Periphyton development during summer stratification in the presence of a metalimnetic bloom of Planktothrix rubescens

Trbojević, Ivana; Blagojević, Ana; Kostić, Dušan; Marjanovic, P.; Krizmanić, Jelena; Popović, Slađana; Simić, Gordana Subakov

doi:10.1016/j.limno.2019.125709

Cited by 5 publications

(4 citation statements)

References 40 publications

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“…These are cyanobacteria communities located below the surface where sufficient light penetrates and the disturbance effects of wind mixing are meager. These deep-water proliferations of cyanobacteria are often unreported due to their inconspicuous nature. , Sometimes referred to as metalimnetic cyanobacteria layers, , metalimnetic blooms, , or deep chlorophyll maxima or layers (a general term used for all phycological groups), these deep-water abundances often occur within the relatively narrow metalimnetic region. , Unlike near-surface cyanobacteria proliferations, deep cyanobacteria layers seldom lead to public responses . Yet deep cyanobacteria layers may consist of toxin-producing genera, posing risks to drinking water, , as drinking water withdrawal systems are often constructed at depths that may align with potential deep cyanobacteria layers. , …”

Section: Introductionmentioning

confidence: 99%

“…These deep-water proliferations of cyanobacteria are often unreported due to their inconspicuous nature. 6 , 7 Sometimes referred to as metalimnetic cyanobacteria layers, 8 , 9 metalimnetic blooms, 10 , 11 or deep chlorophyll maxima or layers (a general term used for all phycological groups), 12 these deep-water abundances often occur within the relatively narrow metalimnetic region. 13 , 14 Unlike near-surface cyanobacteria proliferations, deep cyanobacteria layers seldom lead to public responses.…”

Section: Introductionmentioning

confidence: 99%

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Deep Cyanobacteria Layers: An Overlooked Aspect of Managing Risks of Cyanobacteria

Erratt

Creed

Freeman

et al. 2022

Environ. Sci. Technol.

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The risk of human exposure to cyanotoxins is partially influenced by the location of toxin-producing cyanobacteria in waterbodies. Cyanotoxin production can occur throughout the water column, with deep water production representing a potential public health concern, specifically for drinking water supplies. Deep cyanobacteria layers are often unreported, and it remains to be seen if lower incident rates reflect an uncommon phenomenon or a monitoring bias. Here, we examine Sunfish Lake, Ontario, Canada as a case study lake with a known deep cyanobacteria layer. Cyanotoxin and other bioactive metabolite screening revealed that the deep cyanobacteria layer was toxigenic [0.03 μg L −1 microcystins (max) and 2.5 μg L −1 anabaenopeptins (max)]. The deep layer was predominantly composed of Planktothrix isothrix (exhibiting a lower cyanotoxin cell quota), with Planktothrix rubescens (exhibiting a higher cyanotoxin cell quota) found at background levels. The co-occurrence of multiple toxigenic Planktothrix species underscores the importance of routine surveillance for prompt identification leading to early intervention. For instance, microcystin concentrations in Sunfish Lake are currently below national drinking water thresholds, but shifting environmental conditions (e.g., in response to climate change or nutrient modification) could fashionan environment favoring P. rubescens, creating a scenario of greater cyanotoxin production. Future work should monitor the entire water column to help build predictive capacities for identifying waterbodies at elevated risk of developing deep cyanobacteria layers to safeguard drinking water supplies.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Deep Cyanobacteria Layers: An Overlooked Aspect of Managing Risks of Cyanobacteria

Erratt

Creed

Freeman

et al. 2022

Environ. Sci. Technol.

View full text Add to dashboard Cite

show abstract

“…P. rubescens is highly competitive in nutrient-depleted environments (Carraro et al, 2012) and the subsurface light climate is considered to be critical to its growth (Posch et al, 2012). It regulates the vertical position in water column by adjusting its density according to ambient light levels (Trbojević et al, 2019) in order to generate buoyancy under low light levels. At higher light levels, by contrast, it accumulates carbohydrates which act as a ballast and reduces buoyancy (Walsby and Schanz, 2002).…”

Section: Introductionmentioning

confidence: 99%

Controlling blooms of Planktothrix rubescens by optimized metalimnetic water withdrawal: a modelling study on adaptive reservoir operation

