2010 Vol. 29, No. 6
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Display Method:
2010, (6): 1-11.
doi: 10.1007/s13131-010-0071-6
Abstract:
The wide presence of internal solitary waves (ISWs) in the northern South China Sea (SCS) has been confirmed by both Synthetic Aperture Radar (SAR) images and in situ observations. These ISWs are believed being generated over the varying topography in the Luzon Strait. They typically propagate westwards into the SCS with a diurnal or semidiurnal period. Their generation sites are, however, not yet solidly identified. To obtain a clear picture of the ISWs, we designed numerical experiments to analyze the generation and propagation of the ISWs in the Luzon Strait using a 2-dimensional non-hydrostatic model. The model current is forced by barotropic or baroclinic currents imposed at open boundaries. The experiments show that the tidal current serves as a kind of triggering force for the ISWs over the submarine ridges in the strait. Under the forcing of tidal currents, depressions are formed near the ridges. The ISWs then split from the depressions through a process different from lee-wave generation mechanism. The appearance of the ISWs is influenced by the strength and period of the forcing current:the ISWs are more likely to be generated by a stronger tidal current. That is why the ISWs in the Luzon Strait are frequently observed during spring tide. Compared with diurnal tidal current, the ISWs generated by semidiurnal tidal current with the same amplitude is much more energetic. It is partly because that the wave beams in diurnal frequency have a larger angle with the vertical direction, thus are more likely to be reflected by the topography slope. The impact of the Kuroshio to the ISWs is also analyzed by adding a vertical uniform or shear current at boundaries. A vertically uniform current may generate ISWs directly. On the other hand, a vertically shear current, which is more realistic to represent the Kuroshio branch, seems to have little influence on the generation process and radiating direction of the ISWs in the Luzon Strait.
The wide presence of internal solitary waves (ISWs) in the northern South China Sea (SCS) has been confirmed by both Synthetic Aperture Radar (SAR) images and in situ observations. These ISWs are believed being generated over the varying topography in the Luzon Strait. They typically propagate westwards into the SCS with a diurnal or semidiurnal period. Their generation sites are, however, not yet solidly identified. To obtain a clear picture of the ISWs, we designed numerical experiments to analyze the generation and propagation of the ISWs in the Luzon Strait using a 2-dimensional non-hydrostatic model. The model current is forced by barotropic or baroclinic currents imposed at open boundaries. The experiments show that the tidal current serves as a kind of triggering force for the ISWs over the submarine ridges in the strait. Under the forcing of tidal currents, depressions are formed near the ridges. The ISWs then split from the depressions through a process different from lee-wave generation mechanism. The appearance of the ISWs is influenced by the strength and period of the forcing current:the ISWs are more likely to be generated by a stronger tidal current. That is why the ISWs in the Luzon Strait are frequently observed during spring tide. Compared with diurnal tidal current, the ISWs generated by semidiurnal tidal current with the same amplitude is much more energetic. It is partly because that the wave beams in diurnal frequency have a larger angle with the vertical direction, thus are more likely to be reflected by the topography slope. The impact of the Kuroshio to the ISWs is also analyzed by adding a vertical uniform or shear current at boundaries. A vertically uniform current may generate ISWs directly. On the other hand, a vertically shear current, which is more realistic to represent the Kuroshio branch, seems to have little influence on the generation process and radiating direction of the ISWs in the Luzon Strait.
2010, (6): 12-25.
doi: 10.1007/s13131-010-0072-5
Abstract:
We developed a Global Ocean Circulation and Tide Model (GOCTM) with coarse grids in the open deep ocean degrading 'smoothly' into the highly resolved China Seas (CS) of refined grids to study the tides and circulation there. GOCTM is based on the framework of the Finite Volume approach for better mass conservation through improved transports across the discrete individual control volume. It also takes a full advantage of the geometric flexibility of unstructured mesh using a realistic global topography including the Arctic Ocean. The CS are given a special focus by refining the unstructured grids, but they are embedded into global domain naturally. Furthermore, GOCTM not only successfully avoids the treatment of the open boundaries, but also optimizes the trade-off between computational cost and model accuracy. Meanwhile, GOCTM is driven by the astronomical tide-generating potential and the secondary tide-generating potential directly, together with the wind stress and heat flux. GOCTM succeeds in reproducing the global eight principal tidal harmonic constants. Particularly, the simulated tidal results in the CS are improved compared to some other regional models with the discrepancy of 3.9 cm for M2 tide. This idea of GOCTM can also be referred for other regional ocean study.
