2015 Vol. 34, No. 10

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Marine Chemistry
Investigation of seasonal variability of CDOM fluorescence in the southern Changjiang River Estuary by EEM-PARAFAC
BAI Ying, SU Rongguo, HAN Xiurong, ZHANG Chuansong, SHI Xiaoyong
2015, 34(10): 1-12. doi: 10.1007/s13131-015-0714-8
The southern Changjiang River Estuary has attracted considerable attention from marine scientists because it is a highly biologically active area and is biogeochemically significant. Moreover, land-ocean interactions strongly impact the estuary, and harmful algal blooms (HABs) frequently occur in the area. In October 2010 and May 2011, water samples of chromophoric dissolved organic matter (CDOM) were collected from the southern Changjiang River Estuary. Parallel factor analysis (PARAFAC) was used to assess the samples' CDOM composition using excitation-emission matrix (EEM) spectroscopy. Four components were identified: three were humic-like (C1, C2 and C3) and one was protein-like (C4). Analysis based on spatial and seasonal distributions, as well as relationships with salinity, Chl a and apparent oxygen utilization (AOU), revealed that terrestrial inputs had the most significant effect on the three humic-like Components C1, C2 and C3 in autumn. In spring, microbial processes and phytoplankton blooms were also important factors that impacted the three components. The protein-like Component C4 had autochthonous and allochthonous origins and likely represented a biologically labile component. CDOM in the southern Changjiang River Estuary was mostly affected by terrestrial inputs. Microbial processes and phytoplankton blooms were also important sources of CDOM, especially in spring. The fluorescence intensities of the four components were significantly higher in spring than in autumn. On average, C1, C2, C3, C4 and the total fluorescence intensity (TFI) in the surface, middle and bottom layers increased by 123%-242%, 105%-195%, 167%-665%, 483%-567% and 184%-245% in spring than in autumn, respectively. This finding corresponded with a Chl a concentration that was 16-20 times higher in spring than in autumn and an AOU that was two to four times lower in spring than in autumn. The humification index (HIX) was lower in spring that in autumn, and the fluorescence index (FI) was higher in spring than in autumn. This result indicated that the CDOM was labile and the biological activity was intense in spring.
Burial fluxes and sources of organic carbon in sediments of the central Yellow Sea mud area over the past 200 years
YANG Shu, YANG Qian, LIU Sai, CAI Deling, QU Keming, SUN Yao
2015, 34(10): 13-22. doi: 10.1007/s13131-015-0723-7
Long-term changes of composition, sources and burial fluxes of TOC (total organic carbon) in sediments of the central Yellow Sea mud area and their possible affecting factors are discussed in this paper. Firstly, similarity analysis is employed to confirm that the carbon burial features resulted from two collected cores are typical in the central Yellow Sea mud area where YSWC (Yellow Sea Warm Current) is prevalent. On this basis, the burial flux of TOC here was considered to be 235.5-488.4 μmol/(cm2·a) since the first industrial revolution, accounting for about 70%-90% among burial fluxes of TC (total carbon) in the sediments. Compared TOC/TC ratio in the two cores with that in other marine sediments worldwide, we suggest that the growth of calcareous/non-calcareous organisms and dissolution of IC (inorganic carbon) are important factors controlling the TOC/TC ratio in sediment. Results of two-end mixed model based on δ13C data indicate that marine-derived organic carbon (OCa) is the main part among total burial organic carbon which accounts for a ratio over 85%. Due to the high TOC/TC ratio in the two cores, TC in the sediments also mainly exists as OCa, and the proportion of OCa is about 60%-80%. Away from the shore and relatively high primary production in upper waters are the main reasons that OCa is predominant among all burial OC in sediments of the central Yellow Sea mud area. Burial of OC in this mud area is probably mainly influenced by the human activities. Although the economic development during the late 19th century caused by the first industrial revolution in China did not obviously increase the TOC burial fluxes in the sediments, the rise of industry and agriculture after the founding of new China has clearly increased the TOC burial flux since 1950s. Otherwise, we also realize that among TC burial fluxes, TIC account for about 10%-30% in sediments of the central Yellow Sea mud area, so its burial could not be simply ignored here. Distinct from TOC burial, long-term TIC burial fluxes variations relate with climate changes more closely: the East Asian summer monsoon may influence the strength of the Huanghe River (Yellow River) flood, which could further affect the transport of terrestrial IC from land to the central Yellow Sea as well as the burial of these IC in the sediments.
