2012 Vol. 31, No. 3
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Display Method:
2012, (3): 1-9.
doi: 10.1007/s13131-012-0201-4
Abstract:
With the launch of altimeter,much effort has been made to develop algorithms on the wind speed and the wave period.By using a large data set of collocated altimeter and buoy measurements,the typical wind speed and wave period algorithms are validated.Based on theoretical argument and the concept of wave age,a semi-empirical algorithm for the wave period is also proposed,which has the wave-period dimension,and explicitly demonstrates the relationships between the wave period and the other variables.It is found that Ku and C band data should be applied simultaneously in order to improve either wind speed or wave period algorithms.The dual-band algorithms proposed by Chen et al.(2002) for the wind speed and Quilfen et al.(2004) for the wave period perform best in terms of a root mean square error in the practical applications.
With the launch of altimeter,much effort has been made to develop algorithms on the wind speed and the wave period.By using a large data set of collocated altimeter and buoy measurements,the typical wind speed and wave period algorithms are validated.Based on theoretical argument and the concept of wave age,a semi-empirical algorithm for the wave period is also proposed,which has the wave-period dimension,and explicitly demonstrates the relationships between the wave period and the other variables.It is found that Ku and C band data should be applied simultaneously in order to improve either wind speed or wave period algorithms.The dual-band algorithms proposed by Chen et al.(2002) for the wind speed and Quilfen et al.(2004) for the wave period perform best in terms of a root mean square error in the practical applications.
2012, (3): 10-17.
doi: 10.1007/s13131-012-0202-3
Abstract:
Wave and longshore current interaction was examined based on the numerical models. In these models, water waves in the presence of longshore currents were modeled by parabolic mild slope equation, and wave breaking induced longshore currents were modeled by shallow water equation. Water wave provided the radiation stress gradients to drive current. Wave and longshore current interactions were considered by cycling the wave and longshore current models to a steady state. The experiments for regular and irregular breaking wave induced longshore currents by Hamilton and Ebersole (2001) and Reniers and Battjes (1997) were simulated. The numerical results indicate that the present models are effective for simulating the interaction of wave and breaking wave induced longshore currents, and the numerically simulated longshore current at wave breaking point considering wave and longshore current interaction show some disagreement with those neglecting the wave-current interaction, and the breaking wave induced longshore current effect on wave transformation is not obvious.
Wave and longshore current interaction was examined based on the numerical models. In these models, water waves in the presence of longshore currents were modeled by parabolic mild slope equation, and wave breaking induced longshore currents were modeled by shallow water equation. Water wave provided the radiation stress gradients to drive current. Wave and longshore current interactions were considered by cycling the wave and longshore current models to a steady state. The experiments for regular and irregular breaking wave induced longshore currents by Hamilton and Ebersole (2001) and Reniers and Battjes (1997) were simulated. The numerical results indicate that the present models are effective for simulating the interaction of wave and breaking wave induced longshore currents, and the numerically simulated longshore current at wave breaking point considering wave and longshore current interaction show some disagreement with those neglecting the wave-current interaction, and the breaking wave induced longshore current effect on wave transformation is not obvious.
2012, (3): 18-30.
doi: 10.1007/s13131-012-0203-2
Abstract:
A spatially adaptive (SA) two-dimensional (2-D) numerical wave flume is presented based on the quadtree mesh system, in which a new multiple particle level set (MPLS) method is proposed to solve the problem of interface tracking, in which common intersection may be traversed by multiple interfaces. By using the adaptive mesh technique and the MPLS method, mesh resolution is updated automatically with time according to flow characteristics in the modeling process with higher resolution around the free surface and the solid boundary and lower resolution in less important area. The model has good performance in saving computer memory and CPU time and is validated by computational examples of small amplitude wave, second-order Stokes wave and cnoidal wave. Computational results also indicate that standing wave and wave overtopping are also reasonably simulated by the model.
A spatially adaptive (SA) two-dimensional (2-D) numerical wave flume is presented based on the quadtree mesh system, in which a new multiple particle level set (MPLS) method is proposed to solve the problem of interface tracking, in which common intersection may be traversed by multiple interfaces. By using the adaptive mesh technique and the MPLS method, mesh resolution is updated automatically with time according to flow characteristics in the modeling process with higher resolution around the free surface and the solid boundary and lower resolution in less important area. The model has good performance in saving computer memory and CPU time and is validated by computational examples of small amplitude wave, second-order Stokes wave and cnoidal wave. Computational results also indicate that standing wave and wave overtopping are also reasonably simulated by the model.
