The distribution of diatoms from surface sediments of the West Philippine Basin was analyzed, with 68 species and varieties of diatoms from 26 genera identified. Diatom abundance varied spatially, with the absolute ab...The distribution of diatoms from surface sediments of the West Philippine Basin was analyzed, with 68 species and varieties of diatoms from 26 genera identified. Diatom abundance varied spatially, with the absolute abundance of diatoms ranging from 0 to 3.4× 104 frustules/g. The seven tropical pelagic diatoms were Alveus marinus, Azpeitia africana, Azpeitia nodulifera, Hemidiscus cuneiformis, Hernidiscus cuneiformis var. ventricosus, Roperia tesselata and Rhizosolenia bergonii. The relative abundance of these species was greater than 20%, and their distribution pattern in the sediments was overlaid by the flow of the Kuroshio Current. Ethmodiscus rex was present at 159 stations, formed the most abundant and dominant species in the diatomaceous ooze, and thus referred to as Ethmodiscus ooze. Ethmodiscus rex was also a major contributor to primary production in the region. A principal component analysis was employed to explain the relationship between samples and variations in diatom species from the WPB. Four diatom assemblages were distinguished, representing different oceanographic conditions; their spatial distributions were closely related with the North Equatorial Current and Kuroshio Current patterns in the region. These diatom assemblages can therefore be useful in deciphering late Quaternary palaeoceanographic reconstructions of the West Philippine Basin.展开更多
We studied diatom distribution from 62 samples from the uppermost 1 cm of sedimem in the South China Sea （SCS）, using grabs or box corers in three cruises between 2001-2007. Fifty six genera, 256 species and their v...We studied diatom distribution from 62 samples from the uppermost 1 cm of sedimem in the South China Sea （SCS）, using grabs or box corers in three cruises between 2001-2007. Fifty six genera, 256 species and their varieties were identified. Dominating species included Coscinodiscus africanus, Coscinodiscus nodulifer, Cyclotella stylorum, Hemidiscus cuneiformis, Melosira sulcata, Nitzschia marina, Roperia tesselata, Thalassionema nitzschioides, Thalassiosira excentrica, and Thalassiothrix longissima. Most surface sediments in the SCS were rich ill diatoms, except for a few coarse samples. Average diatom abundance in the study area was 104 607 valve/g. In terms of the abundance, ecology, and spatial distribution, seven diatom zones （Zones 1-7） were recognized. Zone 1 （northern continental shelf） is affected by warm currents, SCS northern branch of the Kuroshio, and northern coastal currents; Zone 2 （northwestern continental shelf） is affected by intense coastal currents; Zone 3 （Xisha Islands sea area） is a bathyal environment with transitional water masses; Zone 4 （sea basin） is a bathyal-to-deep sea with stable and uniform central water masses in a semi-enclosed marginal sea; Zone 5 （Nansba Islands marine area） is a pelagic environment with relatively high surface temperature; Zone 6 （northern Sunda Shelf） is a tropical shelf environment; and Zone 7 （northern Kalimantan Island shelf area） is affected by warm waters from the Indian Ocean and coastal waters. The data indicate that these diatom zones are closely related to topography, hydrodynamics, temperature, nutrients and especially the salinity. Better understanding of the relationship between diatom distribution and the oceanographic factors would help in the reconstruction of the SCS in the past.展开更多
The samples collected from the surface sediments in Xiangshan Bay,Zhejiang province in May and November 2005 were analyzed under a light microscope.The species composition,abundance,community structure and diversity w...The samples collected from the surface sediments in Xiangshan Bay,Zhejiang province in May and November 2005 were analyzed under a light microscope.The species composition,abundance,community structure and diversity were investigated.A total of 179 taxa belonging to 46 genera of diatom were identified.The result showed that the ecotypes of diatom were mostly eurytopic species,followed by warm water species and temperate species.The most dominant species were Cyclotella stylorum and Coscinodiscus jonesianus.The seasonal variation of diatom abundance was remarkable.The cell abundance of diatoms was higher in spring(2.974×10^3 cells/g)than that in autumn(0.071×10^3 cells/g).The number of species varies with change of season,demonstrating the adaptability of diatoms to the temperature of water.The species diversity of benthic diatom was lower in autumn than that in spring.展开更多
Diatoms are widely used to study past and present changes in the marine environment. Unimodal models are appropriate for exploring the relationship between environmental properties in Chinese inshore waters and fossil...Diatoms are widely used to study past and present changes in the marine environment. Unimodal models are appropriate for exploring the relationship between environmental properties in Chinese inshore waters and fossil diatom species derived from modem surface sediments. The best-fit relationships between two multivariate datasets （diatom species and environmental variables） were identified using canonical correspondence analysis （CCA）, which is a constrained ordination technique. The absolute abundance of diatoms in the Chinese inshore waters ranged from 500 to 48 000 valves/g, and the average absolute abundance of all the 29 sites was l l 300 valves/g. 153 species and varieties of diatoms belonging to 42 genera in all were identified in the Chinese inshore waters. There were 28 dominant diatom species in all. According to the absolute abundance of the dominant species and the spatial distribution of the currents from the Chinese inshore waters, 12 diatom assemblages were distinguished from north to south, which reflected the different oceanographic conditions at the regional scale. Of the eight environmental variables considered, the most important environmental variable is winter sea surface salinity （WSS）, which was also the only environmental variable with statistical significance. Therefore, it may be used to establish a transfer functions for the Chinese inshore waters in future paleoclimate studies.展开更多