Burial fluxes and source apportionment of carbon in culture areas of Sanggou Bay over the past 200 years
LIU Sai, HUANG Jiansheng, YANG Qian, YANG Shu, YANG Guipeng, SUN Yao
2015, 34(10): 23-30. doi: 10.1007/s13131-015-0724-6
In this study, we assessed the burial fluxes and source appointment of different forms of carbon in core sediments collected from culture areas in the Sanggou Bay, and preliminarily analyzed the reasons for the greater proportion of inorganic carbon burial fluxes (BFTIC). The average content of total carbon (TC) in the Sanggou Bay was 2.14%. Total organic carbon (TOC) accounted for a small proportion in TC, more than 65% of which derived from terrigenous organic carbon (Ct), and while the proportion of marine-derived organic carbon (Ca) increased a significantly since the beginning of large-scale aquaculture. Total inorganic carbon (TIC) accounted for 60%-75% of TC, an average of which was 60%, with a maximum up to 90% during flourishing periods (1880-1948) of small natural shellfish derived from seashells inorganic carbon (Shell-IC). The TC burial fluxes ranged from 31 g/(m2·a) to 895 g/(m2·a) with an average of 227 g/(m2·a), which was dominated by TIC (about 70%). Shell-IC was the main source of TIC and even TC. As the main food of natural shellfish, biogenic silica (BSi) negatively correlated with BFTIC through affecting shellfish breeding. BFTIC of Sta. S1, influenced greatly by the Yellow Sea Coastal Current, had a certain response to Pacific Decadal Oscillation (PDO) in some specific periods.
Measurement of 129I in ferromanganese crust with AMS
JI Lihong, LIU Guangshan, CHEN Zhigang, HUANG Yipu, XING Na, JIANG Shan, HE Ming
2015, 34(10): 31-35. doi: 10.1007/s13131-015-0718-4
In the present study, the analytical method for 129iodine (129I) in ferromanganese crusts is developed and 129iodine/127iodine (129I/127I) ratio in ferromanganese crusts is measured by the accelerator mass spectrometry (AMS). The developed method is applied to analyze 129I/127I ratio in two ferromanganese crusts MP5D44 and CXD08-1 collected from the Mid-Pacific Ocean. The results show that 129I/127I ratio in MP5D44 and CXD08-1 crusts varies from 7×10-14 to 1.27×10-12, with the lowest value falling on the detection limit level of AMS reported by previous literatures. For the depth distribution of 129I/127I, it is found that both MP5D44 and CXD08-1 crusts have two growth generations, and the 129I/127I profiles in two generations all displayed an approximate exponential decay. According to the 129I/127I ratio, the generate age of bottom layer of MP5D44 and CXD08-1 was estimated to be 54.77 and 69.69 Ma, respectively.
