洋山深水港海域小型底栖动物丰度和生物量分布

Abundance and biomass of meiobenthos in the sea areasof Yangshan Deepwater Port

2005年11月对洋山深水港一期工程海域19个站位的小型底栖动物进行了调查,共获得10个主要类群,包括线虫、桡足类、多毛类、双壳类、介形类、端足类、异足类、涟虫、腹足类和有孔虫.其中线虫的丰度占绝对优势,达154.05 ind/(10 cm^2),占洋山深水港一期工程海域小型底栖动物丰度的55.98%.接下来依次为介形类58.37 ind/(10cm^2),有孔虫30.59 ind/(10 cm^2),及多毛类15.09 ind/(10 cm^2).而生物量位于前四位的分别为介形类、有孔虫、双壳类和多毛类,线虫因个体干重较轻,其生物量仅列第五位.小型底栖动物的丰度和生物量在19个站位的分布有所不相同.其中高丰度区主要分布在芦潮港至小洋山间的海域,而高生物量区主要分布于大小洋山港附近海域,两值分布的规律性都不强.分析认为洋山深水港一期工程可能将原本一体的生物分布带分隔成了若干不相连的生物分布岛.这一现象同时体现在小型底栖动物主要类群的分布及相似生境聚类分析(UPGMA)的结果上.部分主要类群分布在不相连接的站位,同时聚类分析的结果也将相差较甚的站位聚在一起,并且其间无规律可觅.但总的来说,介形类和有孔虫的高丰度区主要分布于洋山港区附近的深水区,线虫主要分布于近岸海域,这符合它们大体的分布规律.

The benthic meiofauna was quantitatively investigated from 19 stations in the sea areas of the First-phase Project of Yangshan Deepwater Port in November, 2005 and ten meiofauna groups, including nematodan, copepodan, polychaetan, bivalvian, ostracodan, amphipodan, tanaidacean, cumacean, gastropodan and foraminiferan, were recorded. Among them, the dominant fauna was nemato-dan with average abundance 154. 05 ind/（10 cm^2 ） ; the following dominant ones in turn were ostracodan （ 58. 37 ind/（ 10 cm^2 ） ）, foraminiferan （ 30. 59 ind/（ 10 cm^2 ） ） and polychaetan （ 15.09 ind/（ 10 cm^2 ））. As to individual dry weights of meiofauna groups, the first four dominant biomass were fora- miniferan（1 254. 10 μg/（ 10 cm^2 ） ）, ostracodan（ 1 517. 52 μg/（ 10 cm^2 ） ）, bivalvian（315. 33 μg/（ 10 cm^2 ））and polychaetan（200. 13 μg/（ 10 cm^2 ））; while nematodan lied below them with its biomass only 61.62 μg/（ 10 cm^2 ）. There were differences of horizontal distribution between the abundance and biomass of meiofauna in 19 stations. The high abundance areas were presented from Luchao Port to Little Yangshan Island, and the high biomass areas were presented near Big and Little Yangshan Islands. Their distribution rules were not found, and the phenomena might be due to the large engineering project in East China Sea which has divided the whole distribution of meiofauna into several discontinuous parts. The results gained support from the analysis of unweighted pair-group method with arithmetic （UPOMA）. The UPGMA analysis showed that some separate stations had been brought together, which did not meet with the distribution rules of fauna. However, the high abundance of ostracodan and foraminiferan was distributed in deeper water while the high abundance of nematodan was presented in coastal water, and they could meet the distribution rules of these fauna groups.