2012, (3): 31-46.
doi: 10.1007/s13131-012-0204-1
Abstract:
Saltwater intrusion is a serious environmental problem in the Zhujiang River Estuary (ZRE), which threatens the water supply of fifteen million people. The hydrological observations as well as meteorological and tidal forcing in the winter of 2007/2008 were analyzed to examine the saltwater intrusion in the ZRE. The observational results suggest that the maximum vertical difference of salinity can reach 10 in the Humen Channel during neap tide, but is very small in the Hengmen Channel. The vertically averaged salinity from time series stations during spring tide is higher than that during neap tide. A three-dimensional finite difference model was developed based on the environmental fluid dynamic code (EFDC) to study the mechanism of saltwater intrusion and salinity stratification in the ZRE. By analyzing the salt transport and the temporal variation of saltwater intrusion, the authors found that the net salt transport due to the estuarine circulation during neap tide was more than that during spring tide. This caused salt to advance more into the estuary during neap tide. However, saltwater intrusion was stronger during spring tide than that during neap tide because the spring-neap variation in salt transport was small relative to the total length of the saltwater intrusion. The physical mechanism causing this saltwater intrusion was investigated by a series of sensitivity experiments, in order to examine saltwater intrusion in response to river discharge and winds. The freshwater source was a dominant influencing factor to the saltwater intrusion and controlled salinity structure, vertical stratification and length of the saltwater intrusion. The prevailing northeast monsoon during winter could increase the saltwater intrusion in the ZRE. Though the southwest wind was unfavorable to saltwater intrusion during spring tide, it could increase stratification and saltwater intrusion during neap tide.
Saltwater intrusion is a serious environmental problem in the Zhujiang River Estuary (ZRE), which threatens the water supply of fifteen million people. The hydrological observations as well as meteorological and tidal forcing in the winter of 2007/2008 were analyzed to examine the saltwater intrusion in the ZRE. The observational results suggest that the maximum vertical difference of salinity can reach 10 in the Humen Channel during neap tide, but is very small in the Hengmen Channel. The vertically averaged salinity from time series stations during spring tide is higher than that during neap tide. A three-dimensional finite difference model was developed based on the environmental fluid dynamic code (EFDC) to study the mechanism of saltwater intrusion and salinity stratification in the ZRE. By analyzing the salt transport and the temporal variation of saltwater intrusion, the authors found that the net salt transport due to the estuarine circulation during neap tide was more than that during spring tide. This caused salt to advance more into the estuary during neap tide. However, saltwater intrusion was stronger during spring tide than that during neap tide because the spring-neap variation in salt transport was small relative to the total length of the saltwater intrusion. The physical mechanism causing this saltwater intrusion was investigated by a series of sensitivity experiments, in order to examine saltwater intrusion in response to river discharge and winds. The freshwater source was a dominant influencing factor to the saltwater intrusion and controlled salinity structure, vertical stratification and length of the saltwater intrusion. The prevailing northeast monsoon during winter could increase the saltwater intrusion in the ZRE. Though the southwest wind was unfavorable to saltwater intrusion during spring tide, it could increase stratification and saltwater intrusion during neap tide.
2012, (3): 47-58.
doi: 10.1007/s13131-012-0205-0
Abstract:
The south to the north project (WDP) on the saltwater intrusion in the Changjiang Estuary is studied by the improved three-dimensional (3D) numerical model. The net unit width flux in the Changjiang Estuary as well as the sectional salt flux is calculated in the North Branch (NB), the South Branch (SB), the North Channel (NC), the South Channel (SC), the North Passage (NP) and the South Passage (SP), respectively. The net seaward water flux in the SB is reduced, and the net water flux spilling over from the NB to the SB is enhanced after the eastern WDP. Under the mean river discharge condition in the dry season, the net salt flux spilling over from the NB to the SB is increased by 2.09 t/s and 0.52 t/s during the spring and neap tides, respectively, due to the eastern WDP. The saltwater intrusion in the Changjiang Estuary is enhanced by the eastern WDP. Compared with that during the spring tide, the net water diversion ratio during the neap tide in the NC is smaller, and thus the enhancement of the saltwater intrusion by the eastern WDP is smaller in the NC, and larger in the NP and the SP. The tidally averaged surface salinity at the water intakes of the Dongfengxisha Reservoir, the Chenhang Reservoir and the Qingcaosha Reservoir rises both during the spring and neap tides.
