC) in sediments. The results indicated that the average content of Fe-OC in surface sediments in the estuaries of Dafeng River and Maowei Sea was 0.16% ± 0.07% and 0.17% ± 0.07%, respectively. These values represented 16.2 ± 5.04% and 10.9 ± 5.63% of the total organic carbon (TOC) content in the respective sediments, which were primarily preserved through adsorption. Furthermore, the preservation of OC by FeR was influenced by the sediment particle size, the content and form of FeR, and the source and composition of TOC. TOC, FeR and Fe-OC were mainly distributed in the smaller grain size sediment fractions. The predominant form of iron in surface sediments was Fe3+, accounting for 87.42% of the total iron, and was relatively higher in high salinity sediments. FeR selectively preserved OC with higher δ13C (stable carbon isotope natural abundance) and aromatic OC. Compared with the Maowei Sea, the proportion of protein-like fluorescent components in Fe-OC of surface sediments from the Dafeng River estuary was higher and the proportion of protein-like fluorescent components increased as the molar ratio of Fe-OC∶Fe increased. This study helps to clarify the selective preservation mechanism of OC by FeR in mangrove surface sediments in Guangxi, and deepen our understanding of the preservation process of OC in land-sea interface sediments.
2024, 46(11): 34-42.
doi: 10.12284/hyxb2024102
Abstract:
To analysis the suitability of using wind field data for forecasting Pacific saury habitat in the northwest Pacific, this paper use the generalized additive model to fit the habitat suitability index (HSI) for Pacific saury in summer and autumn, based on the Chinese fishery data, environmental data and four types of wind field data included the China-France oceanography satellite (CFOSAT) during June to November in 2019−2020. The result indicates that: (1) Weighted analysis shows distinct seasonal variation of environmental variables on catch per unit effort, with chlorophyll concentration and sea surface temperature having the highest weights in summer and autumn respectively, while wind speed had the lowest weight and direct proportionality to the weight. (2) The average accuracy of the four data in summer and autumn is 68.37% and 76.65% respectively, and CFOSAT reaching the highest accuracy of 80.94% in autumn. (3) The high-HSI areas are consistent with the fishing grounds of Pacific saury, while the HSI high-value regions of scatter meter in autumn seems more robust. There are advantages of using wind speed on the forecast model in autumn, as this model can reflect the influence of transient variation factors on the migration and aggregation of Pacific saury.
To analysis the suitability of using wind field data for forecasting Pacific saury habitat in the northwest Pacific, this paper use the generalized additive model to fit the habitat suitability index (HSI) for Pacific saury in summer and autumn, based on the Chinese fishery data, environmental data and four types of wind field data included the China-France oceanography satellite (CFOSAT) during June to November in 2019−2020. The result indicates that: (1) Weighted analysis shows distinct seasonal variation of environmental variables on catch per unit effort, with chlorophyll concentration and sea surface temperature having the highest weights in summer and autumn respectively, while wind speed had the lowest weight and direct proportionality to the weight. (2) The average accuracy of the four data in summer and autumn is 68.37% and 76.65% respectively, and CFOSAT reaching the highest accuracy of 80.94% in autumn. (3) The high-HSI areas are consistent with the fishing grounds of Pacific saury, while the HSI high-value regions of scatter meter in autumn seems more robust. There are advantages of using wind speed on the forecast model in autumn, as this model can reflect the influence of transient variation factors on the migration and aggregation of Pacific saury.
2024, 46(11): 43-52.
