珠江口底栖动物生态学研究

采泥样调查所获底栖动物一般为体形较小，活动能力较弱的种类，往往是一些底层鱼类和虾类等良好的天然饵料。珠江口海域渔业资源丰富，是中国南海区的主要渔场之一，因此，对该海域饵料底栖动物进行研究有重要意义。通过1999年9月和2000年4月分别对珠江口底栖生物进行的两个航次的采泥样调查，分别鉴定出底栖动物15衙睡21种，共计32种。底栖动物的优势种，秋季为光滑河篮蛤Potamocorbula laevis(Hinds)(Y=0.387)，春季为光滑河篮蛤（Y＝0．464）和欧虫Owenia fusformis Delle Chiaje(Y=0.120)。平均个体数量和生物量，春季为591.7ind./m^2和26.7g/m^2，秋季为85.0ing./m^2和7.4g/m^2;而在各类群生物中，软体动物占绝大部分，其次为多毛类，其它各类群所占比例都不足5％。生物多样性，个体数量和生物量的分布均呈由北向南增加的趋势。另外，与近20a中的历史资料相比，珠江口底栖动物个体数量变化不大，除2000年春季较高为591.7ind./m^2外，其变化范围在72.4-128ing./m^2之间。春季生物量除1991年较高为27．0g/m^2外，变化不是很大，大约10g/m^2；但秋季生物量呈明显下降趋势，1980年为30.1g/m^2,1990年为27.8g/m^2,1999年秋季急剧下降至7.4g/m^2。此外，从底栖动物各大类群的百分组成变化情况来看，一般以软体动物个体数量（22．7％－83．2％）和生物量（57．9％－82．5％）都最高；多毛类的个体数量百分组成占第二倍，其范围是13．4％－52．3％；其它各类群的百分组成除个别时候所占比例较大外，一般都较小。

Ecology Study on The Benthic Animals of Pearl River Estuary

Benthic animals collected by grab samples are generally small size and slow activity species. They are usually natural food to fish, shrimp and so on. Pearl River estuary, abundant in fishery resources, is one of the main fishery area in the South China Sea. It has great significance to study the benthic animals in this area. Two cruises for ecological survey of benthic animals at Pearl River estuary were made in Sep. 1999 and April 2000. The sampling stations were presented in Fig. 1. Replicate 0.05m 2 grab samples were collected in each station. A total of 32 species have been identified (15 species in Sep., 21 species in April). The benthic animals were dominated by Potamocorbula laevis (in both seasons) and Owenia fusformis (in spring). The average abundance in terms of individual and biomass are 591.7 ind./m 2 and 26.7 g/m 2 in spring, and 85.0 ind./m 2 and 7.4 g/m 2 in autumn respectively. Mollusca is the majority among the benthic groups, followed by Polychaeta, all the other groups account for less than 5%. The biodiversity, individual abundance and biomass all show an increasing trend from north to south. In addition, comparing with the previous reported data in the recent twenty years, the individual abundance, ranged from 72.4 to 128 ind./m 2, has no significant changes, except for 591.7 ind./m 2 in spring 2000; the biomass, about 10g/m 2, has also no significant changes in spring, except for 27.8g/m 2 in 1991. In autumn, however, the biomass has apparent decreasing trend from 30.1g/m 2 in 1980, 27.8 g/m 2 in 1990, to 7.4 g/m 2 in 2000. Moreover, in terms of the variation of individual abundance and biomass composition, Mollusca is the most abundant by individual abundance, ranged from 22.7%~83.2%, or by biomass, ranged 57.9%~82.5%; Polychaete is the next abundant by individual abundance, made up of 13.4%~52.3%, and all the other groups are minors.