Aureococcus anophagefferens, a small pelagophyte algae, has caused brown tide blooms in coastal waters of Qinhuangdao in recent years, presenting significant negative impacts on the shellfish mariculture industry. Und...Aureococcus anophagefferens, a small pelagophyte algae, has caused brown tide blooms in coastal waters of Qinhuangdao in recent years, presenting significant negative impacts on the shellfish mariculture industry. Under standard light microscopy, it is visually indistinguishable from other small algae in field samples due to its extremely small size. In this study, quantitative polymerase chain reaction（q PCR） based on 18 S r DNA sequences was developed and used to detect and enumerate A. anophagefferens. A linear regression（R2 = 0.91） was generated based on cycle thresholds value（Ct） versus known concentrations of A. anophagefferens. Twenty-two field samples collected in coastal waters of Qinhuangdao were subjected to DNA extraction and then analyzed using q PCR. Results showed that A. anophagefferens had a wide distribution in coastal waters along Qinhuangdao. Elevated A. anophagefferens abundance, category 3 brown tide blooms（〉200 000 cells/m L） occurred at Dongshan Beach and Tiger-stone Beach in August in 2013. In shellfish mariculture areas along coastal waters of Qinhuangdao, 4 stations had category 3 blooms, and 6 stations had category 2 blooms（35 000–200 000 cells/m L） in August and all stations had category 1 blooms（〉0 to ≤35 000 cells/m L） in October. Quantitative PCR allows for detection of A. anophagefferens cells at low levels in filed samples, which is essential to effective management and prediction of brown tide blooms.展开更多
A large-scale algal bloom,caused by Aureococcus anophagefferens,has plagued the coastal embayment of Qinhuangdao,China since 2009.The bay scallop agriculture industry in this area has been adversely affected.Researche...A large-scale algal bloom,caused by Aureococcus anophagefferens,has plagued the coastal embayment of Qinhuangdao,China since 2009.The bay scallop agriculture industry in this area has been adversely affected.Researchers claimed that the poor nutritional value of brown tide cells might be responsible for the detrimental effects on bivalve mollusks.To verify whether brown tide cells are nutritionally inadequate food sources,the biochemical composition(total extractable lipids,amino acids,fatty acids,and monomeric carbohydrates)of the Chinese strain A.anophagefferens was determined during the late logarithmic growth phase when culturing in different nitrogen sources(nitrate,urea and nitrate-urea mixture).Cells cultured in nitrate contained 39.12%protein,21.99%total extractable lipid,10.25% total carbohydrates,and a relatively high amount of polyunsaturated fatty acid(PUFA)(51.98%,percentage of total fatty acids),including eicosapentaenoic acid(EPA)(4.81%)and docosahexaenoic acid(DHA)(14.56%).The gross biochemical composition and PUFA content in A.anophagefferens in nitrate cultivation are comparable with values found in the literature of frequently used species in bivalve feeding.Nine monomeric carbohydrates were significantly reduced when cultivated in urea and nitrate-urea mixture(P<0.05).The DHA,EPA,and PUFA contents significantly decreased when cultivated in urea(P<0.05).Although the nutritional value of A.anophagefferens dropped when cultured in urea,it is still comparable with certain favorably used algal species in bivalve feeding(i.e.,Skeletonema costatum),indicating that A.anophagefferens is not a nutritionally inadequate food source.展开更多
Aureococcus anophagefferens caused brown tides for three consecutive years from 2009 to 2011 in the coastal waters of Qinhuangdao, China, with numerous, widespread ecological and economic impact on ecosystems. To unde...Aureococcus anophagefferens caused brown tides for three consecutive years from 2009 to 2011 in the coastal waters of Qinhuangdao, China, with numerous, widespread ecological and economic impact on ecosystems. To understand the population dy- namics of nanoplankton during the brown tides, sequences of the V9 region of the 18S rDNA gene, used as a marker, were analyzed by Illumina sequencing to assess nanoplankton biomass, and real-time fluorescence quantitative PCR was performed to analyze spa- tial variation in the 18S rDNA copy concentrations of nanoplankton