The seasonal variations in phytoplankton community structure were investigated for the Sanggou Bay(SGB) and the adjacent Ailian Bay(ALB) and Lidao Bay(LDB) in Shandong Peninsula, eastern China. The species composition...The seasonal variations in phytoplankton community structure were investigated for the Sanggou Bay(SGB) and the adjacent Ailian Bay(ALB) and Lidao Bay(LDB) in Shandong Peninsula, eastern China. The species composition and cell abundance of phytoplankton in the bay waters in spring(April 2011), summer(August 2011), autumn(October 2011), and winter(January 2012) were examined using the Utermhl method. A total of 80 taxa of phytoplankton that belong to 39 genera of 3 phyla were identified. These included 64 species of 30 genera in the Phylum Bacillariophyta, 13 species of 8 genera in the Phylum Dinophyta, and 3 species of 1 genus in the Phylum Chrysophyta. During the four seasons, the number of phytoplankton species(43) was the highest in spring, followed by summer and autumn(40), and the lowest number of phytoplankton species(35) was found in winter. Diatoms, especially Paralia sulcata(Ehrenberg) Cleve and Coscinodiscus oculus-iridis Ehrenberg, were predominant in the phytoplankton community throughout the study period, whereas the dominance of dinoflagellate appeared in summer only. The maximum cell abundance of phytoplankton was detected in summer(average 8.08 × 103 cells L-1) whereas their minimum abundance was found in autumn(average 2.60 × 103 cells L-1). The phytoplankton abundance was generally higher in the outer bay than in the inner bay in spring and autumn. In summer, the phytoplankton cells were mainly concentrated in the south of inner SGB, with peak abundance observed along the western coast. In winter, the distribution of phytoplankton cells showed 3 patches, with peak abundance along the western coast as well. On seasonal average, the Shannon-Wiener diversity indices of phytoplankton community ranged from 1.17 to 1.78(autumn > summer > spring > winter), and the Pielou's evenness indices of phytoplankton ranged from 0.45 to 0.65(autumn > spring > summer > winter). According to the results of canonical correspondence analysis, phosphate level was the major factor that limited the occurrence of P. sulcata and C. oculus-iridis, whereas optimal temperature and low salinity were responsible for Prorocentrum blooms in summer. The detailed description of seasonal variations in phytoplankton community structure in the three bays provide reference data for future studies on marine ecosystems and mariculture in adjacent areas.展开更多
A study of coccolith assemblages from a box core from the central South Yellow Sea（SYS） was performed revealing fluctuations on their relative abundance（%） that can be related to climatic and hydrographic changes ...A study of coccolith assemblages from a box core from the central South Yellow Sea（SYS） was performed revealing fluctuations on their relative abundance（%） that can be related to climatic and hydrographic changes over the last 230 years（1780–2011）. Total coccolith abundances ranged from 7.0 to 55.1×10^6 coccoliths·g^-1sediment. Although the abundance of different species varied widely throughout the core, seven taxa dominated the assemblage. Among these species, Gephyrocapsa oceanica was the most dominant species, and it showed an average percentage of 50.1%. The pattern of G. oceanica（eutrophic species） was opposite to that of the combined percentage of Braarudosphaera bigelowii and Umbilicosphaera sibogae（both oligotrophic species）, indicating that in the Yellow Sea（YS）, the distribution pattern of G. oceanica might be characteristic of nutrient availability.Similar patterns between G. oceanica and the Siberian High were observed on an inter-decadal time scale,indicating that the East Asian Winter Monsoon（EAWM） may be an important driver of ecological changes in the YS. When the EAWM prevails, both the Yellow Sea Coastal Current（YSCC） and Yellow Sea Warm Current（YSWC）strengthen, and the increasing nutrient availability and warmer water brought by the strengthened YSWC favor eutrophic and warm-water coccolithophore species, such as G. oceanica. This likely mechanism demonstrates that coccolith assemblages can be used as benign and reliable proxy for climate change and surface oceanography.展开更多