We developed a Global Ocean Circulation and Tide Model (GOCTM) with coarse grids in the open deep ocean degrading 'smoothly' into the highly resolved China Seas (CS) of refined grids to study the tides and circulation there. GOCTM is based on the framework of the Finite Volume approach for better mass conservation through improved transports across the discrete individual control volume. It also takes a full advantage of the geometric flexibility of unstructured mesh using a realistic global topography including the Arctic Ocean. The CS are given a special focus by refining the unstructured grids, but they are embedded into global domain naturally. Furthermore, GOCTM not only successfully avoids the treatment of the open boundaries, but also optimizes the trade-off between computational cost and model accuracy. Meanwhile, GOCTM is driven by the astronomical tide-generating potential and the secondary tide-generating potential directly, together with the wind stress and heat flux. GOCTM succeeds in reproducing the global eight principal tidal harmonic constants. Particularly, the simulated tidal results in the CS are improved compared to some other regional models with the discrepancy of 3.9 cm for M2 tide. This idea of GOCTM can also be referred for other regional ocean study.
2010, (6): 26-34.
doi: 10.1007/s13131-010-0073-4
Abstract:
A correlation analysis is performed to investigate the relationship between El Niño-Southern Oscillation (ENSO) and the Antarctic oscillation (AAO) at the quasi-quadrennial (QQ) timescale. It is found that the cold tongue index (CTI) and the AAO index (AAOI) are negatively correlated with about a 7-month lead-time, while they are positively correlated with about a 15-month lag-time. To further explore this relationship, complex empirical orthogonal function analysis is employed in the QQ sea level pressure (SLP) anomalies from 1951 to 2002. The results indicate that, during the ENSO cycle, there exists one kind of global tropical wave of wavenumber 1 (GTW1) propagating eastward. With the traveling of GTW1, the tropical SLP anomaly tends to intrude into the southern mid-latitudes. Accordingly, three strong signals travel synchronously along the circumSouth-Pacific path, and a relatively weak signal extends eastward and poleward over the South Ocean in the Atlantic-Indian Ocean sector. Following the propagation of these signals, the AAO phase tends to be reversed progressively. As a result, there exists an evident lead-lag correlation between CTI and AAOI. It can be concluded that ENSO plays a key role in the phase transition of AAO at the QQ timescale. It is also noticed that this regular relationship is only evident in the canonical ENSO events, for which sea surface temperature (SST) anomalies extend westward from the tropical eastern Pacific. On the other hand, the similar relationships are not found among those atypical ENSO events for which SST anomalies spread eastward from the central Pacific, such as the 1982-1983 ENSO event.
A correlation analysis is performed to investigate the relationship between El Niño-Southern Oscillation (ENSO) and the Antarctic oscillation (AAO) at the quasi-quadrennial (QQ) timescale. It is found that the cold tongue index (CTI) and the AAO index (AAOI) are negatively correlated with about a 7-month lead-time, while they are positively correlated with about a 15-month lag-time. To further explore this relationship, complex empirical orthogonal function analysis is employed in the QQ sea level pressure (SLP) anomalies from 1951 to 2002. The results indicate that, during the ENSO cycle, there exists one kind of global tropical wave of wavenumber 1 (GTW1) propagating eastward. With the traveling of GTW1, the tropical SLP anomaly tends to intrude into the southern mid-latitudes. Accordingly, three strong signals travel synchronously along the circumSouth-Pacific path, and a relatively weak signal extends eastward and poleward over the South Ocean in the Atlantic-Indian Ocean sector. Following the propagation of these signals, the AAO phase tends to be reversed progressively. As a result, there exists an evident lead-lag correlation between CTI and AAOI. It can be concluded that ENSO plays a key role in the phase transition of AAO at the QQ timescale. It is also noticed that this regular relationship is only evident in the canonical ENSO events, for which sea surface temperature (SST) anomalies extend westward from the tropical eastern Pacific. On the other hand, the similar relationships are not found among those atypical ENSO events for which SST anomalies spread eastward from the central Pacific, such as the 1982-1983 ENSO event.