Diatom taxa in samples collected from the uppermost 1-cm sediment of the South China Sea （SCS） during cruises in 2000, 2001, and 2007 were investigated. Among them, two genera, Rutilaria and Trigoniurn, and 11 marin...Diatom taxa in samples collected from the uppermost 1-cm sediment of the South China Sea （SCS） during cruises in 2000, 2001, and 2007 were investigated. Among them, two genera, Rutilaria and Trigoniurn, and 11 marine taxa （species and varieties） were described for the first time in China. The 11 taxa, Rutilaria radiata, Asterolampra grevillei, Biddulphia turrigera, Cocconeis cyclophora var. decora, Cocconeis ocellata, Dictyoneis rnarginata, Entogonia davyana, Tryblionella campechiana, Plagiogramma kinkeri, Plagiogramma nankoorense and Trigonium cf. contumax, were mainly extant species, although Rutilaria radiata and Entogonia davyana are fossils. Available data show that these species are mainly present in the eastern and western Pacific Ocean and the Indian Ocean. A large number of taxa newly recorded in this study were previously reported in the Philippines. The presence of these taxa in both locations is likely a result of seawater exchange in the SCS through the Bashi Channel Taxonomic descriptions, habitats, and distributions of each diatom taxon are provided herein.展开更多
基金Supported by the National Natural Science Foundation of China(Nos.41306083,41106076)the Special Fund for Scientific Research Foundation of the Third Institute of Oceanography,State Oceanic Administration,China(Nos.2010002,2013032)
文摘The distribution of diatoms from surface sediments of the West Philippine Basin was analyzed, with 68 species and varieties of diatoms from 26 genera identified. Diatom abundance varied spatially, with the absolute abundance of diatoms ranging from 0 to 3.4× 104 frustules/g. The seven tropical pelagic diatoms were Alveus marinus, Azpeitia africana, Azpeitia nodulifera, Hemidiscus cuneiformis, Hernidiscus cuneiformis var. ventricosus, Roperia tesselata and Rhizosolenia bergonii. The relative abundance of these species was greater than 20%, and their distribution pattern in the sediments was overlaid by the flow of the Kuroshio Current. Ethmodiscus rex was present at 159 stations, formed the most abundant and dominant species in the diatomaceous ooze, and thus referred to as Ethmodiscus ooze. Ethmodiscus rex was also a major contributor to primary production in the region. A principal component analysis was employed to explain the relationship between samples and variations in diatom species from the WPB. Four diatom assemblages were distinguished, representing different oceanographic conditions; their spatial distributions were closely related with the North Equatorial Current and Kuroshio Current patterns in the region. These diatom assemblages can therefore be useful in deciphering late Quaternary palaeoceanographic reconstructions of the West Philippine Basin.
基金Supported by the National Natural Science Foundation of China(Nos.40676026,41076079,40831160519)the Basic Research Program of China(973Program)(No.2010CB428704)
文摘We studied diatom distribution from 62 samples from the uppermost 1 cm of sedimem in the South China Sea （SCS）, using grabs or box corers in three cruises between 2001-2007. Fifty six genera, 256 species and their varieties were identified. Dominating species included Coscinodiscus africanus, Coscinodiscus nodulifer, Cyclotella stylorum, Hemidiscus cuneiformis, Melosira sulcata, Nitzschia marina, Roperia tesselata, Thalassionema nitzschioides, Thalassiosira excentrica, and Thalassiothrix longissima. Most surface sediments in the SCS were rich ill diatoms, except for a few coarse samples. Average diatom abundance in the study area was 104 607 valve/g. In terms of the abundance, ecology, and spatial distribution, seven diatom zones （Zones 1-7） were recognized. Zone 1 （northern continental shelf） is affected by warm currents, SCS northern branch of the Kuroshio, and northern coastal currents; Zone 2 （northwestern continental shelf） is affected by intense coastal currents; Zone 3 （Xisha Islands sea area） is a bathyal environment with transitional water masses; Zone 4 （sea basin） is a bathyal-to-deep sea with stable and uniform central water masses in a semi-enclosed marginal sea; Zone 5 （Nansba Islands marine area） is a pelagic environment with relatively high surface temperature; Zone 6 （northern Sunda Shelf） is a tropical shelf environment; and Zone 7 （northern Kalimantan Island shelf area） is affected by warm waters from the Indian Ocean and coastal waters. The data indicate that these diatom zones are closely related to topography, hydrodynamics, temperature, nutrients and especially the salinity. Better understanding of the relationship between diatom distribution and the oceanographic factors would help in the reconstruction of the SCS in the past.
