Long-term changes of phytoplankton community by water sampling method in Xiagu Sea waters of Xiamen,China,were investigated in this study.Species composition of the phytoplankton community in these waters changed grea...Long-term changes of phytoplankton community by water sampling method in Xiagu Sea waters of Xiamen,China,were investigated in this study.Species composition of the phytoplankton community in these waters changed greatly since the 1950s.The numbers of Dinophyta species increased significantly,although Bacillariophyta species are generally dominant.The succession of dominant species in phytoplankton community is obvious： large-size dominant species such as Biddulphia sinensis of the 1950s were gradually replaced by small-size ones such as Cyclotella striata and Nitzschia closterium,and species that still maintain dominant such as Skeletonema costatum are also small ones,leading the whole phytoplankton community of smaller size.Cell density of phytoplankton community increased greatly,among which cell density of the most dominant species Skeletonema costatum have been increasing in exponent function.Margalef index of phytoplankton community decreased,indicating decline of biodiversity of the community,and dominant character of Skeletonema costatum increased.Generally,the structure of the entire phytoplankton community is becoming more and more singular and unstable,which makes the occurrence of red tides more frequent.The succession in the phytoplankton community is related to the long-term changes in marine environment,influenced by human activities and global climate changes,especially the increases of nutrient content.展开更多
Mangroves play an important role in sequestering carbon and trapping sediments. However, the effectiveness of such functions is unclear due to the restriction of knowledge on the sedimentation process across the veget...Mangroves play an important role in sequestering carbon and trapping sediments. However, the effectiveness of such functions is unclear due to the restriction of knowledge on the sedimentation process across the vegetation boundaries. To detect the effects of mangrove forests on sediment transportation and organic carbon sequestration, the granulometric and organic carbon characteristics of mangrove sediments were investigated from three vegetation zones of four typical mangrove habitats on the Leizhou Peninsula coast. Based on our results, sediment transport was often ＂environmentally sensitive＂ to the vegetation friction. A transition of the sediment transport mode from the mudflat zone to the interior/fringe zone was often detected from the cumulative frequency curve. The vegetation cover also assists the trapping of material, resulting in a significantly higher concentration of organic carbon in the interior surface sediments. However, the graphic parameters of core sediments reflected a highly temporal variability due to the sedimentation process at different locations. The sediment texture ranges widely from sand to mud, although the sedimentary environments are restricted within the same energy level along the fluvial-marine transition zone. Based on the PCA results, the large variation was mainly attributed to either the mean grain size features or the organic carbon features. A high correlation between the depth and δ13C value also indicated an increasing storage of mangrove-derived organic carbon with time.展开更多
The PSP toxicity of Alexandrium tamarense （Lebour） Balech on the blue mussel （Mytilus edulis） from the western waters of Xiamen in China was studied by following the standard method of PSP mouse bioassay developed...The PSP toxicity of Alexandrium tamarense （Lebour） Balech on the blue mussel （Mytilus edulis） from the western waters of Xiamen in China was studied by following the standard method of PSP mouse bioassay developed by the Association of Official Analytical Chemists （ AOAC ）. The results showed that the mice survived when the density of A. tamarense cells was lower than 1×10^5 cells per cubic decimetre and died when the density was higher than 1×10^6 cells per cubic decimetre. The past record of red tide events in the western waters of Xiamen showed a general trend of starting from the bloom of non-toxic planktonic diatoms in local waters and resulting in a harmful algal bloom due to the fade of planktonic diatoms which failed in the survival competition in the unfavorable and deteriorated eco-environment. On the basis of experimental results and natural environment of Xiamen waters and by making reference to the critical criteria of shellfish toxins in various states, a prewarning value 1×10^5 cells per cubic decimetre of A. tamarense PSP toxicity was proposed for the areas in South China where red tides frequently occur.展开更多