2010, (6): 35-43.
doi: 10.1007/s13131-010-0074-3
Abstract:
The Kuroshio frontal instable processes (KFIP) in the East China Sea (ECS) not only have a great impact on the hydrologic characteristics, the pollutants drift, the distribution of seafloor sediment and the ships navigation of the ECS, but also are closely related to the climate changes of the coastal areas of the ECS. However the frequency and area of occurrence of the KFIP have not been studied fully and detailedly. Because of its high spatial and temporal resolution, MODIS data is a kind of very good data source for surveying and researching the KFIP in the ECS. The aim of this study is to detect the KFIP in the ECS by using MODIS data, and to study the frequency and region of occurrence of the KFIP in the ECS.
The selection has coverage of level 2 data of MODIS SST and Kd490 ranging from July 1, 2002 to June 30, 2009 of the ECS when there was no cloud impact or little. By using of the data, the minimum standard of the Kuroshio temperature fronts and the diffuse attenuation coefficient (Kd490) fronts of the ECS are given. Based on these standards and the curvature distinguish methods, the standard of curvature distinguish for the KFIP in the ECS are put forward. By making use of this standard, we study a total of 2073 satellite-derived images, and discover that as long as there is no cloud impact from January to May and October to December, the KFIP in the ECS are surely found in MODIS satellite images. From June to September, the frequency of occurrence can also reach to 82.9% at least. Moreover, it is obtained that there are three source regions of these instability processes, namely, (26°N, 121.5°E) nearby, (27°N, 125°E) nearby and (30°N, 128°E) nearby. The differences of the characteristics of these instability processes which are generated in different regions are analyzed in the present study.
The Kuroshio frontal instable processes (KFIP) in the East China Sea (ECS) not only have a great impact on the hydrologic characteristics, the pollutants drift, the distribution of seafloor sediment and the ships navigation of the ECS, but also are closely related to the climate changes of the coastal areas of the ECS. However the frequency and area of occurrence of the KFIP have not been studied fully and detailedly. Because of its high spatial and temporal resolution, MODIS data is a kind of very good data source for surveying and researching the KFIP in the ECS. The aim of this study is to detect the KFIP in the ECS by using MODIS data, and to study the frequency and region of occurrence of the KFIP in the ECS.
The selection has coverage of level 2 data of MODIS SST and Kd490 ranging from July 1, 2002 to June 30, 2009 of the ECS when there was no cloud impact or little. By using of the data, the minimum standard of the Kuroshio temperature fronts and the diffuse attenuation coefficient (Kd490) fronts of the ECS are given. Based on these standards and the curvature distinguish methods, the standard of curvature distinguish for the KFIP in the ECS are put forward. By making use of this standard, we study a total of 2073 satellite-derived images, and discover that as long as there is no cloud impact from January to May and October to December, the KFIP in the ECS are surely found in MODIS satellite images. From June to September, the frequency of occurrence can also reach to 82.9% at least. Moreover, it is obtained that there are three source regions of these instability processes, namely, (26°N, 121.5°E) nearby, (27°N, 125°E) nearby and (30°N, 128°E) nearby. The differences of the characteristics of these instability processes which are generated in different regions are analyzed in the present study.