The south to the north project (WDP) on the saltwater intrusion in the Changjiang Estuary is studied by the improved three-dimensional (3D) numerical model. The net unit width flux in the Changjiang Estuary as well as the sectional salt flux is calculated in the North Branch (NB), the South Branch (SB), the North Channel (NC), the South Channel (SC), the North Passage (NP) and the South Passage (SP), respectively. The net seaward water flux in the SB is reduced, and the net water flux spilling over from the NB to the SB is enhanced after the eastern WDP. Under the mean river discharge condition in the dry season, the net salt flux spilling over from the NB to the SB is increased by 2.09 t/s and 0.52 t/s during the spring and neap tides, respectively, due to the eastern WDP. The saltwater intrusion in the Changjiang Estuary is enhanced by the eastern WDP. Compared with that during the spring tide, the net water diversion ratio during the neap tide in the NC is smaller, and thus the enhancement of the saltwater intrusion by the eastern WDP is smaller in the NC, and larger in the NP and the SP. The tidally averaged surface salinity at the water intakes of the Dongfengxisha Reservoir, the Chenhang Reservoir and the Qingcaosha Reservoir rises both during the spring and neap tides.
2012, (3): 59-66.
doi: 10.1007/s13131-012-0206-z
Abstract:
Many synthetic aperture radar (SAR) wave height retrieval algorithms have been developed. However, the wave height retrievals from most existing methods either depend on other input as the first guess or are restricted to the long wave regime. A semiempirical algorithm is presented, which has the objective to estimate the wave height from SAR imagery without any prior knowledge. The proposed novel algorithm was developed based on the theoretical SAR ocean wave imaging mechanism and the empirical relation between two types of wave period. The dependency of the proposed model on radar incident and wave direction was analyzed. For Envisat advanced synthetic aperture radar (ASAR) wave mode data, the model can be reduced to the simple form with two input parameters, i.e., the cutoff wavelength and peak wavelength of ocean wave, which can be retrieved from SAR imagery without any prior knowledge of wind or wave. Using Envisat ASAR wave mode data and the collocated buoy measurements from NDBC, the semiempirical algorithm is validated and compared with the Envisat ASAR level 2 products. The root-mean-square-error (RMSE) and scatter index (SI) in respect to the in situ measurements are 0.52 m and 19% respectively. Validation results indicate that, for Envisat ASAR wave mode data, the proposed method works well.
Many synthetic aperture radar (SAR) wave height retrieval algorithms have been developed. However, the wave height retrievals from most existing methods either depend on other input as the first guess or are restricted to the long wave regime. A semiempirical algorithm is presented, which has the objective to estimate the wave height from SAR imagery without any prior knowledge. The proposed novel algorithm was developed based on the theoretical SAR ocean wave imaging mechanism and the empirical relation between two types of wave period. The dependency of the proposed model on radar incident and wave direction was analyzed. For Envisat advanced synthetic aperture radar (ASAR) wave mode data, the model can be reduced to the simple form with two input parameters, i.e., the cutoff wavelength and peak wavelength of ocean wave, which can be retrieved from SAR imagery without any prior knowledge of wind or wave. Using Envisat ASAR wave mode data and the collocated buoy measurements from NDBC, the semiempirical algorithm is validated and compared with the Envisat ASAR level 2 products. The root-mean-square-error (RMSE) and scatter index (SI) in respect to the in situ measurements are 0.52 m and 19% respectively. Validation results indicate that, for Envisat ASAR wave mode data, the proposed method works well.
