Limnological description of the Lakes Zürich, Lucerne, and Cadagno

Bossard, Peter; Gammeter, Sonja; Lehmann, Christine; Schanz, Fritz; Bachofen, Reinhard; Bürgi, H. R.; Steiner, Daniel; Zimmermann, U.

doi:10.1007/pl00001353

Cited by 57 publications

(59 citation statements)

References 32 publications

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“…Measurements of physicochemical parameters confirmed earlier reports (16,21,22), showing steep vertical gradients of nutrients and oxygen within the pycnocline and a shift in redox potential between 10-and 11-m depth, indicating anoxic, reducing conditions in the hypolimnion (Fig. 1).…”

Section: Resultssupporting

confidence: 88%

A single-cell view on the ecophysiology of anaerobic phototrophic bacteria

Musat

Halm

Winterholler

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

392

421

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Quantitative information on the ecophysiology of individual microorganisms is generally limited because it is difficult to assign specific metabolic activities to identified single cells. Here, we develop and apply a method, Halogen In Situ HybridizationSecondary Ion Mass Spectroscopy (HISH-SIMS), and show that it allows simultaneous phylogenetic identification and quantitation of metabolic activities of single microbial cells in the environment. Using HISH-SIMS, individual cells of the anaerobic, phototropic bacteria Chromatium okenii, Lamprocystis purpurea, and Chlorobium clathratiforme inhabiting the oligotrophic, meromictic Lake Cadagno were analyzed with respect to H 13 CO3 ؊ and 15 NH4 ؉ assimilation. Metabolic rates were found to vary greatly between individual cells of the same species, showing that microbial populations in the environment are heterogeneous, being comprised of physiologically distinct individuals. Furthermore, C. okenii, the least abundant species representing Ϸ0.3% of the total cell number, contributed more than 40% of the total uptake of ammonium and 70% of the total uptake of carbon in the system, thereby emphasizing that numerically inconspicuous microbes can play a significant role in the nitrogen and carbon cycles in the environment. By introducing this quantification method for the ecophysiological roles of individual cells, our study opens a variety of possibilities of research in environmental microbiology, especially by increasing the ability to examine the ecophysiological roles of individual cells, including those of less abundant and less active microbes, and by the capacity to track not only nitrogen and carbon but also phosphorus, sulfur, and other biological element flows within microbial communities.anaerobic phototrophs ͉ nanoSIMS

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Section: Resultssupporting

confidence: 88%

A single-cell view on the ecophysiology of anaerobic phototrophic bacteria

Musat

Halm

Winterholler

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

392

421

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“…In-situ primary production (PP) was quantified using the 14 C incubation technique (Bossard et al 2001). Depths for in-situ incubations corresponded to the sampling depths and water was incubated for 4.5 h from 9:30 am to 2:00 pm on the 7th of August 2015.…”

Section: In-situ Incubationmentioning

confidence: 99%

Oxygenic primary production below the oxycline and its importance for redox dynamics

et al. 2016

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We present evidence that oxygenic primary production occurs in the virtually anoxic regions (i.e. regions where no oxygen was detected) of the eutrophic, pre-alpine Lake Rot (Switzerland). Chlorophyll-a measurements in combination with phytoplankton densities indicated the presence of oxygenic primary producers throughout the water column. While Chlorophyceae were present as the main class of oxygenic phototrophs above the oxycline, which extended from 8 down to 9.2 m, the phototrophic community in and below the oxycline was dominated by cyanobacteria. In-situ incubation experiments with H 14 CO 3 -conducted in August 2013 revealed an oxygenic primary production rate of 1.0 and 0.5 mg C m -3 h -1 in 9 and 10 m depth, respectively. However, measurements with optical trace oxygen sensors showed that oxygen concentrations were below the detection limit (20 nmol l -1 ) during the incubation period below 9.2 m. Potential oxygen consumption rates, which were 10-20 times higher than oxygen production rates, explain this absence of free oxygen. Our data show that oxygen production in the virtually anoxic zone corresponded to approximately 8 % of the oxygen flux driven by the concentration gradient in the oxycline. This provided an important source of electron acceptors for biogeochemical processes beyond the conventional redox boundary and in the apparently oxygen depleted zone of Lake Rot. This oxygenic primary production in the virtually anoxic zone could allow growth and activity of aerobic microorganisms adapted to low oxygen supply.

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“…Incident, above surface, UV and PAR irradiance were monitored during the incubation using MACAM broadband sensors. For more information on the assessment of radiation and limnological conditions in the Lakes Lucerne and Cadagno during the GAP workshop, see Bossard et al (2001) and Neale et al (2001 c), this issue. Statistical analysis was performed using a two-way ANOVA test (treatments against fractions) for each lake.…”

mentioning

confidence: 99%

Photosynthetic response of pico- and nanoplanktonic algae to UVB, UVA and PAR in a high mountain lake

Callieri

Morabito

Huot³

et al. 2001

Aquat. sci.

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The objective of the present study was to evaluate the influence of UV radiation on photosynthesis rate, in situ and in laboratory incubations, on size fractionated natural algal assemblages (picoplankton: 0.2 -2µm, nanoplankton: >2µm) and whole water (total organic carbon TOC). Near surface samples from a mesotrophic high mountain lake (LCD: L. Cadagno, Swiss Alps, Switzerland, 1923 m a.s.l.) and from the oligotrophic pre-alpine L. Lucerne (LLU: Swiss Alps, Switzerland, 434 m a.s.l.) were both incubated at a depth of 30 cm (50% of surface UV at 323 nm ) in L. Cadagno. At the same time, biological weighting functions for UV inhibition of photosynthesis (BWFs) were determined for the autotrophic picoplankton and whole fraction in a spectral incubator. Photosynthetic assimilation of the pico-and nanoplanktonic algal communities as well as the assimilated total organic carbon (TOC) was estimated separately by 14 C uptake under three irradiance conditions: PAR (photosynthetically active radiation), PAR + UVA and PAR + UVA + UVB. UV radiation reduced significantly photosynthesis rate in samples from both lakes (LLU: P = 0.0012; LCD: P = 0.0001). It appears that UVA plus UVB significantly affect the algal assemblage in both lakes; however most of the effect is due to UVA (Mann Whitney U test, two tailed: P = 0.0022). The natural assemblages from LLU transplanted to LCD were more inhibited by UV than the autochthonous assemblages of LCD. Photosynthetic rates of picoplankton from LLU and LCD under full UV exposure was reduced by 73% and 55% respectively relative to PAR only. A higher sensitivity of autotrophic picoplankton to the UV radiation, with respect to the nanoplankton, was observed in the biological weighting functions. However this difference was not statistically significant for the in situ incubations.

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Limnological description of the Lakes Zürich, Lucerne, and Cadagno

Cited by 57 publications

References 32 publications

A single-cell view on the ecophysiology of anaerobic phototrophic bacteria

A single-cell view on the ecophysiology of anaerobic phototrophic bacteria

Oxygenic primary production below the oxycline and its importance for redox dynamics

Photosynthetic response of pico- and nanoplanktonic algae to UVB, UVA and PAR in a high mountain lake

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