2010, (6): 44-50.
doi: 10.1007/s13131-010-0075-2
Abstract:
Since the mild-slope equation was derived by Berkhoff (1972), the researchers considered various mechanism to simplify and improve the equation, which has been widely used for coastal wave field calculation. Recently, some scholars applied the mild-slope equation in simulating the tidal motion, which proves that the equation is capable to calculate the tide in actual terrain. But in their studies, they made a lot of simplifications, and did not consider the effects of Coriolis force and bottom friction on tidal wave. In this paper, the first-order linear mild-slope equations are deduced from Kirby mild-slope equation including wave and current interaction. Then, referring to the method of wave equations' modification, the Coriolis force and bottom friction term are considered, and the effects of which have been performed with the radial sand ridges topography. Finally, the results show that the modified mild-slope equation can be used to simulate tidal motion, and the calculations agree well with the measurements, thus the applicability and validity of the mild-slope equation on tidal simulation are further proved.
Since the mild-slope equation was derived by Berkhoff (1972), the researchers considered various mechanism to simplify and improve the equation, which has been widely used for coastal wave field calculation. Recently, some scholars applied the mild-slope equation in simulating the tidal motion, which proves that the equation is capable to calculate the tide in actual terrain. But in their studies, they made a lot of simplifications, and did not consider the effects of Coriolis force and bottom friction on tidal wave. In this paper, the first-order linear mild-slope equations are deduced from Kirby mild-slope equation including wave and current interaction. Then, referring to the method of wave equations' modification, the Coriolis force and bottom friction term are considered, and the effects of which have been performed with the radial sand ridges topography. Finally, the results show that the modified mild-slope equation can be used to simulate tidal motion, and the calculations agree well with the measurements, thus the applicability and validity of the mild-slope equation on tidal simulation are further proved.
2010, (6): 51-61.
doi: 10.1007/s13131-010-0076-1
Abstract:
The morphodynamic evolution of an idealized inlet system is investigated using a 2-D depthaveraged process-based model, incorporating the hydrodynamic equations, Englund-Hansen's sediment transport formula and the mass conservation equation. The model has a fixed geometry, impermeable boundaries and uniform sediment grain size, and driven by shore-parallel tidal elevations. The results show that the model reproduces major elements of the inlet system, i.e., flood and ebb tidal deltas, inlet channel. Equilibrium is reached after several years when the residual transport gradually decreases and eventually diminishes. At equilibrium, the flow field characteristics and morphological patterns agree with the schematized models proposed by O'Brien (1969) and Hayes (1980). The modeled minimum cross-sectional entrance area of the tidal inlet system is comparable with that calculated with the statistical P-A relationship for tidal inlets along the East China Sea coast. The morphological evolution of the inlet system is controlled by a negative feedback between hydrodynamics, sediment transport and bathymetric changes. The evolution rates decrease exponentially with time, i.e., the system develops rapidly at an early stage while it slows down at later stages. Temporal changes in hydrodynamics occur in the system; for example, the flood velocity decreases while its duration increases, which weakens the flood domination patterns. The formation of the multi-channel system in the tidal basin can be divided into two stages; at the first stage the flood delta is formed and the water depth is reduced, and at the second stage the flood is dissected by a number of tidal channels in which the water depth increases in response to tidal scour.
The morphodynamic evolution of an idealized inlet system is investigated using a 2-D depthaveraged process-based model, incorporating the hydrodynamic equations, Englund-Hansen's sediment transport formula and the mass conservation equation. The model has a fixed geometry, impermeable boundaries and uniform sediment grain size, and driven by shore-parallel tidal elevations. The results show that the model reproduces major elements of the inlet system, i.e., flood and ebb tidal deltas, inlet channel. Equilibrium is reached after several years when the residual transport gradually decreases and eventually diminishes. At equilibrium, the flow field characteristics and morphological patterns agree with the schematized models proposed by O'Brien (1969) and Hayes (1980). The modeled minimum cross-sectional entrance area of the tidal inlet system is comparable with that calculated with the statistical P-A relationship for tidal inlets along the East China Sea coast. The morphological evolution of the inlet system is controlled by a negative feedback between hydrodynamics, sediment transport and bathymetric changes. The evolution rates decrease exponentially with time, i.e., the system develops rapidly at an early stage while it slows down at later stages. Temporal changes in hydrodynamics occur in the system; for example, the flood velocity decreases while its duration increases, which weakens the flood domination patterns. The formation of the multi-channel system in the tidal basin can be divided into two stages; at the first stage the flood delta is formed and the water depth is reduced, and at the second stage the flood is dissected by a number of tidal channels in which the water depth increases in response to tidal scour.
