2013 Vol. 32, No. 6
Display Method:
2013, 32(6): 1-5.
doi: 10.1007/s13131-013-0318-0
Abstract:
A recurring spring mesoscale eddy in the western South China Sea (SCS) is studied using remote sensing data and historical in situ observations. The feature first appears east of the central Vietnam coast in February as a high sea-level anomaly, grows rapidly to a well-developed anticyclonic eddy by March, matures in April, and decays in May. Besides the warm-core feature, it also has an inherent low-salinity property, so it is named "spring mesoscale high (SMH)". Though with clear interannual variation in terms of intensity and spatial coverage, the SMH always emerges in the region between 110°E and 114°E and between 12°N and 16°N. The formation of SMH is ascribed to the combined effects of wind forcing and releasing of potential energy set up by winter monsoon. In particular, the wind-stress curl plays an important role in its development,maintenance, and dissipation.
A recurring spring mesoscale eddy in the western South China Sea (SCS) is studied using remote sensing data and historical in situ observations. The feature first appears east of the central Vietnam coast in February as a high sea-level anomaly, grows rapidly to a well-developed anticyclonic eddy by March, matures in April, and decays in May. Besides the warm-core feature, it also has an inherent low-salinity property, so it is named "spring mesoscale high (SMH)". Though with clear interannual variation in terms of intensity and spatial coverage, the SMH always emerges in the region between 110°E and 114°E and between 12°N and 16°N. The formation of SMH is ascribed to the combined effects of wind forcing and releasing of potential energy set up by winter monsoon. In particular, the wind-stress curl plays an important role in its development,maintenance, and dissipation.
2013, 32(6): 6-12.
doi: 10.1007/s13131-013-0319-z
Abstract:
The South China Sea summer monsoon (SCSSM) behaves with prominent climate variability from the intraseasonal to interdecadal time scales. On the interannual time scale, the biennial variability (so-called tropospheric biennial oscillation, TBO) is as important as the El Niño-Southern Oscillation (ENSO) period. Some observed data sets, including reanalysis data, are used to explore the associated air-sea interactive physical processes and how the SCSSM TBO affects the ENSO. The results show that the shearing vorticity induced by the north Indian Ocean sea surface temperature anomalies (SSTAs) and the anomalous Philippine Sea anticyclone both contribute to the TBO in the SCSSM. The results also indicate that the ENSO has a weak effect on the SCSSMTBO, whereas the latter affects the ENSO to some extent.
The South China Sea summer monsoon (SCSSM) behaves with prominent climate variability from the intraseasonal to interdecadal time scales. On the interannual time scale, the biennial variability (so-called tropospheric biennial oscillation, TBO) is as important as the El Niño-Southern Oscillation (ENSO) period. Some observed data sets, including reanalysis data, are used to explore the associated air-sea interactive physical processes and how the SCSSM TBO affects the ENSO. The results show that the shearing vorticity induced by the north Indian Ocean sea surface temperature anomalies (SSTAs) and the anomalous Philippine Sea anticyclone both contribute to the TBO in the SCSSM. The results also indicate that the ENSO has a weak effect on the SCSSMTBO, whereas the latter affects the ENSO to some extent.
2013, 32(6): 13-17.
doi: 10.1007/s13131-013-0320-6
Abstract:
The distributions of partial pressure of carbon dioxide (pCO2) in the surface waters of the Changjiang River Estuary and adjacent Hangzhou Bay were examined in the summer of 2010. Surface water pCO2 ranged from 751-2 095 μatm (1 atm=101 325 Pa) in the inner estuary, 177-1 036 μatm in the outer estuary, and 498-1 166 μatm in Hangzhou Bay. Overall, surface pCO2 behaved conservatively during the estuary mixing. In the inner estuary, surface pCO2 was relatively high due to urbanized pollution and a high respiration rate. The lowest pCO2 was observed in the outer estuary, which was apparently induced by a phytoplankton bloom because the dissolved oxygen and chlorophyll a were very high. The Changjiang River Estuary was a significant source of atmospheric CO2 and the degassing fluxes were estimated as 0-230 mmol/(m2·d)[61 mmol/(m2·d) on average] in the inner estuary. In contrast, the outer estuary acted as a CO2 sink. Key words:carbon dioxide, air-sea flux, Changjiang River Estuary, Hangzhou Bay.
