【作者】 康伟；

【导师】 王朝晖；

【作者基本信息】 暨南大学 ， 生态学， 2010， 硕士

【摘要】 采集了广东沿海典型养殖海域表层沉积物样品以及沉积物捕捉器样品,对沉积物中的孢囊进行分类鉴定,同时在25℃下对沉积物进行了直接萌发实验,对萌发的优势种类进行形态学和分子生物学鉴定,以了解广东典型海域沉积物中甲藻孢囊的分布状况、探讨浮游植物休眠体对营养细胞种群动态的贡献、揭示广东典型养殖海域赤潮发生潜势,为赤潮发生机制和防治研究提供参考和依据。研究结果显示,柘林湾、桂山岛海域甲藻孢囊种类多样性较低,分析鉴定出甲藻孢囊16种、22种。两海域孢囊类型大部分为世界各海域常见类型,且均以异养型孢囊占优势,其中以原多甲藻孢囊种类和密度最为丰富,显示了两海域较高的富营养化程度。柘林湾沉积物为较粗的泥沙型,不利于孢囊的沉降和积累,孢囊密度较低,在16.59-83.37 cysts/g DWt之间,平均为39.52 cysts/g D Wt,柘林湾较低的孢囊密度也与异养型孢囊的低产量有关；桂山岛海域沉积物为富含有机质的深棕色细沙粘土,而且防波堤降低了水体扰动,较有利于孢囊的沉积,孢囊密度较高,在110.33-315.08 cysts/g DWt之间,平均为202.37 cysts/gD Wt。有毒种巴哈马梨甲藻孢囊在柘林湾海域出现。桂山岛海域表层沉积物中亚历山大藻孢囊分布广泛,最高百分比可达56.88%,为亚历山大藻赤潮的发生提供了潜在种源。通过对柘林湾和桂山岛海域表层沉积物以及大亚湾大鹏澳海域沉积物捕捉器样品萌发实验得出,三个海域萌发出的浮游植物种类数均较少,低于同期浮游植物种类数的调查。柘林湾共萌发出浮游植物26属33种、桂山岛海域19属22种、大亚湾大鹏澳海域27属37种。硅藻种类主要有菱形藻、舟形藻、圆筛藻、具槽帕拉藻、骨条藻、角毛藻、海链藻等；甲藻种类数较少,包括亚历山大藻、斯氏藻、裸甲藻等常见有害种类。裸甲藻(Gymnodinium corii Schiller)为三个海域的甲藻优势种,其占甲藻细胞数量的平均百分比为73.1%,最高百分比可达100%；萌发还出现了大量金色藻、粘四集藻、色球藻、固氮蓝藻及球形棕囊藻。通过对沉积物的萌发,发现了一些研究海域未见报道的种类,丰富了海域浮游植物的信息。萌发的浮游植物优势种类与沉积物捕捉时间有一定的关系,种类组成随孢囊形成的季节变化而出现一定差异。研究结果表明,沉积物中休眠体的萌发可在一定程度上更为全面反映水体浮游植物组成,而在萌发中大量出现的一些微型和微微型浮游植物可能会由于体型过小而在浮游植物监测中被忽略。对萌发的优势种类裸甲藻进行了电子显微镜观察和分子生物学鉴定,通过形态学特征及rDNA ITS和LSU序列分析和对比,确定该裸甲藻为Gymnodinium corii。该裸甲藻在我国沿海尚未见报道,但由于其细胞裸露,体型微小,在常规生态学调查中很难区分至种,因此难以判断其是否为我国沿海新记录种。该藻在本研究萌发的浮游植物中频繁高密度出现,应加强对其监控,防止其赤潮的发生。更多还原