2012, (3): 67-73.
doi: 10.1007/s13131-012-0207-y
Abstract:
Based on 5 831 continuous in situ measurements of the partial pressure of carbon dioxide on the sea surface p (CO2), related parameters of the sea surface temperature (SST) and chlorophyll-a (Chl a) concentration in 2010 winter, spring and summer of the Huanghai Sea and the Bohai Sea, the inherent relations among them are investigated preliminarily. This study reveals that the seasonal variability of SST and Chl a concentration has a significant influence on p (CO2). The authors have proposed a new algorithm to estimate p (CO2) from SST and Chl a concentration measurements. Compared with the vessel data, the root mean square error (RMSE) of p (CO2) retrieved by using the new model is 13.45 μatm (1atm=101.325 kPa) and the relative error is less than 4%. Then, SST and Chl a concentration data observed by satellite are used to retrieve p (CO2) in the Huanghai Sea and the Bohai Sea; and a better accuracy can be obtained if the quality control for sea surface chlorophyll-a concentration observed by satellite is used. The RMSE of retrieved p (CO2) data with quality control and that without quality control are 15.82 μatm and 31.74 μatm, respectively.
Based on 5 831 continuous in situ measurements of the partial pressure of carbon dioxide on the sea surface p (CO2), related parameters of the sea surface temperature (SST) and chlorophyll-a (Chl a) concentration in 2010 winter, spring and summer of the Huanghai Sea and the Bohai Sea, the inherent relations among them are investigated preliminarily. This study reveals that the seasonal variability of SST and Chl a concentration has a significant influence on p (CO2). The authors have proposed a new algorithm to estimate p (CO2) from SST and Chl a concentration measurements. Compared with the vessel data, the root mean square error (RMSE) of p (CO2) retrieved by using the new model is 13.45 μatm (1atm=101.325 kPa) and the relative error is less than 4%. Then, SST and Chl a concentration data observed by satellite are used to retrieve p (CO2) in the Huanghai Sea and the Bohai Sea; and a better accuracy can be obtained if the quality control for sea surface chlorophyll-a concentration observed by satellite is used. The RMSE of retrieved p (CO2) data with quality control and that without quality control are 15.82 μatm and 31.74 μatm, respectively.
2012, (3): 74-86.
doi: 10.1007/s13131-012-0208-x
Abstract:
The characteristics of grain-size, total organic carbon (TOC) and total nitrogen (TN) contents, TOC/TN ratios, stable carbon isotope (δ13C) and 210Pb dating were measured in six sediment cores from the Xiaohai Lagoon. The results show distinct spatial and temporal variations in sedimentation patterns. The sediments are dominated by clayey silt, sandy silt and by silty sand in the southern, middle lagoon and the northern lagoon, respectively. TOC and TN contents decline from south to north. Sedimentation rates, determined by 210Pb dating, tend to decrease from south to middle. However, the determination of sedimentation rate in the north is difficult. These spatial variations are related to the variations in sediment sources and hydrodynamic conditions in the Xiaohai Lagoon. The variations of organic matter signatures can be divided into two stages in the cores from the southern and middle lagoon. Before 1988, the organic matter signatures are relatively stable. The contribution of terrestrial organic carbon sources varies between 60% and 85%. After 1988, the organic matter signatures demonstrate significant variations. TOC and TN contents increase rapidly, TOC/TN ratios decrease, δ13C values shift to higher and the contribution of terrestrial organic carbon sources decreases to 40%-50%. The contributions of phytoplankton organic matter have increased in the sediment since 1988. Increasing aquaculture activities have had a significant impact on organic matter signatures since 1988. The sedimentation rates have increased rapidly in the southern and middle lagoon since 1988 due to the anthropogenic activities which include aquaculture, mining and deforestation. These activities have caused eutrophication and increased siltation in the southern and middle lagoon.
The characteristics of grain-size, total organic carbon (TOC) and total nitrogen (TN) contents, TOC/TN ratios, stable carbon isotope (δ13C) and 210Pb dating were measured in six sediment cores from the Xiaohai Lagoon. The results show distinct spatial and temporal variations in sedimentation patterns. The sediments are dominated by clayey silt, sandy silt and by silty sand in the southern, middle lagoon and the northern lagoon, respectively. TOC and TN contents decline from south to north. Sedimentation rates, determined by 210Pb dating, tend to decrease from south to middle. However, the determination of sedimentation rate in the north is difficult. These spatial variations are related to the variations in sediment sources and hydrodynamic conditions in the Xiaohai Lagoon. The variations of organic matter signatures can be divided into two stages in the cores from the southern and middle lagoon. Before 1988, the organic matter signatures are relatively stable. The contribution of terrestrial organic carbon sources varies between 60% and 85%. After 1988, the organic matter signatures demonstrate significant variations. TOC and TN contents increase rapidly, TOC/TN ratios decrease, δ13C values shift to higher and the contribution of terrestrial organic carbon sources decreases to 40%-50%. The contributions of phytoplankton organic matter have increased in the sediment since 1988. Increasing aquaculture activities have had a significant impact on organic matter signatures since 1988. The sedimentation rates have increased rapidly in the southern and middle lagoon since 1988 due to the anthropogenic activities which include aquaculture, mining and deforestation. These activities have caused eutrophication and increased siltation in the southern and middle lagoon.
