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Physical structure and vertical distribution of chlorophyll a in winter sea ice from the northwestern Weddell Sea, Antarctica
DAI Fangfang, WANG Zipan, YAN Xiaojun, LI Zhijun, ALLHUSEN Erika, DIECKMANN Gerhard
2010(3): 97-105. doi: 10.1007/s13131-010-0041-z
Keywords: physical structure, chlorophyll a, Antarctica, winter sea-ice
The investigation on sea-ice biology in combination with physics, chemistry and ecology was carried out in the northwestern Weddell Sea, Antarctica, during the cruise ANT/XX Ⅲ-7 on board POLARSTERN in the austral winter (August-October) in 2006. The distribution of chlorophyll a was measured and related to sea ice texture. The mean concentrations of chlorophyll a in the sea ice varied considerably with ice texture. The concentration of chlorophyll a per core ranged from 2.10-84.40 μg/dm3 with a mean of 16.56 μg/dm3. And the value of R (chlorophyll a/gross chlorophyll) ranged from 0.79-0.83. These high winter chlorophyll values indicate that primary production is considerable and confirms that there is significant primary production in Antarctic sea ice during winter. Thus this constitutes a major proportion of southern ocean primary production and carbon flux before the sea ice retreats.
Phylogenetic diversity of Type I polyketide synthase genes from sediments of Ardley Island in Antarctica
ZHAO Jing, YANG Ning, CHEN Xinglin, JIANG Qingru, ZENG Runying
2011(6): 104-111. doi: 10.1007/s13131-011-0167-7
Keywords: polyketide synthase, diversity, Antarctica
The diversity of modular polyketide synthase (PKS) genes in sediments of Ardley Island in Antarctica, was studied by restriction fragment length polymorphism (RFLP) analysis. Phylogenetic analysis of 14 amino acid (AA) sequences indicates that the identified ketosynthase (KS) domains were clustered with those from diverse bacterial groups, including Cyanobacteria, γ-Proteobacteria, Actinobacteria, Firmicutes, and some unidentified microorganisms from marine sponge, bryozoan and other environmental samples. The obtained KS domains showed 43%-81% similarity at the AA level to reference sequences in GenBank. Six identified KS domains showed diverse sequences of the motif (VQTACSTS) that was used to identify the hybrid PKS/nonribosomal peptide synthetase (NRPS) enzyme complex, and formed a new branch. These results reveal a high diversity and novelty of PKS genes in antarctic sediments.
Macrobenthic communities on the continental shelf of the Prydz Bay, East Antarctica
Kun Liu, Heshan Lin, Xuebao He, Yaqin Huang, Zhong Li, Junhui Lin, Jianfeng Mou, Shuyi Zhang, Jianjun Wang, Jun Sun
2020, 39(2): 38-48. doi: 10.1007/s13131-018-1280-7  Published:2020-02-25
Keywords: macrobenthic communities, functional feeding groups, environmental factors, Antarctica, Prydz Bay
To explore the spatial pattern of macrobenthic communities and their response to environmental factors in the Prydz Bay, samples were collected using a 0.25-m2 box corer at 10 stations from November 2012 to April 2013. A total of 50 species of macrobenthos belonging to 8 phyla and 33 families were identified, of which polychaetes (e.g., Maldane sarsi) and sponges (e.g., Halichondria sp. and Leucosolenia sp.) were the most prominent groups. The macrobenthos in study area were categorized into five functional groups based on the feeding type, and the detritivorous group represented by polychaetes showed the highest average abundance, while the planktophagous group represented by sponges showed the highest average biomass. Macrobenthos abundance (0–592 ind./m2) and biomass (0–1 155.5 g/m2) in the Prydz Bay were relatively lower than those of other Antarctic shelf soft-bottom waters, although the compositions of the dominant species and functional feeding groups were similar. The results of the Spearman rank correlation analysis indicated that the average biomass of the macrobenthos and the biomass of the planktophagous group in the study area were negatively correlated with the water depth, sediment grain size and silt percentage. However, these variables were clearly not strong determinants of macrobenthos assemblage structure. Many factors not measured in the study, e.g., sediment organic matter and iceberg interference, have probably influenced the spatial distribution of macrobenthic community structure in the Prydz Bay.