Marine Geology
Heavy metals in suspended matters during a tidal cycle in the turbidity maximum around the Changjiang (Yangtze) Estuary
ZHANG Huaijing, ZHAI Shikui, ZHANG Aibin, ZHOU Yonghua, YU Zenghui
2015, 34(10): 36-45. doi: 10.1007/s13131-015-0675-y
In order to discuss the content distributions and fluxes of heavy metals in suspended matters during a tidal cycle in the turbidity maximum around the Changjiang (Yangtze) Estuary, the contents of heavy metals (Zn, Pb, Cd, Co and Ni) have been analyzed. During a tidal cycle, the average contents of heavy metals are in the order of Zn >Ni >Pb >Co >>Cd. The average contents in ebb tide are generally higher than that in flood tide. However, at the inshore Sta. 11, influenced by the contamination from the nearby waste treatment plant, the average contents of Zn and Ni in flood tide are higher than those in ebb tide and at the offshore Sta. 10, the content of Cd in flood tide higher than that in ebb tide due to marine-derived materials. The five heavy metals, mainly terrigenous, are transported towards east-northeast, and settle down with suspended matters in the area between Sta. 11 and Sta. 10. Influenced by marine-derived materials, the flux value of Cd does not alter significantly with obviously changing in flux direction towards northwest. The source of heavy metals, the salinity of water and the concentration of suspended matters are the main factors controlling the content distributions of heavy metals during a tidal cycle. There is a positive correlation between the contents of heavy metals (Zn, Pb, Co and Ni) and the salinity of water, while the opposite correlation between the contents and the concentrations of suspended matters. Because of marine-derived materials, the content of Cd is not correlated with the concentration of suspended matters and the salinity of water.
Grain size composition and transport of sedimentary organic carbon in the Changjiang River (Yangtze River) Estuary and Hangzhou Bay and their adjacent waters
ZHANG Weiyan, JIN Haiyan, YAO Xuying, JI Zhongqiang, ZHANG Xiaoyu, YU Xiaoguo, ZHANG Fuyuan, GAO Aigen
2015, 34(10): 46-56. doi: 10.1007/s13131-015-0711-y
Surface sediments from the Changjiang River (Yangtze River) Estuary, Hangzhou Bay, and their adjacent waters were analyzed for their grain size distribution, organic carbon (OC) concentration, and stable carbon isotope composition (δ13C). Based on this analysis, about 36 surface sediment samples were selected from various environments and separated into sand (>0.250 mm, 0.125-0.250 mm, 0.063-0.125 mm) and silt (0.025-0.063 mm) fractions by wet-sieving fractionation methods, and further into silt- (0.004-0.025 mm) and clay-sized (<0.004 mm) fractions by centrifugal fractionation. Sediments of six grain size categories were analyzed for their OC and δ13C contents to explore the grain size composition and transport paths of sedimentary OC in the study area. From fine to coarse fractions, the OC content was 1.18%, 0.51%, 0.46%, 0.42%, 0.99%, and 0.48%, respectively, while the δ13C was -21.64‰, -22.03‰, -22.52‰, -22.46‰, -22.36‰, and -22.28‰, respectively. In each size category, the OC contribution was 42.96%, 26.06%, 9.82%, 5.75%, 7.09%, and 8.33%, respectively. The OC content in clay and fine silt fractions (<0.025 mm) was about 69.02%. High OC concentrations were mainly found in offshore modern sediments in the northeast of the Changjiang River Estuary, in modern sediments in the lower estuary of the Changjiang River and Hangzhou Bay, and in Cyclonic Eddy modern sediments to the southwest of the Cheju Island. Integrating the distribution of terrestrial OC content of each grain size category with the δ13C of the bulk sediment indicated that the terrestrial organic material in the Changjiang River Estuary was transported seaward and dispersed to the Cyclonic Eddy modern sediments to the southwest of the Cheju Island via two pathways: one was a result of the Changjiang River Diluted Water (CDW) northeastward extending branch driven by the North Jiangsu Coastal Current and the Yellow Sea Coastal Current, while the other one was the result of the CDW southward extending branch driven by the Taiwan Warm Current.
