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Competition as driving force for bacterioplankton successions in lake Zürich

English title Competition as driving force for bacterioplankton successions in lake Zürich
Applicant Posch Thomas
Number 117765
Funding scheme Project funding
Research institution Limnologische Station Universität Zürich
Institution of higher education University of Zurich - ZH
Main discipline Ecology
Start/End 01.01.2008 - 31.12.2010
Approved amount 197'000.00
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Keywords (6)

algae-bacteria interactions; aquatic microbial ecology; bacterial taxa; competition; fluorescence in situ hybridization; freshwater bacterioplankton

Lay Summary (English)

Lead
Lay summary
The dynamics of freshwater bacterioplankton are determined by the interplay of bottom-up and top-down factors. In addition, heterotrophic bacteria also have to compete with pro- and eukaryotic phototrophs for nutrients. Although competition has been investigated in detail for all major planktonic organisms, knowledge on the competitive abilities of freshwater bacterial populations is very restricted. Studying competition as driving force for bacterial successions in the photic zone of Lake Zürich implies to study the competition for nutrients between heterotrophic bacterial taxa and phototrophic organisms, primarily algae (during spring bloom) and the cyanobacterium Planktothrix rubescens (during its autumnal dominance). As P. rubescens is regarded as a photoheterotroph, competition for organic substrates should also be considered. In addition, we should expect also strong competitive processes between and within bacterial taxa, using corporate resources.Three work packages will be addressed:•Methods development: To adequately investigate the seasonal and spatial patterns, a fully automated microscope for the quantification of fluorescently stained microorganisms will be developed. For a characterization of substrate affinities by bacterial taxa, incorporation rates of labelled amino acids and sugars will be tested via microautoradiography and fluorescence in situ hybridization (MAR-FISH).•Description of seasonal successions: During a one-year-monitoring, we will characterize the in situ dynamics of bacterial taxa in relation to nutrients, grazing, algal groups and P. rubescens. This dataset will allow for detailed correlation analyses. A biweekly monitoring of the epilimnion, and monthly sampling of the hypolimnion will allow insight into the competitive abilities of bacterial taxa. Additional physical, chemical but also biological data will be gained in collaboration with the City of Zürich Water Supply.•Field experiments: Size fractionation and nutrient enrichment experiments will be conducted during several periods of the year (spring phytoplankton bloom, summer stratification, P. rubescens bloom, mixis). Parallel set-ups will be used with nutrients added in pulses and in alternating succession. We will apply approaches to manipulate C:N:P availability, (1) enrichment of samples in bottles and (2) incubation of samples in dialysis tubes. The following questions should be answered:•Which bacterial taxa dominate during the seasonal cycle in terms of biomasses and abundances, i.e., can be assigned as the successful competitors within the bacterioplankton?•What are the substrate preferences of the major bacterial taxa in Lake Zürich?•Can we interpret opposite trends of bacterial and algal dynamics as a mirror of competition for corporate resources? •Is there a consistently positive or negative correlation between the occurrence of P. rubescens and specific bacterial taxa? Are P. rubescens and specific bacterial taxa competing for the same substrates?
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
In situ substrate preferences of abundant bacterioplankton populations in a prealpine freshwater lake
Salcher Michaela M., Posch Thomas, Pernthaler Jakob (2013), In situ substrate preferences of abundant bacterioplankton populations in a prealpine freshwater lake, in ISME Journal, 7, 896-907.
Vertical and longitudinal distribution patterns of differnt bacterioplankton populations in a canyon-shaped, deep prealpine lake
Salcher Michaela M., Pernthaler Jakob, Frater Nakita, Posch Thomas (2011), Vertical and longitudinal distribution patterns of differnt bacterioplankton populations in a canyon-shaped, deep prealpine lake, in Limnology and Oceanography, 56(6), 2027-2039.
Seasonal bloom dynamics and ecophysiology of the freshwater sister clade of SAR11 bacteria 'that rule the waves' (LD12)
Salcher Michaela M., Pernthaler Jakob, Posch Thomas (2011), Seasonal bloom dynamics and ecophysiology of the freshwater sister clade of SAR11 bacteria 'that rule the waves' (LD12), in ISME Journal, 5(8), 1242-1252.
Quantitative dominance of seasonally persistent filamentous cyanobacteria (Planktothrix rubescens) in the microbial assemblages of a temperate lake.
Van den Wyngaert Silke, Salcher Michaela M., Pernthaler Jakob, Zeder Michael, Posch Thomas (2011), Quantitative dominance of seasonally persistent filamentous cyanobacteria (Planktothrix rubescens) in the microbial assemblages of a temperate lake., in Limnology and Oceanography, 56(1), 97-109.
Spatiotemporal distribution and activity patterns of bacteria from three phylogenetic groups in an oligomesotrophic lake
Salcher Michaela M., Pernthaler Jakob, Posch Thomas (2010), Spatiotemporal distribution and activity patterns of bacteria from three phylogenetic groups in an oligomesotrophic lake, in Limnology and Oceanography, 55(2), 846-856.
New image analysis tool to study biomass and morphotypes of three major bacterioplankton groups in an alpine lake
Posch Thomas, Franzoi Josef, Prader Martin, Salcher Michaela M. (2009), New image analysis tool to study biomass and morphotypes of three major bacterioplankton groups in an alpine lake, in Aquatic Microbial Ecology, 54, 113-126.

Awards

Title Year
Brock Post-doctoral award for the accomplishments and promise of outstanding postdoctoral research 2012

Associated projects

Number Title Start Funding scheme
130023 Limnobotics: Understanding blooms of toxic freshwater cyanobacteria using an autonomous sampling platform and molecular strain typing 01.04.2010 Interdisciplinary projects
121331 AquaProbe: from Monitoring towards Understanding, Predicting and Managing Plankton in changing Aquatic Ecosystems 01.07.2008 R'EQUIP

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