Buoyancy regulation in a red Oscillatoria unable to collapse gas vacuoles by turgor pressure

Utkilen, H. C.; Oliver, Rod L.; Walsby, A. E.

doi:10.1127/archiv-hydrobiol/102/1985/319

Cited by 65 publications

(9 citation statements)

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“…This value is then used instead of that in [CU] to calculate the new value of (ρ – ρ w ) in [CW]. The last step in calculating the excess density, [BD], is to apply finite limits (Howard et al ., 1996): measurements by Utkilen et al . (1985) indicate that the maximum (ρ – ρ w ) ≤ 27 kg m −3 (gas‐vacuolate Planktothrix filaments left at 55 µmol m −2 s −1 for 24 h), and the minimum (ρ – ρ w ) ≥ −30 kg m −3 (filaments left for 3 d at 1.5 µmol m −2 s −1 and the last 12 h in darkness).…”

Section: Methods and Calculationsmentioning

confidence: 99%

“…Using numerical methods, the values of the coefficients that give the minimum residual error were calculated as D m = 12.39 kg m −3 h −1 , D 0 = −1.44 kg m −3 h −1 , α = 0.3450 kg m −3 h −1 (µmol m −2 s −1 ) −1 , β = −1.5940 kg m −3 h −1 (µmol m −2 s −1 ) −1 , and γ = 0.1961. When Planktothrix is placed in the dark, its carbohydrate reserves are depleted and its density decreases (Utkilen et al ., 1985). The rate of density decrease is higher after the cyanobacterium has been in high irradiance and has accumulated more reserves.…”

Section: Methods and Calculationsmentioning

confidence: 99%

“…and γ = 0.1961. When Planktothrix is placed in the dark, its carbohydrate reserves are depleted and its density decreases (Utkilen et al, 1985). The rate of density decrease is higher after the cyanobacterium has been in high irradiance and has accumulated more reserves.…”

Section: Algorithms For the Buoyancy Responsementioning

confidence: 99%

“…They lose buoyancy at high irradiance by accumulating carbohydrate and regain buoyancy in low irradiance as carbohydrate is consumed (Thomas & Walsby, 1985; Konopka et al ., 1987; Kromkamp et al ., 1988; Wallace & Hamilton, 1999). Additional buoyancy changes may result from production or collapse of gas vesicles (Oliver & Walsby, 1984; Utkilen et al ., 1985; Kinsman et al ., 1991). These responses are driven by light but are modulated by nutrient availability (Klemer et al ., 1982; Konopka et al ., 1987; Oliver, 1994; Brookes & Ganf, 2001).…”

Section: Introductionmentioning

confidence: 99%

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

Walsby

2005

New Phytologist

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Summary• The ability of the Planktothrix rubescens to stratify in Lake Zürich is related to the size and shape of the cyanobacterial filaments.• Detailed measurements made in the lake are used in a dynamic computer model of buoyancy regulation to investigate the vertical movements of filaments tracking the depth at which the irradiance would support neutral buoyancy. The movement of the filament lags behind the constantly changing target depth owing to (a) the time taken for the filament to respond to the irradiance by changing its density and (b) the time it takes to move by sinking down or floating up through the water column.• The model simulates the stratification depth over a 5-month period of the summer from the continuous measurements of irradiance and weekly measurements of light attenuation and temperature, without any further adjustment over the period. Models using filaments of the size observed in Lake Zürich explain several details of the observed depth changes: smaller planktonic cyanobacteria (e.g. Limnothrix sp.) are unable to migrate fast enough and larger ones (e.g. Anabaena spp.) will overshoot and become entrained in the epilimnion.• The model can be used to simulate recruitment of Planktothrix filaments from different depths after vernal stratification. Recruitment of filaments from depths down to 45 m will contribute to the metalimnetic population increase in early July.

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Section: Methods and Calculationsmentioning

confidence: 99%

Section: Methods and Calculationsmentioning

confidence: 99%

Section: Algorithms For the Buoyancy Responsementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Walsby

2005

New Phytologist

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“…Additionally, high light intensities dilute cyanobacteria gas vesicles, also contributing to a decrease in cell buoyancy (Utkilen et al, 1985).…”

Section: Lightmentioning

confidence: 99%

Phytoplankton response to water quality threats in Midwest reservoirs

Cianci-Gaskill¹

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Harmful cyanobacterial blooms and invasive species threaten water quality. These threats are expected to worsen in the future, emphasizing the need for creative management solutions and a thorough understanding of their impacts. The objective of this dissertation is to investigate the influence of light on biomass and community composition of phytoplankton with the hypothesis that light will have an impact, regardless of nutrients and grazing. We investigate a novel geoengineering approach designed to control cyanobacteria by reducing light. We demonstrate that daily application of glacial rock flour, a fine particulate that floats on the water's surface, reduces light by half and results in up to a 78 percent decrease in cyanobacterial biovolume. We also look at the accumulation of microcystin in the tissues of bluegill and largemouth bass. Microcystin is higher in bluegill, likely because they feed from lower trophic levels. It is also higher in spring and decreases throughout the year, suggesting that time of the year might be an important consideration for microcystin fish consumption advisories. We also find that invasive zebra mussels are not causing an increase in water clarity in MO reservoirs like they are in natural, northern latitude lakes. This could be because reservoir conditions are suboptimal for zebra mussels, thus preventing them from reaching high densities. Understanding how aquatic resources have responded to stressors in the past enables us to predict how they will respond to changes in the future.

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Modelling the growth of cyanobacteria (GrowSCUM)

Howard

Kirkby

Kneale

et al. 1995

Hydrological Processes

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Toxic cyanobacteria have become a common nuisance in freshwater lakes and reservoirs throughout the world. sometimes resulting in the closure of sites with high amenity value. Cyanobacteria are able to regulate their buoyancy state in response to changing photosynthetic rates. Additionally, the cyanobacteria are liable to become entrained within wind-induced near-surface turbulent currents, resulting in mixing and mass transport. These movement processes have been modelled. A mathematical function is presented which describes light-and nutrient-limited cyanobacterial growth. The growth model is integrated with a previous movement model (SCUM: simulation of cyanobacterial underwater movement) as movement patterns and wind-induced lake mixing strongly affect the intensity and duration of light received by the cyanobacteria and thereby determine the photosynthetic potential. Results of the model suggest that cyanobacteria are resistant to periods of lake mixing and continue to increase their biomass, but at a depressed rate. Growth is most rapid under calm conditions. The results agree well with field-based findings, confirming the validity of the growth function.

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Buoyancy regulation in a red Oscillatoria unable to collapse gas vacuoles by turgor pressure

Cited by 65 publications

References 0 publications

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

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

Phytoplankton response to water quality threats in Midwest reservoirs

Modelling the growth of cyanobacteria (GrowSCUM)

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