2010, (6): 62-72.
doi: 10.1007/s13131-010-0077-0
Abstract:
Between April 2002 and April 2003, in situ measurements of water depth, current velocity and suspended sediment content were carried out in edge region of East Chongming salt marsh and neighboring bald flat in the Changjiang (Yangtze) Estuary under different weather conditions. Cross-shore suspended sediment flux was calculated and analyzed. The results show that under calm weather conditions, the current velocity process in bald field and salt marsh area varied differently during semidiurnal tidal cycles. Owing to current velocity asymmetry, mean SSC during flood tide phase was 1.8 times higher than that of ebb tide phase. As a result, net onshore sediment flux controlled cross-shore suspended sediment transport process and salt marsh pioneer zone was generally accreting. There was significant positive correlation between total sediment flux and quartic power of maximum water depth. It indicates that tidal ranges dominate suspended sediment transport and sedimentation process in the salt marsh pioneer zone under the calm weather condition. The sedimentation rate on the adjacent mudflat was higher than the salt marsh, which induced stable accreting of salt marsh towards the sea. The wind events enhanced SSC and current velocity during the semidiurnal tides. And the remarkable onshore net sediment flux could occur on the high marsh and mudflat close to the marsh fringe during the short period under the rough weather condition.
Between April 2002 and April 2003, in situ measurements of water depth, current velocity and suspended sediment content were carried out in edge region of East Chongming salt marsh and neighboring bald flat in the Changjiang (Yangtze) Estuary under different weather conditions. Cross-shore suspended sediment flux was calculated and analyzed. The results show that under calm weather conditions, the current velocity process in bald field and salt marsh area varied differently during semidiurnal tidal cycles. Owing to current velocity asymmetry, mean SSC during flood tide phase was 1.8 times higher than that of ebb tide phase. As a result, net onshore sediment flux controlled cross-shore suspended sediment transport process and salt marsh pioneer zone was generally accreting. There was significant positive correlation between total sediment flux and quartic power of maximum water depth. It indicates that tidal ranges dominate suspended sediment transport and sedimentation process in the salt marsh pioneer zone under the calm weather condition. The sedimentation rate on the adjacent mudflat was higher than the salt marsh, which induced stable accreting of salt marsh towards the sea. The wind events enhanced SSC and current velocity during the semidiurnal tides. And the remarkable onshore net sediment flux could occur on the high marsh and mudflat close to the marsh fringe during the short period under the rough weather condition.
2010, (6): 73-82.
doi: 10.1007/s13131-010-0078-z
Abstract:
Macrobenthic infauna and associated environmental factors influencing the benthic community in the eastern coastal region of Shandong Peninsula were analyzed in four seasonal surveys from January 2007 to October 2007 (30 stations in winter, 20 stations in other three seasons), in order to understand the community structure and the factors unfluencing the benthic distribution. PRIMER 6.0 and SPSS 15.0 software packages were adopted to analyze the environmental and macrobenthic data. The results show that there were 260 macrobenthic species in total collected from the research region. The composition of species is:Polychaeta (94 species), Crustacea (75), Mollusca (56) and Echinoderm (12), among which, only 23 species were common species in the cruises of every season. The dominant species varied from season to season; however, the polychaete species Paralacydonia paradoxa Fauvel and Echinoderm species Amphioplus japonicus (Matsumoto) were always present year-round. The abundance and biomass of the macrobenthos in the research region were variable from season to season. The results of CLUSTER and MDS analysis show that the similarities of macrobenthic structures between the stations were low; most of the similarities were at about 30% of similarity value, only two stations were up to 70%. In accordance with the similarity values of the macrobenthic structures, we divided the 20 stations into five groups by arbitrary similarity level of 30%. The ABC curve indicates that the marcofauna communities in the research region had not been disturbed massively, except two stations, SB1 and SB3. Ecologically, benthos were controlled by a combination of factors such as salinity, phytoplankton, zooplankton, SiO3-Si and temperature, and no single factor could be considered as an ecological master factor.
