Community differentiation and population enrichment ofSargassoSea bacterioplankton in the euphotic zone of a mesoscale mode‐water eddy

Abstract

Eddies are mesoscale oceanographic features (∼ 200 km diameter) that can cause transient blooms of phytoplankton by shifting density isoclines in relation to light and nutrient resources. To better understand how bacterioplankton respond to eddies, we examined depth-resolved distributions of bacterial populations across an anticyclonic mode-water eddy in the Sargasso Sea. Previous work on this eddy has documented elevated phytoplankton productivity and diatom abundance within the eddy centre with coincident bacterial productivity and biomass maxima. We illustrate bacterial community shifts within the eddy centre, differentiating populations uplifted along isopycnals from those enriched or depleted at horizons of enhanced bacterial and primary productivity. Phylotypes belonging to the Roseobacter, OCS116 and marine Actinobacteria clades were enriched in the eddy core and were highly correlated with pigment-based indicators of diatom abundance, supporting developing hypotheses that members of these clades associate with phytoplankton blooms. Typical mesopelagic clades (SAR202, SAR324, SAR406 and SAR11 IIb) were uplifted within the eddy centre, increasing bacterial diversity in the lower euphotic zone. Typical surface oligotrophic clades (SAR116, OM75, Prochlorococcus and SAR11 Ia) were relatively depleted in the eddy centre. The biogeochemical context of a bloom-inducing eddy provides insight into the ecology of the diverse uncultured bacterioplankton dominating the oligotrophic oceans.

Dose-dependent regulation of microbial activity on sinking particles by polyunsaturated aldehydes: Implications for the carbon cycle

“…This is consistent with a report that γ-Proteobacteria became dominant in the surface community in the North Sea only after a bloom of potentially PUA-rich diatoms subsided (40). By contrast, the relative abundance of Actinobacteria was positively correlated with PUA addition, and this clade was previously shown to be strongly correlated with diatom pigments in the Sargasso Sea (41). We found no other correlations between PUA amendments and any of the other clades we were able to resolve with ARISA.…”

The biogeochemistry of lipid derived infochemical signals in the ocean

“…This is consistent with a report that γ-proteobacteria became dominant in the surface community in the North Sea only after a bloom of potentially PUA-rich diatoms subsided (Teeling, 2012). By contrast, the relative abundance of Actinobacteria was positively correlated with PUA addition, and this clade was previously shown to be strongly correlated with diatom pigments in the Sargasso Sea (Nelson et al, 2014).…”

The pathogenBatrachochytrium dendrobatidisdisturbs the frog skin microbiome during a natural epidemic and experimental infection

“…Briefly, the V1-V2 regions of the 16S gene were amplified from each sample, and pooled, multiplexed PCR products were sequenced on a Roche/454 GS FLX instrument using Titanium chemistry. The program mothur (version 1.30) (70) was used to quality-filter (denoise and screen for short, potentially low-quality, or chimeric reads) sequences, align them to a curated 16S alignment database (71), and cluster them into OTUs. Sequences were classified using the Bayesian classifier of Wang et al (72), and each OTU was assigned a consensus taxonomy from SILVA version 111.…”