Phylogenetic analysis of the succession of bacterial communities in the Great South Bay (Long Island)

Bacterial community composition and succession were examined over the cours e of the summer season in the Great South Bay, Long Island, NY, USA, using a 165 rDNA clone library approach. There was a progression of changes in do minant species in the libraries during the summer of 1997. The July library had several groups dominant. the SAR407 relatives of the alpha -Proteobact eria (24%) and the SAR86 (18%), sulfur-oxidizing symbiont relatives (80%) o f the gamma -Protcobacteria, and unidentified Cytophaga-Flexibacter represe ntatives (22%). In August, the Cytophaga-Flexibacter (Gelidibacter sp. and unidentified Cytophaga-Flexibacter representative) and Cyanobacteria (Synec hococcus sp.) increased to 28% and 14%, respectively. Nigh GC Gram-positive s appeared at 18%, and beta -Proteobacteria (Ralstonia sp.) at 10%. By Sept ember these groups had either declined or were absent, while the SAR86 clus ter, Pseudoalteromonas and Alteromonas of the gamma -Proteobacteria were do minant in the community (61%). The dominance of open ocean bacteria along w ith the presence of Aureococcus anophagefferens (Pelagophyeeae) in July sug gests possible open ocean coupling to bloom events. Many clones in this stu dy were related to previously described clones from a wide distribution of marine environments, substantiating the cosmopolitan nature of pelagic bact eria. Only one isolated bacterium was closely related to 16S rDNA found in the August library. (C) 2001 Federation of European Micro biological Societ ies. Published by Elsevier Science B.V. All rights reserved.