Nitrogen uptake regime regulated by ice melting during austral summer in the Prydz Bay, Antarctica
Zhang Run, Ma Qiang, Chen Min, Zheng Minfang, Cao Jianping, Qiu Yusheng
2019, 38(8): 1-7. doi: 10.1007/s13131-019-1434-2
Keywords: nitrogen uptake regime, ice melting, Prydz Bay, Antarctica
Using a combination of stable isotope (15N) and radionuclide (226Ra) analyses, we examine possible controls on the interactions between melting ice and the uptake of nitrogen in the Prydz Bay during the 2006 austral summer. We find that specific rates of uptake for nitrate and ammonium correlate positively to their concentrations, thus suggesting a substrate effect. In the study area, we observe that regions along open, oceanic water have high f-ratios (nitrate uptake/nitrate+ammonium uptake), while areas near the Amery Ice Shelf have significantly low f-ratios. Further analysis reveals a negative correlation between the f-ratio and the melt water fraction, thus implying that the melting of ice plays an essential role in regulating pelagic N dynamics in the Southern Ocean (SO). Stratification, produced by melting ice, should profoundly affect the efficiency of the SO’s biological pump and consequently affect the concentration of CO2 in the atmosphere. Results presented in this study add information to an already significant base of understanding of the controls on pelagic C and N dynamics in the SO. This provides unique insights for either interpreting past changes in geologic records or for predicting future climate change trends.
Distribution of dissolved organic carbon in and near the Prydz Bay, Antarctica
Qiu Yusheng, Chen Min, Huang Yipu, Liu Guangshan
2003(4): 547-556.
Keywords: The Prydz Bay, Antarctica, dissolved organic carbon
During the 16th Chinese National Antarctic Research Expedition(CHINARE)(from November 1999 to April 2000) seawater samples were collected for(DOC) determination in the Prydz Bay and its nearby sea areas.DOC concentrations were determined by high temperature catalytic oxidation(HTCO) method.The results shows that DOC concentrations in the upper water column(0~100 m) range from 14.3 to 181.1 μmol/dm3,with averaging 52.5 μ mol/dm3(n=55).These values are slightly higher than those reported for the Ross Sea,the Pacific Ocean and others.Profiles of DOC concentration in the study areas show a decreasing concentration with increasing depth in the upper 100 m,which is related to biological activities in the water column.DOC concentrations below 100 m are relatively constant with a mean of 40.4 μmol/dm3.These DOC are unactive for physical and biological activities and are called refractory DOC.Concentration of the refractory DOC in the study area is consistent with the previous reported values for the Southern Ocean,which is about 41 μmol/dm3.Based on the difference between the measured DOC concentration and the refractory concentration,the excess DOC concentration in the upper column can be calculated at every station.The excess DOC shows a spatial variability with a higher excess in the north of 64°S and little excess in the south of 64°S.In conclusion,DOC concentrations in the Prydz Bay and its nearby sea areas are consistent with the previous reported values in the Southern Ocean,which show a low DOC concentration with respect to the other oceans.Distribution of surface DOC concentrations in the study areas shows an increase from the southwestern to the northeastern,which is ascribed to the northern spread of continental shelf water from the Prydz Bay in summer.Contents of DOC and their distribution in the Prydz Bay and its nearby sea areas are mainly controlled by physical and biological processes.
Sea ice characteristics between the middle Weddell Sea and the Prydz Bay, Antarctica during the austral summer of 2003
TANG Shulin, KANG Jiancheng, ZHOU Shangzhe, LI Zhijun
2005(2): 9-15.
Keywords: Antarctica, sea ice, characteristics
The antarctic sea ice was investigated upon five occasions between January 4 and February 15, 2003. The investigations included:(1)estimation of sea ice distribution by ship-based observations between the middle Weddell Sea and the Prydz Bay; (2) estimation of sea ice distribution by aerial photography in the Prydz Bay; (3) direct measurements of fast ice thickness and snow cover, as well as ice core sampling in Nella Fjord; (4) estimation of melting sea ice distribution near the Zhongshan Station; and (5) observation of sea ice early freeze near the Zhongshan Station. On average, sea ice covered 14.4% of the study area. The highest sea ice concentration (80%)was observed in the Weddell Sea. First-year ice was dominant (99.7%~99.8%). Sea ice distributions in the Prydz Bay were more variable due to complex inshore topography, proximity of the Larsemann Hills, and/or grounded icebergs. The average thickness of landfast ice in Nella Fjord was 169.5 cm. Wind-blown snow redistribution plays an important role in affecting the ice thickness in Nella Fjord. Preliminary freezing of sea ice near the Zhongshan Station follows the first two phases of the pancake cycle.
Community succession of zooplankton in marine derived saline lakes in antarctic continental margin
Wang Zipan, D. Eslake
1997(1): 109-119.
Keywords: Zooplankton, community succession, saline lake, Antarctica
Ecological research has been made for quite a long period in some marine-derived saline lakes in the Vestfold Hills,Antarctica.The results show distinct succession of zooplankton community in those lakes.The change in community structure of zooplankton is related directly to environmental evolution in nature and the variation of lake conditions,such as physical and chemical factors as well.In the Burton Lake,there is a rather stable annual fluctuation in both temperature and salinity,and the community has probably been in the stage of climax succession.The Fletcher Lake is still undergoing a process by unregular tide flood from nearby bay,so that zooplankton community has been changing due to variance in temperature and salinity.