2012, (3): 87-97.
doi: 10.1007/s13131-012-0209-9
Abstract:
Ferritin is an iron storage protein that plays a key role in the processes of physiology and pathology. In the present study, the authors reported the ferritin gene from abalone Haliotis diversicolor supertexta, which we named hds-ferritin. The full-length of hds-ferritin cDNA consisted of 879 bp with an ORF encoding a 171 amino acids. Amino acid sequence analysis revealed that hds-ferritin shared highly homology with other species. Real time PCR and western blot analysis showed that hds-ferritin was distributed ubiquitously in abalone tissues and had the highest expression level in digestive glands, but its transcripts are not modified remarkably by the stimulation with LPS. The recombinant protein was successfully expressed in Escherichia coli BL21 (DE3), and the titre of anti-ferritin antibody was about 1:14 000. The effects of ROS and RNS on ferritin were analyzed in the present study. The results showed that H2O2 played an important role in decreasing hds-ferritin, however NO cation appeared to have a protecting effect on H2O2-medied reduction of hds-ferritin.
Ferritin is an iron storage protein that plays a key role in the processes of physiology and pathology. In the present study, the authors reported the ferritin gene from abalone Haliotis diversicolor supertexta, which we named hds-ferritin. The full-length of hds-ferritin cDNA consisted of 879 bp with an ORF encoding a 171 amino acids. Amino acid sequence analysis revealed that hds-ferritin shared highly homology with other species. Real time PCR and western blot analysis showed that hds-ferritin was distributed ubiquitously in abalone tissues and had the highest expression level in digestive glands, but its transcripts are not modified remarkably by the stimulation with LPS. The recombinant protein was successfully expressed in Escherichia coli BL21 (DE3), and the titre of anti-ferritin antibody was about 1:14 000. The effects of ROS and RNS on ferritin were analyzed in the present study. The results showed that H2O2 played an important role in decreasing hds-ferritin, however NO cation appeared to have a protecting effect on H2O2-medied reduction of hds-ferritin.
2012, (3): 98-108.
doi: 10.1007/s13131-012-0210-3
Abstract:
This study concerned the accumulation of trace metals in tissues of seagrass (Thalassia hemprichii) exposed to various concentrations of Zn2+, Cd2+, Pb2+ and Cu2+ for 10 d, and the effect of excessive metals on quantum yield (ΔF/F'm), photosynthetic pigments and antioxidative enzymes like superoxide dismutase (SOD), guaiacol peroxidase (POD) were also examined. Cadmium was the most highly accumulated metal. Meanwhile, high metals levels led to a remarkable breakdown of photosynthetic parameters. Especially, ΔF/F'm, chlorophyll and carotenoid were significantly low during prolonged Cu exposure. Besides, ΔF/F'm was more severely depressed by Cu and Zn than Pb and Cd. However, T. hemprichii had positive response by increasing the activity of SOD and POD. The results indicate that T. hemprichii is the most sensitive to Cu, and the antioxidative protection mechanisms of T. hemprichii are more efficiently activated to avoid damage of Zn, Cd and Pb stress. Finally, due to the high Cd-accumulation and strong Cd-tolerance capacity, T. hemprichii can be used for phytoremediation in Cd-contaminated areas.
This study concerned the accumulation of trace metals in tissues of seagrass (Thalassia hemprichii) exposed to various concentrations of Zn2+, Cd2+, Pb2+ and Cu2+ for 10 d, and the effect of excessive metals on quantum yield (ΔF/F'm), photosynthetic pigments and antioxidative enzymes like superoxide dismutase (SOD), guaiacol peroxidase (POD) were also examined. Cadmium was the most highly accumulated metal. Meanwhile, high metals levels led to a remarkable breakdown of photosynthetic parameters. Especially, ΔF/F'm, chlorophyll and carotenoid were significantly low during prolonged Cu exposure. Besides, ΔF/F'm was more severely depressed by Cu and Zn than Pb and Cd. However, T. hemprichii had positive response by increasing the activity of SOD and POD. The results indicate that T. hemprichii is the most sensitive to Cu, and the antioxidative protection mechanisms of T. hemprichii are more efficiently activated to avoid damage of Zn, Cd and Pb stress. Finally, due to the high Cd-accumulation and strong Cd-tolerance capacity, T. hemprichii can be used for phytoremediation in Cd-contaminated areas.