doi: 10.12284/hyxb2024104
Abstract:
The phenomenon of marine phytoplankton bloom in ocean refers to the annual cycle increase in biomass caused by rapid reproduction, which plays an important role in the biochemical cycles of marine organisms. However, the spatiotemporal variation characteristics of global phytoplankton blooms and their response mechanisms to the environment still require further exploration. Based on the chlorophyll a products of the MODIS-Aqua (Moderate Resolution Imaging Spectroradiometer) from 2003 to 2022, we extracted the bloom indexes of global ocean phytoplankton (the ratio of bloom duration and bloom intensity). Then, we analyzed their spatiotemporal characteristics, trends, and correlations with environmental factors. The results indicated that there are significant seasonal and latitudinal difference in the distribution of the bloom indexes. Blooms in high latitudes of the Northern Hemisphere mainly occur from April to October, while in mid-low latitudes, blooms mainly occur from November to March of the following year. In the Southern Hemisphere, blooms develop in the month of November and persist until March of the following year in high latitudes, while those in low and middle latitudes occur from May to September. The ratio of bloom duration and bloom intensity show decreasing trends mainly in the mid-low latitude regions of the North Pacific, while increasing trends are observed in mid-high latitude regions of the Southern Hemisphere. The distribution and trends of bloom indices are both regulated by environmental factors. Sea surface temperature and photosynthetically active radiation promote blooms intensity in high latitude waters, but inhibit them in low latitude waters. Meanwhile, the wind speed plays a restraining role in the high latitude sea area and a promoting role in the low latitude sea area.
The phenomenon of marine phytoplankton bloom in ocean refers to the annual cycle increase in biomass caused by rapid reproduction, which plays an important role in the biochemical cycles of marine organisms. However, the spatiotemporal variation characteristics of global phytoplankton blooms and their response mechanisms to the environment still require further exploration. Based on the chlorophyll a products of the MODIS-Aqua (Moderate Resolution Imaging Spectroradiometer) from 2003 to 2022, we extracted the bloom indexes of global ocean phytoplankton (the ratio of bloom duration and bloom intensity). Then, we analyzed their spatiotemporal characteristics, trends, and correlations with environmental factors. The results indicated that there are significant seasonal and latitudinal difference in the distribution of the bloom indexes. Blooms in high latitudes of the Northern Hemisphere mainly occur from April to October, while in mid-low latitudes, blooms mainly occur from November to March of the following year. In the Southern Hemisphere, blooms develop in the month of November and persist until March of the following year in high latitudes, while those in low and middle latitudes occur from May to September. The ratio of bloom duration and bloom intensity show decreasing trends mainly in the mid-low latitude regions of the North Pacific, while increasing trends are observed in mid-high latitude regions of the Southern Hemisphere. The distribution and trends of bloom indices are both regulated by environmental factors. Sea surface temperature and photosynthetically active radiation promote blooms intensity in high latitude waters, but inhibit them in low latitude waters. Meanwhile, the wind speed plays a restraining role in the high latitude sea area and a promoting role in the low latitude sea area.
2024, 46(11): 53-64.
doi: 10.12284/hyxb2024120
Abstract:
During June 9th to 15th in 2017, the dynamic of Gymnodinium catenatum bloom along the coast of Hui’an County Fujian Province, were investigated. Six monitoring stations were established for marine environmental factors assessment over seven sampling trips. The water quality data from June 6th, along with the phytoplankton data collected in March and November 2017, was selected for comparative analysis. Furthermore, the survey results of dinoflagellate cysts and paralytic shellfish poison (PSP) in cultured shellfish were integrated to explore the relationship between dormant cysts and the bloom dynamics, as well as the patterns of PSP accumulation and elimination in cultured shellfish. The results revealed that during the bloom, conditions were characterized by sunny weather and favorable sea states, with water temperature ranging from 24.2℃ to 26.8℃ and the salinity between 30.4 and 33.2. The concentrations of nutrients were low, indicating oligotrophic conditions, while the density of G. catenatum peaked at 1.79×106 cells/L during the bloom period. The interplay of favorable hydro-meteorological conditions, N/P ratio and the trophic pattern of G. catenatum provided a basis for the evolution of the bloom, whereas adverse weather conditions primarily contributed to its decline. The average density of G. catenatum cysts in the surveyed sea area was 33.2 cysts/g, suggesting potential for these cysts to germinate into trophic cells, which could lead to the reemergence of the bloom and therefore it necessitates further attention. During the bloom period, both oysters and mussels rapidly accumulated high concentrations of PSP toxins, with levels directly proportional to G. catenatum density. Additionally, even low densities of G. catenatum posed a risk for PSP exceedances. Mussels exhibited a rapid accumulation and slow elimination of PSP, with a significantly greater capacity for toxin accumulation compared to oysters, while their elimination rate was significantly slower.