【Abstract】 Dinoflagellate cysts were identified and counted in surface sediments from Zhelin Bay and Guishan Island area of Guangdong province, in order to understand the distribution of dinoflagellate cyst in typical Guangdong coastal waters. Surface sediments from these two sea areas together with samples in sediment trap deposited in Daya Bay were incubated at 25℃under laboratory conditions to study the germination of cyst and other phytoplankton spores, and to discuss the contribution of resting spores to the vegetative population. Meanwhile, the dominant germinated species was identified by the morphological and molecular biology methods. The purpose of this study was to reveal the potential of the occurrence of harmful algal blooms (HAB) in Guangdong coastal waters, and to provide basic data and reference from HAB controlling and prevention.Results showed that cyst species diversities were lower in Zhelin Bay and Guishan Island area, with a total of 16 and 22 type identified respectively. Cyst types were of the common species in the two areas and the dominant species were those of heterotrophic species. Protoperidinium was the most abundant group in both species richness and quantitative number indicating the high eutrophic level in both sites. The cyst concentrations in Zhelin Bay were generally low due to the coarse sediment partials, which are not benefit for cyst deposition. Cyst concentrations in Zhelin Bay ranged from16.59 to 83.37 cysts/g D Wt with an average of 39.52 cysts/g D Wt. In addition, the predominance of cyst of heterotrophic dinoflagellates also contributed to the low cyst production in Zhelin Bay. The brown organic rich fine clay sediments in Guishan Island area favorite for the deposition and accumulation of cyst, and the embankment acts as a barrier to prevent the transference of cyst to the out area, which resulted in the high cyst concentrations. Cyst concentrations ranged from10.33 to 315.08 cysts/g D Wt with an average of 202.37 cysts/g D Wt in Guishan Island area. Cysts of the toxic species were observed in the survey, e.g. Polysphaeridinium zoharyi in Zhelin Bay, and cysts of Alexandrium spp. widely distributed in Guishan Island area with the highest proportion of 56.88%, indicating rich seed bed for Alexandrium blooms.Results from the germination experiments showed that the germinated phytoplankton species richness was lower than phytoplankton survey in all the three study areas. The species number was 33 in 26 genus in Zhelin Bay,22 in 19 genus in Guishan Island area and 37 in 27 genus in Daya Bay. The dominant diatom species included Nitzschia spp., Navicula spp., Coscinodiscus spp., Paralia sulcata, Skeletonema spp., Chaetoceros spp., Thalassiosira spp., and dominant dinoflagellate were Alexandrium spp., Scrippsiella spp., Gymnodinium spp. etc. Gymnodinium corii Schiller was the dominant dinoflagellate species in all of the three sites, with an average accounting for 73.1% of the proliferating dinoflagellate cells and the highest proportion up to 100%. Species in other phytoplankton groups such as haptophyta species Chrysochromulima spp. and Phaeocystis globosa, cyanobacteria species Anabaenopsis spp. and Chroococcus spp., chlorophyta specie Palmella mucosa, occurred abundantly in some samples. Species, which were not reported in study areas in previous surveys, were observed as well, which enriched phytoplankton information. The species composition of geminated phytoplankton was different after 20d and 40d incubation, and differed in samples collected from different months. Results from germination experiments suggested that the germination of resting spore better mirrored the phytoplankton composition in the water column to some extent. However, some nannophytoplankton species occurred abundantly in germinated phytoplankton, were seldom reported in water column in previous phytoplankton surveys, which might be ignored due to their small sizes.The dominant geminated species Gymnodinium sp. was observed under scanning electron microscope (SEM), and the sequences of ITS and LSU rDNA were analyzed. This species was identified as Gymnodinium corii based on morphological characteristics on SEM and rDNA sequences. This species has not been recorded in Chinese coastal water yes to the best of our knowledge. However, it is not meant that this species should be a new record in China and do not exist in the water column, due to the small cell size and naked cell wall. In our study, Gymnodinium corii occurred frequently and abundantly. Therefore, this species and other nanno harmful species should be put into regular monitoring to prevent the occurrence of its blooms.更多还原