AME 71:131-140 (2013)  -  DOI: https://doi.org/10.3354/ame01668

ABSTRACT: Physical and chemical characteristics define oceanographic regions. The potential for a distinct biogeography of bacterial communities in these oceanic provinces was studied in epi-pelagic and upper mesopelagic water bodies of the North Atlantic Ocean by terminal restriction fragment length polymorphism (T-RFLP) analysis of bacterial 16S rRNA genes and flow cytometry. Water samples from 67°N to 34°N along the 30°W meridian contained epipelagic populations of Synechococcus in the north and Prochlorococcus in the south. Bacterial communities were generally more diverse in phototrophic layers above the pycnocline. Communities significantly differed in the epipelagic zone along the latitudinal transect through the different oceanic provinces and between the epipelagic and the upper mesopelagic zone. Differences in the T-RFLP patterns coincided well with differences in the physico-chemical conditions of the sampling sites. Changes in bacterial communities were traced to characteristic terminal restriction fragments (TRFs). In silico assignments of phylogenetic groups to TRFs, e.g. populations of high-light and low-light ecotypes of Prochlorococcus, supported our T-RFLP analysis of bacterial communities. Distinct bacterial communities in water bodies of the North Atlantic Ocean hosted different bacterial populations, which may serve as biological markers for oceanic provinces.

KEY WORDS: Synechococcus · Prochlorococcus · North Atlantic Ocean · Gulf Stream · Canonical correspondence analysis · T-RFLP · 16S rRNA gene fingerprint