Macrobenthic infauna and associated environmental factors influencing the benthic community in the eastern coastal region of Shandong Peninsula were analyzed in four seasonal surveys from January 2007 to October 2007 (30 stations in winter, 20 stations in other three seasons), in order to understand the community structure and the factors unfluencing the benthic distribution. PRIMER 6.0 and SPSS 15.0 software packages were adopted to analyze the environmental and macrobenthic data. The results show that there were 260 macrobenthic species in total collected from the research region. The composition of species is:Polychaeta (94 species), Crustacea (75), Mollusca (56) and Echinoderm (12), among which, only 23 species were common species in the cruises of every season. The dominant species varied from season to season; however, the polychaete species Paralacydonia paradoxa Fauvel and Echinoderm species Amphioplus japonicus (Matsumoto) were always present year-round. The abundance and biomass of the macrobenthos in the research region were variable from season to season. The results of CLUSTER and MDS analysis show that the similarities of macrobenthic structures between the stations were low; most of the similarities were at about 30% of similarity value, only two stations were up to 70%. In accordance with the similarity values of the macrobenthic structures, we divided the 20 stations into five groups by arbitrary similarity level of 30%. The ABC curve indicates that the marcofauna communities in the research region had not been disturbed massively, except two stations, SB1 and SB3. Ecologically, benthos were controlled by a combination of factors such as salinity, phytoplankton, zooplankton, SiO3-Si and temperature, and no single factor could be considered as an ecological master factor.
2010, (6): 83-91.
doi: 10.1007/s13131-010-0079-y
Abstract:
Simple sequence repeat (SSR) markers were obtained for the large yellow croaker Pseudosciaena crocea using 1 205 expressed sequences tags (ESTs) from the NCBI database. Primers for 48 ESTSSR loci were designed and screened with 30 P.crocea specimens captured from Guanjingyang sea area in Fujian Province of China. Sixteen of the loci were polymorphic, which were amplified with 3 to 11 alleles per locus and the mean of 6.13. The observed and expected heterozygosity per locus ranged from 0.091 to 0.844 (mean 0.544) and from 0.118 to 0.892 (mean 0.644), respectively. Polymorphic information content (PIC) ranged from 0.115 to 0.866 (mean 0.593). The results for cross-species amplification of the 16 large yellow croaker EST-SSRs on P. polyactis, C. niveatus, C. lucidus, A. argentatus and J. belengeri revealed that 14, 12, 11, 7 and 6 loci were successfully amplified with 1 to 10 alleles with an average of 4.5 per locus, respectively, which are suitable for population genetics studies of these species and useful for phylogenetic relationship analysis among these species. Overall, this study provides a set of type I markers for population genetics studies and genome mapping for large yellow croaker and its closely related species.
Simple sequence repeat (SSR) markers were obtained for the large yellow croaker Pseudosciaena crocea using 1 205 expressed sequences tags (ESTs) from the NCBI database. Primers for 48 ESTSSR loci were designed and screened with 30 P.crocea specimens captured from Guanjingyang sea area in Fujian Province of China. Sixteen of the loci were polymorphic, which were amplified with 3 to 11 alleles per locus and the mean of 6.13. The observed and expected heterozygosity per locus ranged from 0.091 to 0.844 (mean 0.544) and from 0.118 to 0.892 (mean 0.644), respectively. Polymorphic information content (PIC) ranged from 0.115 to 0.866 (mean 0.593). The results for cross-species amplification of the 16 large yellow croaker EST-SSRs on P. polyactis, C. niveatus, C. lucidus, A. argentatus and J. belengeri revealed that 14, 12, 11, 7 and 6 loci were successfully amplified with 1 to 10 alleles with an average of 4.5 per locus, respectively, which are suitable for population genetics studies of these species and useful for phylogenetic relationship analysis among these species. Overall, this study provides a set of type I markers for population genetics studies and genome mapping for large yellow croaker and its closely related species.
