三峡库区典型支流春季特征及其水华优势种差异分析

三峡水库蓄水后,多年来众多支流水华频发引起广泛关注。为研究春季三峡库区不同区域典型支流特征及水华的差异性,选取小江、大宁河、香溪河为研究对象,于2015年春季对三条支流进行监测与分析。结果表明:三条支流回水区长度与宽度有所区别,小江、大宁河、香溪河的蜿蜒度分别为2.151、1.384、1.126;长江干流水体以表层倒灌潜入小江,以中上层倒灌潜入大宁河,由中层倒灌潜入香溪河,越靠近库首,其倒灌影响距离相对越远,分别占研究回水范围的61.9%、69.2%和80.7%;温跃层梯度逐渐减小,水温呈现不同的层化结构,回水区上游水温较下游高;三条支流的光混比变化规律相似,水体中的总氮、总磷含量能够为藻类生长提供丰富的营养条件;春季水华的优势藻种及各优势种的分布区域有所不同,回水区上游更易暴发高强度水华,小江水华优势种主要包括蓝藻、绿藻、甲藻、硅藻;大宁河多发生以绿藻为优势藻种的水华,偶尔伴有甲藻、硅藻和隐藻水华,香溪河春季优势共存的水华类型较多见,多发生硅藻、甲藻水华,有时出现绿藻水华。倒灌异重流是三条支流水华暴发呈现分区的主要原因,水温及水动力条件差异是造成三条典型支流水华优势藻种存在差异的主要因素。

THE VARIANCE ANALYSIS OF CHARACTERISTICS AND BLOOMS OF THE TYPICAL TRIBUTARIES OF THE THREE GORGES RESERVOIR IN SPRING

In order to understand the fish diversity and the community structure in Northwest Hubei,investigation was carried out in Baguashan,Duheyuan,Yerengu,Nanhe,Wudaoxia and Zhangheyuan nature reserves in Northwest Hubei from 2007 to 2012.We recorded 79 species,belonging to 4 orders,15 families and 51 genera.Among all the species,order Cypriniformes was the most dominant component (70.89％),with 56 species recorded.Feeding diets and ecological groups of fish were similar among the six nature reserves.Carnivorous and omnivorous fish were most abundant,and herbivorous fish were among the minority.Limnophilic fish was far more than diadromous and rheophilic species.The Margalef index (D) at Duheyuann natural reserve was the largest,with a value 2.60,whereas the lowest D was found at Baguashan natnral reserve (0.91).The diversity index showed that the nature reserves in the same drainage system had a low βC index and βR index than those between different drainage systems.The index of similarity (Cj) was high between the natural reserves in the same drainage system and low between different drainage systems,explaining well the fact that the nature reserves in the same drainage system has the continuity of the geographical environment while the nature reserves between different drainage systems existed the geographical isolation.The hydropower development and overfishing are the greatest threat to the region fish.It is suggested to strengthen the fishery management and establish artificial fish breeding sites,to reduce the negative effects of water-power engineering and restore natural fishery resources.