我国典型潮间带底栖硅藻群落空间分布特征

摘要

Benthic diatom is an important biological community in ecosystems of estuaries and mud flats.The abundance and distribution of the benthic diatom could affect the food supply of marine organism and the survival and migration of sea birds.In this study,the community structure and spatial distribution of benthic diatoms in the surface sediments were investigated at the 14 intertidal zones along the Chinese coastline.153 diatom species were identified from the samples,and diversity index (Shannon-Weaver index from 1.61 to 4.39) and biomass (from 0.09 × 103 to 10 × 103 valves/g DW;DW means dry sediment weight) are significantly different in the spatial distribution.Cluster analysis and ANOSIM (r=0.738,P=0.1％＜0.01) indicated that the 14 sampling sites can classify 4 geological groups,according to their diversity and biomass,and the geological groups are in response to the geographical distribution of phytoplankton in the Bohai,Yellow,East and South China Seas,respectively.The correlation analysis indicated that the sediment types and salinity had significant effects on diatom diversity and biomass.Muddy sediments were better for diatom preservation,and species diversity was higher at sites with sandy mud and low salinity.The contents of organic carbon and the biomasses of benthic diatoms in the surface sediments showed significant positive correlation,and the carbon stable isotope ratio (δ13 C) values (from-25 ‰ to-20‰) indicated that organic matters were a mixture of terrestrial and sea sources at most sites.Lower δ13 C values in tidal flats of Jian River,Yellow River,Dagu River and Subei coast indicated the significant contribution of benthic diatoms on the organic carbon.%底栖硅藻是河口、泥质海滩生态系统的重要生物类群,其数量与分布变化直接或间接地影响到多种海洋生物的饵料供给、海鸟的生存与迁徙.通过对我国从南到北14个典型潮间带表层沉积物中底栖硅藻的分析,共鉴定出硅藻153种,其物种多样性(Shannon-Weaver指数范围:1.61～ 4.39)与生物量(范围:0.09×103～10×103个/g,干质量)在空间上存在显著差异;聚类分析与相似性分析检验(r=0.738,P=0.1％＜0.01)表明,14个调查区域的硅藻群落在空间上可分为4个大的组合,分别对应着渤、黄、东、南海4个区域,吻合了我国近海浮游植物的地理分布特征.与环境因素的相关性分析表明,底栖硅藻群落的物种多样性与生物量受沉积物类型与盐度的影响显著,泥质区域更有利于硅藻的保存,而生物多样性在泥砂质低盐区域相对较高.此外,底栖硅藻生物量与表层沉积物中TOC含量表现出显著正相关性;δ13 C数值的空间变化范围为-25‰～-20‰,指示了有机质陆海混合的特征,其中,涧河河口、黄河口、大沽河口、苏北浅滩区域,δ13C数值明显偏正,表明底栖硅藻可能是这些区域沉积物中有机碳的重要贡献者.