为了解三峡水库长江干流不同水文期底栖硅藻群落变化及其与环境因子的关系,分别于非蓄水期(2015年7~9月)和蓄水期(2015年12月~2016年3月)对干流32个样点进行底栖硅藻采集和分析.结果表明,蓄水期与非蓄水期在水温(WT)、水下光强(PAR)、p H、电导率(Spc)、溶解氧(DO)、氧化还原电位(ORP)、浊度(Tur)、透明度(SD)、流速(v)和高锰酸盐指数具有显著性差异. 2个水情期共鉴定出底栖硅藻96种,隶属28属,非蓄水期鉴定出13种优势种,蓄水期鉴定出3种,且2个时期优势种在组成和分布上存在一定的差异,但α-中污染性、富营养化的种类变异直链藻(Melosira varians)为两个时期的绝对优势种.通过冗余分析(RDA)发现,非蓄水期显著影响长江干流底栖硅藻群落组成的环境因子是pH、流速和正磷酸盐,且上、下游样点存在明显分区;而蓄水期影响底栖硅藻群落的主要环境因子是水温、浊度、高锰酸盐指数和溶解氧,上、下游样点分区不明显.这些结果表明三峡库区蓄水对底栖硅藻群落组成具有重要影响,导致群落结构发生变化.
In order to study changes in benthic diatom communities and their relationships with environmental factors during different hydrological periods,32 sites were sampled in the main stream of the Three Gorges Reservoir during the non-storage period( July 2015 to September 2015) and the storage period(December 2015 to March 2016). Results showed that there were significant differences in water temperature(WT),underwater light intensity(PAR),p H,conductivity(Spc),dissolved oxygen(DO),redox potential(ORP),turbidity(Tur),transparency(SD),flow rate(v),and permanganate index between the storage and non-storage periods.Ninety-six species of benthic diatoms,belonging to 28 genera,were identified during the two hydrological periods. Thirteen dominant species and three dominant species were identified during the non-storage period and the storage period,respectively,suggesting that some differences existed in the composition and distribution of dominant species between the two periods. However,Melosira varians,an α-polluting and eutrophic species,was dominant during both of the hydrological periods. Redundancy analysis(RDA) found that p H,flow rate,and orthophosphate (PO43--P) were the main environmental factors affecting the composition of benthic diatom communities,and a significant difference was found between up-and down-stream areas during the non-storage period. In comparison,water temperature,turbidity,permanganate index,and dissolved oxygen(DO) were the main environmental factors influencing the patterns of benthic diatoms communities,for which an insignificant difference was observed between up-and down-stream areas during the storage period. These results suggest that water storage in the Three Gorges Reservoir has an important impact on the composition of benthic diatom communities,and that this results in a change in community structure.
main stream of Yangtze River
Three Gorges Reservoir