The distributions of partial pressure of carbon dioxide (pCO2) in the surface waters of the Changjiang River Estuary and adjacent Hangzhou Bay were examined in the summer of 2010. Surface water pCO2 ranged from 751-2 095 μatm (1 atm=101 325 Pa) in the inner estuary, 177-1 036 μatm in the outer estuary, and 498-1 166 μatm in Hangzhou Bay. Overall, surface pCO2 behaved conservatively during the estuary mixing. In the inner estuary, surface pCO2 was relatively high due to urbanized pollution and a high respiration rate. The lowest pCO2 was observed in the outer estuary, which was apparently induced by a phytoplankton bloom because the dissolved oxygen and chlorophyll a were very high. The Changjiang River Estuary was a significant source of atmospheric CO2 and the degassing fluxes were estimated as 0-230 mmol/(m2·d)[61 mmol/(m2·d) on average] in the inner estuary. In contrast, the outer estuary acted as a CO2 sink. Key words:carbon dioxide, air-sea flux, Changjiang River Estuary, Hangzhou Bay.
2013, 32(6): 18-25.
doi: 10.1007/s13131-013-0305-5
Abstract:
Understanding phosphorus dynamics in marine environment is of great importance, and appropriate tracers for phosphorus cycling in oceans are invaluable. In this study, two methods were developed for extraction, purification, and determination of naturally occurring 32P and 33P in rainwater, marine plankton and sediments using both a low-level beta counter (LBC) and an ultra-low-level liquid scintillation spectrometer (LSS). Blanks, chemical yields and counting efficiencies were quantified for both methods. The chemical purification of 32P and 33P separated by both procedures was validated by their decay curves. The absorber thickness of aluminum for LBC was assessed as 39.2 mg/cm2. 32P and 33P specific activities in some rain samples were determined by both methods and showed good consistent results. The advantage of the LSS over the LBC is apparent in its high counting efficiency and in determining samples with high concentration of stable phosphorus. However, when measuring environmental samples with low concentration of stable phosphorus, such as rainwater, both methods can be used and each has its distinct advantage.
Understanding phosphorus dynamics in marine environment is of great importance, and appropriate tracers for phosphorus cycling in oceans are invaluable. In this study, two methods were developed for extraction, purification, and determination of naturally occurring 32P and 33P in rainwater, marine plankton and sediments using both a low-level beta counter (LBC) and an ultra-low-level liquid scintillation spectrometer (LSS). Blanks, chemical yields and counting efficiencies were quantified for both methods. The chemical purification of 32P and 33P separated by both procedures was validated by their decay curves. The absorber thickness of aluminum for LBC was assessed as 39.2 mg/cm2. 32P and 33P specific activities in some rain samples were determined by both methods and showed good consistent results. The advantage of the LSS over the LBC is apparent in its high counting efficiency and in determining samples with high concentration of stable phosphorus. However, when measuring environmental samples with low concentration of stable phosphorus, such as rainwater, both methods can be used and each has its distinct advantage.
2013, 32(6): 26-39.
doi: 10.1007/s13131-013-0306-4
Abstract:
The distribution and chemical properties of chromophoric dissolved organic matter (CDOM) in the Jiaozhou Bay, China were examined during four cruises in 2010-2011. The influence of freshwater and industrial and municipal sewage along the eastern coast of the bay was clearly evident as CDOM levels (defined as a305), and dissolved organic carbon (DOC) concentrations were well correlated with salinity during all the cruises. Moreover, DOC concentrations were significantly correlated with chlorophyll a concentrations in the surface microlayer as well as in the subsurface water. The concentrations of DOC and CDOM displayed a gradually decreasing trend from the northwestern and eastern coast to the central bay, and the values and gradients of their concentrations on the eastern coast were generally higher than those on the western coast. In addition, CDOM and DOC levels were generally higher in the surface microlayer than in the subsurface water. In comparison with DOC, CDOM exhibited a greater extent of enrichment in the microlayer in each cruise, with average enrichment factor (EF) values of 1.38 and 1.84, respectively. Four fluorescent components were identified from the surface microlayer and subsurface water samples and could be distinguished as peak A, peak T, peak B and peak M. For all the cruises, peak A levels were higher in the surfacemicrolayer than in the subsurface water. This pattern of variationmight be attributed to the terrestrial input.