2012, (3): 109-119.
doi: 10.1007/s13131-012-0211-2
Abstract:
Horizontal distributions of phytoplankton abundance, species composition as well as environmental factors were investigated in the surface waters of southern South China Sea (SCS) in early summer (May 16 to June 7) of 2009. In most areas of southern SCS, the concentrations of nitrogen and phosphorus were very low and DIN/DIP ratios usually were lower than the Redfield N/P Ratio of 16:1. Nitrogen nutrients were significant lower in the upwelling region off Vietnam. A total of 144 taxa of phytoplankton were identified in the study area. The dominant genera were Prorocentrum, Gonyaulax, Gyrodinium, Scrippsiella and Chaetoceros, respectively. Spatial patterns of early-summer phytoplankton abundance and species composition should be mainly controlled by the upwelling off Vietnam and the discharge of Mekong River in the southern SCS. Diatoms dominated in the nutritious Mekong River Estuary or upwelling region off Vietnam; while dinoflagellates dominated in the oligotrophic pelagic region. The canonical correspondence analysis (CCA) indicates that most of diatoms favor higher levels of silicate and phosphorus, as well as lower temperature; while most of dinoflagellates favor the lower silicate and phosphorous and higher temperature. Correlation and CCA results indicate that silicate, nitrate and temperature were the most relevant environmental factors to regulate the horizontal pattern of early-summer phytoplankton in the surface waters of southern SCS.
Horizontal distributions of phytoplankton abundance, species composition as well as environmental factors were investigated in the surface waters of southern South China Sea (SCS) in early summer (May 16 to June 7) of 2009. In most areas of southern SCS, the concentrations of nitrogen and phosphorus were very low and DIN/DIP ratios usually were lower than the Redfield N/P Ratio of 16:1. Nitrogen nutrients were significant lower in the upwelling region off Vietnam. A total of 144 taxa of phytoplankton were identified in the study area. The dominant genera were Prorocentrum, Gonyaulax, Gyrodinium, Scrippsiella and Chaetoceros, respectively. Spatial patterns of early-summer phytoplankton abundance and species composition should be mainly controlled by the upwelling off Vietnam and the discharge of Mekong River in the southern SCS. Diatoms dominated in the nutritious Mekong River Estuary or upwelling region off Vietnam; while dinoflagellates dominated in the oligotrophic pelagic region. The canonical correspondence analysis (CCA) indicates that most of diatoms favor higher levels of silicate and phosphorus, as well as lower temperature; while most of dinoflagellates favor the lower silicate and phosphorous and higher temperature. Correlation and CCA results indicate that silicate, nitrate and temperature were the most relevant environmental factors to regulate the horizontal pattern of early-summer phytoplankton in the surface waters of southern SCS.
2012, (3): 120-131.
doi: 10.1007/s13131-012-0212-1
Abstract:
The spatial and temporal variability and size fractionation of chlorophyll a (Chl a) were investigated in the tropical and subtropical Pacific Ocean during four survey cruises from 2005 to 2009. The surface Chl a (S-Chl a) concentration ranged from 0.002 to 0.497 mg/m3 and was obviously higher in the eastern Pacific than in the western and central Pacific. The vertical distribution of Chl a displayed a single peak pattern, and the maximum Chl a layer (MCL) was observed at a shallower depth in the eastern Pacific than in the western Pacific. All three size fractions of Chl a measurements in the surface water showed a similar distribution to total Chl a and were found in higher concentrations in the eastern Pacific than in the western and central Pacific. Picoplankton dominated the phytoplankton in the surveyed tropical and subtropical Pacific Ocean. Furthermore, pico-Chl a (0.2-2 μm) accounted for a larger percentage of the total Chl a in the central Pacific than it did in the western Pacific and eastern Pacific. In the western Pacific, there seemed to be a latitudinal variability in the phytoplankton community composition where small-sized phytoplankton (<2 μm) were more dominant in the tropical than in the subtropical western Pacific. The spatial and temporal variability and size fractionation of Chl a were controlled by hydrological and chemical characteristics and climate events, such as El Niño and La Niña.