Natural Gas Geology and Accumulation Mechanism in Deep-water Area, Northern South China Sea
Geology and hydrocarbon accumulations in the deepwater of the northwestern South China Sea—with focus on natural gas
WANG Zhenfeng, SUN Zhipeng, ZHANG Daojun, ZHU Jitian, LI Xushen, HUANG Baojia, GUO Minggang, JIANG Rufeng
2015, 34(10): 57-70. doi: 10.1007/s13131-015-0715-7
vThe deepwater of the northwestern South China Sea is located in the central to southern parts of the Qiongdongnan Basin (QDN Basin), which is a key site for hydrocarbon exploration in recent years. In this study, the authors did a comprehensive analysis of gravity-magnetic data, extensive 3D seismic survey, cores and cuttings, paleontology and geochemical indexes, proposed the mechanism of natural gas origin, identified different oil and gas systems, and established the model of hydrocarbon accumulations in the deep-water region. Our basin tectonic simulation indicates that the evolution of QDN Basin was controlled by multiple-phased tectonic movements, such as Indochina-Eurasian Plate collision, Tibetan Uplift, Red River faulting and the expansion of the South China Sea which is characterized by Paleogene rifting, Neogene depression, and Eocene intensive faulting and lacustrine deposits. The drilling results show that this region is dominated by marine-terrestrial transitional and neritic-bathyal facies from the early Oligocene. The Yacheng Formation of the early Oligocene is rich in organic matter and a main gas-source rock. According to the geological-geochemical data from the latest drilling wells, Lingshui, Baodao, Changchang Sags have good hydrocarbon-generating potentials, where two plays from the Paleogene and Neogene reservoirs were developed. Those reservoirs occur in central canyon structural-lithologic trap zone, Changchang marginal trap zone and southern fault terrace of Baodao Sag. Among them, the central canyon trap zone has a great potential for exploration because the various reservoir-forming elements are well developed, i.e., good coal-measure source rocks, sufficient reservoirs from the Neogene turbidity sandstone and submarine fan, faults connecting source rock and reservoirs, effective vertical migration, late stage aggregation and favorable structural-lithological composite trapping. These study results provide an important scientific basis for hydrocarbon exploration in this region, evidenced by the recent discovery of the significant commercial LS-A gas field in the central canyon of the Lingshui Sag.
Characteristics and distribution patterns of reef complexes on the carbonate platform margin in deep water areas: the western South China Sea
CHEN Ping, LI Xushen, WANG Yahui, LU Yongchao, ZHONG Zehong, CHEN Lei, ZUO Qianmei, MA Yiquan, WANG Chao, DU Xuebin
2015, 34(10): 71-80. doi: 10.1007/s13131-015-0716-6
As a potential oil and gas reservoir, reef complexes have been a research focus from petroleum geologists for a long time. There are favorable conditions for the development of reef complexes in the South China Sea; however, their internal structures, evolution and distribution are still poorly understood. Based on 2D and 3D seismic data, the internal structures and evolution patterns of the reef complexes on the carbonate platform margin in the deep water areas over the western South China Sea were studied in detail. The result shows that two types of reef complexes, i.e., fault controlling platform margin reef complexes and ramp reef complexes have been developed in the study area. The reef complexes have independent or continuous mound or lenticular seismic reflections, with three internal structures (i.e., aggrading, prograding and retrograding structures). There are different growth rates during the evolution of the reef complexes, resulting in the formation of catch-up reefs, keep-up reefs and quick step reefs. The study also reveals that different platform margin reef complexes have different internal structures and distributions, because of the different platform types. These results may be applied to the exploration and prediction of carbonate platform margin reef complexes in other areas that are similar to the study area.
