【摘要】 广西三娘湾是中华白海豚(Sousa chinensis)春、秋季的重要栖息地之一,生境现状不容乐观.根据2011年10月(秋)、2012年3月(春)在三娘湾近海15个测站获取的51份浮游植物样品,分析该区浮游植物群落结构与变化,比对毗邻海区分析讨论测区浮游植物与环境因子的关联关系,并从浮游植物角度探讨中华白海豚的生存状态.共鉴定浮游植物4门45属123种(不包括未定种),群落组成以硅藻为主,其次是甲藻.两季共有优势种1种,10月优势种为旋链角毛藻(Chaetoceros curvisetus)、丹麦细柱藻(Leptocylindrus danicus)、柔弱伪菱形藻(Pseudo-nitzschia delicatissima)、尖刺伪菱形藻(Pseudo-nitzschia pungens)等多个物种;3月则为几内亚藻(Guinardia)的3个物种完全占优势.测区浮游植物平均丰度为222.49×10~3 cells/L,10月比3月约高1倍.10月丰度的表底两层分布一致,3月则不一致.两季浮游植物物种多样性和均匀度总体较好,群落结构处于较完整和稳定状态,但3月群落状态相对较脆弱.与广西毗邻海区相比,本区总物种数目处于中等水平,种类组成与其他海区相似,相同季节的优势种却有大差别.测区10月表层浮游植物丰度与磷酸盐浓度、叶绿素a浓度表现出显著正相关;3月表、底两层的丰度均与水温呈现较好的正相关.尖刺伪菱形藻、夜光藻(Noctiluca scintillans)等赤潮藻在三娘湾均可检出一定丰度,一旦爆发藻华,就可能危及中华白海豚生存.因此为了长期保护濒危物种中华白海豚,除了长期监测其种群外,还应定期调查评估栖息地生境.更多还原

【Abstract】 For a comprehensive understanding of the phytoplankton community structure, ecological status related to environmental factors of the habitat of Sousa chinensis needs to be investigated. This paper aimed to study the role of phytoplankton in the habitat of Sousa chinensis in Sanniangwan Bay of Guangxi Province, China. Based on 2 cruise surveys at 15 stations in 2011 and 2012, we analyzed the phytoplankton community in terms of species composition and cell density quantification, and compared it with that of adjacent area. We also determined the relationship between phytoplankton and environmental factors to evaluate the survival state of Sousa chinensis from the view-point of phytoplankton. A total of 123 species(excluding unknown taxa) belonging to 45 genera of 4 classes were identified in 51 samples, in which diatoms were predominant in both species composition and abundance. Dinoflagellates contributed the second major group. The dominant species were Chaetoceros curvisetus, Leptocylindrus danicus, Pseudo-nitzschia delicatissima, P. pungens and others in October, but mainly Guinardia flaccida, G. striata, and G. delicatula in March. G. striata was the only common dominant species in the two seasons. The average phytoplankton abundance was 222.49 × 103 cells/L, with that of October about two times greater than that of March. Significant difference existed for phytoplankton abundance between the surface layer and the bottom in March but not in October. Both Shannon-wiener diversity index and Pielou’s evenness index were higher in October than in March, indicating an integrated and stable state of phytoplankton community in October but a relatively vulnerable one in March. Compared with the adjacent areas in Guangxi, the Sanniangwan Bay had medium level of richness of phytoplankton species, similar species composition but different dominant species of the same season. Pearson Correlation Analysis of phytoplankton abundance with environmental factors indicated that the phytoplankton abundance was positively correlated to the abio-phosphate and chlorophyll a content in the surface water of October, and to the temperature in both surface andbottom of March. The results showed that the biotope status of the Sanniangwan Bay of Guangxi Province is not at present a sound environment for the population reproduction of Sousa chinensis. Red tide algal species such as P. pungens and Noctiluca scintillans abound in Sanniangwan Bay, which may endanger the Sousa chinensis population if explosive proliferation of HAB species occurs. For better protection of endangered species of Sousa chinensis, long-term monitoring of the Sousa chinensis population and regular evaluation surveys for habitat environment are needed.更多还原