乐清湾潮间带大型底栖动物群落分布格局及其对人类活动的响应

于2006年9月和2007年5月对乐清湾5条潮间带断面进行了大型底栖动物调查。 共鉴定出大型底栖动物113种, 其中软体动物40种, 多毛类25种, 甲壳动物24种, 棘皮动物9种, 其它动物15种。从季节来看, 物种数秋季(81种)高于春季(68种),但平均生物量和平均栖息密度春季(分别为(91.90±59.14) g/m²和(1541±1261.41)个/m²)明显高于秋季(29.20±22.20)g/m²和(201±52.97)个/m²);春季以焦河蓝蛤 幼体、彩虹明樱蛤 、婆罗囊螺 、绯拟沼螺 为主要优势种,而秋季以短拟沼螺 、彩虹明樱蛤、淡水泥蟹 、巢沙蚕 为主要优势种,说明乐清湾大型底栖动物群落特征随着季节有着较大的变化。各断面的Shannon-Winner指数(H')为2.34-3.31,平均为2.85±0.35;Margalef's species richness 指数(d)为3.02-6.42,平均为4.29±1.10;Pielou's evenness 指数(J')为0.46-0.73,平均为0.62±0.09。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,群落结构已受到中度干扰,稳定性差。与以往历史资料相比,乐清湾大型底栖动物向次生型群落转化,原因可能与过度采捕、生境恶化、海岸工程以及围塘养殖等人类活动的影响有关。

The community distribution pattern of intertidal macrozoobenthos and the responses to human activities in Yueqing Bay

The intertidal zone between the land and the sea was impacted seriously by all kinds of human activities. Influences of environment conditions and pollution can be shown by the macrozoobenthic community and species distributed in the intertidal zone. With rapid economic development and overexploiting, Yueqing Bay (a semi-enclosed bay) is seriously threaten by human activities; such as industrial and agricultural discharges, aquaculture ponds and land reclamation. Resultant effects are: 1) the landscapes of intertidal regions are damaged, 2) polluted water and sediments, and, 3) recession of the marcozoobenthic community. Five different stations were investigated in September 2006 and May 2007 to assess impacts of human activities on intertidal macrozoobenthic community distribution patterns in Yueqing Bay. One hundred and thirteen species were identified, including 40 species of molluscs, 25 of polychetes, 24 of carapace, 9 of echinoderm, and 15 others. The number of species fluctuated across seasons. The 81 species in Autumn exceeded the 68 species in Spring. However, the average macrozoobenthic biomass and inhabit density in spring were (91.90±59.14)g/m² and (1541±1261.41)ind./m², respectively; which were higher than those in Autumn; these being (29.20±22.20)g/m² and (201±52.97)ind./m², respectively. Dominant species were juveniles of Potamocorbula ustulata (Reeve), Moerella iridescens (Benson), Retusa (Coelophysis) boenensis (A.Adams), Assiminea latericea (H. et A.Adams) in Spring; and, Assiminea brevicula, Moerella iridescens (Benson), Ilyoplax tansuiensis Sakai, Diopatra neapolitana (Delle Chiaje) in Autumn. The results indicate that the functional status of the macrozoobenthic community changes with seasons. The biodiversity index varied from 2.34 to 3.31, the average being 2.85±0.35. The index of Margalef's species richness was from 3.02 to 6.42, the average being 4.29±1.10. The Pielou's evenness was from 0.46 to 0.73, the average being 0.62±0.09. Upon analysis of the macrozoobenthic community structure by ABC curve, only the Huanghua section had not been affected in Spring. According to hierarchical clustering analysis and MDS diagrams, community stability is bad in Yueqing Bay. The community with more than 40% of similarity could be clustered into three groups; the first was all of the sections in Spring, the second was sections including Huwu, Ximen Island, Nantang and Wengyang in Autumn, and, the third is the Huanghua section in Autumn. The data analyzed by MDS were consistent with the results of the hierarchical clustering analysis. The above mentioned results show that the structure of macrozoobenthic community had suffered moderate disturbance with the consequence of poor stability in Yueqing Bay. Compared to previous research, biomass and density were significantly decreased, and the dominant species changed from large to small ones; such as Cyclina sinensis (Gmelin), Sinonovacula constricta (Lamarck) and Cultellus scalprum (Gould) being replaced by Retusa (Coelophysis) boenensis (A.Adams), Assiminea latericea H. et A.Adams, and Assiminea brevicula. Changed variety of the macrozoobenthic community from its original type to the secondary type reflects the adverse impact of human activities that include excessive exploitation, habitat degradation, coastal engineering and pond farming.