Institutional Repository of Key Laboratory of Marine Ecology & Environmental Sciences, CAS
|Alternative Title||Simulation study on the effects of Sargassum horneri golden tide on harmful algae and zooplankton|
|Place of Conferral||中国科学院海洋研究所|
近几年来，铜藻（Sargassum horneri）金潮灾害在我国沿海影响加剧，对沿海地区生态环境和海水养殖业造成了严重的影响，2016年底至2017年初，大量的铜藻入侵了苏北浅滩的紫菜养殖区，对江苏紫菜养殖行业造成了超过5亿元的经济损失； 2017年夏季，南黄海35°N断面又出现了铜藻金潮、浒苔（Ulva prolifera）绿潮和微藻赤潮“三潮”齐发的现象。本文针对铜藻金潮灾害，通过实验模拟研究了铜藻腐烂液和铜藻培养液对绿潮和赤潮原因种生长、浮游动物存活的影响，以及铜藻腐败过程中海水pH、溶解氧含量和营养盐浓度的变化，旨在探明金潮发生过程对绿潮和赤潮发生的影响，对浮游动物以及水体环境的影响，以期为评价铜藻金潮的生态效应提供一定的依据。
本文首先研究了铜藻腐烂液和培养液对绿潮和赤潮原因种生长的影响，选取了绿潮原因种浒苔和五种赤潮原因种--中肋骨条藻（Skeletonema costatum）、链状亚历山大藻（Alexandrium catenella）、东海原甲藻（Prorocentrum donghaiense）、米氏凯伦藻（Karenia mikimotoi）和赤潮异弯藻（Heterosigma akashiwo）为研究对象。结果显示，高浓度的铜藻腐烂液（40 g/L）和培养液（10 g/L）均能够抑制浒苔微观繁殖体的附着萌发和幼苗生长，高浓度腐烂液在第12 d对微观繁殖体附着萌发的抑制率为45.8 %，第15 d对幼苗生长重量的抑制率为25 %，高浓度培养液在第12 d对微观繁殖体附着萌发的抑制率为29.6 %，第15 d对幼苗生长重量的抑制率为22.8 %；此外，较低浓度的腐烂液（10 g/L和20 g/L）和培养液（5 g/L）能够对浒苔幼苗的生长产生促进作用；铜藻腐烂液和培养液能够对不同的赤潮原因种生长产生不同的影响，米氏凯伦藻的生长受到的抑制作用显著，高浓度腐烂液（40 g/L）和高浓度培养液（10 g/L）在第12 d对米氏凯伦藻生长的抑制率分别能够高达90.4 %和92.9 %，高浓度腐烂液（40 g/L）在第12 d对东海原甲藻生长的抑制率为65.9 %，高浓度培养液（10 g/L）在第12 d对中肋骨条藻生长的抑制率为27.7 %，赤潮异弯藻和链状亚历山大藻的生长受到的抑制作用均不显著。以上结果显示，较低浓度的铜藻腐烂液（10 g/L和20 g/L）和培养液（5 g/L）能够抑制浒苔微观繁殖体的附着萌发、促进浒苔幼苗的生长，但高浓度的腐烂液（40 g/L）和培养液（10 g/L）则能够抑制浒苔微观繁殖体的附着萌发和幼苗的生长，还会显著抑制米氏凯伦藻的生长，高浓度的腐烂液（40 g/L）能够显著抑制东海原甲藻的生长，高浓度培养液（10 g/L）则能够显著抑制中肋骨条藻的生长。由此可见，金潮的衰亡期和暴发期会对绿潮和赤潮的发生产生一定的作用。
本研究还进一步开展了铜藻腐烂液和培养液对浮游动物存活的影响实验，选取了卤虫（Artemia salina）、褶皱臂尾轮虫（Brachionus plicatilis）和黑褐新糠虾（Neomysis awatschensis）三种实验生物。结果发现，铜藻腐烂液（40 g/L）处理组的卤虫幼虫96 h内全部死亡，培养液（50 g/L）处理组中的卤虫幼虫96 h内的存活率仅为21 %，影响极显著；铜藻腐烂液也能够影响黑褐新糠虾的存活，40 g/L腐烂液处理组的糠虾96 h内全部死亡，而所有浓度的培养液对糠虾的存活状况无显著影响；铜藻腐烂液和培养液对褶皱臂尾轮虫的存活未造成影响。铜藻金潮在衰亡期和暴发期会威胁某些浮游动物的存活，严重时甚至有可能对浮游动物的群落结构产生一定的影响。
此外，铜藻藻体在10℃、15℃、20℃、25℃四个温度的光照和黑暗条件下腐烂时，通过分析腐烂过程中海水的 pH、溶解氧含量和营养盐浓度的变化发现：铜藻藻体在腐烂分解过程中会造成局部海水 pH的变化，并造成溶解氧含量的降低，光照和黑暗处理下的实验结果差别不大，但随着温度升高影响显著增加。其中25℃条件下，50 g/L实验组的 pH由开始的6.15升高到7.39、溶解氧含量由7.03 mg/L降到1.54 mg/L。此外，铜藻藻体在腐烂分解过程中还会释放大量的铵氮和磷酸盐，20℃条件下，50 g/L的铜藻腐烂液磷酸盐含量在第10 d时为356 μmol/L，铵氮含量在第15 d达到2120 μmol/L，25℃下，同浓度腐烂液第10 d的磷酸盐含量能达到268 μmol/L，铵氮含量在第5 d就达到2105 μmol/L。实验结果说明，铜藻在腐烂过程中会显著影响水体的pH、溶解氧含量和营养盐浓度，金潮在衰亡过程中会引发严重的环境效应和生态效应。
In recent years, the Sargassum horneri golden tide had been intensified in coastal areas of China, which had a serious impact on the ecological environment and marine aquaculture industry. From the end of 2016 to the beginning of 2017, a large number of S. horneri invaded the north of Jiangsu Province. The Porphyra yezoensis aquaculture had been caused economic losses of more than 500 million yuan in the farming industry. And in the summer of 2017, gold tide, green tide and red tide appeared in the 35°N transect of the South Yellow Sea. In this paper, we studied how the decomposing liquid and culture medium of the golden tide causative species S. horneri affected the growth of green tide and red tide species, the survival of zooplankton, and the changes of pH, dissolved oxygen and nutrient concentration. The study was aimed to find out the effects of the golden tide process on the occurrence of green tide and red tide, as well as the impact of on the zooplankton and environment. As a result, we could provide a basis for evaluating the ecological effects of the golden tide.