The spatial and temporal variability and size fractionation of chlorophyll a (Chl a) were investigated in the tropical and subtropical Pacific Ocean during four survey cruises from 2005 to 2009. The surface Chl a (S-Chl a) concentration ranged from 0.002 to 0.497 mg/m3 and was obviously higher in the eastern Pacific than in the western and central Pacific. The vertical distribution of Chl a displayed a single peak pattern, and the maximum Chl a layer (MCL) was observed at a shallower depth in the eastern Pacific than in the western Pacific. All three size fractions of Chl a measurements in the surface water showed a similar distribution to total Chl a and were found in higher concentrations in the eastern Pacific than in the western and central Pacific. Picoplankton dominated the phytoplankton in the surveyed tropical and subtropical Pacific Ocean. Furthermore, pico-Chl a (0.2-2 μm) accounted for a larger percentage of the total Chl a in the central Pacific than it did in the western Pacific and eastern Pacific. In the western Pacific, there seemed to be a latitudinal variability in the phytoplankton community composition where small-sized phytoplankton (<2 μm) were more dominant in the tropical than in the subtropical western Pacific. The spatial and temporal variability and size fractionation of Chl a were controlled by hydrological and chemical characteristics and climate events, such as El Niño and La Niña.
2012, (3): 132-137.
doi: 10.1007/s13131-012-0213-0
Abstract:
Population genetic structure and historical demography of Chinese horseshoe crab (T. tridentatus) along southeast coast of China were inferred from the sequence data of mitochondrial cytochrome c oxidase subunit I (COI) fragment. The sequence analysis for 964 bp COI fragment was conducted in 28 individuals collected from five localities:Ninghai in Zhejiang Province, Meizhou and Zhangpu in Fujian Province, Beihai of Guangxi Zhuang Autonomous Region and Danzhou of Hainan Province. Sequence variation was relatively low with a total of seven transitions observed. In all localities, Haplotype H3 was the dominant type observed among eight haplotypes defined previously, and was at the center of radiation in Median-Joining network. The prolonged star-like network suggests a signature of population expansions. The level of diversity was low in total, with haplotype diversity (Hd) being equal to 0.765 and nucleotide diversity (π) being equal to 0.001 18, respectively. The genetic structure analysis revealed the significant genetic difference between Ninghai and Danzhou populations. Both mismatch distribution analysis and Fu's Fs test provided consistent inference of historic population expansion. The low genetic diversity of horseshoe crab observed along China coast indicated that urgent measures should be taken to protect this rare marine animal.
Population genetic structure and historical demography of Chinese horseshoe crab (T. tridentatus) along southeast coast of China were inferred from the sequence data of mitochondrial cytochrome c oxidase subunit I (COI) fragment. The sequence analysis for 964 bp COI fragment was conducted in 28 individuals collected from five localities:Ninghai in Zhejiang Province, Meizhou and Zhangpu in Fujian Province, Beihai of Guangxi Zhuang Autonomous Region and Danzhou of Hainan Province. Sequence variation was relatively low with a total of seven transitions observed. In all localities, Haplotype H3 was the dominant type observed among eight haplotypes defined previously, and was at the center of radiation in Median-Joining network. The prolonged star-like network suggests a signature of population expansions. The level of diversity was low in total, with haplotype diversity (Hd) being equal to 0.765 and nucleotide diversity (π) being equal to 0.001 18, respectively. The genetic structure analysis revealed the significant genetic difference between Ninghai and Danzhou populations. Both mismatch distribution analysis and Fu's Fs test provided consistent inference of historic population expansion. The low genetic diversity of horseshoe crab observed along China coast indicated that urgent measures should be taken to protect this rare marine animal.
