洋山港潮间带大型底栖动物群落结构及多样性

2009-2010年在洋山港海域大洋山岛和圣姑礁进行四个季度潮间带大型底栖动物生态学研究。共采集到大型底栖动物61种,以广布种为主,部分为河口低盐种,其中软体动物22种,环节动物16种,节肢动物12种,苔藓动物5种,腔肠动物4种,星虫动物和棘皮动物各1种。优势种为短滨螺(Littorina brevicula)、多齿围沙蚕(Perinereis nuntia)、日本笠藤壶(Tetraclita japonica)、齿纹蜒螺(Nerita yoldii)和特异大权蟹(Macromedaeus distinguendus)。丰度和生物量在不同季节明显不同(P<0.05):丰度的最高值出现在春季,为(3204.9±837.84)个/m²,最低值出现在秋季,仅为(2213.2±731.27)个/m²;生物量的最高值则出现在夏季(2233.2±1493.42)g/m²,冬季最少,仅为(819.95±484.80) g/m²。大洋山岛和圣姑礁的丰度和生物量具有较大差异(P<0.05):年均丰度以大洋山断面较高,为(3090±742.74)个/m²,圣姑礁断面较低,为(2133±372.51)个/m²;而年均生物量则以圣姑礁断面较高,为(1711.1±1180.76) g/m²,大洋山断面较低,仅为(1028.5±627.61) g/m²。运用ABC曲线、等级聚类和MDS对大型底栖动物群落结构分析发现:大洋山潮带间大型底栖动物群落尚未受到干扰或干扰较轻,群落结构相对稳定;而圣姑礁断面的潮间带大型底栖动物群落受到了中度的干扰,群落结构稳定性下降。与15年前的研究相比,圣姑礁大型底栖动物的密度和生物量均有大幅度的降低,这与洋山港海域盐度的升高、生态环境变化和人为干扰强度增加等有关。

Community structure and diversity of macrobenthos in the intertidal zones of Yangshan Port

The intertidal zone between the sea and the land is one of the most sensitive ecosystem in nature with high production. With rapid economic development and overexploitation, the ecosystem of the intertidal zone is seriously threatened by human activities. The Yangshan deep-water port is a new port in Hangzhou Bay south of Shanghai. It is built on the offshore islands of Greater and Lesser Yangshan (part of the Zhoushan archipelago), which have been amalgamated by land reclamation and connected to the mainland via the Donghai Bridge, the latter of which was opened on 1st December, 2005 as the third-longest bridge in the world at 32.5 km in length. In recent years the development and exploitation of the Yangshan deep-water port has caused increasing fragmentation of intertidal regions. These human activities could seriously affect the structure and function of the intertidal zone ecosystem. Macrobenthos is an important part of intertidal zone ecosystem, playing an important role in material cycling and energy utilization. The changes in community structure of macrobenthos are indicators for the stability for intertidal zone ecosystem, because macrobenthos have slow mobility, long life history, and stable habitat requirements. For this reason, the macrobenthos in intertidal zone has great significance for coastal environmental monitoring and evaluation of the coastal engineering environment. In order to better understand the effects of human disturbance, this study explored the influence of anthropogenic changes on macrobenthos biodiversity. The investigation spanned four seasons, from October 2009 to July 2010, in two different stations in the intertidal zones of Yangshan Port. Sixty-one species were identified, including 22 species of Mollusca, 16 species of Annelida, 12 species of Arthropoda, 5 species of Bryozoa, 4 species of coelenterate, 1 species of Sipuncula and 1 species of Echinodermata. The dominant species were Littorina brevicula, Perinereis nuntia, Tetraclita japonica, Nerita yoldii and Macromedaeus distinguendus. In geneeral, the characteristics of macrobenthos in Yangshan port were euryokous or hypohalinokous, which is typical along the coast or near an estuary. The average abundance and biomass varied significantly with the seasons (P<0.05). Abundance was highest in Spring ((3204.9±837.84)ind./m²) and lowest in Autumn ((2213.2±731.27)ind./m²). However, biomass was highest in Summer ((2233.2±1493.42)g/m²) and lowest in Winter ((819.95±484.80) g/m²). Comparing the two stations, the average abundance in Dayang island ((3090±742.74)ind./m²) was higher than Shenggu island ((2133±372.5)1ind./m²). But the average biomass in Dayang island ((1028.5±627.61) g/m²)was lower than Shenggu island ((1711.1±1180.76) g/m²). ABC curves, hierarchical clustering and MDS were used to analyze the data of community structure. The results showed that Dayang island had suffered less disturbance with the consequence of a more stable community structure. By contrast, Shenggu island had suffered moderate disturbance with the consequence of a less stable community structure. Biomass and density of macrobenthos in Shenggu island were significantly decreased compared to previous research. This trend is closely related to increased salinity, altered habitat and intensified anthropogenic disturbance of Yangshan port.