【作者】 王朝晖；

【导师】 韩博平；

【作者基本信息】 暨南大学 ， 水生生物学， 2007， 博士

【摘要】 对我国沿海重要港湾沉积物中甲藻孢囊的分布进行了较为全面的调查，共分析鉴定出甲藻孢囊61种，其中我国沿海新记录孢囊类型14种；有毒的亚历山大藻和链状裸甲藻的孢囊在我国沿海分布广泛，但在大部分海域密度较低。通过对孢囊的分类学研究和形态学描述，建立了我国常见甲藻孢囊图谱。对南海大亚湾、深圳湾、柘林湾海域孢囊的垂直分布进行了深入研究，揭示了孢囊组成与近20年来海域富营养化趋势的关系。近年来南海养殖海域富营养化趋势日趋明显，而且有鱼类养殖区>贝类养殖区>近岸海域>远岸海域的趋势。通过对长江口赤潮高发区赤潮发生前后的孢囊组成及孢囊的季节变化研究，发现长江口海域孢囊种类丰富，孢囊种类数和孢囊密度均在远离河口海域较为丰富；而在2002年和2004年长江口海域亚历山大藻赤潮过后，其孢囊并未在该海域沉积物中积累，可能随长江冲淡水的流动向东北方向迁移，在粘土含量较高、水较深的黄海中心海域沉降并积累。大亚湾海域常见有害赤潮藻——锥状斯氏藻是一种较易形成孢囊的藻类，中度N限制能促进其孢囊的形成；该藻孢囊萌发率也较高，高温和长时间保存不利于孢囊的萌发，强制性休眠期为15～25d。锥状斯氏藻孢囊的大量形成导致了营养细胞种群密度的消减和赤潮的消亡，并为下一次赤潮的发生积累了丰富的种源；而该藻孢囊高的萌发率及较短的休眠期致使该藻在一年内多个季节反复引发赤潮。通过3d一次的浮游植物分析，首次观察到了大亚湾大鹏澳海域亚历山大藻营养细胞的冬季高峰，最大细胞密度达603cells／mL，之后孢囊形成率也达到高峰，最高为4．56×10⁴cysts／m²d。全年大部分季节，贝类体内PSP毒素含量均在联合国粮农组织规定食品卫生标准4 MU/g_贝肉以下，但毒素含量出现了明显的冬季高峰，最高值为72．2 MU／g_贝肉。毒素主要集中在贝类消化腺，最高可达350．4 MU／g_贝肉。毒素含量与亚历山大藻细胞密度、孢囊形成率之间存在明显正相关关系。结果说明，大亚湾冬季贝类体内高含量的PSP毒素是由高密度亚历山大藻营养细胞和孢囊共同作用的结果。更多还原

【Abstract】 Distribution of dinoflagellate cysts in surface sediments from Chinese coastal waters was inverstigated, and 61 cyst types were detected during the survey, in which 14 morphotypes were first reported from the China sea. Cysts of toxic dinoflagellates, Alexandrium spp. and Gymnodinium catenation distributed widely but in low concentrations in most stations. A collection of illustrative plates of common cyst types in sediments collected from Chinese coastal sea areas were established by taxonomy study and characteristic description.Vertical distributions of cysts were studied in Daya Bay, Shenzhen Bay and Zhelin Bay, the South China Sea. The cyst assemblages recorded in about 20 cm sediment cores revealed the envirenmental changes and HAB records in the recent twenty years. Results indicated that the eutrophication was more severe resently, and the trophic levels from higher to lower were: fish cage areas, shellfish aquacultural areas, inshore areas and offshore areas, respecitively.Composition and seasonal distribution of cysts were studied from 2002 to 2003 and in spring of 2004 during a huge bloom of Prorocentrum donghaiense accompanied by Alexandrium sp. in Changjiang Estuary. Both cyst species richness and concentrations were higher in regions with higher longitude and lower latitude, where is more far away the river mouth. Low concentrations of Alexandrium cyst were analyzed in surface sediments during and after Alexandrium blooms, which suggested that cysts formed during the bloom did not settled and accumulated in the bloom area. It is supposed that these cysts of Alexandrium might move northward with diluted water of Changjiang River, and settled in the central area of the Yellow Sea.Scrippsiella trochoidea, the common HAB species of Daya Bay, had high efficiency to produce cyst. Moderate nitrogen depletion was favorable for its cyst formation. The germination rates were from 75% to 82%, and decreased obviously after stored under high temperature （25℃） and in long duration （over 30d）. The dormancy period for S. trochoidea cysts was 15-25d. The results suggest that massive cyst formations results in a considerable loss of S. trochoidea population in the water column, which contribute to the collapse of algal blooms, whereas, the cysts supply rich "seed bed" for the occurrence of next bloom. Meanwhile the high germination rate and short dormancy period provide this species the ability to germinate and form blooms repeatedly in all seasons of the year in coastal areas of Guangdong Province. The PSP contents in shellfish were generally below the limit level suggested by FAO of UN (4 MU/g _tissue) in most samples, however an obvious peak value occurred in winter, and maximum of 72.2 MU/g _tissue was analyzed, just after the peak abundance of Aexandrium vegetative cells and cysts. The maximum cell density and cyst flux of Alexandrium were 603cells/mL and 4.56×10⁴ cysts/m² d, respectively. The toxins mainly accumulated in peptic of the shellfish, the maximum toxin content in peptic was high up to 350.4 MU/g _tissue. There were significant positive relationships between toxin level and vegetative cell density and cyst flux. From the results, it could be suggested that abundance of vegetative cells and cysts of Alxandrium influenced the toxin content directly and therefore resulted in the high winter level of PSP toxin in this area.更多还原