Abstract

The CARD-FISH approach with the HRP labeled oligonucleotide probe Pla-46 was applied to investigate the abundance of Planctomycetes in the China seas. Our data subtly revealed that the abundance of Planctomycetes was varied from 0.23 to 20.53×10⁴cells/ml in 10 sampling sites of Yangtze River estuary and from 0.15 to 10.25×10³ cells/ml in the 3 water depth profiles of the South China Sea (the maximum abundance found in the euphotic zones) respectively. Even though 20 times higher than in the water depth profiles of the oligotrophic South China Sea, the abundance of Planctomycetes in Yangtze River estuary is lower than that of in soils and sediments according to previous publications. To the best of our knowledge, the present work is the first systematic assessment and comparison of the abundance of Planctomycetes in typical aquatic environments. Our results showed that the variation of abundance of Planctomycetesdiffered with hydrological, physical, and chemical features, providing the patterns of the abundance in oligotrophic water, estuary, and water depth profiles; this is importantinformation of their quantitative distribution, potential ecological roles.

Key words: Planctomycetes, the China Seas, CARD-FISH, abundance, seawater.