, Volume 56, Issue 2, pp 383-389
Date: 07 Dec 2007

Relationship of Geographic Distance, Depth, Temperature, and Viruses with Prokaryotic Communities in the Eastern Tropical Atlantic Ocean

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Abstract

The richness and biogeographical distribution pattern of bacterial and archaeal communities was assessed by terminal restriction fragment length polymorphism analysis of polymerase chain reaction-amplified fragments of the 16S rRNA gene at the surface (15–25 m depth), in the deep chlorophyll maximum layer (DCM; 50 m depth), and deep waters (75–1000 m depth) of the eastern tropical Atlantic Ocean. Additionally, prokaryotic and viral abundance and the frequency of infected prokaryotic cells (FIC) were determined along with physico-chemical parameters to identify factors influencing prokaryotic richness and biogeography. Viral abundance was highest in the DCM layer averaging 45.5 × 106 ml−1, whereas in the mixed surface layer and in the waters below the DCM, average viral abundance was 11.3 × 106 and 4.3 × 106 ml−1, respectively. The average estimate of FIC was 8.3% in the mixed surface layer and the DCM and 2.4% in deeper waters. FIC was positively related to prokaryotic and viral abundance and negatively to archaeal richness. There was no detectable effect of geographic distance (maximum distance between stations ∼4600 km) or differences between water masses on bacterial and archaeal community composition. Bacterial communities showed a clear depth zonation, whereas changes in archaeal community composition were related to temperature and FIC. The results indicate that planktonic archaeal virus host systems are a dynamic component of marine ecosystems under natural conditions.