西洞庭湖鱼类物种多样性及其时空变化

洞庭湖是长江中游现存仅有的两大通江湖泊之一，研究其鱼类资源对了解湖泊通江的生态作用有着重要意义。为此，在2002年9月~2004年6月每月定期定点在西洞庭湖区开展鱼类调查，结果如下：① 实地调查到鱼类111种，隶属9目20科，包括中华鲟、胭脂鱼等珍稀物种；②鱼类物种数年动态波动较大,最高月份达69种，最低为26种，月均50±13种；③物种多样性指数年动态与物种数年动态大体一致，最高达3.34，最低为1.89，月均2.84±0.38；④空间分布上，位于入湖口的调查点物种数和多样性指数高于内湖，且差异有显著性(p<0.05)；⑤在数量上，湖泊定居型鱼类占50%以上，其中，鲫数量最多，占16%左右。可见：西洞庭湖作为通江湖泊在鱼类多样性的保护上起到避难所和交流场所的作用；目前，西洞庭湖鱼类在生态组成上，湖泊定居型鱼类比重有逐渐增加的趋势。

FISH SPECIES DIVERSITY AND ITS SPATIO-TEMPORAL VARIATION IN WEST DONGTING LAKE

As Dongting Lake is one of the two biggest lakes still linked with the Yangtze River, its fish resource study becomes important and valuable for the evaluation of lakes in the river basin. Therefore, a monthly survey of fish resource was carried out from September 2002 to June 2004. 111 species belonging to 9 orders and 21 families were recorded, including some cherish and rare species, e.g. Acipenser sinensis Gray, and Myxocyprinus asiaticus. The number of fish species varied within the year, with the highest number 69 species, the lowest 26. The dynamics of diversity index matched well with the number of species, with its fluctuation being relatively even at an average of 2.84±0.38. The number of species and then diversity in connecting areas with water flowing into lakes were higher than those in opening water areas of the lake. The limnicolous fishes accounted for over 50% of individual fishes, among which the common carp Carassius auratus auratus was the most abundant, accounting for 16%. In conclusion, as a linking lake, west Dongting Lake acts as shelter and intercourse grounds for fishes and is a place for the protection and restoration of fish diversity in the lake and also in the Yangtze River. The fact that the percentage of limnicolous fishes increased over recent years at west Dongting Lake should be considered in any project in order to protect the natural fish resource in the lake and also in the river.