Hamilton

Frassl

et al. 2022

Preprint

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Background: Aggregations of cyanobacteria in lakes and reservoirs are commonly associated with surface blooms, but may also occur in the metalimnion as subsurface or deep chlorophyll maxima. Metalimnetic cyanobacteria blooms are of great concern when potentially toxic species, such as Planktothrix rubescens, are involved. Metalimnetic blooms of P. rubescens have apparently increased in frequency and severity in recent years, so there is a strong need to identify reservoir management options to control it. We hypothesized that P. rubescens blooms in reservoirs can be suppressed using selective withdrawal to maximize its export from the reservoir. We also expect that altering the light climate can affect the dynamics of this species. We tested our hypothesis in Rappbode Reservoir (the largest drinking water reservoir in Germany) by establishing a series of withdrawal and light scenarios based on a calibrated water quality model (CE-QUAL-W2). Results: The novel withdrawal strategy, in which water is withdrawn from a certain depth below the surface within the metalimnion instead of at a fixed elevation relative to the dam wall, significantly reduced P. rubescens biomass in the reservoir. According to the simulation results, we defined an optimal withdrawal volume to control P. rubescens blooms in the reservoir as approximately 10 million m3 (10% of the reservoir volume) during its bloom phase. The results also illustrated that P. rubescens growth can be most effectively suppressed if the metalimnetic withdrawal is applied in the early stage of its rapid growth, i.e., before the bloom occurs. Additionally, our study showed that P. rubescens biomass gradually decreased with increasing light extinction and nearly disappeared when the extinction coefficient exceeded 0.55 m-1. Conclusion: Our study indicates the rise in P. rubescens biomass can be effectively offset by selective withdrawal strategy and controlling light intensity beneath the water surface. Considering the widespread occurrence of P. rubescens in stratified lakes and reservoirs worldwide, we believe the results will be helpful for scientists and water managers working on other water bodies to minimize the negative impacts of this harmful algae.

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“…rubescens is highly competitive in nutrient-depleted environments [6] and the subsurface light climate is considered to be critical to its growth [49]. It regulates the vertical position in water column by adjusting its density according to ambient light levels [60] to generate buoyancy under low light levels. At higher light levels, by contrast, it accumulates carbohydrates which act as a ballast and reduces buoyancy [63].…”

Section: Introductionmentioning

confidence: 99%

Controlling blooms of Planktothrix rubescens by optimized metalimnetic water withdrawal: a modelling study on adaptive reservoir operation

Hamilton

Frassl

et al. 2022

Environ Sci Eur

View full text Add to dashboard Cite

Background Aggregations of cyanobacteria in lakes and reservoirs are commonly associated with surface blooms, but may also occur in the metalimnion as subsurface or deep chlorophyll maxima. Metalimnetic cyanobacteria blooms are of great concern when potentially toxic species, such as Planktothrix rubescens, are involved. Metalimnetic blooms of P. rubescens have apparently increased in frequency and severity in recent years, so there is a strong need to identify reservoir management options to control it. We hypothesized that P. rubescens blooms in reservoirs can be suppressed using selective withdrawal to maximize its export from the reservoir. We also expect that altering the light climate can affect the dynamics of this species. We tested our hypothesis in Rappbode Reservoir (the largest drinking water reservoir in Germany) by establishing a series of withdrawal and light scenarios based on a calibrated water quality model (CE-QUAL-W2). Results The novel withdrawal strategy, in which water is withdrawn from a certain depth below the surface within the metalimnion instead of at a fixed elevation relative to the dam wall, significantly reduced P. rubescens biomass in the reservoir. According to the simulation results, we defined an optimal withdrawal volume to control P. rubescens blooms in the reservoir as approximately 10 million m3 (10% of the reservoir volume) during its bloom phase. The results also illustrated that P. rubescens growth can be most effectively suppressed if the metalimnetic withdrawal is applied in the early stage of its rapid growth, i.e., before the bloom occurs. In addition, our study showed that P. rubescens biomass gradually decreased with increasing light extinction and nearly disappeared when the extinction coefficient exceeded 0.55 m−1. Conclusions Our study indicates the rise in P. rubescens biomass can be effectively offset by selective withdrawal as well as by reducing light intensity beneath the water surface. Considering the widespread occurrence of P. rubescens in stratified lakes and reservoirs worldwide, we believe the results will be helpful for scientists and managers working on other water bodies to minimize the negative impacts of this harmful cyanobacteria. Our model may serve as a transferable tool to explore local dynamics in other standing waters.

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Periphyton development during summer stratification in the presence of a metalimnetic bloom of Planktothrix rubescens

Cited by 5 publications

References 40 publications

Deep Cyanobacteria Layers: An Overlooked Aspect of Managing Risks of Cyanobacteria

Deep Cyanobacteria Layers: An Overlooked Aspect of Managing Risks of Cyanobacteria

Controlling blooms of Planktothrix rubescens by optimized metalimnetic water withdrawal: a modelling study on adaptive reservoir operation

Controlling blooms of Planktothrix rubescens by optimized metalimnetic water withdrawal: a modelling study on adaptive reservoir operation

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