The distribution and chemical properties of chromophoric dissolved organic matter (CDOM) in the Jiaozhou Bay, China were examined during four cruises in 2010-2011. The influence of freshwater and industrial and municipal sewage along the eastern coast of the bay was clearly evident as CDOM levels (defined as a305), and dissolved organic carbon (DOC) concentrations were well correlated with salinity during all the cruises. Moreover, DOC concentrations were significantly correlated with chlorophyll a concentrations in the surface microlayer as well as in the subsurface water. The concentrations of DOC and CDOM displayed a gradually decreasing trend from the northwestern and eastern coast to the central bay, and the values and gradients of their concentrations on the eastern coast were generally higher than those on the western coast. In addition, CDOM and DOC levels were generally higher in the surface microlayer than in the subsurface water. In comparison with DOC, CDOM exhibited a greater extent of enrichment in the microlayer in each cruise, with average enrichment factor (EF) values of 1.38 and 1.84, respectively. Four fluorescent components were identified from the surface microlayer and subsurface water samples and could be distinguished as peak A, peak T, peak B and peak M. For all the cruises, peak A levels were higher in the surfacemicrolayer than in the subsurface water. This pattern of variationmight be attributed to the terrestrial input.
2013, 32(6): 40-46.
doi: 10.1007/s13131-013-0304-6
Abstract:
Two morphotypes of Plectropomus leopardus have been identified; morphometric and meristic analyses show that there is no diagnostic difference between them. A difference in color pattern was the most appropriate phenotypic character with which to distinguish between the two morphotypes. Complete mitochondrial DNA sequencing, however, indicated a clear difference between the two morphotypes. Barcoding analysis revealed no significant difference (P>0.05) in CO1 or ND2 divergence among intramorphotypic individuals, even between geographically separated populations, whereas the intermorphotypic CO1 and ND2 divergences were large enough (averaging 0.95% for CO1 and 1.37% for ND2) to clearly discriminate between the two morphotypes. The color pattern difference, geographical distribution, together with the mtDNA and barcode sequencing data, suggest that the two morphotypes should be of two subspecies or even two species.
Two morphotypes of Plectropomus leopardus have been identified; morphometric and meristic analyses show that there is no diagnostic difference between them. A difference in color pattern was the most appropriate phenotypic character with which to distinguish between the two morphotypes. Complete mitochondrial DNA sequencing, however, indicated a clear difference between the two morphotypes. Barcoding analysis revealed no significant difference (P>0.05) in CO1 or ND2 divergence among intramorphotypic individuals, even between geographically separated populations, whereas the intermorphotypic CO1 and ND2 divergences were large enough (averaging 0.95% for CO1 and 1.37% for ND2) to clearly discriminate between the two morphotypes. The color pattern difference, geographical distribution, together with the mtDNA and barcode sequencing data, suggest that the two morphotypes should be of two subspecies or even two species.
