底栖动物对长江口水域生态环境的修复作用

Restoration effect of benthos on the ecological environment of the Changjiang River estuary

2002年3月在长江口新建的北导堤N6区段试投放底栖动物10 t的基础上,2004年3月在南、北导堤通过投放以巨牡蛎为主的底栖动物5 t,开展底栖生物修复试验。试验结果表明:经过15个月,试验区底栖动物种类共有21种,比本底值增加了9.5倍;总生物量和总栖息密度分别为26 489.43 g.m-2和3399.11 ind.m-2,比本底值分别增加了40.31倍和7.50倍,Shannon-Wiener多样性指数为0.98,比本底值提高了3.08倍。其中巨牡蛎生物量和栖息密度增加明显,巨牡蛎的生物量和栖息密度分别为19 328.84 g.m-2和918.67 ind.m-2,分别是所投放巨牡蛎生物量和栖息密度的483.39倍和140.47倍。初步评估整个长江口导堤巨牡蛎的总重量已达719 076 t以上,已初步形成以附着型贝类为主的底栖动物群落。根据2005年6月的测定结果,推算出整个长江口导堤巨牡蛎对营养盐和重金属的累积量为:N为986×103kg、P为67×103kg、Cu为16 675 kg、Zn为39 258 kg、Pb为410 kg、Cd为171 kg、Hg为0.118 kg和As为222 kg。

A restoration experiment of benthos was conducted on the newly built northern and southern guided dykes located at the Changjiang River estuary. Ten tons of benthos had been put in the N6 region of northern guided dyke in March of 2002 and 5 tons of benthos（ main Crassostrea sp. ） were put on the intertide zone of the northern and southern guided dykes with 10 000 m long in March of 2004. The mean biomass and mean density of putting benthos were 43.15 g · m^-2 and 10.70 ind · m^-2 respectively in 2004. The result shows that the benthos reaches 21 species, the biomass and density are 26 489.43 g · m^-2 and 3 399.11 ind · m^-2 respectively, Shannon-Wiener diversity index is 0.98 in the experiment zone, after 15 months. The species number, biomass, density and diversity index increased 9.5 times, 40.31 times, 7.50 times and 3.08 times respectively compared with the background. Among them, the biomass and density of Crassostrea sp. are 19 328.84 g · m^-2 and 918.67 ind · m^-2, increased 483.39 times and 140.47 times respectively compared with putting biomass and density. weight of Crassostrea sp. has reached 719 076 tons in the The preliminary estimating result is that the total northern and southern guided dykes. The benthos community with main adhesive oysters has been preliminarily formed and it can offer quality food for fish in this area. The estimated values of accumulating number for N, P, Cu, Zn, Pb, Cd, Hg and As are 986 000 kg,67 000 kg,16 675 kg,39 258 kg,410 kg, 171 kg,0. 118 kg and 222 kg respectively based on the monitoring result in June of 2005. It plays important role in improving the water quality of the Changjiang River estuary.