off the Qinhuangdao coast in July, 2011. The results showed that A. anophagefferens and Minutocellus polymorphus were the dominant species in the local phytoplankton community during the brown tide in July 2011. The highest 18S rDNA copy concentrations of A. anophagefferens and M. polymorphus were detected at stations SHG and FN, respectively. The central area most strongly affected by the brown tide migrated southward from 2011 to 2013. Redundancy analysis (RDA) showed that the decreasing NOx concentration might provide suitable nutrient conditions for the A. anophagefferens outbreak. During the brown tide caused by A. anophagefferens, other phytoplankton, such as diatoms, cryptophytes, chlorophytes, dinoflagellates and other flagellates, could co-occur with it. For zooplankton, due to less selective feeding behavior, Amoebozoa was the most abundant zooplankton at station SHG, while Ciliophora was the most abundant zooplankton at other sta- tions for its more selective feeding.展开更多
Since 2009, the newly recorded species Aureococcus anophagefferens has successively induced brown tides in the Qinhuangdao coastal waters of the Bohai Sea. Here, we focus on the phytoplankton community structure in th...Since 2009, the newly recorded species Aureococcus anophagefferens has successively induced brown tides in the Qinhuangdao coastal waters of the Bohai Sea. Here, we focus on the phytoplankton community structure in this region and try to point out the biological background characteristics of the outbreaks of successive brown tides. We analyzed species composition,cell abundance, diversity indices and size-fractionated chlorophyll a(Chl-a) concentration monthly from March 2013 to January2014. The phytoplankton community, as observed by microscopy, underwent succession from nano-celled chained diatoms to dinoflagellates in the spring and summer, and then to micro-celled diatoms and nano-celled chained diatoms as the most prominent groups in the subsequent autumn and winter. Canonical correspondence analysis revealed that changes in the abundance of diatoms were related to nutrient availability, especially of nitrogen, while water temperature was the crucial factor influencing the abundance of dinoflagellates and A. anophagefferens. Considering the contribution of nano-celled chained species to the micro-sized Chl-a,small phytoplankton(<20 μm) composed the majority of total Chl-a and were generally abundant during our study. Abundant and diverse small phytoplankton seemed to serve as a background or seedbank for the formation of blooms of A. anophagefferens and other small-celled algae.展开更多
基金The National Natural Science Foundation of China under contract No.40906081the Public Science and Technology Research Funds Projects of Ocean under contract Nos 2011418021 and 201305030Integrated Environmental Governances and Restoration in Beidaihe Coast of Hebei Province
文摘Aureococcus anophagefferens, a small pelagophyte algae, has caused brown tide blooms in coastal waters of Qinhuangdao in recent years, presenting significant negative impacts on the shellfish mariculture industry. Under standard light microscopy, it is visually indistinguishable from other small algae in field samples due to its extremely small size. In this study, quantitative polymerase chain reaction（q PCR） based on 18 S r DNA sequences was developed and used to detect and enumerate A. anophagefferens. A linear regression（R2 = 0.91） was generated based on cycle thresholds value（Ct） versus known concentrations of A. anophagefferens. Twenty-two field samples collected in coastal waters of Qinhuangdao were subjected to DNA extraction and then analyzed using q PCR. Results showed that A. anophagefferens had a wide distribution in coastal waters along Qinhuangdao. Elevated A. anophagefferens abundance, category 3 brown tide blooms（〉200 000 cells/m L） occurred at Dongshan Beach and Tiger-stone Beach in August in 2013. In shellfish mariculture areas along coastal waters of Qinhuangdao, 4 stations had category 3 blooms, and 6 stations had category 2 blooms（35 000–200 000 cells/m L） in August and all stations had category 1 blooms（〉0 to ≤35 000 cells/m L） in October. Quantitative PCR allows for detection of A. anophagefferens cells at low levels in filed samples, which is essential to effective management and prediction of brown tide blooms.
