Temporal variability and phylogenetic characterization of planktonic anammox bacteria in the coastal upwelling ecosystem off central Chile

• Published in: Progress in oceanography 2012-01, Vol.92, p.110-120
• Main Authors: Galán, Alexander, Molina, Verónica, Belmar, Lucy, Ulloa, Osvaldo
• Format: Article
• Language: English
• Subjects: Abundance; anaerobic ammonium oxidation; Bacteria; Cloning; Coastal; continental shelf; ecosystems; genes; in situ hybridization; Marine; nitrifying bacteria; phylogeny; ribosomal RNA; ribotypes; Seasons; Temporal logic; temporal variation; Upwelling; Vertical distribution
• ISSN: 0079-6611; 1873-4472
• DOI: 10.1016/j.pocean.2011.07.007

The phylogenetic affiliation and temporal variability in the abundance of planktonic anammox bacteria were studied at a time-series station above the continental shelf off central Chile (∼36°S; bottom depth 93m), a wind-driven, seasonal upwelling area, between August 2006 and April 2008. The study was carried out by cloning and sequencing the 16S rRNA gene and by using catalyzed reporter deposition-fluorescence in situ hybridization (CARD-FISH). Our results showed the presence of a single anammox bacteria-like ribotype during both upwelling and non-upwelling seasons, which was phylogenetically associated with a recently described oxygen-minimum-zone subcluster within the Candidatus Scalindua clade. Moreover, clear differences were observed in the temporal and vertical distribution of anammox cells. During the upwelling season (austral spring–summer), relatively high abundances (∼5500cellsmL⁻¹) and large cells (0.8μm³–75.7fgCcell⁻¹) were found below 20m depth. In contrast, during the non-upwelling season (austral fall–winter), lower abundances (∼600cellsmL⁻¹) and smaller cells (0.1μm³–22.8fgCcell⁻¹) were found, predominantly associated with the bottom layer. Overall, our results indicate that the abundance and vertical distribution of anammox planktonic assemblages are related to the occurrence of seasonal, wind-driven, coastal upwelling, which in turn appears to offer favorable conditions for the development of these microorganisms. The dominance of a unique anammox bacteria-like ribotype could be related to the high environmental variability observed in the system, which prevents the establishment of other anammox lineages.