Microbial community characterization of the Gully: a marine protected area

The Gully is the first Fisheries and Oceans Canada marine protected area off the eastern coast of Canada. To ensure success of conservation efforts in this area, it is essential to develop a better understanding of microbial community composition from the euphotic zone to the deep sea in this previously unsurveyed environment. Denaturing gradient gel electrophoresis (DGGE) and nucleotide sequencing were used to characterize microbial community structure. DGGE results showed a clear difference in the microbial community structure between the euphotic zone and the deep sea water. Cluster analysis showed high similarity (>85%) for all the samples taken from below 500 m, but lower similarity (49%-72%) when comparing samples from above and below 500 m. Changes in microbial community structure with depth corresponded well with changes in oceanographic physical parameters. Furthermore, 16S rRNA gene analysis showed that the bacterioplankton sequences generally clustered into 1 of 9 major lineages commonly found in marine systems. However, not all the major lineages were detected at all the different depths. The SAR11 and SAR116 sequences were only present in the surface water, and the SAR324 and Actinobacteria sequences were only present in deep sea water. These findings provide a preliminary characterization of the microbial communities of this unique ecosystem.