2010, (6): 92-103.
doi: 10.1007/s13131-010-0080-5
Abstract:
The invasive red alga Grateloupia turuturu Yamada could turn Vibrio parahaemolyticus into nonculturable state in live algal culture. In order to elucidate the mechanism of such an effect, a series of culture experiments were performed in this investigation based on three hypothesized causes, namely bacterial attachment, production of reactive oxygen species (ROS) and the discharge of water soluble secondary metabolic compounds. The results reveal that attachment to the thallus surface of G. turuturu was the major reason for the decrease of V. parahaemolyticus in seawater. Further investigations show that V. parahaemolyticus attachment to the surface of algal thallus in live cultures of seaweeds was a common phenomenon. However, the disappearance of the culturability of V. parahaemolyticus occurred only on the thallus of G. turuturu over 72 h among all six algal species tested. Electron microscopic scanning shows that most of V. parahaemolyticus attached to G. turuturu changed from the initial normal bacilli to coccoid-shape after 72 h. The enclosure experiments by enclosing the algal thallus in tubes demonstrate that the nonculturability of V. parahaemolyticus in the water of live culture of G. turuturu occurred after the physical contact of the V. parahaemolyticus to the alga. The capacity of G. turuturu in affecting the culturability of V. parahaemolyticus was not influenced after inhibition of photosynthesis by treatment of 3'-(3,4-dichlorophenyl)-1',1'-dimethyl urea (DCMU) at non-lethal levels. Production of reactive oxygen species after addition of live culture of bacteria was excluded by on-line analyzing the oxidation of dichlorohydrofluorescein (DCFH) to dichlorofluorescein (DCF) in the presence of peroxidase on a VersaFluor fluorometer.
The invasive red alga Grateloupia turuturu Yamada could turn Vibrio parahaemolyticus into nonculturable state in live algal culture. In order to elucidate the mechanism of such an effect, a series of culture experiments were performed in this investigation based on three hypothesized causes, namely bacterial attachment, production of reactive oxygen species (ROS) and the discharge of water soluble secondary metabolic compounds. The results reveal that attachment to the thallus surface of G. turuturu was the major reason for the decrease of V. parahaemolyticus in seawater. Further investigations show that V. parahaemolyticus attachment to the surface of algal thallus in live cultures of seaweeds was a common phenomenon. However, the disappearance of the culturability of V. parahaemolyticus occurred only on the thallus of G. turuturu over 72 h among all six algal species tested. Electron microscopic scanning shows that most of V. parahaemolyticus attached to G. turuturu changed from the initial normal bacilli to coccoid-shape after 72 h. The enclosure experiments by enclosing the algal thallus in tubes demonstrate that the nonculturability of V. parahaemolyticus in the water of live culture of G. turuturu occurred after the physical contact of the V. parahaemolyticus to the alga. The capacity of G. turuturu in affecting the culturability of V. parahaemolyticus was not influenced after inhibition of photosynthesis by treatment of 3'-(3,4-dichlorophenyl)-1',1'-dimethyl urea (DCMU) at non-lethal levels. Production of reactive oxygen species after addition of live culture of bacteria was excluded by on-line analyzing the oxidation of dichlorohydrofluorescein (DCFH) to dichlorofluorescein (DCF) in the presence of peroxidase on a VersaFluor fluorometer.