During June 9th to 15th in 2017, the dynamic of Gymnodinium catenatum bloom along the coast of Hui’an County Fujian Province, were investigated. Six monitoring stations were established for marine environmental factors assessment over seven sampling trips. The water quality data from June 6th, along with the phytoplankton data collected in March and November 2017, was selected for comparative analysis. Furthermore, the survey results of dinoflagellate cysts and paralytic shellfish poison (PSP) in cultured shellfish were integrated to explore the relationship between dormant cysts and the bloom dynamics, as well as the patterns of PSP accumulation and elimination in cultured shellfish. The results revealed that during the bloom, conditions were characterized by sunny weather and favorable sea states, with water temperature ranging from 24.2℃ to 26.8℃ and the salinity between 30.4 and 33.2. The concentrations of nutrients were low, indicating oligotrophic conditions, while the density of G. catenatum peaked at 1.79×106 cells/L during the bloom period. The interplay of favorable hydro-meteorological conditions, N/P ratio and the trophic pattern of G. catenatum provided a basis for the evolution of the bloom, whereas adverse weather conditions primarily contributed to its decline. The average density of G. catenatum cysts in the surveyed sea area was 33.2 cysts/g, suggesting potential for these cysts to germinate into trophic cells, which could lead to the reemergence of the bloom and therefore it necessitates further attention. During the bloom period, both oysters and mussels rapidly accumulated high concentrations of PSP toxins, with levels directly proportional to G. catenatum density. Additionally, even low densities of G. catenatum posed a risk for PSP exceedances. Mussels exhibited a rapid accumulation and slow elimination of PSP, with a significantly greater capacity for toxin accumulation compared to oysters, while their elimination rate was significantly slower.
2024, 46(11): 65-74.
doi: 10.12284/hyxb2024128
Abstract:
Sargassum horneri has good economic traits and value, and its culture is gradually being emphasized. However, the suitable water depth for culture is still unclear, and the physiological characteristics and ecological functions of S. horneri in different water depths are also unclear. In this paper, we compared the primary productivity, nutrient uptake capacity, and algal trophic composition of S. horneri at different water depths (0.5 m and 2 m) based on light intensity in different water depths. The results showed that light intensity varied significantly (P < 0.05) with water depths and that the difference in light intensity due to water depth was significantly correlated with the primary productivity of S. horneri. The total productivity of S. horneri grown at 0.5 m water depth (upper layer) was significantly higher than that of S. horneri grown at 2 m water depth (lower layer) (P < 0.05), and S. horneri in the upper layer showed higher primary productivity and carbon sequestration capacity. The uptake of \begin{document}${{\rm {NH}}_4^+} $\end{document} ![]()
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2024, 46(11): 75-90.
doi: 10.12284/hyxb2024122
Abstract:
The tidal creek system is an active geomorphic unit in coastal wetlands, and the water environment of different level tidal creeks changes significantly, leading to spatial distribution differences of biological communities. This study selected a typical tidal creek unit in the Huanghe River Delta and used environmental DNA metabarcoding (eDNA) technique to detect the diversity of invertebrates. The biological co-occurrence network analysis and redundancy analysis (RDA) were respectively used to reveal the keystone species and driving factors of the invertebrate community in the typical tidal creek. The results showed that a total of 127 operational taxonomic units (OTUs) of invertebrates were detected in the tidal creek unit, belonging to 9 phyla, 24 classes, 53 orders, 103 families, 87 genera, and 90 species; among them, the class level was dominated by the Arthropoda (43.9%), and the genus level was dominated by the Perinereis (25.2%). The comprehensive diversity index (CD) analysis showed that the comprehensive diversity of invertebrates in the third-level tidal creek was the highest, and the comprehensive diversity of invertebrates in the first-level tidal creek was the lowest. The biological co-occurrence network analysis showed that the Perinereis linea and the Obelia dichotoma were the keystone species, which played a key role in maintaining the stability of the invertebrate community structure in the tidal creek. The RDA showed that the silicate content of the water body, temperature, and the proportion of fine sand and clay in the sediment were the main environmental factors affecting the invertebrate community characteristics in the tidal creek. Correlation network analysis showed that the keystone species were significantly affected by silicate content, clay, and nitrogen content in water (P < 0.05). The research results are helpful for understanding the community structure of typical tidal creek invertebrates, revealing the keystone species of typical tidal ditch invertebrates, and providing data support and theoretical reference for the monitoring and protection of invertebrate diversity.
