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太湖微囊藻水华及其产毒的生态学研究
Alternative TitleECOLOGICAL STUDIES OF MICROCYSTIS BLOOMS AND MICROCYSTINS IN LAKE TAIHU
刘娅琴
Subtype硕士
Thesis Advisor谢平
2007-06-16
Degree Grantor中国科学院水生生物研究所
Place of Conferral水生生物研究所
Degree Discipline水生生物学
Keyword微囊藻 微囊藻毒素 选择性滤食 生物操纵
Abstract本文研究了太湖处于不同营养状态的两个湖湾中浮游植物的季节动态、水体微囊藻毒素季节动态以及微囊藻水华及其产毒对两种优势河蚌对浮游植物选择性滤食的影响,同时关注了滤食性鱼类对浮游植物的生态学效应。实验期间 (2004.11-2005.10), 共鉴定出浮游植物125种,隶属8门71属。其中3、4、5月绿藻占优势,其它时间蓝藻占优势。在温暖季节,浮游植物总生物量非常高,梅梁湾浮游植物总生物量年平均值显著高于贡湖湾。两湖湾中不仅浮游植物生物量有显著差异,群落结构也不尽相同。构成太湖蓝藻水华的微囊藻在5月份开始出现,6月份其生物量急剧增长并在7月达到峰值,尽管在10月份之后微囊藻生物量下降到1 mg/l 之下,但其绝对优势地位一直持续到次年2月,微囊藻生物量与 N 水平显著负相关。本研究中,微囊藻毒素的检测分为胞内毒素和胞外毒素。胞内毒素含量范围在检测限之下到5.80µg/l ,胞外毒素含量从检测限之下到0.22 µg/l。微囊藻毒素含量与微囊藻生物量之间具有显著正相关关系, 但在微囊藻生物量高的梅梁湾,毒素含量反而较低,这表明微囊藻毒素除了与生物量有关外,还可能与其他因素比如有毒藻株和无毒藻株的比率有关。此外,微囊藻毒素含量与N水平显著负相关,N 是微囊藻水华暴发和产毒的重要影响因子,N可能通过对微囊藻生长的影响来间接影响其产毒。研究期间,三角帆蚌和褶纹冠蚌蚌肠道内微囊藻占浮游植物的百分率远小于水体中微囊藻占总浮游植物的百分率,表明这两种淡水河蚌对微囊藻均有明显的拒食作用。研究发现,蚌对微囊藻的选择度(蚌肠道内微囊藻的百分率/水体中微囊藻的百分率)随着水体中微囊藻百分率的升高而降低,在蚌不能自主运动的时候,拒食能力降低。研究还发现蚌对栅藻具有很高的偏好,这可以部分由于绿藻含有相对较多的多不饱和脂肪酸,因而是高质量的食物。蚌对栅藻的这种偏好不受微囊藻的影响,却能被丝藻极大程度的抑制,而蚌对丝藻的选择性不强。鱼控藻区,围栏内浮游植物年平均生物量为8.39mg/L,围栏外为9.74mg/L。在微囊藻水华大量暴发时(7-8月),围栏内的微囊藻生物量(20.5mg/L)远低于围栏外(47.9mg/L);鲢、鳙对浮游植物的滤食同时还改变了浮游植物的群落结构,在水华暴发期间,围栏内浮游植物生物量中72.0%来自微囊藻 (2005年8月),硅藻和隐藻占有一定的份额,而在围栏外,由于缺乏鲢、鳙对微囊藻的控制作用,微囊藻占浮游植物总生物量的比例甚高 达88.0%(2005年8月)。研究还显示,在鲢、鳙降低微囊藻生物量的同时,微囊藻毒素含量也相应的降低了,所有这些都表明在梅梁湾通过非经典生物操纵来控制水华蓝藻及微囊藻毒素污染是一条行之有效的途径。
Other AbstractSeasonal dynamics of phytoplankton biomass and microcystins content, and the selectivity of phytoplankton by two freshwater bivalve mussels (Hyriopsis cumingii and Cristaria plicata) were investigated from November 2004 to October 2005 in two bays of Lake Taihu with different nutrient status. We also studied the ecological effects of silver and bighead carp on phytoplankton. During the survey period, 71 phytoplankton genera were identified belonging to eight phyla: Cyanaphyta, Chlorophyta, Bacillariophyta, Cryptophyta, Euglenophyta, Pyrrophyta, Chrysophyta and Xanthophyta. Cyanaphyta and Chlorophyta comprised over 90% of total numeric abundance. Dominant phytoplankton were Chlorophyta during May and July, and Cyanaphyta in the other months. There were significant differences in both biomass and structure of phytoplankton between the two bays. Biomass of phytoplankton was significantly higher in Meiliang Bay (0.56-10.31 mg/l) than in Gonghu Bay (1.02-7.31mg/l) (p < 0.05, n = 36). Microcystis was an absolutely dominant spicies, significantly correlated with N loading. It appeared in May, increased dramatically in June, and peaked (3.7×108 cells/l) in July. There were also significant differences in both density and biomass of Microcystis between the two bays (p < 0.05, n = 36). The toxins from phytoplankton samples were identified as microcystin (MC), including three variants, MC-LR, MC-RR and MC-YR. The intracellular MC content, ranging from undetectable to 5.80µg/l, was relatively high in summer (from July to September) when heavy cyanobacterial blooms occurred. The highest amounts of intracellular MCs were found in the July samples from Gonghu Bay. The mean concentration of intracellular MCs was much higher in Gonghu Bay than in Meiliang bay (p<0.01). The intracellular MC content was positively correlated with Microcystis biomass in both bays. The reason for the lower MC concentration in Meiliang Bay whereas Microcystis biomass was higher might be due to a lower ratio of toxic to nontoxic strains. Percentage of Microcystis in total phytoplankton in the gut contents of two mussels (Hyriopsis cumingi and Cristaria plicata) were much lower than those in water column, indicating that both mussels had an ability of rejecting Microcystis. The selectivity of Microcystis by mussels declined with increasing percentage of Microcystis in the water column. Both mussels preferred Scenedesmus, probably because Chlorophyta are a good food. This favor of mussels was little influenced by Microcystis but strongly suppressed by Ulothrix. Because of intense feeding of silver and bighead carp on phytoplankton, Microcystis biomass was much lower in the fish pens than in the surrounding lake waters. Grazing pressure of silver and bighead carp not noly decreased total phytoplankton biomass and microcystin concentration, but also changed structure of phytoplankton community. These indicate that it is an effective way to control the Microcystis blomms and microcystins product through non-traditional biomanipulation.
Pages84
Language中文
Document Type学位论文
Identifierhttp://ir.ihb.ac.cn/handle/342005/12206
Collection学位论文
Recommended Citation
GB/T 7714
刘娅琴. 太湖微囊藻水华及其产毒的生态学研究[D]. 水生生物研究所. 中国科学院水生生物研究所,2007.
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