The impact of light and water mass on bacterial population dynamics in the Amundsen Sea Polynya
(English)Manuscript (preprint) (Other academic)
Although the Antarctic Ocean is perpetually cold, mostly ice-covered and dark, it is a highly productive and diverse marine ecosystem. During austral summer, ice-free patches (polynyas) form, exposing marine organisms to sunlight, while mobilizing large amounts of nutrients from the melting ice. As a result, intense phytoplankton blooms form that sustain life across the entire Antarctic food web. This seasonality is likely to shape microbial communities, but the main environmental drivers controlling these communities and the biogeochemical processes they mediate are largely unknown.
In this study, the remote Amundsen Sea Polynya (ASP) was used as a model system to identify the influence of some of the most important environmental drivers of the Southern Ocean. We studied the dynamics in occurrence and activity of abundant members of the bacterioplankton community, directly in environmental samples as well as in microcosm experiments, by using next-generation sequencing of bar-coded 16S rRNA genes in combination with immunochemical detection of DNA-synthesis using bromodeoxyuridine as a tracer.
We found that the photic zone harbored a bacterioplankton community with a low species richness. Here, the dominant populations were related to taxa known to benefit from high organic carbon and nutrient loads (copiotrophs). In contrast, the dark water masses below the photic zone hosted bacterial communities of higher richness, and were dominated by oligotrophs. Results from enrichment studies suggested that indirect impacts of light via photosynthetic production and competition for dissolved nutrients provided in the water masses are the two main factors shaping bacterial communities of the ASP.
marine bacterioplankton, population dynamics, Southern Ocean
Research subject Biology with specialization in Microbiology
IdentifiersURN: urn:nbn:se:uu:diva-229138OAI: oai:DiVA.org:uu-229138DiVA: diva2:735856