Stratification by cyanobacteria in lakes: a dynamic buoyancy model indicates size limitations met by <i>Planktothrix rubescens</i> filaments

Walsby, A. E.

doi:10.1111/j.1469-8137.2005.01508.x

Cited by 57 publications

(60 citation statements)

References 47 publications

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“…It could be hypothesized that filamentous cyanobacteria outcompete unicellular cyanobacteria for light by their ability to migrate toward optimal light conditions. At lower light intensities this advantage could be reduced because of a lower light-affinity coefficient [27,31].…”

Section: Discussionmentioning

confidence: 99%

Heterotrophic Pioneers Facilitate Phototrophic Biofilm Development

2007

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Phototrophic biofilms are matrix-enclosed microbial communities, mainly driven by light energy. In this study, the successional changes in community composition of freshwater phototrophic biofilms growing on polycarbonate slides under different light intensities were investigated. The sequential changes in community composition during different developmental stages were examined by denaturing gradient gel electrophoresis (DGGE) of polymerase chain reaction (PCR)-amplified 16S rRNA gene fragments in conjugation with sequencing and phylogenetic analysis. Biofilm development was monitored with subsurface light sensors. The development of these biofilms was clearly light dependent. It was shown that under high light conditions the initial colonizers of the substratum predominantly consisted of green algae, whereas at low light intensities, heterotrophic bacteria were the initial colonizers. Cluster analysis of DGGE banding patterns revealed a clear correlation in the community structure with the developmental phases of the biofilms. At all light intensities, filamentous cyanobacteria affiliated to Microcoleus vaginatus became dominant as the biofilms matured. It was shown that the initial colonization phase of the phototrophic biofilms is shorter on polycarbonate surfaces precolonized by heterotrophic bacteria.

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Section: Discussionmentioning

confidence: 99%

Heterotrophic Pioneers Facilitate Phototrophic Biofilm Development

2007

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“…The mechanism is passive: cells receiving a great deal of light produce carbohydrates, which increases the density of each cell so it sinks; cells receiving too little light use up their carbohydrates, which reduces the density of each cell so it floats upward (351). The rates of ascent and descent are sufficiently low that the cells gradually equilibrate to inhabit an optimized depth range (351).…”

Section: Hovercraftmentioning

confidence: 99%

“…In a virtuoso balancing act, many cyanobacteria position themselves at defined depths of the water column so they receive just the right amount of light (351). The mechanism is passive: cells receiving a great deal of light produce carbohydrates, which increases the density of each cell so it sinks; cells receiving too little light use up their carbohydrates, which reduces the density of each cell so it floats upward (351).…”

Section: Hovercraftmentioning

confidence: 99%

“…Cells that are too small do not move quickly enough to stay in their optimum light range, and cells that are too large overshoot their optimum range and are buried in the sediment or are ensnared in the mass of organisms floating near the surface (351). To illustrate these effects, a Planktothrix filament 800 m long and 4 m wide sinks or rises at about 30% the rate of a filament 8 m wide; a filament 10 mm long rises 50% faster; and filaments of Limnothrix, which are only 2 m wide, sink or rise only 10% as fast as the 8-m-wide Planktothrix (351). At the other extreme, Anabaena filaments, which may be 10 mm long and 16 m wide, rise so fast that they become trapped at the surface (351).…”

Section: Hovercraftmentioning

confidence: 99%

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The Selective Value of Bacterial Shape

Young

2006

Microbiol Mol Biol Rev

849

777

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SUMMARY Why do bacteria have shape? Is morphology valuable or just a trivial secondary characteristic? Why should bacteria have one shape instead of another? Three broad considerations suggest that bacterial shapes are not accidental but are biologically important: cells adopt uniform morphologies from among a wide variety of possibilities, some cells modify their shape as conditions demand, and morphology can be tracked through evolutionary lineages. All of these imply that shape is a selectable feature that aids survival. The aim of this review is to spell out the physical, environmental, and biological forces that favor different bacterial morphologies and which, therefore, contribute to natural selection. Specifically, cell shape is driven by eight general considerations: nutrient access, cell division and segregation, attachment to surfaces, passive dispersal, active motility, polar differentiation, the need to escape predators, and the advantages of cellular differentiation. Bacteria respond to these forces by performing a type of calculus, integrating over a number of environmental and behavioral factors to produce a size and shape that are optimal for the circumstances in which they live. Just as we are beginning to answer how bacteria create their shapes, it seems reasonable and essential that we expand our efforts to understand why they do so.

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“…This species is particularly efficient at harvesting light due to its high phycobiliprotein content (Bright and Walsby, 2000;Greisberger and Teubner, 2007) and ability to optimize its position in the water column (Reynolds et al, 1987). Walsby and his coauthors (Walsby, 2005;Walsby et al, 2006) used a modelling approach to demonstrate that the ability of the Planktothrix rubes'cens to stratify in Lake ZUrich was related to the size and shape of its filaments; which respond to the irradiance by changing their density. This model was also used to explain the Burgundy-blood phenomenon sometimes observed in Lake ZUrich in November and December when, after deeper mixing and lower insolation, Planktothrix filaments become buoyant and float to the surface in subsequent calm periods.…”

Section: Phytoplankton Species Favoured By Climate Changementioning

confidence: 99%

The Impact of Variations in the Climate on Seasonal Dynamics of Phytoplankton

Nõges¹,

Adrian²,

Anneville³

et al. 2009

The Impact of Climate Change on European Lakes

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Phytoplankton, an assemblage of suspended, primarily autotrophic single cells and colonies, forms part of the base of the pelagic food chain in lakes. The responses of phytoplankton to anthropogenic pressures frequently provide the most visible indication of a long-term change in water quality. Several attributes related to the growth and composition of phytoplankton, such as their community structure, abundance as well as the frequency and the intensity of blooms, are included as indicators of water quality in the Water Framework Directive. The growth and seasonal succession of phytoplankton is regulated by a variety of external as well as internal factors (Reynolds et aI., 1993;Reynolds, 2006). Among the most important external factors ate light, temperature, and those associated with the supply of nutrients from point and diffuse sources in the catchment. The internal factors include the residence time of the lakes, the underwater light regime and the mixing characteristics of the water column. The schematic diagram (Fig. 14.1) shows some of the ways in which systematic changes in the climate can modulate these seasonal and inter-annual variations. The effects associated with the projected changes in the rainfall are likely to be most pronounced in small lakes with shOlt residence times (see George et aI., 2004 for some examples). In contrast, those connected with the projected changes in irradiance and wind mixing, are likely to be most important in deep, thermally stratified lakes.In this chapter, we use results acquired from a range of different European lakes to explore the potential effects of climate change on the seasonal development and the composition of phytoplankton. The time-series analysed are amongst the longest available in the region. Some of the lakes studied in CLIME have been sampled at weekly or fortnightly intervals for more than fifty years. These sites also cover a range of lake types from shallow to deep, small to large, and oligotrophic to eutrophic. P. Noges ([8)

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Stratification by cyanobacteria in lakes: a dynamic buoyancy model indicates size limitations met by Planktothrix rubescens filaments

Cited by 57 publications

References 47 publications

Heterotrophic Pioneers Facilitate Phototrophic Biofilm Development

Heterotrophic Pioneers Facilitate Phototrophic Biofilm Development

The Selective Value of Bacterial Shape

The Impact of Variations in the Climate on Seasonal Dynamics of Phytoplankton

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