The present study describes the abundance of major marine bacterioplankton groups and 2 bacterial genera (Pseudoalteromonas and Vibrio) in surface seawater at 24 stations around the world. Catalyzed reporter deposition-fluorescence in situ hybridization showed that Alphaproteobacteria (average relative abundance 37%, average absolute abundance 3.7 × 10 5 cells ml )] showed cosmopolitan occurrence. Principal component analysis revealed a latitudinal pattern in bacterial abundances by clustering samples according to lower and higher latitudes. This was related to significantly different relative abundances of Bacteroidetes (peaking at higher latitudes) and of unclassified Bacteria and Vibrio (both peaking at lower latitudes) between warmer and colder oceans. Relative abundances of Alphaproteobacteria (peaking at subtropical) and Gammaproteobacteria (polar stations) varied between major oceanic biomes, as did absolute abundances of Roseobacter (peaking at temperate and polar stations). For almost all groups, absolute abundances were positively correlated with nutrient concentrations in warmer oceans and negatively correlated with oxygen saturation in colder oceans. On a global scale, Roseobacter and SAR86 were correlated with chlorophyll a. Linkages of environmental parameters with relative abundances were more complex, with e.g. Bacteroidetes being associated with chlorophyll a. The finding of differing communities in warmer and colder oceans underlined the presence of biogeographical patterns among marine bacteria and the influence of environmental parameters on bacterial distribution.
KEY WORDS: Marine bacterioplankton · Global quantification · Latitudinal pattern · Biogeography · CARD-FISH · PCA
Resale or republication not permitted without written consent of the publisherAquat Microb Ecol 61: [179][180][181][182][183][184][185][186][187][188][189] 2010 Characterization of marine bacterial communities on larger geographical scales has been done by shotgun sequencing (Rusch et al. 2007), polymerase chain reaction (PCR)-based techniques (Baldwin et al. 2005, Pommier et al. 2007, Taniguchi & Hamasaki 2008 and catalyzed reporter deposition-fluorescence in situ hybridization (CARD-FISH) (Schattenhofer et al. 2009). These studies have indicated that the composition of bacterioplankton differs between oceanic regions, probably related to oceanographic factors such as water temperature (Baldwin et al. 2005, Fuhrman et al. 2008, nutrient availability (Abell & Bowman 2005), or water masses (Teira et al. 2006, Galand et al. 2010. The analysis of a global sample set showed marked variation in bacterial community structure on the 16S rRNA sequence level, with a high degree of endemism and few cosmopolitan sequences (Pommier et al. 2007). A latitudinal gradient in species richness, comparable to observations in the animal and plant kingdoms, has been shown in this context (Pommier et al. 2007, Fuhrman et al. 2008. Terminal-restriction fragment length polymorphism (T-RFLP) demonstrated distinct microbial clusters...