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Richert, Inga
Publications (5 of 5) Show all publications
Richert, I., Yager, P. L., Dinasquet, J., Logares, R., Riemann, L., Wendeberg, A., . . . Scofield, D. (2019). Summer comes to the Southern Ocean: How phytoplankton shape bacterioplankton communities far into the deep dark sea. Ecosphere, 10(3), Article ID e02641.
Open this publication in new window or tab >>Summer comes to the Southern Ocean: How phytoplankton shape bacterioplankton communities far into the deep dark sea
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2019 (English)In: Ecosphere, ISSN 2150-8925, E-ISSN 2150-8925, Vol. 10, no 3, article id e02641Article in journal (Refereed) Published
National Category
urn:nbn:se:uu:diva-382662 (URN)10.1002/ecs2.2641 (DOI)000463977000027 ()
Available from: 2019-03-12 Created: 2019-05-07 Last updated: 2019-05-07Bibliographically approved
Dinasquet, J., Richert, I., Logares, R., Yager, P., Bertilsson, S. & Riemann, L. (2017). Mixing of water masses caused by a drifting iceberg affects bacterial activity, community composition and substrate utilization capability in the Southern Ocean. Environmental Microbiology, 19(6), 2453-2467
Open this publication in new window or tab >>Mixing of water masses caused by a drifting iceberg affects bacterial activity, community composition and substrate utilization capability in the Southern Ocean
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2017 (English)In: Environmental Microbiology, ISSN 1462-2912, E-ISSN 1462-2920, Vol. 19, no 6, p. 2453-2467Article in journal (Refereed) Published
Abstract [en]

The number of icebergs produced from ice-shelf disintegration has increased over the past decade in Antarctica. These drifting icebergs mix the water column, influence stratification and nutrient condition, and can affect local productivity and food web composition. Data on whether icebergs affect bacterioplankton function and composition are scarce, however. We assessed the influence of iceberg drift on bacterial community composition and on their ability to exploit carbon substrates during summer in the coastal Southern Ocean. An elevated bacterial production and a different community composition were observed in iceberg-influenced waters relative to the undisturbed water column nearby. These major differences were confirmed in short-term incubations with bromodeoxyuridine followed by CARD-FISH. Furthermore, one-week bottle incubations amended with inorganic nutrients and carbon substrates (a mix of substrates, glutamine, Nacetylglucosamine, or pyruvate) revealed contrasting capacity of bacterioplankton to utilize specific carbon substrates in the iceberg-influenced waters compared with the undisturbed site. Our study demonstrates that the hydrographical perturbations introduced by a drifting iceberg can affect activity, composition, and substrate utilization capability of marine bacterioplankton. Consequently, in a context of global warming, increased frequency of drifting icebergs in polar regions holds the potential to affect carbon and nutrient biogeochemistry at local and possibly regional scales.

National Category
urn:nbn:se:uu:diva-329709 (URN)10.1111/1462-2920.13769 (DOI)000404007700028 ()28429510 (PubMedID)
Swedish Research Council, 2008-6430Science for Life Laboratory - a national resource center for high-throughput molecular bioscienceKnut and Alice Wallenberg Foundation
Available from: 2017-10-03 Created: 2017-10-03 Last updated: 2017-10-03Bibliographically approved
Yager, P. L., Sherrell, R. M., Stammerjohn, S. E., Ducklow, H. W., Schofield, O. M., Ingall, E. D., . . . van Dijken, G. (2016). A carbon budget for the Amundsen Sea Polynya, Antarctica: estimating net community production and export in a highly productive polar ecosystem. Elementa: Science of the Anthropocene, 4, Article ID 000140.
Open this publication in new window or tab >>A carbon budget for the Amundsen Sea Polynya, Antarctica: estimating net community production and export in a highly productive polar ecosystem
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2016 (English)In: Elementa: Science of the Anthropocene, ISSN 2325-1026, Vol. 4, article id 000140Article in journal (Refereed) Published
Abstract [en]

Polynyas, or recurring areas of seasonally open water surrounded by sea ice, are foci for energy and material transfer between the atmosphere and the polar ocean. They are also climate sensitive, with both sea ice extent and glacial melt influencing their productivity. The Amundsen Sea Polynya (ASP) is the greenest polynya in the Southern Ocean, with summertime chlorophyll a concentrations exceeding 20 µg L−1. During the Amundsen Sea Polynya International Research Expedition (ASPIRE) in austral summer 2010–11, we aimed to determine the fate of this high algal productivity. We collected water column profiles for total dissolved inorganic carbon (DIC) and nutrients, particulate and dissolved organic matter, chlorophyll a, mesozooplankton, and microbial biomass to make a carbon budget for this ecosystem. We also measured primary and secondary production, community respiration rates, vertical particle flux and fecal pellet production and grazing. With observations arranged along a gradient of increasing integrated dissolved inorganic nitrogen drawdown (ΔDIN; 0.027–0.74 mol N m−2), changes in DIC in the upper water column (ranging from 0.2 to 4.7 mol C m−2) and gas exchange (0–1.7 mol C m−2) were combined to estimate early season net community production (sNCP; 0.2–5.9 mol C m−2) and then compared to organic matter inventories to estimate export. From a phytoplankton bloom dominated by Phaeocystis antarctica, a high fraction (up to ~60%) of sNCP was exported to sub-euphotic depths. Microbial respiration remineralized much of this export in the mid waters. Comparisons to short-term (2–3 days) drifting traps and a year-long moored sediment trap capturing the downward flux confirmed that a relatively high fraction (3–6%) of the export from ~100 m made it through the mid waters to depth. We discuss the climate-sensitive nature of these carbon fluxes, in light of the changing sea ice cover and melting ice sheets in the region.