2013, 32(6): 47-55.
doi: 10.1007/s13131-013-0321-5
Abstract:
Insular marine biotas are often richer in faunal diversity than those from the open sea in the same geographical region. The existence of particular island effects were tested under polar conditions by comparing infaunal benthic assemblages on Peter I Island with those of similar latitudes in the open ocean at the Bellingshausen Sea and also from the coast of the Antarctic Peninsula. Sampling was carried out aboard the R/V Hespérides during the expedition named BENTART-2003 from 24 January to 3 March 2003. Benthic samples were collected at 18 stations ranging from 90 to 2 044m depth, using anUSNEL-type box corer (BC) dredge. Representatives of 32 higher taxa of invertebrates were found. Univariate and multivariate analyses revealed various patterns in the data. First, significant differences in polychaete abundance were detected between the stations located in the open sea and the remaining sites (island plus mainland sites). Bivalve abundances were also distinct between island and mainland sampling sites. Sediment columns taken from the island seafloor exhibited the highest rate of bioturbation by the infauna. These findings confirm the model that islands develop distinct assemblages characterized by the enhancement of the benthic communities even in cold waters. Several abiotic factors were measured simultaneously at the seafloor and along the water column to investigate faunal distribution patterns. Significant correlations were found between the benthic assemblages and a combination of two environmental variables:"island effect" (measured as a categorical variable) and the redox state of sediments. Richer and more complex benthic assemblages were found in Peter I Island's sea bottom, whereas the more depauperate bottoms remained in the open sea.
Insular marine biotas are often richer in faunal diversity than those from the open sea in the same geographical region. The existence of particular island effects were tested under polar conditions by comparing infaunal benthic assemblages on Peter I Island with those of similar latitudes in the open ocean at the Bellingshausen Sea and also from the coast of the Antarctic Peninsula. Sampling was carried out aboard the R/V Hespérides during the expedition named BENTART-2003 from 24 January to 3 March 2003. Benthic samples were collected at 18 stations ranging from 90 to 2 044m depth, using anUSNEL-type box corer (BC) dredge. Representatives of 32 higher taxa of invertebrates were found. Univariate and multivariate analyses revealed various patterns in the data. First, significant differences in polychaete abundance were detected between the stations located in the open sea and the remaining sites (island plus mainland sites). Bivalve abundances were also distinct between island and mainland sampling sites. Sediment columns taken from the island seafloor exhibited the highest rate of bioturbation by the infauna. These findings confirm the model that islands develop distinct assemblages characterized by the enhancement of the benthic communities even in cold waters. Several abiotic factors were measured simultaneously at the seafloor and along the water column to investigate faunal distribution patterns. Significant correlations were found between the benthic assemblages and a combination of two environmental variables:"island effect" (measured as a categorical variable) and the redox state of sediments. Richer and more complex benthic assemblages were found in Peter I Island's sea bottom, whereas the more depauperate bottoms remained in the open sea.
2013, 32(6): 56-65.
doi: 10.1007/s13131-013-0322-4
Abstract:
Year-round investigations were carried out to address the population dynamics of amphipod Ampithoe valida and its potential regulating factors in the Yundang Lagoon (a eutrophic subtropical coastal lagoon in Xiamen City, China) from October 2007 to October 2008. The results show that A. valida population was largely composed of juveniles and reached a peak abundance (12.02×103 ind./m2) in March, but sharply shrunk in July. The monthly variation pattern of A. valida seemed to follow that of Ulva lactuca which is the main food resource for A. valida, indicating a strong influence of food availability on A. valida population dynamics. Life cycle studies in laboratory indicate that A. valida adopted an r-selected life strategy, e.g., rapid growth rate (0.216-0.302 mm/d), consecutive breeding (4-10 times), short reproductive rhythm (9-17 d) and huge fecundity (24-192 eggs or 6-94 juveniles per brood), which contributed to the fast population growth of A. valida from January to March. Although temperature may also be a significant cause, A. valida could grow quickly and show normal reproductive traits (i.e., the timing of sexual differentiation or maturity, the reproductive rhythm, the number of broods all through its lifespan and offspring production) in temperature between 15-30℃. Therefore, the temperature variation in the lagoon water should not account for the sharp variation of A. valida population by affecting the survival, growth and reproduction of the amphipod. However, negative correlation between water temperature and U. lactuca biomass in the lagoon suggested that temperature could have indirectly affected the population dynamics of A. valida by affecting its food availability. The authors conclude that, in the Yundang Lagoon, the population dynamics of A. valida was mainly controlled by the food availability rather than water temperature.