Difference in full-filled time and its controlling factors in the Central Canyon of the Qiongdongnan Basin
SHANG Zhilei, XIE Xinong, LI Xushen, ZHANG Daojun, HE Yunlong, YANG Xing, CUI Mingzhe
2015, 34(10): 81-89. doi: 10.1007/s13131-015-0717-5
Based on the interpretation of high resolution 2D/3D seismic data, sedimentary filling characteristics and full-filled time of the Central Canyon in different segments in the Qiongdongnan Basin of northwestern South China Sea have been studied. The research results indicate that the initial formation age of the Central Canyon is traced back to 11.6 Ma (T40), at which the canyon began to develop due to the scouring of turbidity currents from west to east. During the period of 11.6-8.2 Ma (T40-T31), strong downcutting by gravity flow occurred, which led to the formation of the canyon. The canyon fillings began to form since 8.2 Ma (T31) and were dominated by turbidite deposits, which constituted of lateral migration and vertical superposition of turbidity channels during the time of 8.2-5.5 Ma. The interbeds of turbidity currents deposits and mass transport deposits (MTDs) were developed in the period of 5.5-3.8 Ma (T30-T28). After then, the canyon fillings were primarily made up of large scale MTDs, interrupted by small scale turbidity channels and thin pelagic mudstones. The Central Canyon can be divided into three types according to the main controlling factors, geomorphology-controlled, fault-controlled and intrusion-modified canyons. Among them, the geomorphology-controlled canyon is developed at the Ledong, Lingshui, Songnan and western Baodao Depressions, situated in a confined basin center between the northern slope and the South Uplift Belt along the Central Depression Belt. The fault-controlled canyon is developed mainly along the deep-seated faults in the Changchang Depression and eastern Baodao Depression. Intrusion-modified canyon is only occurred in the Songnan Low Uplift, which is still mainly controlled by geomorphology, the intrusion just modified seabed morphology. The full-filled time of the Central Canyon differs from west to east, displaying a tendency of being successively late eastward. The geomorphology-controlled canyon was completely filled before 3.8 Ma (T28), but that in intrusion-modified canyon was delayed to 2.4 Ma (T27) because of the uplifted southern canyon wall. To the Changchang Depression, the complete filling time was successively late eastward, and the canyon in eastern Changchang Depression is still not fully filled up to today. Difference in full-filled time in the Central Canyon is mainly governed by multiple sediment supplies and regional tectonic activities. Due to sufficient supply of turbidity currents and MTDs from west and north respectively, western segment of the Central Canyon is entirely filled up earlier. Owing to slower sediment supply rate, together with differential subsidence by deep-seated faults, the full-filled time of the canyon is put off eastwards gradually.
Marine Biology
Evaluation of reference genes for quantitative real-time PCR analysis of gene expression during early development processes of the tongue sole (Cynoglossus semilaevis)
MA Qian, ZHUANG Zhimeng, FENG Wenrong, LIU Shufang, TANG Qisheng
2015, 34(10): 90-97. doi: 10.1007/s13131-015-0725-5
Differential expression of genes is crucial to growth and development of fish. To select the appropriate genes for gene normalization during Cynoglossus semilaevis early developmental process, eight candidate reference genes (ACTB, B2M, EF1A, GADPH, RPL7, TUBA, UBCE and 18S) were tested for their adequacy by using quantitative real-time PCR. The results showed that the expression of all the examined genes exhibited tissue dependent variations in the mature C. semilaevis. EF1A was listed as the most stable reference among the 14 tissues by RefFinder. Furthermore, the recommended comprehensive ranking of the stability determined by RefFinder showed that 18S was the most stable gene during the early developmental stages (from oosphere to 90 days old) in this study. However, when divided the Ct value data of the above mentioned early developmental stages into two separate periods (embryo and post-hatching periods), TUBA and 18S represented the most stable references of these two developmental periods, respectively. Consequently, the reference gene should be carefully and accurately chosen even for studies of the same species at various developmental processes. The relevant data may help in selecting appropriate reference genes for mRNA expression analysis, and is of great value in the studies of fish growth and development.