THE HETEROTROPHIC MICROBES IN DRY VALLEYS VICTORIA LAND AND ROSS ISLAND, ANTARCTICA
NI CHUNZHI, LIN YANSHUN, ZHOU ZONGCHENG, YE DEZAN, ZENG HUOSHUI, LI ZHITANG, LIANG ZIYUAN, ZHANG NANFENG
1987(2): 273-280.
During the expedition from Dec. 1981 to Feb. 1982, Dry Valley, Victoria and Ross Island Beach in Antarctica were visited. From ten stations samples of water, soil, snows and seawater were collected, from which heterotrophic microbes (including bacteria, yeast and fungi) were isolated and identified. Results show that there are ten genera of bacteria, nine genera of yeast and nine genera of fungi. Most of the strains grow at the temperatures of 20℃ and 5℃, while a few grow only below 5℃. More bacterial genera were isolated from the beach and nearby lakes than those from the inland Dry Valley, indicating the relations between the strain composition and geographical location and environmental conditions of the polar zone.
Modelling the annual cycle of landfast ice near Zhongshan Station, East Antarctica
Jiechen Zhao, Tao Yang, Qi Shu, Hui Shen, Zhongxiang Tian, Guanghua Hao, Biao Zhao
2021, 40(7): 129-141. doi: 10.1007/s13131-021-1727-0  Published:2021-07-25
Keywords: landfast ice, annual cycle, snow influence, Zhongshan Station, East Antarctica
A high resolution one-dimensional thermodynamic snow and ice (HIGHTSI) model was used to model the annual cycle of landfast ice mass and heat balance near Zhongshan Station, East Antarctica. The model was forced and initialized by meteorological and sea ice in situ observations from April 2015 to April 2016. HIGHTSI produced a reasonable snow and ice evolution in the validation experiments, with a negligible mean ice thickness bias of (0.003±0.06) m compared to in situ observations. To further examine the impact of different snow conditions on annual evolution of first-year ice (FYI), four sensitivity experiments with different precipitation schemes (0, half, normal, and double) were performed. The results showed that compared to the snow-free case, the insulation effect of snow cover decreased bottom freezing in the winter, leading to 15%–26% reduction of maximum ice thickness. Thick snow cover caused negative freeboard and flooding, and then snow ice formation, which contributed 12%–49% to the maximum ice thickness. In early summer, snow cover delayed the onset of ice melting for about one month, while the melting of snow cover led to the formation of superimposed ice, accounting for 5%–10% of the ice thickness. Internal ice melting was a significant contributor in summer whether snow cover existed or not, accounting for 35%–56% of the total summer ice loss. The multi-year ice (MYI) simulations suggested that when snow-covered ice persisted from FYI to the 10th MYI, winter congelation ice percentage decreased from 80% to 44% (snow ice and superimposed ice increased), while the contribution of internal ice melting in the summer decreased from 45% to 5% (bottom ice melting dominated).
Upper limits for chlorophyll a changes with brine volume in sea ice during the austral spring in the Weddell Sea, Antarctica
LI Zhijun, LI Runling, WANG Zipan, HAAS Christian, DIECKMANN Gerhard
2016, 35(2): 68-75. doi: 10.1007/s13131-015-0740-6
Keywords: Antarctic, brine volume, chlorophyll a, ice crystal, mode, sea ice
During the winter and spring of 2006, we investigated the sea ice physics and marine biology in the northwest Weddell Sea, Antarctica aboard R/V Polarstern. We determined the texture of each ice core and 71 ice crystal thin sections from 27 ice cores. We analyzed 393 ice cores, their temperatures, 348 block density and salinity samples, and 311 chlorophyll a (Chl a) and phaeophytin samples along the cruise route during the investigation. Based on the vertical distributions of 302 groups of data for the ice porosity and Chl a content in the ice at the same position, we obtained new evidence that ice physical parameters influence the Chl a content in ice. We collected snow and ice thickness data, and established the effects of the snow and ice thickness on the Chl a blooms under the ice, as well as the relationships between the activity of ice algae cells and the brine volume in ice according to the principle of environmental control of the ecological balance. We determined the upper limits for Chl a in the brine volume of granular and columnar ice in the Antarctica, thereby demonstrating the effects of ice crystals on brine drainage, and the contributions of the physical properties of sea ice to Chl a blooms near the ice bottom and on the ice-water interface in the austral spring. Moreover, we found that the physical properties of sea ice affect ice algae and they are key control elements that modulate marine phytoplankton blooms in the ice-covered waters around Antarctica.
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