Restoration Effect of Benthos on the Ecological Environment of the Changjiang River Estuar

27 Mar Restoration Effect of Benthos on the Ecological Environment of the Changjiang River Estuar

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Abstract

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-W iener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 × 103 kg、P为 67 ×103 kg、Cu为 16 675 kg、Zn为 39 258 kg、Pb为 410 kg、Cd 为 171 kg、H g为 0. 118 kg和 A s为 222 kg 。

English Abstract

A restoration experi m ent of benthos w as conduc ted on the new ly built northern and southern
guided dykes loca ted at the Changjiang R iver estuary. Ten tons of ben thos had been pu t in the N 6 reg ion of
northern gu ided dyke in M arch of 2002 and 5 tons of benthos(m a in Crassostrea sp. ) were put on the intertide zone of the northern and southern guided dykes w ith 10 000 m long in M arch of 2004. The mean
biom ass and mean density of putting benthos w ere 43. 15 g m -2 and 10. 70 ind m -2 respective ly in 2004.
The result show s tha t the benthos reaches 21 spec ies, the biom ass and density are 26 489. 43 g m – 2 and
3 399. 11 ind m – 2 respec tively, Shannon -W iener d iversity index is 0. 98 in the experi m ent zone, after 15
m onths. The species num ber, biom ass, density and diversity index increased 9. 5 ti m es, 40. 31 ti m es, 7. 50
ti mes and 3. 08 ti m es respec tively com pared w ith 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 ti m es and 140. 47 ti m es respectively compared w ith putting b iom ass and density. The prelim inary estim ating result is that the total
weigh t of Crassostrea sp. has reached 719 076 tons in the northern and southern guided dykes. The ben thos
commun ity w ith m ain adhesive oysters has been prelim inarily formed and it can offer quality food for fish in
th is area. The estim ated values of accum ulating num ber 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
m onitoring result in June of 2005. It plays importan t ro le in im prov ing the water quality of the Changjiang
R iver estuary