2012, (3): 138-144.
doi: 10.1007/s13131-012-0214-z
Abstract:
Allelopathic effects of several concentrations of fresh tissue, dry powder and dry tissue of three bloom-forming green macroalgae Ulva pertusa, Ulva linza and Enteromopha intestinalis on the red tide microalga Heterosigma akashiwo were evaluated in microcosms systems. The effects of macroalgae culture medium filtrate were investigated on H. akashiwo using initial or semi-continuous filtrate addition. Preliminary studies on the algicidal effects of one aqueous and four organic solvent extracts from the macroalgae on the microalga were carried out to confirm the existence of allelochemicals in the tissue of these macroalgae. The dry powder of U. pertusa was extracted with methanol, and the methanol extracts were partitioned to petroleum ether phase, ethyl acetate phase, butanol phase and distilled phase by liquid-liquid fractionation. The bioassays of the activity of every fraction were carried out on H. akashiwo. The resultant microcosms assay showed that the growth of H. akashiwo was strongly inhibited by using fresh tissues, dry powder or dry tissue of these three macroalgae, while aqueous and methanol extracts of both macroalgae had strong inhibitory effects on the growth of H. akashiwo, and the EC50 values for methanol extract of U. pertusa, U. linza or E. intestinalis were 0.016, 0.028×10-12 or 0.033×10-12, respectively. While the other three organic solvent extracts (acetone, ether and chloroform) had no apparent effect on its growth, this suggests that the allelochemicals from these three macroalgae had relatively high polarities. The activity of petroleum ether phase, ethyl acetate phase, butanol phase and distilled phase of U. pertusa methanol extract was carried out on H. akashiwo indicating that petroleum ether phase and ethyl acetate phase had stronger algicidal effect on H. akashiwo. The inhibition effect of the ethyl acetate phase was not as strong as that of petroleum ether phase, and effective concentration of petroleum ether phase was 17 mg/L for H. akashiwo. However, no significant algicidal effects were observed on the butanol phase and distilled water phase. These three macroalgae's culture medium filtrate exhibited no apparent growth inhibitory effect on the microalga under initial filtrate addition whereas the growth of H. akashiwo was significantly inhibited under semi-continuous filtrate addition, which suggests that continuous release of small quantities of rapidly degradable allelochemicals from the fresh tissue of both macroalgae was effective in inhibiting the growth of H. akashiwo.
Allelopathic effects of several concentrations of fresh tissue, dry powder and dry tissue of three bloom-forming green macroalgae Ulva pertusa, Ulva linza and Enteromopha intestinalis on the red tide microalga Heterosigma akashiwo were evaluated in microcosms systems. The effects of macroalgae culture medium filtrate were investigated on H. akashiwo using initial or semi-continuous filtrate addition. Preliminary studies on the algicidal effects of one aqueous and four organic solvent extracts from the macroalgae on the microalga were carried out to confirm the existence of allelochemicals in the tissue of these macroalgae. The dry powder of U. pertusa was extracted with methanol, and the methanol extracts were partitioned to petroleum ether phase, ethyl acetate phase, butanol phase and distilled phase by liquid-liquid fractionation. The bioassays of the activity of every fraction were carried out on H. akashiwo. The resultant microcosms assay showed that the growth of H. akashiwo was strongly inhibited by using fresh tissues, dry powder or dry tissue of these three macroalgae, while aqueous and methanol extracts of both macroalgae had strong inhibitory effects on the growth of H. akashiwo, and the EC50 values for methanol extract of U. pertusa, U. linza or E. intestinalis were 0.016, 0.028×10-12 or 0.033×10-12, respectively. While the other three organic solvent extracts (acetone, ether and chloroform) had no apparent effect on its growth, this suggests that the allelochemicals from these three macroalgae had relatively high polarities. The activity of petroleum ether phase, ethyl acetate phase, butanol phase and distilled phase of U. pertusa methanol extract was carried out on H. akashiwo indicating that petroleum ether phase and ethyl acetate phase had stronger algicidal effect on H. akashiwo. The inhibition effect of the ethyl acetate phase was not as strong as that of petroleum ether phase, and effective concentration of petroleum ether phase was 17 mg/L for H. akashiwo. However, no significant algicidal effects were observed on the butanol phase and distilled water phase. These three macroalgae's culture medium filtrate exhibited no apparent growth inhibitory effect on the microalga under initial filtrate addition whereas the growth of H. akashiwo was significantly inhibited under semi-continuous filtrate addition, which suggests that continuous release of small quantities of rapidly degradable allelochemicals from the fresh tissue of both macroalgae was effective in inhibiting the growth of H. akashiwo.