The tidal creek system is an active geomorphic unit in coastal wetlands, and the water environment of different level tidal creeks changes significantly, leading to spatial distribution differences of biological communities. This study selected a typical tidal creek unit in the Huanghe River Delta and used environmental DNA metabarcoding (eDNA) technique to detect the diversity of invertebrates. The biological co-occurrence network analysis and redundancy analysis (RDA) were respectively used to reveal the keystone species and driving factors of the invertebrate community in the typical tidal creek. The results showed that a total of 127 operational taxonomic units (OTUs) of invertebrates were detected in the tidal creek unit, belonging to 9 phyla, 24 classes, 53 orders, 103 families, 87 genera, and 90 species; among them, the class level was dominated by the Arthropoda (43.9%), and the genus level was dominated by the Perinereis (25.2%). The comprehensive diversity index (CD) analysis showed that the comprehensive diversity of invertebrates in the third-level tidal creek was the highest, and the comprehensive diversity of invertebrates in the first-level tidal creek was the lowest. The biological co-occurrence network analysis showed that the Perinereis linea and the Obelia dichotoma were the keystone species, which played a key role in maintaining the stability of the invertebrate community structure in the tidal creek. The RDA showed that the silicate content of the water body, temperature, and the proportion of fine sand and clay in the sediment were the main environmental factors affecting the invertebrate community characteristics in the tidal creek. Correlation network analysis showed that the keystone species were significantly affected by silicate content, clay, and nitrogen content in water (P < 0.05). The research results are helpful for understanding the community structure of typical tidal creek invertebrates, revealing the keystone species of typical tidal ditch invertebrates, and providing data support and theoretical reference for the monitoring and protection of invertebrate diversity.
2024, 46(11): 91-105.
doi: 10.12284/hyxb2024118
Abstract:
In November 2020, sediment samples were collected from the Yalong Bay Qingmei Port mangrove nature reserve and the Sanya River mangrove nature reserve in Hainan Province. The present study focused on the community characteristics of marine nematodes and their influencing factors in these two mangroves. The results of the present study showed that the average abundance of marine nematodes was (80.4 ± 40.3) ind./cm2 in the Qingmei Port mangrove, while it was (96.7 ± 55.6) ind./cm2 in the Sanya River mangrove. In this study, the average abundance of marine nematodes in the two study mangrove wetlands was (88.5 ± 47.1) ind./cm2. There were significant differences in the abundance of marine nematodes between the two mangrove wetlands. A total of 77 species of marine nematodes were identified, belonging to 56 genera, 21 families and 7 orders. The dominant genera in the Qingmei Port mangrove were Neochromadora, Terschellingia, Paramonohystera, Daptonema and Desmodora, and epigrowth feeders were the dominant feeding type. The dominant genera in the Sanya River mangrove were Terschellingia, Sabatieria, Eleutherolaimus, Parodontophora and Ptycholaimellus, and the selective deposit feeders dominated. Terschellingia dominated in both mangroves. There were spatial differences in the community structure of marine nematodes in study mangroves. Although the marine nematode communities differentiated between the two mangroves, the difference was not significant. Organic matter content and phaeophorbide content in sediments were important factors affecting the abundance and community structure of marine nematodes in Sanya River mangrove. The differences in mangrove vegetation types may affect the abundance and community structure of marine nematodes in Qingmei Port mangrove to some extent. The differences of sediment granularity characteristics, seawater pH and salinity could explain the differentiation of marine nematode communities at selected sites of the two mangrove. In addition, there are sewage project, port construction and tourism development in Qingmei Port mangrove. And there are felling, dike construction, salt pan development and wastewater discharge from shrimp ponds in Sanya River mangrove. The different pollution status in these two mangroves may also be the reason for the differences in the abundance and community structure of marine nematodes in this study.
