茂名市大放鸡岛海域浮游植物群落的季节变化

Seasonal variation of phytoplanktonic community in the waters around Dafangji Island,Maoming City,Guangdong Province

2003年8月、12月和2004年2月、5月在大放鸡岛海域多个站位进行了浮游生物调查,对该海区的浮游植物种类组成、不同季节各站位的细胞丰度分布、优势种及群落多样性进行了分析。四次调查共鉴定出浮游植物57种,大多数属浮游硅藻。角毛藻属、丹麦细柱藻、脆根管藻和尖刺菱形藻为全年优势种类。浮游植物细胞丰度大致为8月>12月>5月>2月。5月和8月浮游植物群落多样性水平较高,12月和2月浮游植物群落多样性水平较低。2月和5月群落均匀度较高,较为稳定,而8月和12月群落均匀度较低,稳定性差,少数种类因此大量繁殖,形成优势类群,成为赤潮暴发的潜在生物要素。

The present paper deals with the species composition, cell abundance, predominant species and community diversity of phytoplankton in the waters around Dafangji Island based on the materials taken from the planktonic surveys carried out in August and December 2003, and February and May 2004. There were 57 species of phytoplankton collected and examined during four investigations mentioned above, most of them were planktonic diatom. The predominant species were Chaetoseros spp. , Nitzschia pungens, Leptocylindrus danicus, Rhizosolenia. stolteoCothii and Rhiz.fragilissima throughout the year. The cell abundance from high to low could be listed as August, December, May and February. The diversity of phytoplanktonic community was greater in May and August than that in December and February. Moreover, the evenness of phytoplanktonic community was greater in February and May as compared with that in August and December. There was a possibility in happening red tide as a result of mass reproduction of predominant species in the case of low community evenness.