Year-round investigations were carried out to address the population dynamics of amphipod Ampithoe valida and its potential regulating factors in the Yundang Lagoon (a eutrophic subtropical coastal lagoon in Xiamen City, China) from October 2007 to October 2008. The results show that A. valida population was largely composed of juveniles and reached a peak abundance (12.02×103 ind./m2) in March, but sharply shrunk in July. The monthly variation pattern of A. valida seemed to follow that of Ulva lactuca which is the main food resource for A. valida, indicating a strong influence of food availability on A. valida population dynamics. Life cycle studies in laboratory indicate that A. valida adopted an r-selected life strategy, e.g., rapid growth rate (0.216-0.302 mm/d), consecutive breeding (4-10 times), short reproductive rhythm (9-17 d) and huge fecundity (24-192 eggs or 6-94 juveniles per brood), which contributed to the fast population growth of A. valida from January to March. Although temperature may also be a significant cause, A. valida could grow quickly and show normal reproductive traits (i.e., the timing of sexual differentiation or maturity, the reproductive rhythm, the number of broods all through its lifespan and offspring production) in temperature between 15-30℃. Therefore, the temperature variation in the lagoon water should not account for the sharp variation of A. valida population by affecting the survival, growth and reproduction of the amphipod. However, negative correlation between water temperature and U. lactuca biomass in the lagoon suggested that temperature could have indirectly affected the population dynamics of A. valida by affecting its food availability. The authors conclude that, in the Yundang Lagoon, the population dynamics of A. valida was mainly controlled by the food availability rather than water temperature.
2013, 32(6): 66-74.
doi: 10.1007/s13131-013-0271-y
Abstract:
Planktonic bacteria are abundant in the Chukchi Borderland region. However, little is known about their diversity and the roles of various bacteria in the ocean. Seawater samples were collected from two stations K2S and K4S where sea ice was melting obviously. The analysis of water samples with fluorescence in situ hybridization (FISH) showed that DMSP-degrading bacteria accounted for 13% of the total bacteria at the station K2S. No aerobic anoxygenic phototrophic (AAP) bacteria were detected in both samples. The bacterial communities were characterized by two 16S rRNA gene clone libraries. Sequences fell into four major lineages of the domain Bacteria, including Proteobacteria (Alpha, Beta and Gamma subclasses), Bacteroidetes, Actinobacteria and Firmicutes. No significant difference was found between the two clone libraries. SAR11 and Rhodobacteraceae clades of Alphaproteobacteria and Pseudoalteromonas of Gammaproteobacteria constituted three dominant fractions in the clone libraries. A total of 191 heterotrophic bacterial strains were isolated and 76% showed extracellular proteolytic activity. Phylogenetic analysis reveals that the isolates fell into Gammaproteobacteria,Bacteroidetes, Actinobacteria and Firmicutes. The most common genus in both the bacterial isolates and protease-producing bacteria was Pseudoalteromonas. UniFrac data showed suggestive differences in bacterial communities between the Chukchi Borderland and the northern Bering Sea.
Planktonic bacteria are abundant in the Chukchi Borderland region. However, little is known about their diversity and the roles of various bacteria in the ocean. Seawater samples were collected from two stations K2S and K4S where sea ice was melting obviously. The analysis of water samples with fluorescence in situ hybridization (FISH) showed that DMSP-degrading bacteria accounted for 13% of the total bacteria at the station K2S. No aerobic anoxygenic phototrophic (AAP) bacteria were detected in both samples. The bacterial communities were characterized by two 16S rRNA gene clone libraries. Sequences fell into four major lineages of the domain Bacteria, including Proteobacteria (Alpha, Beta and Gamma subclasses), Bacteroidetes, Actinobacteria and Firmicutes. No significant difference was found between the two clone libraries. SAR11 and Rhodobacteraceae clades of Alphaproteobacteria and Pseudoalteromonas of Gammaproteobacteria constituted three dominant fractions in the clone libraries. A total of 191 heterotrophic bacterial strains were isolated and 76% showed extracellular proteolytic activity. Phylogenetic analysis reveals that the isolates fell into Gammaproteobacteria,Bacteroidetes, Actinobacteria and Firmicutes. The most common genus in both the bacterial isolates and protease-producing bacteria was Pseudoalteromonas. UniFrac data showed suggestive differences in bacterial communities between the Chukchi Borderland and the northern Bering Sea.