National Category
Meteorology and Atmospheric Sciences
urn:nbn:se:uu:diva-311392 (URN)10.12952/journal.elementa.000140 (DOI)000389924300002 ()

Part of an Elementa Special Feature ASPIRE: The Amundsen Sea Polynya International Research Expedition

Available from: 2016-12-27 Created: 2016-12-27 Last updated: 2020-01-07Bibliographically approved
Richert, I., Dinasquet, J., Logares, R., Riemann, L., Yager, P. L., Wendeberg, A. & Bertilsson, S. (2015). The influence of light and water mass on bacterial population dynamics in the Amundsen Sea Polynya. Elementa: Science of the Anthropocene, 3(1), Article ID 44.
Open this publication in new window or tab >>The influence of light and water mass on bacterial population dynamics in the Amundsen Sea Polynya
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2015 (English)In: Elementa: Science of the Anthropocene, ISSN 2325-1026, Vol. 3, no 1, article id 44Article in journal (Refereed) Published
Abstract [en]

Despite being perpetually cold, seasonally ice-covered and dark, the coastal Southern Ocean is highly productive and harbors a diverse microbiota. During the austral summer, ice-free coastal patches (or polynyas) form, exposing pelagic organisms to sunlight, triggering intense phytoplankton blooms. This strong seasonality is likely to influence bacterioplankton community composition (BCC). For the most part, we do not fully understand the environmental drivers controlling high-latitude BCC and the biogeochemical cycles they mediate. In this study, the Amundsen Sea Polynya was used as a model system to investigate important environmental factors that shape the coastal Southern Ocean microbiota. Population dynamics in terms of occurrence and activity of abundant taxa was studied in both environmental samples and microcosm experiments by using 454 pyrosequencing of 16S rRNA genes. We found that the BCC in the photic epipelagic zone had low richness, with dominant bacterial populations being related to taxa known to benefit from high organic carbon and nutrient loads (copiotrophs). In contrast, the BCC in deeper mesopelagic water masses had higher richness, featuring taxa known to benefit from low organic carbon and nutrient loads (oligotrophs). Incubation experiments indicated that direct impacts of light and competition for organic nutrients are two important factors shaping BCC in the Amundsen Sea Polynya.

National Category
Biological Sciences Earth and Related Environmental Sciences
urn:nbn:se:uu:diva-270733 (URN)10.12952/journal.elementa.000044 (DOI)
Available from: 2016-01-04 Created: 2016-01-04 Last updated: 2017-05-31Bibliographically approved
Richert, I. (2014). Environmental filtering of bacteria in low productivity habitats. (Doctoral dissertation). Uppsala: Acta Universitatis Upsaliensis
Open this publication in new window or tab >>Environmental filtering of bacteria in low productivity habitats
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Microbes fulfill important ecosystem functions by contributing as drivers of global nutrient cycles. Their distribution patterns are mainly controlled by environmental heterogeneities. So far, little is known about the mode of action of particular environmental drivers on the microbiota, particularly in low productivity habitats.

The aim of this thesis was to investigate the relationships between local environmental drivers and the microbial responses at the level of communities, individuals and realized function, using three structurally different model habitats sharing the feature of overall low productivity. Using a hypothesis-based approach and extensive 16S rRNA amplicon mapping of bacterioplankton colonizing the polar Southern Ocean, I identified how the seasonal formation of open-water polynyas and coupled phytoplankton production affected the diversity of surface bacterial communities and resulted in a cascading effect influencing the underlying dark polar water masses. Additional laboratory experiments, with cultures exposed to light, resulted in reduction in alpha diversity and promoted opportunistic populations with most bacterial populations thriving in the cultures typically reflected the dominants in situ.

Furthermore it was experimentally tested how induced cyclic water table fluctuations shaping environmental heterogeneity in a constructed wetland on temporal scale, by directly affecting redox conditions. Twelve months of water table fluctuations resulted in enhanced microbial biomass, however a shift in community composition did not lead to a significant increase in pollutant removal efficiency when compared to a static control wetland. I detected phyla that have previously been proposed as key players in anaerobic benzene break-down using a protocol that was developed for single cell activity screening using isotope-substrate uptake and microautoradiography combined with taxonomic identification based on fluorescent in situ hybridization targeting the 16S rRNA. Eventually, I provide an example of how anthropogenic pollution with polyaromatic hydrocarbons induced a strong environmental filtering on intrinsic microbial communities in lake sediments.

In conclusion, my studies reveal that microorganisms residing in low productivity habitats are greatly influenced by environmental heterogeneity across both spatial and temporal scales. However, such variation in community composition or overall abundance does not always translate to altered community function.


Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2014. p. 44
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1157
bacteria, environmental filtering, diversity, ecosystem service, hydrocarbon utilization, Southern Ocean, sediment
National Category
Natural Sciences Biological Sciences
Research subject
Biology with specialization in Microbiology
urn:nbn:se:uu:diva-229144 (URN)978-91-554-8986-1 (ISBN)
Public defence
2014-09-16, Fries salen, Evolutionsbiologiskt centrum, EBC, Norbyvägen 18, 752 36 Uppsala, Uppsala, 10:00 (English)
Available from: 2014-08-26 Created: 2014-08-01 Last updated: 2014-09-08

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