Impact of grazing, resource availability and light on prokaryotic growth and diversity in the oligotrophic surface global ocean

Summary The impact of grazing, resource competition and light on prokaryotic growth and taxonomic composition in subtropical and tropical surface waters were studied through 10 microcosm experiments conducted between 30°N and 30°S in the Atlantic, Pacific and Indian oceans. Under natural sunlight co...

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Bibliographic Details
Published in:Environmental microbiology 2019-04, Vol.21 (4), p.1482-1496
Main Authors: Teira, Eva, Logares, Ramiro, Gutiérrez‐Barral, Alberto, Ferrera, Isabel, Varela, Marta M., Morán, Xosé Anxelu G., Gasol, Josep M.
Format: Article
Language:English
Subjects:
Abundance
Bacteria - metabolism
Bacteria - radiation effects
Bacterial Physiological Phenomena
Biological competition
Coexistence
Communities
Community composition
Competition
Composition
Darkness
Dilution
Exposure
Food Chain
Grazing
Growth
Oceans
Oceans and Seas
Predators
Reduction
Resource availability
Seawater - microbiology
Specialization
Sunlight
Surface water
Taxonomy
Tropical climate
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Summary:Summary The impact of grazing, resource competition and light on prokaryotic growth and taxonomic composition in subtropical and tropical surface waters were studied through 10 microcosm experiments conducted between 30°N and 30°S in the Atlantic, Pacific and Indian oceans. Under natural sunlight conditions, significant changes in taxonomic composition were only observed after the reduction of grazing by sample filtration in combination with a decrease in resource competition by sample dilution. Sunlight exposure significantly reduced prokaryote growth (11 ± 6%) and community richness (14 ± 4%) compared to continuous darkness but did not significantly change community composition. The largest growth inhibition after sunlight exposure occurred at locations showing deep mixed layers. The reduction of grazing had an expected and significant positive effect on growth, but caused a significant decrease in community richness (16 ± 6%), suggesting that the coexistence of many different OTUs is partly promoted by the presence of predators. Dilution of the grazer‐free prokaryotic community significantly enhanced growth at the level of community, but consistently and sharply reduced the abundance of Prochlorococcus and SAR11 populations. The decline of these oligotrophic bacterial taxa following an increase in resource availability is consistent with their high specialization for exploiting the limited resources available in the oligotrophic warm ocean.
ISSN:1462-2912
1462-2920
DOI:10.1111/1462-2920.14581