基金The Scientific Research Foundation of Third Institute of Oceanography,State Oceanic Administration under contract Nos TIO 2007009 and TIO 2009007the River basin-Estuary ecological security assessment and Management strategy under contract No.200805064+4 种基金the Natural Science Foundation of Fujian Province under contract No.2010J01260the "908" Project under contract No.908-02-02-01 special subjectthe Program of Chinese Marine Chemistry Investigation and Research under contract No.908-ZC-I-03the Special Fund of State Oceanic Administration under contract No.908-02-01-02the Major State Basic Research Development Program of China (973 Program) under contract Nos 2010CB428704 and 2005CB422305
文摘Long-term changes of phytoplankton community by water sampling method in Xiagu Sea waters of Xiamen,China,were investigated in this study.Species composition of the phytoplankton community in these waters changed greatly since the 1950s.The numbers of Dinophyta species increased significantly,although Bacillariophyta species are generally dominant.The succession of dominant species in phytoplankton community is obvious： large-size dominant species such as Biddulphia sinensis of the 1950s were gradually replaced by small-size ones such as Cyclotella striata and Nitzschia closterium,and species that still maintain dominant such as Skeletonema costatum are also small ones,leading the whole phytoplankton community of smaller size.Cell density of phytoplankton community increased greatly,among which cell density of the most dominant species Skeletonema costatum have been increasing in exponent function.Margalef index of phytoplankton community decreased,indicating decline of biodiversity of the community,and dominant character of Skeletonema costatum increased.Generally,the structure of the entire phytoplankton community is becoming more and more singular and unstable,which makes the occurrence of red tides more frequent.The succession in the phytoplankton community is related to the long-term changes in marine environment,influenced by human activities and global climate changes,especially the increases of nutrient content.
基金The National Natural Science Foundation of China under contract Nos 41006051 and 41106108the Scientific Research Foundation for Returned Scholars of the Ministry of Education of China+1 种基金the Fundamental Research Funds for the Central Universities under contract No.2652012032the State Key Laboratory of Earth Surface Processes and Resource Ecology under contract No.257-2013-KF-13
文摘Mangroves play an important role in sequestering carbon and trapping sediments. However, the effectiveness of such functions is unclear due to the restriction of knowledge on the sedimentation process across the vegetation boundaries. To detect the effects of mangrove forests on sediment transportation and organic carbon sequestration, the granulometric and organic carbon characteristics of mangrove sediments were investigated from three vegetation zones of four typical mangrove habitats on the Leizhou Peninsula coast. Based on our results, sediment transport was often ＂environmentally sensitive＂ to the vegetation friction. A transition of the sediment transport mode from the mudflat zone to the interior/fringe zone was often detected from the cumulative frequency curve. The vegetation cover also assists the trapping of material, resulting in a significantly higher concentration of organic carbon in the interior surface sediments. However, the graphic parameters of core sediments reflected a highly temporal variability due to the sedimentation process at different locations. The sediment texture ranges widely from sand to mud, although the sedimentary environments are restricted within the same energy level along the fluvial-marine transition zone. Based on the PCA results, the large variation was mainly attributed to either the mean grain size features or the organic carbon features. A high correlation between the depth and δ13C value also indicated an increasing storage of mangrove-derived organic carbon with time.
文摘The PSP toxicity of Alexandrium tamarense （Lebour） Balech on the blue mussel （Mytilus edulis） from the western waters of Xiamen in China was studied by following the standard method of PSP mouse bioassay developed by the Association of Official Analytical Chemists （ AOAC ）. The results showed that the mice survived when the density of A. tamarense cells was lower than 1×10^5 cells per cubic decimetre and died when the density was higher than 1×10^6 cells per cubic decimetre. The past record of red tide events in the western waters of Xiamen showed a general trend of starting from the bloom of non-toxic planktonic diatoms in local waters and resulting in a harmful algal bloom due to the fade of planktonic diatoms which failed in the survival competition in the unfavorable and deteriorated eco-environment. On the basis of experimental results and natural environment of Xiamen waters and by making reference to the critical criteria of shellfish toxins in various states, a prewarning value 1×10^5 cells per cubic decimetre of A. tamarense PSP toxicity was proposed for the areas in South China where red tides frequently occur.