基金Supported by the National Natural Science Foundation of China(Nos.42176142,41906111,41806127)the Science&Technology Basic Resources Investigation Program of China(No.2018FY100200)and the Natural Science Foundation of Guangdong Province(No.2018A030313956)。
文摘A large-scale algal bloom,caused by Aureococcus anophagefferens,has plagued the coastal embayment of Qinhuangdao,China since 2009.The bay scallop agriculture industry in this area has been adversely affected.Researchers claimed that the poor nutritional value of brown tide cells might be responsible for the detrimental effects on bivalve mollusks.To verify whether brown tide cells are nutritionally inadequate food sources,the biochemical composition(total extractable lipids,amino acids,fatty acids,and monomeric carbohydrates)of the Chinese strain A.anophagefferens was determined during the late logarithmic growth phase when culturing in different nitrogen sources(nitrate,urea and nitrate-urea mixture).Cells cultured in nitrate contained 39.12%protein,21.99%total extractable lipid,10.25% total carbohydrates,and a relatively high amount of polyunsaturated fatty acid(PUFA)(51.98%,percentage of total fatty acids),including eicosapentaenoic acid(EPA)(4.81%)and docosahexaenoic acid(DHA)(14.56%).The gross biochemical composition and PUFA content in A.anophagefferens in nitrate cultivation are comparable with values found in the literature of frequently used species in bivalve feeding.Nine monomeric carbohydrates were significantly reduced when cultivated in urea and nitrate-urea mixture(P<0.05).The DHA,EPA,and PUFA contents significantly decreased when cultivated in urea(P<0.05).Although the nutritional value of A.anophagefferens dropped when cultured in urea,it is still comparable with certain favorably used algal species in bivalve feeding(i.e.,Skeletonema costatum),indicating that A.anophagefferens is not a nutritionally inadequate food source.
基金supported by the Public Science and Technology Research Funds Projects of Ocean (No. 201205031)the National Natural Science Foundation of China (No. 41521064)the Scientific and Technological Innovation Project of the Qingdao National Laboratory for Marine Science and Technology (No. 2016ASKJ02)
文摘Aureococcus anophagefferens caused brown tides for three consecutive years from 2009 to 2011 in the coastal waters of Qinhuangdao, China, with numerous, widespread ecological and economic impact on ecosystems. To understand the population dy- namics of nanoplankton during the brown tides, sequences of the V9 region of the 18S rDNA gene, used as a marker, were analyzed by Illumina sequencing to assess nanoplankton biomass, and real-time fluorescence quantitative PCR was performed to analyze spa- tial variation in the 18S rDNA copy concentrations of nanoplankton off the Qinhuangdao coast in July, 2011. The results showed that A. anophagefferens and Minutocellus polymorphus were the dominant species in the local phytoplankton community during the brown tide in July 2011. The highest 18S rDNA copy concentrations of A. anophagefferens and M. polymorphus were detected at stations SHG and FN, respectively. The central area most strongly affected by the brown tide migrated southward from 2011 to 2013. Redundancy analysis (RDA) showed that the decreasing NOx concentration might provide suitable nutrient conditions for the A. anophagefferens outbreak. During the brown tide caused by A. anophagefferens, other phytoplankton, such as diatoms, cryptophytes, chlorophytes, dinoflagellates and other flagellates, could co-occur with it. For zooplankton, due to less selective feeding behavior, Amoebozoa was the most abundant zooplankton at station SHG, while Ciliophora was the most abundant zooplankton at other sta- tions for its more selective feeding.
基金supported by the National Natural Science Foundation of China-Shandong Joint Fund for Marine Science Research Centers (Grant No. U1606404)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA11020601)the Public Science and Technology Research Funds Projects of Ocean (Grant No. 201305003-3)
文摘Since 2009, the newly recorded species Aureococcus anophagefferens has successively induced brown tides in the Qinhuangdao coastal waters of the Bohai Sea. Here, we focus on the phytoplankton community structure in this region and try to point out the biological background characteristics of the outbreaks of successive brown tides. We analyzed species composition,cell abundance, diversity indices and size-fractionated chlorophyll a(Chl-a) concentration monthly from March 2013 to January2014. The phytoplankton community, as observed by microscopy, underwent succession from nano-celled chained diatoms to dinoflagellates in the spring and summer, and then to micro-celled diatoms and nano-celled chained diatoms as the most prominent groups in the subsequent autumn and winter. Canonical correspondence analysis revealed that changes in the abundance of diatoms were related to nutrient availability, especially of nitrogen, while water temperature was the crucial factor influencing the abundance of dinoflagellates and A. anophagefferens. Considering the contribution of nano-celled chained species to the micro-sized Chl-a,small phytoplankton(<20 μm) composed the majority of total Chl-a and were generally abundant during our study. Abundant and diverse small phytoplankton seemed to serve as a background or seedbank for the formation of blooms of A. anophagefferens and other small-celled algae.
