作 者 ：赵汉取,李纯厚,杜飞雁,王学锋,李占东,贾晓平
期 刊 ：生态学报 2007年 27卷 1期 页码：25~33
Keywords:Planktonic Ostracoda, species composition, abundance distribution, biodiversity, Beibu Gulf,
摘 要 ：根据1998年1月～1999年5月北部湾海域4个航次生态环境综合调查资料，对北部湾海域浮游介形类进行分析研究。结果表明，北部湾渔场浮游介形类物种组成较为简单，记录有小型海萤（Cypridina nana）、齿形海萤（Cypridina dentata）、尖尾海萤（Cypridina acuminata）、纳米海萤（Cypridina nami）、针刺真浮萤（Euconchoecia aculeata）、细长真浮萤（Euconchoecia elongata）、后圆真浮萤（Euconchoecia maimai）等18 种；隶属于2亚目、2科、4亚科、12属，其中有4种周年出现，9种只在特定的单一季节出现，其余5种季节性出现；夏季和冬季出现的物种数最多，达到11种；春季次之，为9种；秋季最少，只有6种。北部湾浮游介形类可以划分为3个生态类群，即低盐暖水类群、广温广盐类群和高温高盐类群，优势种群主要是近岸低盐暖水类群的针刺真浮萤和尖尾海萤。全海域栖息密度变化范围为0.02~51.58 ind./m3，年平均1.22 ind./m3，春季最高，达2.73 ind./m3，在湾西北部密集有大量的针刺真浮萤；夏季此密集区逐渐向湾中部移动，纳米海萤为其密集种，栖息密度也有所降低；秋、冬季量少，但在湾南、北部各出现一个丰度相对较高的密集区，并由南北向湾中部递减。总生物量具有明显的季节性变化，平面分布趋势与栖息密度相似。生物多样性指数低，以湾口较高、湾顶较低，呈湾口向湾内西北方向递减趋势；全海域年平均多样性阈值为0.329，四季多样性水平皆为Ⅰ级，多样性程度低；多样性程度较高的区域，多出现于受外海水影响较大、水文状况变化较为复杂的海域。对浮游介形类的物种组成、丰度分布及多样性与北部湾的水系、水团、水温及盐度等环境因子的关系进行了探讨。
Abstract:Species composition, abundance and diversity of the Planktonic Ostracoda were investigated during four cruises conducted in the Beibu Gulf, between Feb 1998 and May 1999. A total of 18 species of planktonic Ostracoda were identified, including Cypridina nana, Cypridina dentata, Cypridina acuminata, Cypridina nami, Euconchoecia aculeata, Euconchoecia elongata, Euconchoecia maimai, and other taxa. Species composition was relatively simple, with four species occurring year round, nine species only appearing in one certain season, and five species appearing in several seasons. The maximum number of Ostracod species (11) was recorded during both summer and winter, while a minimum of 6 species were present in autumn. Planktonic Ostracoda in the gulf were divided into 3 ecological types: (1) a hyposaline and warm-water group, (2) a eurythermal and eurysaline group, and (3) a hyperthermal and hysaline group. The warm water species such as Euconchoecia aculeate and Cypridina acuminate were the dominant Ostracod species in the gulf, where overall Ostracoda density ranged from 0.02 to 51.58 ind./m3 and averaged 1.22 ind./m3. The highest average value (2.73 ind./m3) was found in spring. In the northwest region of the gulf, the assemblage consisted of Euconchoecia aculeate, and in summer the dominant species shifted to Cypridina nami in the middle of the gulf. In autumn and winter, although Ostracoda density was low, two assemblages with relatively high abundances could be found in the southern and northern gulf. The density was gradually lower toward the center from the southern and northern gulf. Seasonal variations in horizontal distribution of biomass showed similar patterns as those in density mentioned above. The diversity threshold of Ostracoda averaged 0.329 in the gulf. The mouth and the head regions of the gulf had the maximum and minimum diversity index values, respectively. A trend toward decreasing diversity was observed along the gulf northwestward from the mouth. Fuzzy evaluation measures indicated that the diversity in the gulf remained low (class 1 level) during all seasons. Diversity appeared to be relatively higher in some regions in which the water mass was strongly influenced by the open sea and had complex structures. This paper also discusses how the species composition, abundance, and diversity of planktonic Ostracoda are influenced by environmental factors (e.g., aquatic system, water mass, water temperature, salinity) in the Beibu Gulf.