Initiation of two ovarian cell lines from Fugu rubripes (Temminck et. Schlegel)
ZHENG Debin, ZHANG Bo, SONG Wenping, PAN Luqing, MA Chao, XIAO Guangxia
2015, 34(10): 98-102. doi: 10.1007/s13131-015-0727-3
The ovary is an excellent system for studying stem cell renewal and differentiation, which is under the control of ovarian somatic cells. In order to understand oogenesis in Fugu rubripes (Temminck et. Schlegel) as a marine fish model of aquaculture importance, we established cell lines called TSOC1 and TSOC2 from a juvenile ovary of this organism. TSOC1 is composed of spindle epithelial-like cells, while the other is cobblestone-like cells. Therefore, TSOC1 and TSOC2 appear to consist of ovarian somatic cells. Growth requirement condition was investigated including temperature, concentration of FBS and pH. Significant fluorescent signals were observed after TSOC1 and TSOC2 cells were transfected with pEGFP-N3 vector, indicating its potential utility for genetic manipulation such as gene function studies. It is shown that these cell lines are effective for infection by the turbot reddish body iridovirus and flounder lymphosystis disease virus as evidenced by the appearance of cytopathic effect and virus propagation in the virus-infected cells, and most convincingly, the observation of viral particles by electron microscopy, demonstrating that TSOC1 and TSOC2 are suitable to study interactions between virus and host cells. It is believed that TSOC1 and TSOC2 will be useful tools to study sex-related events and interactions between primordial germ cells and oogonia cells during oogenesis. Therefore, establishment of ovary cell lines from Fugu rubripes seems to be significant for those research areas.
Evaluation of the “fishing down marine food web” process in the north-west of Persian Gulf (Khuzestan Province) during the period of 2002-2011
2015, 34(10): 103-110. doi: 10.1007/s13131-015-0726-4
The worldwide increase in commercial fisheries and its impact on ecosystems as well as inefficient fishery management have led to overfishing and frequent breakdown of traditional fish stocks. In this context, an analysis of Khuzestan inshore fisheries data covering the years 2002-2011, was conducted in reliance on testing for occurrence of the fishing down marine food webs (FDMFW) phenomenon in the North of Persian Gulf Large Marine Ecosystem (LME). In this study, the mean trophic level (mTL) and the fishing-in-balance (FIB)-index of Khuzestan landings during this period of time were estimated using the trophic level of 47 fishery resources. Increase in total landings (Y) was observed, which explained the high fishing yield in major fishery resources (especially demersal). Moreover, the moderates decreasing trend in mTL per decade, and the increasing trend in FIB-index were observed. The status of fishery resources in Khuzestan inshore waters (under exploited but not overexploited), the rise in Y, FIB and slightly drop in mTL can be considered as indirect indicators of the fishing impacts on the trophic structure of marine communities. Based on this result, probability occurrence of FDMFW process in Khuzestan inshore waters is low to some extent. However, we suggest that the goal of management programs in Khuzestan inshore waters should prevent the continuance of this trend in the long-term using an ecosystem-based approach.
Assessing the benthic quality status of the Bohai Bay (China) with proposed modifications of M-AMBI
CAI Wenqian, BORJA Angel, LIN Kuixuan, ZHU Yanzhong, ZHOU Juan, LIU Lusan
2015, 34(10): 111-121. doi: 10.1007/s13131-015-0713-9
Multivariate AZTI's Marine Biotic Index (M-AMBI) was designed to indicate the ecological status of European coastal areas. Based upon samples collected from 2009 to 2012 in the Bohai Bay, we have tested the response of variations of M-AMBI, using biomass (M-BAMBI) in the calculations, with different transformations of the raw data. The results showed that the ecological quality of most areas in the study indicated by M-AMBI was from moderate to bad status with the worse status in the coastal areas, especially around the estuaries, harbors and outfalls, and better status in the offshore areas except the area close to oil platforms or disposal sites. Despite large variations in nature of the input data, all variations of M-AMBI gave similar spatial and temporal distribution patterns of the ecological status within the bay, and showed high correlation between them. The agreement of new ecological status obtained from all M-AMBI variations, which were calculated according to linear regression, was almost perfect. The benthic quality, assessed using different input data, could be related to human pressures in the bay, such as water discharges, land reclamation, dredged sediment and drilling cuts disposal sites. It seems that M-BAMBI were more effective than M-NABMI (M-AMBI calculated using abundance data) in indicating human pressures of the Bay. Finally, indices calculated with more severe transformations, such as presence/absence data, could not indicate the higher density of human pressures in the coastal areas of the north part of our study area, but those calculated using mild transformation (i.e., square root) did.
