| Fluorescence in situ hybridization (FISH) is widely used to characterize the phylogenetic diversity of microbial communities. Here I present the results of a laboratory-based study of the effects of sample storage on the detection of bacterial cells using FISH, as well as a field- and laboratory-based study of changes in the phylogenetic diversity of the microbial community in biogeochemical provinces of the Northwest Atlantic Ocean over three consecutive seasons, and how these changes relate to biogeochemical and ecosystem processes on a large geographical and temporal scale. Results from the 12-month time-course study of storage effects indicate that samples can be stored for up to six months with no significant change in target cell detection, and stored for up to 12 months with a minimal (< 7%) effect of storage. Results from the Northwest Atlantic study show variations in microbial community structure between biogeochemical provinces, as well as seasonally within each province. From summer to fall, there was a noticeable decrease in the proportion of Cytophaga-Flavobacteria, and the alpha-, beta-, and gamma-Proteobacteria dominated the fall community at all stations. Seasonally, the most noticeable shift in the relative abundances of specific phylogenetic groups occurred from summer to fall. Spatially, the greatest differences in bacterial community composition were observed between the North Atlantic Subtropical Gyre and the Atlantic Arctic province. |
