Spatial distribution of benthic diatom in the typical intertidal zones in China

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 (δ¹³C) values (from-25‰ to-20‰) indicated that organic matters were a mixture of terrestrial and sea sources at most sites. Lower δ¹³C 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.