Diversity and distribution of bacterial community in the coastal sediments of Bohai Bay, China
WANG Liping, ZHENG Binghui, LEI Kun
2015, 34(10): 122-131. doi: 10.1007/s13131-015-0719-3
In order to understand the diversity and distribution of the bacterial community in the coastal sediment of the Bohai Bay, China, high-throughput barcoded pyrosequencing of the 16S rRNA gene was used. Metagenomic DNA was extracted from the sediment samples, and was sequenced using a 454 GS FLX Titanium system. At 97% similarity, the sequences were assigned to 22 884 operational taxonomic units (OTUs) which belonged to 41 phyla, 84 classes, 268 genera and 789 species. At the different taxonomic levels, both the dominants and their distribution varied significantly among the six coastal sediments. Proteobacteria was the first dominant phylum across all the six coastal sediments, representing 57.52%, 60.66%, 45.10%, 60.92%, 56.63% and 56.59%, respectively. Bacteroidetes was the second dominant phylum at Stas S1, S2 and S4, while Chloroflexi was the second dominant phylum at Stas S3, S5 and S6. At class level, γ-Proteobacteria was the first dominant class at Stas S1, S2, S4 and S6, while δ-Proteobacteria became the first dominant class at Stas S3 and S5. In addition, a large proportion of unclassified representatives have distributed at the different taxonomic levels. Canonical correspondence analysis (CCA) results indicated that the sediment texture, water depth (D), dissolved oxygen (DO), total nitrogen (TN) and nine EPA priority control polycyclic aromatic hydrocarbons (PAHs) including naphthalene, acenaphthylene, acenaphthene, fluorine, phenanthrene, fluoranthene, pyrene, benzo[a]anthracene and indeno[1,2,3-cd]pyrene were the important factors in regulating the bacterial community composition. Those results are very important to further understand the roles of bacterial community in the coastal biogeochemical cycles.
Spring and autumn living coccolithophores in the Bohai Sea and Yellow Sea, China
JIN Hualong, FENG Yuanyuan, LI Xiaoqian, ZHAI Weidong, SUN Jun
2015, 34(10): 132-146. doi: 10.1007/s13131-015-0712-x
The living coccolithophores (LCs) are an important class of calcified taxa of phytoplankton functional groups, and major producers of marine biogenic inorganic carbon, playing an important role in the marine carbon cycle. In this study, we report the two-demensional abundance, composition of LCs and its correlation with the environmental parameters in spring and autumn, in order to understand the ecological role of LCs in the Yellow Sea and the Bohai Sea. In spring, totally 9 taxa belonging to coccolithophyceae were identified using a polarized microscope at the 1 000× magnification. The dominant species were Emiliania huxleyi, Gephyrocapsa oceanica, Helicosphaera carteri, and Calcidiscus leptoporus. The abundance of coccosphores and coccoliths ranged 0-7.72 cells/mL, and 0-216.09 coccoliths/mL, with the average values of 0.21 cells/mL, and 11.36 coccoliths/mL, respectively. The Emiliania huxleyi distribution was similar to Gephyrocapsa oceanica. The highest abundance of coccoliths was observed in the east of Shandong Peninsula in northern Yellow Sea, whereas Helicosphaera carteri distributed more widely. Emiliania huxleyi and Gephyrocapsa oceanica were the two predominant species in LCs with higher abundances. The distribution of LCs was similar to that of coccoliths. In autumn, 14 taxa belonging to coccolithophyceae were identified with dominant species as Emiliania huxleyi, Gephyrocapsa oceanica, Helicosphaera carteri, Calcidiscus leptoporus and Oolithotus fragilis. The abundance of coccosphores and coccoliths ranged 0-24.69 cells/mL, and 0-507.15 coccoliths/mL, with the average values of 1.47 cells/mL, and 55.89 coccoliths/mL, respectively. The highest abundance of coccoliths was located in Qingdao coastal waters and south of the survey area. The distribution of LCs was similar to the coccoliths; in addition, LCs presented large abundance in the east of the central Yellow Sea area.