These observations can be explained, at least in part, by the fact that marine snow can be highly enriched in nutrients compared with the surrounding water column (Shanks & Trent, 1979). Bacterial cell densities on marine snow are typically orders of magnitude higher than background measurements (Caron et al., 1986), and the processes of photosynthesis, decomposition, and nutrient regeneration on these particles also occur at rates much higher than on the surrounding water column (Alldredge & Silver, 1988 Smith et al., 1992). Organic matter aggregates and sinking particles in marine systems (commonly known as marine snow) appear to provide an ecological niche for bacteria.
This study further demonstrates that particle origin may be insignificant regarding the heterotrophic bacterial population that degrades them.ĭNA sequencing, marine bacteria, marine snow, sediment traps Introduction This study provides further evidence that Roseobacters are rapid colonizers of marine aggregates and that colonization can occur on short timescales. The most abundant early colonizer was a Sulfitobacter sp. There was a little change in the bacterial assemblage after the initial 24-h incubation period. Our findings indicated that rapid changes – within 24 h of collection – occurred to the microbial community associated with aggregates from either bloom type. and multiple members of the Flavobacteria, Actinobacteria, and α- Proteobacteria were elevated in water column samples, while trap samples contained members of the Roseobacter clade of α- Proteobacteria in high relative abundances. Statistically significant differences were found between the water column and sediment trap bacteria. Water column samples were also collected and sequenced for comparison between sinking-particle-associated and planktonic bacterial communities.
We determined the phylogenetic affiliation for the microorganisms growing on aggregates by pyrosequencing partial 16S rRNA gene amplicons. Using marine sediment traps (named RESPIRE for REspiration of Sinking Particles In the subsuRface ocEan) designed to collect sinking particles and associated microbial communities in situ, we collected and incubated marine aggregates/particles in the southern Pacific Ocean from separate phytoplankton bloom events in situ.
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