北部湾海域秋、冬季毛颚类的种类组成与数量分布

Species composition and quantity distribution of Chaetognatha in Beibu Bay in autumn and winter

为了解和掌握北部湾渔场生态环境的动态变化规律,于2001年11月至2002年1月对北部湾海域进行了2个航次的调查。结果表明,该海域毛颚类种类组成较为简单,样品中共鉴定出13种,其组成无明显季节变化。调查期间毛颚类栖息密度、生物量和多样性指数的变化范围分别为0.76～45.70/m^3、2.00～70.04mg/m^3和0.18～1.99;秋、冬季平均值分别为12.03/m^3、23.19mg/m^3、0.81和6.29/m^3、19.61mg/m^3、0.90。主要优势种为肥胖箭虫(Sagitta enflata)、小箭虫(Sagitta neglecta)和百陶箭虫(Sagitta bedoti)。三者栖息密度分别占毛颚类总栖息密度的10.4％、3.1％和1.8％。栖息密度和生物量的分布总体呈现北高南低、西高东低的趋势,不同季节表现略有差异。多样性指数以湾口较高、湾顶较低,呈湾口向湾内西北方向递减趋势。此外,本研究对毛颚类的种类组成、数量分布与水系、水团、水温及盐度等环境因子的关系进行了初步的探讨。

Two cruises were carried out for ecological survey on zooplankton in Beibu Bay (South China sea) from November 2001 to Januaray 2002. Thirteen species of Chaetognatha were identified, and the species composition in the collected specimens was simple. No obvious seasonal variation was observed. During the survey, the density of Chaetognatha ranged from 0. 76 to 45.7 ind/m3 with the average of 12. 03 ind/m3 in autumn and 6. 29 ind/m3 in winter, and the biomass ranged from 2.00 to 70.04 mg/m3 with the average of 23. 19 mg/m3 in autumn and 19.61 mg/m3 in winter, while the diversity index ranged from 0.18 to 1. 99 with the average of 0. 81 in autumn and 0.90 in winter. The Chaetognatha were mainly dominated by Sagitta enflata (in both seasons) , S. neglecta (in autumn) and S. bedoti (in winter) ,which accounted for 10.4% , 3. 1% and 1.8% of the total density, respectively. From north to south and west to east, the distributions of Chaetognatha density and biomass showed decreasing tendency , but varied slightly in different seasons. The diversity index was high in the mouth and low in the top of the bay, and showed an decreasing trend from the bay mouth to the northwest inside the bay. The relationships between the species composition and quantity distribution of Chaetognatha and the environmental factors, such as aquatic system, water mass, water temperature and salinity, etc, are also discussed.