In November 2020, sediment samples were collected from the Yalong Bay Qingmei Port mangrove nature reserve and the Sanya River mangrove nature reserve in Hainan Province. The present study focused on the community characteristics of marine nematodes and their influencing factors in these two mangroves. The results of the present study showed that the average abundance of marine nematodes was (80.4 ± 40.3) ind./cm2 in the Qingmei Port mangrove, while it was (96.7 ± 55.6) ind./cm2 in the Sanya River mangrove. In this study, the average abundance of marine nematodes in the two study mangrove wetlands was (88.5 ± 47.1) ind./cm2. There were significant differences in the abundance of marine nematodes between the two mangrove wetlands. A total of 77 species of marine nematodes were identified, belonging to 56 genera, 21 families and 7 orders. The dominant genera in the Qingmei Port mangrove were Neochromadora, Terschellingia, Paramonohystera, Daptonema and Desmodora, and epigrowth feeders were the dominant feeding type. The dominant genera in the Sanya River mangrove were Terschellingia, Sabatieria, Eleutherolaimus, Parodontophora and Ptycholaimellus, and the selective deposit feeders dominated. Terschellingia dominated in both mangroves. There were spatial differences in the community structure of marine nematodes in study mangroves. Although the marine nematode communities differentiated between the two mangroves, the difference was not significant. Organic matter content and phaeophorbide content in sediments were important factors affecting the abundance and community structure of marine nematodes in Sanya River mangrove. The differences in mangrove vegetation types may affect the abundance and community structure of marine nematodes in Qingmei Port mangrove to some extent. The differences of sediment granularity characteristics, seawater pH and salinity could explain the differentiation of marine nematode communities at selected sites of the two mangrove. In addition, there are sewage project, port construction and tourism development in Qingmei Port mangrove. And there are felling, dike construction, salt pan development and wastewater discharge from shrimp ponds in Sanya River mangrove. The different pollution status in these two mangroves may also be the reason for the differences in the abundance and community structure of marine nematodes in this study.
2024, 46(11): 125-134.
doi: 10.12284/hyxb2024124
Abstract:
Seagrass meadows play a vital role in protecting marine biodiversity, mitigating ocean acidification, and preventing soil erosion in the coastal ecosystem. However, global climate change and human activities seriously affect the life of seagrass, which cause the widespread degradation of the seagrass and threaten the safety of coastal ecosystems. Recently, the vital value of microorganisms in promoting the energy flow of seagrass meadows and their growth and development has gradually gained attention. Plant growth-promoting microorganisms(PGPM) will play their value in seedling cultivation, plant transplantation, seed planting and other techniques of seagrass meadow restoration. This paper reviewed the research on how microorganisms interacts with seagrass to promote the growth of plants and increase the resistance to abiotic stress. We introduced the mechanism of PGPM to enhance plant stress tolerance under high temperature, high salt, and low light. We propsoed that modern molecular biological technique should be used to screen seagrass PGPM, clarify the colonization site of PGPM, and explore the molecular interaction mechanism between PGPM and seagrass in different environmental conditions. This paper is some advice for promoting the application of PGPM in seagrass meadow restoration and seagrass protection.
Seagrass meadows play a vital role in protecting marine biodiversity, mitigating ocean acidification, and preventing soil erosion in the coastal ecosystem. However, global climate change and human activities seriously affect the life of seagrass, which cause the widespread degradation of the seagrass and threaten the safety of coastal ecosystems. Recently, the vital value of microorganisms in promoting the energy flow of seagrass meadows and their growth and development has gradually gained attention. Plant growth-promoting microorganisms(PGPM) will play their value in seedling cultivation, plant transplantation, seed planting and other techniques of seagrass meadow restoration. This paper reviewed the research on how microorganisms interacts with seagrass to promote the growth of plants and increase the resistance to abiotic stress. We introduced the mechanism of PGPM to enhance plant stress tolerance under high temperature, high salt, and low light. We propsoed that modern molecular biological technique should be used to screen seagrass PGPM, clarify the colonization site of PGPM, and explore the molecular interaction mechanism between PGPM and seagrass in different environmental conditions. This paper is some advice for promoting the application of PGPM in seagrass meadow restoration and seagrass protection.