基金funded by the National Key Research and Development Program of China(Grant No.2016YFA0601302)the Natural Science Foundation of China(Grant No.41876146,No.41476116)the China-EU Cooperation Project:Ecological farming research in coastal zone composite system(INCO-CT-2004-510706).
文摘The samples collected from the surface sediments in Xiangshan Bay,Zhejiang province in May and November 2005 were analyzed under a light microscope.The species composition,abundance,community structure and diversity were investigated.A total of 179 taxa belonging to 46 genera of diatom were identified.The result showed that the ecotypes of diatom were mostly eurytopic species,followed by warm water species and temperate species.The most dominant species were Cyclotella stylorum and Coscinodiscus jonesianus.The seasonal variation of diatom abundance was remarkable.The cell abundance of diatoms was higher in spring(2.974×10^3 cells/g)than that in autumn(0.071×10^3 cells/g).The number of species varies with change of season,demonstrating the adaptability of diatoms to the temperature of water.The species diversity of benthic diatom was lower in autumn than that in spring.
基金Supported by the National Natural Science Foundation of China(No.41306083)the Special Fund for Basic Work of Science and Technology from the Ministry of Science and Technology of China(No.2009FY210400)the Special Fund of the Third Institute of Oceanography,State Oceanic Administration for Basic Scientific Research Operations(No.HSK 2011028)
文摘Diatoms are widely used to study past and present changes in the marine environment. Unimodal models are appropriate for exploring the relationship between environmental properties in Chinese inshore waters and fossil diatom species derived from modem surface sediments. The best-fit relationships between two multivariate datasets （diatom species and environmental variables） were identified using canonical correspondence analysis （CCA）, which is a constrained ordination technique. The absolute abundance of diatoms in the Chinese inshore waters ranged from 500 to 48 000 valves/g, and the average absolute abundance of all the 29 sites was l l 300 valves/g. 153 species and varieties of diatoms belonging to 42 genera in all were identified in the Chinese inshore waters. There were 28 dominant diatom species in all. According to the absolute abundance of the dominant species and the spatial distribution of the currents from the Chinese inshore waters, 12 diatom assemblages were distinguished from north to south, which reflected the different oceanographic conditions at the regional scale. Of the eight environmental variables considered, the most important environmental variable is winter sea surface salinity （WSS）, which was also the only environmental variable with statistical significance. Therefore, it may be used to establish a transfer functions for the Chinese inshore waters in future paleoclimate studies.
基金Supported by the National Natural Science Foundation of China (Nos.40676026,41076079,40876079,40831160519,40906058)the National Basic Research Program of China(973 Program)(No. 2010CB428704)
文摘Diatom taxa in samples collected from the uppermost 1-cm sediment of the South China Sea （SCS） during cruises in 2000, 2001, and 2007 were investigated. Among them, two genera, Rutilaria and Trigoniurn, and 11 marine taxa （species and varieties） were described for the first time in China. The 11 taxa, Rutilaria radiata, Asterolampra grevillei, Biddulphia turrigera, Cocconeis cyclophora var. decora, Cocconeis ocellata, Dictyoneis rnarginata, Entogonia davyana, Tryblionella campechiana, Plagiogramma kinkeri, Plagiogramma nankoorense and Trigonium cf. contumax, were mainly extant species, although Rutilaria radiata and Entogonia davyana are fossils. Available data show that these species are mainly present in the eastern and western Pacific Ocean and the Indian Ocean. A large number of taxa newly recorded in this study were previously reported in the Philippines. The presence of these taxa in both locations is likely a result of seawater exchange in the SCS through the Bashi Channel Taxonomic descriptions, habitats, and distributions of each diatom taxon are provided herein.