In the beginning of the research, we studied the effects of S. horneri decomposing liquid and culture medium to the growth of Ulva prolifera green tide and five red tide causitive species. We selected five red tide species, including Skeletonema costatum, Alexandrium catenella, Prorocentrum donghaiense, Karenia mikimotoi and Heterosigma akashiwo. The results showed that the high concentration of the S. horneri decomposing liquid (40g/L) and culture medium (10 g/L) could inhibit the attachment and germination process of microscopic propagules and seedling growth of U. prolifera. The inhibition rate of the decomposing liquid (40g/L) on the attachment germination process of microscopic propagules was 45.8 % on the 12th day, and the rate of seedling growth was 25 % on the 15th day. The inhibition rate of the culture medium (10 g/L) on the attachment germination process of microscopic propagules was 29.6 % on the 12th day , and the rate of seedling growth was 22.8 % on the 15th day. In addition, lower concentrations of decomposing liquid (20g/L and 10g/L) and culture medium (5g/L) could promote the growth of seedling. The S. horneri decomposing liquid and culture medium could affect the growth of red tide causative species. The growth of K. mikimotoi was most significantly inhibited. The inhibition rate of decomposing liquid (40 g/L) and culture medium (10 g/L) were 90.4% and 92.9% on the 12th day. The inhibition rate of decomposing liquid (40 g/L) on the growth of P. donghaiense was 65.9 % on the 12th day. The inhibition rate of culture medium (10 g/L) on the growth of S. costatum was 27.7 % on the 12th day. While the growth inhibition of H. akashiwo and A. catenella were not significant. Above all, the results indicated that the S. horneri decomposing liquid (20g/L and 10g/L) and culture medium (5g/L) could inhibit the attachment and germination of microscopic propagules and promote the growth of U. prolifera seedling. However, high concentration of decomposing liquid (40 g/L) and culture medium (10 g/L) could inhibit the attachment and germination of microscopic propagules and the growth of seedling, and also significantly inhibit the growth of K. mikimotoi. The high concentration of decomposing liquid (40 g/L) could significantly inhibit the growth of P. donghaiense. The high concentration of culture medium (10 g/L) could significantly inhibit the growth of S. costatum. It could be seen that the decline and outbreak stage of the golden tide would affect the occurrence of the green tide and red tide.
Then we further explored the effects of S. horneri decomposing liquid and culture medium on the survival of zooplankton. We selected Artemia salina, Brachionus plicatilis and Neomysis awatschensis as the tested organisms. The results showed that the A. salina larva in the experimental group of the S. horneri decomposing liquid (40 g/L) died within 96h, and the survival rate in the culture medium (50 g/L) was 21%, the impact was extremely significant. The S. horneri decomposing liquid could also affect the survival of N. awatschensis. The N. awatschensis in the decomposing liquid-treated group (40 g/L) died within 96h, and all concentrations of the culture medium had no significant effect. The survival of the B. plicatilis was not affected by the decomposing liquid and culture medium. Therefore, the gold tide would threaten the survival of some zooplankton during the decline and outbreak stage, and may even had an impact on the zooplankton community structure in severe cases.
In addition, when the S. horneri body was decomposed in light and dark conditions at 10℃, 15℃, 20℃ and 25℃, it was found that the decomposition of S. horneri would cause the change of seawater pH and the decrease of dissolved oxygen content. The experimental results under light and dark treatments are not much different, but they increased significantly with increasing temperature. At 25°C, the pH of the experimental group (50 g/L) increased from 6.15 to 7.39, and the dissolved oxygen content decreased from 7.03mg/L to 1.54mg/L. Anymore, the S. horneri body could also release large amount of ammonium nitrogen and phosphate during the decomposition. At 20°C, the phosphate content of the high concentration group (50 g/L) of the decomposing liquid was 356 μmol/L on the 10th day, and the ammonium nitrogen content reached 2120 μmol/L on the 15th day. At 25°C, the phosphate content of the same concentration of decomposing liquid on the 10th day could reach 268 μmol/L, and the ammonium nitrogen content reached 2105 μmol/L on the 5th day. The results showed that the S. horneri would significantly affect the pH, dissolved oxygen content and nutrient concentration of the water in the process of decomposition. Therefore, the golden tide would cause serious environmental and ecological effects in the process of decline.
Through the above experiments, it was proved that the S. horneri gold tide could not only affect the occurrence of the green tide and red tide, but also cause serious impact on zooplankton and ecological environment during the decline and outbreak stage. The ecological effects caused by the golden tide should be payed enough attention.
|MOST Discipline Catalogue||理学::海洋科学 ; 理学::生态学|
|Table of Contents|
|蔡佳宸. 铜藻金潮对有害藻华原因种和浮游动物影响的模拟研究[D]. 中国科学院海洋研究所. 中国科学院大学,2019.|
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