Phytoplankton photoadaptation during the spring period in Lake Zürich

Schanz, Fritz; Burri, Judith

doi:10.2166/wst.1995.0166

Cited by 2 publications

(4 citation statements)

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“…Below 10 m, dissolved oxygen has dropped to 0 and a strong increase in turbidity is observed, the latter due to the presence of a population of purple sulfur bacteria consisting mainly of C. okenii and A. purpureus. The vertical light attenuation coefficients, K,, in the mixolimnion ranged in 1986 and 1987 from 0.26 to 0.39 m-l, values similar to those found in other lakes (Schanz 1985). The light reaching 10-m depth is restricted to the green part of the spectrum (Fischer et al 1996).…”

Section: Methodssupporting

confidence: 70%

“…The PAR measurements in the lake were done before the incubation for the determination of the photosynthetic productivity (between 0900 and 1000 h) and at the time of the highest irradiance (1200 h). The vertical attenuation coefficient, Kll (m-l), was calculated as outlined by Schanz (1985).…”

Section: Methodsmentioning

confidence: 99%

“…where E,,(PAR, Zi) is the downward h-radiance of the photosynthetically available radiation (400-700 nm) at depth zi (in meters), calculated from the h-radiance measurements in air and the vertical light attenuation properties of the lake water at the sampling day (K,, determined separately for the layers 0.05-10-m and 10-12-m depth; see Fischer et al 1996) and assuming a surface irradiance loss of 7% (Schanz 1983). The quantum yield 4 at depth z is…”

Section: Methodsmentioning

confidence: 99%

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Photosynthetic production and photoadaptation of phototrophic sulfur bacteria in Lake Cadagno (Switzerland)

Schanz

Fischer-Romero

Bachofen

1998

Limnology & Oceanography

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Lake Cadagno is a meromictic lake of 21-m depth in the central Swiss Alps at 1,923 m asl. Its mixolimnion reaches from the surface down to 10-m depth. A dense population of phototrophic bacteria dominated by Chromatium okenii is located in the subsequent 2-m layer containing up to 200 mg bacteriochlorophyll (Bchl) m-7.Maximum cell concentration was found at 10.8-m depth during the summer season. The light intensity at the upper edge of the bacterial layer averages 4.7% of the subsurface radiation (at 0.05 m depth) and at the density peak of the layer it averages 0.4%. Variations over the summer season in the photosynthetic properties of the bacterial population at the depth of highest cell density have been observed in in situ 14C-CO, incorporation experiments. These changes are random, and no photoadaptation effect was found. Thus, the population of phototrophic bacteria was physiologically uniform during the investigation period and it had the following photosynthetic properties (medians for the 25th and 75th percentiles are in parentheses): P,,,, 0.154 mg C (mg Bchl)-I h-l (0.048, 0.174); Ik, 0.016 mol quanta m-2 h-l (0.012, 0.019); (Y, 7.7 mg C (mg Bchl) I h-l (mol quanta mP2 h-l)-' (4.8, 11.6). The specific dark production rate was 0.016 mg C (mg Bchl)-' h-l (0.014, 0.023). The average quantum yield for CO, assimilation at the depth of maximum cell density, (b,, was low at 0.012 (0.007, 0.020). The cells were sensitive to light intensities higher than the optimum found at -0.036 mol quanta mm2 h-I. Maximum inhibition by excessive light was determined to be 80% at light intensities >0.108 mol quanta m-2 h-l (=30 pmol quanta m-2 s-l) when cells were exposed for periods of 2.5 h or longer. The bacterial biomass increment assuming no losses, p*, was calculated to be 0.05 d-l (0.03, 0.08) and the loss rate, A, to be 0.03 d-l (-0.10, 0.06).

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Section: Methodssupporting

confidence: 70%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Photosynthetic production and photoadaptation of phototrophic sulfur bacteria in Lake Cadagno (Switzerland)

Schanz

Fischer-Romero

Bachofen

1998

Limnology & Oceanography

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“…Diatoms of Lake Toblino were mainly represented by Stephanodiscus hantzschii, a key species in nutrient rich lakes (Schanz and Burri 1995;Kolmakov et al 2002), but especially in turbid and nutrient rich potamal rivers, river oxbows, fluvial lakes and canyon reservoirs at all latitudes (Köhler and Hoeg 2000;Ha et al 2002, Reynolds andDescy 1996;Reynolds et al 2002, Komárková et al 2003Friedrich and Pohlmann 2009). The particular fit of this C-strategist species for such aquatic environments is due to tolerance toward relatively high flushing (Reynolds et al 2002) and low light intensity (Kolmakov et al 2002), very high affinity for nutrients (in particular Si, Van Donk and Kilham 1990), and to its high growth rate even at low temperature (up to ca.…”

Section: Discussionmentioning

confidence: 99%

Comparative analysis of phytoplankton patterns in two modified lakes with contrasting hydrological features

2009

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Hydrological management represents one of the main factors controlling physical and chemical characteristics as well as biodiversity and productivity of planktonic communities in artificial and modified lakes. In Alpine piedmont reservoirs, which often receive large water inputs from high altitude watersheds, control operated by hydrological regime over ecological processes is also mediated by other related variables such as water temperature and turbulence, and load of inorganic suspended solids. This contribution reports on results obtained from a comparative study on the impact of hydrological regime on phytoplankton patterns in two modified piedmont lakes of different size and hydrology located in the NE Italian Alps: Lake Santa Croce (V = 147 9 10 6 km 3 ) and Lake Toblino (V = 5.7 9 10 6 km 3 ). Phytoplankton of both lakes was characterised by a pronounced dominance of diatoms, accompanied by cryptophytes and green algae. The mesotrophic Lake Santa Croce showed a typical seasonal succession of dominant groups, while phytoplankton growth in the eutrophic Lake Toblino was variable and showed pronounced pulses in relation to dramatic changes in the hydrological regime. The comparative study of phytoplankton, based on morpho-functional classification and application of multivariate analyses (non-metric multidimensional scaling, principal components analysis, and redundancy analysis), showed that hydrological regime affected phytoplankton growth in the two lakes both directly, i.e. through renewal time, and indirectly, i.e. regulating thermal conditions in Lake Santa Croce and nutrient availability in both lakes. Nevertheless, effectiveness of hydrological constraints largely depended on lake size and morphology, being more pronounced in the shallower and smaller Lake Toblino.

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Phytoplankton photoadaptation during the spring period in Lake Zürich

Cited by 2 publications

References 0 publications

Photosynthetic production and photoadaptation of phototrophic sulfur bacteria in Lake Cadagno (Switzerland)

Photosynthetic production and photoadaptation of phototrophic sulfur bacteria in Lake Cadagno (Switzerland)

Comparative analysis of phytoplankton patterns in two modified lakes with contrasting hydrological features

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