蓝藻水华暴发期间养殖池塘浮游藻类动态变化

Dynamic Changes of Phytoplankton Composition During Cyanobacteria Blooms in Aquaculture Ponds

中文关键词: 养殖池塘  理化因子  浮游藻类  蓝藻水华  微囊藻毒素

英文关键词: Aquaculture Ponds  Physio-chemical variables  Phytoplankton  Cyanobaterial blooms  Microcystins

中文摘要:

      2017年7~9月对河南师范大学养殖基地暴发蓝藻水华的养殖池塘进行监测。结果显示，共鉴定浮游藻类 25 种(属)，隶属于 5 门。7 月水华初期和 8 月水华中期，优势种均为微囊藻(Microcystis sp.)，占总浮游藻类的 99%以上。浮游藻类丰度和生物量波动范围分别为(0.883~12.666)× 108 cells/L和9.740~70.020 mg/L，生物多样性为0.05~1.15。总磷(TP)和总氮(TN)含量分别为0.32~0.51和4.18~7.09 mg/L，水温为22.1~30.6℃。TP、TN、水温较高是造成蓝藻水华暴发的主要原因之一，蓝藻水华暴发造成生物多样性整体偏低。冗余分析(RDA)结果显示，浮游藻类密度和生物量与TP、TN含量呈正相关，蓝藻门(Cyanophyta)与水温、TP、TN呈正相关。同时，微囊藻暴发最大的威胁是微囊藻毒素(Microcystins, MCs)的释放，根据世界卫生组织规定的MCs含量不得超过1.0 µg/L，否则就会对水生生物产生危害。实验结束时，对水样和胞内MCs的测定。研究表明，水样中MCs含量为0.040 µg/L，胞内MCs含量为0.686 µg/L，该养殖池塘微囊藻毒素含量在安全范围内。

英文摘要:

      In order to further understand the dynamics of phytoplankton and its physio-chemical variables during the development of cyanobacterial blooms in aquaculture ponds, water samples were collected and evaluated in an aquaculture pond during the cyanobacterial bloom (July to September, 2017) in Henan Normal University, Xinxiang, Henan (351938.363N, 1135409.482E). The results showed that during the study periods, in total, 25 phytoplankton species belonging to six phyla were identified, and the total phytoplankton abundance and biomass were (0.883~12.666) × 108 cells/L and 9.740~ 70.020 mg/L, respectively. Furthermore, the Shannon-Wiener index was determined, ranging between 0.05 and 1.15. Additionally, the total phosphorus (TP) and total nitrogen (TN) concentrations were 0.32~0.51 mg/L and 4.18~7.09 mg/L, respectively; the water temperature was 22.1~30.6℃. It was suggested that the high amount of TN and TP contents, combined with the high water temperature, might play important roles in this occurrence of cyanobacterial blooms and the low biodiversity in ponds. To further understand the key factors affecting phytoplankton composition, Redundancy analysis was applied. The results showed that cyanobacteria were closely related to the TP and TN concentrations and water temperature. In addition, in consideration of microcystin release due to the occurrence of Microcystis blooms, microcystin content was also determined in this study. At the end of the study periods, according to the ELISA, microcystin content was detected in algal cells and pond water, which were 0.686 µg/L and 0.040 µg/L, respectively. The World Health Organization suggested that the contents of microcystin should be no more than 1.0 µg/L in water samples. Thus, according to the present study, it suggested that the microcystin content was within the safety range in this bloom-occurring pond.