2013, 32(6): 75-81.
doi: 10.1007/s13131-013-0323-3
Abstract:
Members of Thermococcales are organoheterotrophic hyperthermophilic anaerobes consisting of three genera, Thermococcus, Pyrococcus, and Palaeococcus, among which Thermococcus are the most frequently isolated. In this study, a variety of Thermococcales strains were isolated from the Guaymas Basin hydrothermal vents under different temperatures and pressures. Based on their 16S rRNA gene sequences, all the strains isolated from 85℃ or 95℃ enrichment cultures at ambient pressure were classified as Thermococcus, while strains isolated from 108℃-30MPa enrichment cultures belonged to Pyrococcus. The combination of high pressure and high temperature for enrichment was shown to be an efficient method for isolating Pyrococcus strains. Through selecting and analyzing with multiple molecular phylogenetic markers, the isolated Thermococcales strains were found quite diversified including several putative novel species. This demonstrates a vast genetic reservoir of Thermoccoccales in the deep-sea hydrothermal vents, and a fast evolving of the Thermococcales species adapting to the fast changing environment.
Members of Thermococcales are organoheterotrophic hyperthermophilic anaerobes consisting of three genera, Thermococcus, Pyrococcus, and Palaeococcus, among which Thermococcus are the most frequently isolated. In this study, a variety of Thermococcales strains were isolated from the Guaymas Basin hydrothermal vents under different temperatures and pressures. Based on their 16S rRNA gene sequences, all the strains isolated from 85℃ or 95℃ enrichment cultures at ambient pressure were classified as Thermococcus, while strains isolated from 108℃-30MPa enrichment cultures belonged to Pyrococcus. The combination of high pressure and high temperature for enrichment was shown to be an efficient method for isolating Pyrococcus strains. Through selecting and analyzing with multiple molecular phylogenetic markers, the isolated Thermococcales strains were found quite diversified including several putative novel species. This demonstrates a vast genetic reservoir of Thermoccoccales in the deep-sea hydrothermal vents, and a fast evolving of the Thermococcales species adapting to the fast changing environment.
2013, 32(6): 82-88.
doi: 10.1007/s13131-013-0324-2
Abstract:
To verify the feasibility of high-affinity nitrate transporter gene (Nrt2) as an indicator of nitrogen status, changes in the transcript levels of transcripts associated with phosphate starvation and different nitrate concentrations were studied using real-time quantitative reverse-transcription PCR (QRT-PCR) technology in batch cultures of Skeletonema costatum. The results show that compared with P-replete condition, P starvation could reduce the Nrt2 transcript levels apparently. Nrt2 transcript levels had a significant negative linear correlation with nitrate concentrations below 40 μmol/L. The results of 48 h short-term incubation experiment under different nitrate concentrations confirmed this correlation, and the following regression equation is built:y=-3.305x+98.95, R2=0.988, where x represents nitrate concentrations (<40 μmol/L) and y represents the Nrt2 transcript levels.
To verify the feasibility of high-affinity nitrate transporter gene (Nrt2) as an indicator of nitrogen status, changes in the transcript levels of transcripts associated with phosphate starvation and different nitrate concentrations were studied using real-time quantitative reverse-transcription PCR (QRT-PCR) technology in batch cultures of Skeletonema costatum. The results show that compared with P-replete condition, P starvation could reduce the Nrt2 transcript levels apparently. Nrt2 transcript levels had a significant negative linear correlation with nitrate concentrations below 40 μmol/L. The results of 48 h short-term incubation experiment under different nitrate concentrations confirmed this correlation, and the following regression equation is built:y=-3.305x+98.95, R2=0.988, where x represents nitrate concentrations (<40 μmol/L) and y represents the Nrt2 transcript levels.