2010, (6): 104-114.
doi: 10.1007/s13131-010-0081-4
Abstract:
Long-term changes of phytoplankton community by water sampling method in Xiagu Sea waters of Xiamen, China, were investigated in this study. Species composition of the phytoplankton community in these waters changed greatly since the 1950s. The numbers of Dinophyta species increased significantly, although Bacillariophyta species are generally dominant. The succession of dominant species in phytoplankton community is obvious:large-size dominant species such as Biddulphia sinensis of the 1950s were gradually replaced by small-size ones such as Cyclotella striata and Nitzschia closterium, and species that still maintain dominant such as Skeletonema costatum are also small ones, leading the whole phytoplankton community of smaller size. Cell density of phytoplankton community increased greatly, among which cell density of the most dominant species Skeletonema costatum have been increasing in exponent function. Margalef index of phytoplankton community decreased, indicating decline of biodiversity of the community, and dominant character of Skeletonema costatum increased. Generally, the structure of the entire phytoplankton community is becoming more and more singular and unstable, which makes the occurrence of red tides more frequent. The succession in the phytoplankton community is related to the long-term changes in marine environment, influenced by human activities and global climate changes, especially the increases of nutrient content.
Long-term changes of phytoplankton community by water sampling method in Xiagu Sea waters of Xiamen, China, were investigated in this study. Species composition of the phytoplankton community in these waters changed greatly since the 1950s. The numbers of Dinophyta species increased significantly, although Bacillariophyta species are generally dominant. The succession of dominant species in phytoplankton community is obvious:large-size dominant species such as Biddulphia sinensis of the 1950s were gradually replaced by small-size ones such as Cyclotella striata and Nitzschia closterium, and species that still maintain dominant such as Skeletonema costatum are also small ones, leading the whole phytoplankton community of smaller size. Cell density of phytoplankton community increased greatly, among which cell density of the most dominant species Skeletonema costatum have been increasing in exponent function. Margalef index of phytoplankton community decreased, indicating decline of biodiversity of the community, and dominant character of Skeletonema costatum increased. Generally, the structure of the entire phytoplankton community is becoming more and more singular and unstable, which makes the occurrence of red tides more frequent. The succession in the phytoplankton community is related to the long-term changes in marine environment, influenced by human activities and global climate changes, especially the increases of nutrient content.
2010, (6): 115-120.
doi: 10.1007/s13131-010-0082-3
Abstract:
A new method of detecting abnormal sounding data based on LS-SVM is presented. The theorem proves that the trend surface filter is the especial result of LS-SVM. In order to depict the relationship of trend surface filter and LS-SVM, a contrast is given. The example shows that abnormal sounding data could be detected effectively by LS-SVM when the training samples and kernel function are reasonable.
A new method of detecting abnormal sounding data based on LS-SVM is presented. The theorem proves that the trend surface filter is the especial result of LS-SVM. In order to depict the relationship of trend surface filter and LS-SVM, a contrast is given. The example shows that abnormal sounding data could be detected effectively by LS-SVM when the training samples and kernel function are reasonable.
2010, (6): 121-124.
doi: 10.1007/s13131-010-0083-2
Abstract:
Ten novel polymorphic microsatellite loci were developed using an enrichment and colony hybridization protocol and characterized for the cuttlefish, Sepiella maindroni. Polymorphism was explored by using 30 individuals from the coastal waters of Zhanjiang, Guangdong province, China, in December 2007. The number of alleles ranged from 5 to 13. The ranges of observed and expected heterozygosity were from 0.578 9 to 1.000 0 and 0.682 8 to 0.925 7, respectively, and the average polymorphic information content (PIC) was 0.778 5. These microsatellite loci will certainly facilitate the detection of the genetic variation and population structure of S. maindroni.
Ten novel polymorphic microsatellite loci were developed using an enrichment and colony hybridization protocol and characterized for the cuttlefish, Sepiella maindroni. Polymorphism was explored by using 30 individuals from the coastal waters of Zhanjiang, Guangdong province, China, in December 2007. The number of alleles ranged from 5 to 13. The ranges of observed and expected heterozygosity were from 0.578 9 to 1.000 0 and 0.682 8 to 0.925 7, respectively, and the average polymorphic information content (PIC) was 0.778 5. These microsatellite loci will certainly facilitate the detection of the genetic variation and population structure of S. maindroni.
