丹江口水库浮游植物及其演变

COMPOSITION AND ECOLOGICAL CHANGES OF PHYTOPLANKTON IN DANJIANGKOU RESERVOIR

１９９２年１２月至１９９３年９月对丹江口水库进行四季调查，共采集到浮游植物６０属；年平均密度为４２．１８×１０＾４个／Ｌ，生物量为０．７１ｍｇ／Ｌ。浮游植物种类和现存量在库区的分布均表现为汉江库区较丹江库区丰富。本文还根据１９５８年、１９８６￣８７年和１９９２￣１９９３年丹江口水库库区的三次 调查资料，分析丹江口水库蓄水前后以及建库２６年以来浮游植物群落结构（包括密度、生物量。

The community composition of phytoplankton was investigated in Danjiangkou Reservoir in December 1992, January, April and September 1993. A total of 60 genera were collected including 19 genera of Bacillariophycea, 26 genera of Chlorophycea and 8 genera of Cyanophycea. There were 42. 18 × 10~4ind./L in annual mean density and 0.71 mg/L in biomass. It is showed that the number of species (37 genus) and standing crop (54. 5×10~4 ind. /L) in Hanjiang district were higher than those (26 genera and 26. 5×10~4 ind. /L) in Danjiang district. This paper also summarizes the data of phytoplankton taken from the surveys made in 1958, 1986~1987 and 1992 - 1993 in Danjiangkou Reservoir, and discusses the main ecological changes of phytoplankton association (abundance, biomass, species composition and seasonal variation) before and after the construction of the reservoir. After dammed, the adun-dance of planktonic algae was increased by several times, from ten thousand to millions of individuals per liter. The dominance of Bacillariophycea was gradually replaced by Bacillariophycea, Cryptomonads and blue-green algae.