基金supported by the National Program on Key Basic Research Project of China (Grant Nos. 2011CB409804 and 2015CB954002)Program for New Century Excellent Talents in University (NCET-12-1065)the National Natural Science Foundation of China (Grant No.41176136) to J. Sun
文摘The seasonal variations in phytoplankton community structure were investigated for the Sanggou Bay(SGB) and the adjacent Ailian Bay(ALB) and Lidao Bay(LDB) in Shandong Peninsula, eastern China. The species composition and cell abundance of phytoplankton in the bay waters in spring(April 2011), summer(August 2011), autumn(October 2011), and winter(January 2012) were examined using the Utermhl method. A total of 80 taxa of phytoplankton that belong to 39 genera of 3 phyla were identified. These included 64 species of 30 genera in the Phylum Bacillariophyta, 13 species of 8 genera in the Phylum Dinophyta, and 3 species of 1 genus in the Phylum Chrysophyta. During the four seasons, the number of phytoplankton species(43) was the highest in spring, followed by summer and autumn(40), and the lowest number of phytoplankton species(35) was found in winter. Diatoms, especially Paralia sulcata(Ehrenberg) Cleve and Coscinodiscus oculus-iridis Ehrenberg, were predominant in the phytoplankton community throughout the study period, whereas the dominance of dinoflagellate appeared in summer only. The maximum cell abundance of phytoplankton was detected in summer(average 8.08 × 103 cells L-1) whereas their minimum abundance was found in autumn(average 2.60 × 103 cells L-1). The phytoplankton abundance was generally higher in the outer bay than in the inner bay in spring and autumn. In summer, the phytoplankton cells were mainly concentrated in the south of inner SGB, with peak abundance observed along the western coast. In winter, the distribution of phytoplankton cells showed 3 patches, with peak abundance along the western coast as well. On seasonal average, the Shannon-Wiener diversity indices of phytoplankton community ranged from 1.17 to 1.78(autumn > summer > spring > winter), and the Pielou's evenness indices of phytoplankton ranged from 0.45 to 0.65(autumn > spring > summer > winter). According to the results of canonical correspondence analysis, phosphate level was the major factor that limited the occurrence of P. sulcata and C. oculus-iridis, whereas optimal temperature and low salinity were responsible for Prorocentrum blooms in summer. The detailed description of seasonal variations in phytoplankton community structure in the three bays provide reference data for future studies on marine ecosystems and mariculture in adjacent areas.
基金The National Key Basic Research Program of China under contract No.2010CB428902the United Program of National Natural Science Foundation of China and Shandong Province under contract No.U1406403the Program for New Century Excellent Talents in University under contrast No.NCET-12-1065
文摘A study of coccolith assemblages from a box core from the central South Yellow Sea（SYS） was performed revealing fluctuations on their relative abundance（%） that can be related to climatic and hydrographic changes over the last 230 years（1780–2011）. Total coccolith abundances ranged from 7.0 to 55.1×10^6 coccoliths·g^-1sediment. Although the abundance of different species varied widely throughout the core, seven taxa dominated the assemblage. Among these species, Gephyrocapsa oceanica was the most dominant species, and it showed an average percentage of 50.1%. The pattern of G. oceanica（eutrophic species） was opposite to that of the combined percentage of Braarudosphaera bigelowii and Umbilicosphaera sibogae（both oligotrophic species）, indicating that in the Yellow Sea（YS）, the distribution pattern of G. oceanica might be characteristic of nutrient availability.Similar patterns between G. oceanica and the Siberian High were observed on an inter-decadal time scale,indicating that the East Asian Winter Monsoon（EAWM） may be an important driver of ecological changes in the YS. When the EAWM prevails, both the Yellow Sea Coastal Current（YSCC） and Yellow Sea Warm Current（YSWC）strengthen, and the increasing nutrient availability and warmer water brought by the strengthened YSWC favor eutrophic and warm-water coccolithophore species, such as G. oceanica. This likely mechanism demonstrates that coccolith assemblages can be used as benign and reliable proxy for climate change and surface oceanography.