2024, 46(11): 106-114.
doi: 10.12284/hyxb2024126
Abstract:
The distribution of wave energy in enclosure aquaculture areas not only significantly influences nutrient transport but also constitutes a critical hydrological factor in validating the design of structures in inner aquaculture area. Investigating the changes in wave field energy influenced by these structures is crucial. The FUNWAVE 2.0 numerical model was employed to simulate irregular wave propagation in aquaculture areas with varying pile-net enclosure structures. The effects of pile spacing and incident wave angles in the evolution of wave energy was examined. The results indicate that if the internal facilities are positioned close to the outer pile-net enclosure structure, the pile spacing should be less than 10 m, provided that structural stability is ensured. Conversely, if the internal facilities are located farther from the outer pile-net enclosure, a pile spacing greater than 10 m should be selected. Additionally, oblique wave incidents may pose greater structural challenges at certain locations compared to normally incident waves, which should also be considered during design.
The distribution of wave energy in enclosure aquaculture areas not only significantly influences nutrient transport but also constitutes a critical hydrological factor in validating the design of structures in inner aquaculture area. Investigating the changes in wave field energy influenced by these structures is crucial. The FUNWAVE 2.0 numerical model was employed to simulate irregular wave propagation in aquaculture areas with varying pile-net enclosure structures. The effects of pile spacing and incident wave angles in the evolution of wave energy was examined. The results indicate that if the internal facilities are positioned close to the outer pile-net enclosure structure, the pile spacing should be less than 10 m, provided that structural stability is ensured. Conversely, if the internal facilities are located farther from the outer pile-net enclosure, a pile spacing greater than 10 m should be selected. Additionally, oblique wave incidents may pose greater structural challenges at certain locations compared to normally incident waves, which should also be considered during design.
2024, 46(11): 115-124.
doi: 10.12284/hyxb2024132
Abstract:
In response to contingencies that arise during the underwater coverage missions of multiple autonomous underwater vehicles (AUVs), this study addresses the problem of coverage path replanning for multiple AUVs. A multi-robot multi-regional coverage path planning (M2CPP) method is proposed to reassign uncovered areas to available AUVs and plan their coverage paths. Initially, the lawnmower algorithm is employed to determine the internal paths and candidate entry points within each region. Subsequently, a coevolutionary approach is utilized to solve for the optimal region allocation, region sequence, and the best entry points for each region. Three populations coevolve collaboratively to determine the complete paths for all AUVs, ensuring population diversity and preventing convergence into local optima. Simulation results demonstrate that the proposed method not only replans shorter paths for multiple AUVs based on their initial positions and remaining energy but also optimizes the path structure to ensure a balanced workload among the AUVs, effectively resolving the replanning issue under such scenarios.
In response to contingencies that arise during the underwater coverage missions of multiple autonomous underwater vehicles (AUVs), this study addresses the problem of coverage path replanning for multiple AUVs. A multi-robot multi-regional coverage path planning (M2CPP) method is proposed to reassign uncovered areas to available AUVs and plan their coverage paths. Initially, the lawnmower algorithm is employed to determine the internal paths and candidate entry points within each region. Subsequently, a coevolutionary approach is utilized to solve for the optimal region allocation, region sequence, and the best entry points for each region. Three populations coevolve collaboratively to determine the complete paths for all AUVs, ensuring population diversity and preventing convergence into local optima. Simulation results demonstrate that the proposed method not only replans shorter paths for multiple AUVs based on their initial positions and remaining energy but also optimizes the path structure to ensure a balanced workload among the AUVs, effectively resolving the replanning issue under such scenarios.
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