低盐度围隔调控系统中浮游植物群落的组成

Community composition of phytoplankton in controlled enclosure system at low salinity levels

通过池塘陆基围隔实验,对凡纳滨对虾低盐度(2‰～6‰)调控养殖系统中的浮游植物群落与动态进行了研究。结果表明:低盐度调控实验围隔中共发现浮游植物7门58属86种,其中绿藻50种(丰富度为58.1%)、蓝藻18种(20.9%)、硅藻9种(10.5%)、裸藻4种(4.7%)及隐藻3种(3.5%);主要优势种有美丽胶网藻、狭形纤维藻、栅藻,铜绿微囊藻、拟柱胞藻、梅尼小环藻及尖尾蓝隐藻等;早期优势种多更替快,以绿藻为主,中后期蓝藻占优势,60%围隔以铜绿微囊藻为主要优势种;优势种的平均优势度达到59.6%。浮游植物密度平均2.97×107cells.L-1,Shannon-Wiener多样性指数2.18;施有机肥的围隔浮游植物种类丰富,多样性和密度高,群落稳定,有利于对虾健康养殖;大量施用无机肥,易诱发有害微囊藻爆发。

Experimental enclosures were set up in prawn （Litopenaeus vannamei） culture pond to study the community composition and its dynamics of phytoplankton at low salinity levels （2‰- 6‰）. A total of 86 phytoplankton species were identified, belonging to 7 phyla and 58 genera. There were 50 species of Chlorophyta （58.1% in species abundance） , 18 species of Cyanophyta （ 20. 9% ）, 9 species of Bacillariophyta （ 10.5% ）, 4 species of Euglenophyta （4.7%）, and 3 species of Cryptophyta （3.5%）. Dictyosphaerium pulchellum, Ankistrodesmus angustus, Scenedesmu sp. , Microcystis aeruginosa, neghinian and Chroomonas acuta were the dominant Cylindrospermopsis raciborskii, CycloteUa mespecies. In the early period of phytoplankton cultivation, the majority of the dominant species was of Chlorophyta, and its subrogation was rapid; while in the mid and late periods, Cyanophyta was in predominance, and M. aeruginosa was the dominant species in 60% of the enclosures. The average dominance of dominant species was 59.6%. The phytoplankton had an average density of 2.97×107 cells.L^-1, and its Shannon-Wiener diversity index was 2. 18. In the enclosures applied with organic manure, phytoplankton species were abundant, diversity and density were higher, and the community was stable, being favorable for prawn growth. Applying large amount of chemical fertilizers was liable to cause harmful M. aeruginosa bloom.