Strong coast–ocean and surface–depth gradients in prokaryotic assemblage structure and activity in a coastal transition zone region

Abstract

The distribution of marine Crenarchaeota Group I, marine Euryarchaeota Group II and some major groups of Bacteria (SAR 11, Roseobacter, Gammaproteobacteria and Bacteroidetes) was investigated in the North Atlantic water column (surface to 2000 m depth) along a transect from the coastal waters of the NW African upwelling to the offshore waters of the Canary Coastal Transition Zone (CTZ). Catalyzed reporter deposition-fluorescence in situ hybridization (CARD-FISH) was used to describe the prokaryotic assemblages. Bulk picoplankton abundance and leucine incorporation were determined. Pronounced changes in prokaryotic assemblage composition were observed from the coast to the open ocean and at the deep chlorophyll maximum (DCM) with decreasing bulk heterotrophic activity. All bacterial groups decreased in absolute abundances from the coast to the open ocean; both archaeal groups increased towards the open ocean. Prokaryotic abundance and activity decreased 2 and 3 orders of magnitude, respectively, from the surface to 2000 m. Prokaryotic growth rates were high in the mesopelagic zone (~0.13 d ), compared to other reports from the central North Atlantic. SAR11 in total picoplankton abundance decreased from 42% in the DCM to 4% at 2000 m, while marine Crenarchaeota Group I increased from 1% in the DCM to 39% in the oxygen minimum layer. A clear influence of the different intermediate water masses was observed on the bulk heterotrophic picoplankton activity, with lower leucine incorporation rates corresponding to layers where patches of Antarctic Intermediate Water were detected. Coast -ocean and surface-depth gradients in bulk prokaryotic abundance and production and assemblage composition were comparable to changes observed in basin-scale studies, pinpointing the CTZs as regions of strong variability in microbial diversity and metabolism.

Marine bacterial community structure resilience to changes in protist predation under phytoplankton bloom conditions

“…The resulting prevalence of Rhodobacteraceae in a community subjected to strong grazing pressure could be related to a smaller effect of HNF on this group compared with the others. However, as grazing losses did not seem to be phylotypespecific in this experiment, the resulting dominance of Rhodobacteraceae was most likely because of their reported genotypic and metabolic diversity (Brinkhoff et al, 2008) and their ability to take advantage of the environmental conditions associated with algal blooms (Eilers et al, 2001;Pinhassi et al, 2004;Allers et al, 2007;Baltar et al, 2007;Buchan et al, 2014) and the phytoplanktonderived DOC produced (Zubkov et al, 2001;Vila et al, 2004;Alonso and Pernthaler, 2006;Sarmento and Gasol, 2012), more than due to a superior grazing-avoidance capability. Thus, whether avoidance or lessening of grazing losses is a crucial ecological trait for bacteria, and thus a critical factor for the observed dominance of marine bacterial clusters such as Rhodobacteraceae, remains to be shown for marine systems.…”

Twelve previously unknown phage genera are ubiquitous in global oceans

“…5. Box plots show the percent amino acid identity for metagenomic reads (all 137 metagenomes available at CAMERA, Broad Phage Metagenome, January 2012) recruiting to predicted genes from C. baltica phages (designated as genera [1][2][3][4][5][6][7][8][9][10][11][12], as well as three T4-like phages: marine Prochlorococcus phage P-SSM4 (GenBank accession no. NC_006884), marine Vibrio phage KVP40 (GenBank accession no.…”

“…In humans, Bacteroidetes comprise 30% of the gut microbiota and play important roles for fat storage (9) and the immune system (10). In the oceans, Bacteroidetes is the third most abundant bacterial phylum (7,8), and there these bacteria are active in degrading biopolymers (11) and involved in recycling of phytoplankton bloom-related organic matter (12).…”

“…4,5). Bacteroidetes bacteria are abundant and active members of bacterial communities in various habitats ranging from Antarctic soil (6) to surface (7) and deep (8) oceans and even the human gut. In humans, Bacteroidetes comprise 30% of the gut microbiota and play important roles for fat storage (9) and the immune system (10).…”

Bacterial and Archaeal Communities Variability Associated with Upwelling and Anthropogenic Pressures in the Protection Area of Arraial do Cabo (Cabo Frio region - RJ)

“…Martinez et al 1996). Their abundance and activity are associated with temperature and the concentration of nutrients (Baltar et al 2007, Carlsson et al 2012. How its composition varies over space and time is of major importance for understanding the role of microorganisms in marine biogeochemistry (Riemann et al 1999).…”