三沙湾浮游动物生态类群演替特征

根据2010年6月-2011年5月三沙湾海域5个航次海洋综合调查资料,对三沙湾浮游动物种群特征进行分析,并与我国不同纬度海湾生态类群结构进行比较.探讨三沙湾海域浮游动物生态类群季节变化特征及其受水团季节变化的影响.研究结果表明:4月和5月三沙湾海域主要受到浙闽沿岸流影响,生物多样性H'指数分别为2.03和2.02；种类数分别仅为17种和19种,明显低于6月、8月和10月;浮游动物生态类群以暖温带近海种为主；优势种种类数少,单一优势种优势性明显,4月中华哲水蚤丰度占浮游动物总丰度的65.03％；群落结构特征与同期我国长江口浮游动物区系特征相似.6月三沙湾海域受到浙闽沿岸流和台湾暖流共同影响,同时因闽北雨季导致大量大陆径流汇入,使得该月浮游动物种群结构复杂,生物多样性指数和种类数全年最高,为3.12和45种,与5月相比,种类更替明显,物种更替率为69.39％；亚热带近海种丰度百分比最高(73.03％),亚热带外海种种类数百分比次之(48.89％),是海域浮游动物生态类群由以暖温带近海种为主向以亚热带外海种为主的过渡时期.8月和10月浙闽沿岸流消失,三沙湾海域受台湾暖流控制,海水温度和盐度升高,生物多样性指数和种类数均略低于6月；生态类群结构以亚热带外海种为主；优势种特征表现为种类数多而各个优势种丰度较低；浮游动物群落结构特征与南海北部海域浮游动物组成极为相似.

Seasonal succession of zooplankton in Sansha Bay, Fujian

The semi-enclosed coastal waters of northeastern Fujian (Sansha Bay) are an important natural spawning ground for the large yellow croaker (Larimichthys crocea) in China. The yellow croaker is an important species for Chinese fisheries, and depends on a healthy zooplankton population. In this study, the seasonal succession of zooplankton in Sansha Bay was described and its relationship to the currents from the open sea was analyzed. Sampling was carried out in June, August and October 2010, and in April and May 2011. Seasonal changes in the zooplankton community structure were strongly influenced by the coastal current and the Taiwan Warm Current as well as an influx of freshwater from the mainland. A total number of 71 species of zooplankton were identified, which consisted of 19.72% warm temperate nearshore species, 30.99% subtropical nearshore species and 47.89% subtropical offshore species. In April and May, influenced by the coastal current, the water temperature and salinity were both low, which induced a bottoming-out in the diversity index (H') (2.03 and 2.02, respectively) as well as the number of species (17 and 19, respectively). The zooplankton fauna was exclusively of the warm temperate nearshore type, especially in April. Both the species number and abundance of warm temperate nearshore species were high (76.47% and 96.28%, respectively). Calanus sinicus, one of only a few dominant species in April, comprised 65.03% of the total abundance of all zooplankton. The simple structure of the zooplankton fauna comprised only a few species and with a high contribution made by each of the dominant species in this period was similar to characteristics noted in the warm-temperate water area north of the Yangtze River. During the June rainy season, a high diversity index (3.12) and species number (45) were recorded owing to the impact of the coastal current, the Taiwan Warm Current and a high volume of fresh water input. These were the most influential factors on the complex taxonomic structure and eco-group composition of the zooplankton fauna. June also displayed the highest species turnover rate, reaching up to 69.39%, compared with other months. The dominate eco-group type changed rapidly from warm temperate and subtropical nearshore species to subtropical offshore species in this month. Subtropical nearshore species comprised the highest proportion of species (73.03%). Subtropical offshore species contributed 48.89% of the overall abundance. After the rainy season, in August and October, there was a slight decrease in diversity index and species number, and the water temperature and salinity increased sharply owing to the strong affect of the Taiwan Warm Current. The zooplankton community was dominated (in terms of species numbers and density) by highly diversified subtropical offshore species. Its proportion of species number and abundance in August were 57.14% and 59.94%, respectively, and species number proportion was 57.58% in October. The community structure had many more dominant species than in April and May, of which the vast majority were subtropical offshore species. The characteristics of the zooplankton community in Sansha Bay were similar to those in the subtropical water areas of the South China Sea.