Harmonizing science and management options to reduce risks of cyanobacteria

Erratt, Kevin J.; Creed, Irena F.; Trick, Charles G.

doi:10.1016/j.hal.2022.102264

Cited by 22 publications

(20 citation statements)

References 104 publications

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“…A diverse suite of harmful metabolites produced in deeper waters suggests scientist and lake managers should incorporate “vertical tuning” in toxin analyses. Like regional tuning (i.e., modifying toxin screening to reflect frequently encountered compounds in geographic regions and using scientific advancements to update protocols), 3 “vertical tuning” would incorporate toxins and bioactive metabolites commonly associated with deep cyanobacteria layers. However, as deep cyanobacteria layers are a relatively understudied topic, further research is required to build this toxin inventory.…”

Section: Resultsmentioning

confidence: 99%

“…Near-surface cyanobacteria proliferations have drawn considerable public attention due to their visibility. , However, not all cyanobacteria proliferations occur near the surface. − A prime example is the “deep cyanobacteria layer”. These are cyanobacteria communities located below the surface where sufficient light penetrates and the disturbance effects of wind mixing are meager.…”

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: Resultsmentioning

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.

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“…The concurrent rise in Chl‐ a and cyanobacteria abundance in unmanaged (predominately northern) lakes in the modern paleorecord suggest nutrient enrichment (Erratt, Creed, & Trick, 2022; Smith & Schindler, 2009). Instead of direct human modifications to landscapes, these nutrient contributions are thought to be introduced by climate change modifications to landscape and internal‐lake processes (Lu et al, 2019; Rodgers, 2021; Smol, 2019).…”

Section: Discussionmentioning

confidence: 99%

Climate change amplifies the risk of potentially toxigenic cyanobacteria

Erratt

Creed

Lobb

et al. 2023

Global Change Biology

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Cyanobacterial blooms pose a significant threat to water security, with anthropogenic forcing being implicated as a key driver behind the recent upsurge and global expansion of cyanobacteria in modern times. The potential effects of land‐use alterations and climate change can lead to complicated, less‐predictable scenarios in cyanobacterial management, especially when forecasting cyanobacterial toxin risks. There is a growing need for further investigations into the specific stressors that stimulate cyanobacterial toxins, as well as resolving the uncertainty surrounding the historical or contemporary nature of cyanobacterial‐associated risks. To address this gap, we employed a paleolimnological approach to reconstruct cyanobacterial abundance and microcystin‐producing potential in temperate lakes situated along a human impact gradient. We identified breakpoints (i.e., points of abrupt change) in these time series and examined the impact of landscape and climatic properties on their occurrence. Our findings indicate that lakes subject to greater human influence exhibited an earlier onset of cyanobacterial biomass by 40 years compared to less‐impacted lakes, with land‐use change emerging as the dominant predictor. Moreover, microcystin‐producing potential increased in both high‐ and low‐impact lakes around the 1980s, with climate warming being the primary driver. Our findings chronicle the importance of climate change in increasing the risk of toxigenic cyanobacteria in freshwater resources.

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“…Moreover, these insights into stringent response mechanisms hold significant implications for addressing the challenges posed by the management of cyanoHABs, especially in the context of ongoing anthropogenic activities and climate change effects. − Gaining a comprehensive understanding of cyanobacteria’s ability to persist in eutrophic lakes even under nutrient limitations provides crucial insights for addressing and mitigating cyanoHABs. By understanding the genetic and metabolic pathways implicated in the stringent response, along with traditional physicochemical metrics, we can potentially develop early warning systems and predictive models for cyanoHABs. − Moreover, targeted interventions disrupting cyanobacteria’s nutrient acquisition and utilization could be designed to curb their growth and persistence in eutrophic lakes. , Overall, the insights gained from studying stringent response mechanisms in cyanoHABs have the potential to inform and enhance management strategies. , By targeting the specific molecular mechanisms that enable cyanobacterial persistence, we can develop more effective and sustainable approaches for the prevention, control, and mitigation of cyanoHABs in aquatic ecosystems.…”

Section: Discussionmentioning

confidence: 99%

“…127,128 Overall, the insights gained from studying stringent response mechanisms in cyanoHABs have the potential to inform and enhance management strategies. 129,130 By targeting the specific molecular mechanisms that enable cyanobacterial persistence, we can develop more effective and sustainable approaches for the prevention, control, and mitigation of cyanoHABs in aquatic ecosystems.…”

Section: Implications Of Nutrient Controlling Onmentioning

confidence: 99%

Stringent Response of Cyanobacteria and Other Bacterioplankton during Different Stages of a Harmful Cyanobacterial Bloom

Li,

Bhattarai,

Barber

et al. 2023

Environ. Sci. Technol.

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We conducted a field study to investigate the role of stringent response in cyanobacteria and coexisting bacterioplankton during nutrient-deprived periods at various stages of bloom in a freshwater lake (Utah Lake) for the first time. Using metagenomics and metatranscriptomics analyses, we examined the cyanobacterial ecology and expression of important functional genes related to stringent response, N and P metabolism, and regulation. Our findings mark a significant advancement in understanding the mechanisms by which toxic cyanobacteria survive and proliferate during nitrogen (N) and phosphorus (P) limitations. We successfully identified and analyzed the metagenome-assembled genomes (MAGs) of the dominant bloom-forming cyanobacteria, namely, Dolichospermum circinale, Aphanizomenon flos-aquae UKL13-PB, Planktothrix agardhii, and Microcystis aeruginosa. By mapping RNA-seq data to the coding sequences of the MAGs, we observed that these four prevalent cyanobacteria species activated multiple functions to adapt to the depletion of inorganic nutrients. During and after the blooms, the four dominant cyanobacteria species expressed high levels of transcripts related to toxin production, such as microcystins (mcy), anatoxins (ana), and cylindrospermopsins (cyr). Additionally, genes associated with polyphosphate (poly-P) storage and the stringent response alarmone (p)ppGpp synthesis/hydrolysis, including ppk, relA, and spoT, were highly activated in both cyanobacteria and bacterioplankton. Under N deficiency, the main N pathways shifted from denitrification and dissimilatory nitrate reduction in bacterioplankton toward N2-fixing and assimilatory nitrate reduction in certain cyanobacteria with a corresponding shift in the community composition. P deprivation triggered a stringent response mediated by spoT-dependent (p)ppGpp accumulation and activation of the Pho regulon in both cyanobacteria and bacterioplankton, facilitating inorganic and organic P uptake. The dominant cyanobacterial MAGs exhibited the presence of multiple alkaline phosphatase (APase) transcripts (e.g., phoA in Dolichospermum, phoX in Planktothrix, and Microcystis), suggesting their ability to synthesize and release APase enzymes to convert ambient organic P into bioavailable forms. Conversely, transcripts associated with bacterioplankton-dominated pathways like denitrification were low and did not align with the occurrence of intense cyanoHABs. The strong correlations observed among N, P, stringent response metabolisms and the succession of blooms caused by dominant cyanobacterial species provide evidence that the stringent response, induced by nutrient limitation, may activate unique N and P functions in toxin-producing cyanobacteria, thereby sustaining cyanoHABs.

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Harmonizing science and management options to reduce risks of cyanobacteria

Cited by 22 publications

References 104 publications

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

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

Climate change amplifies the risk of potentially toxigenic cyanobacteria

Stringent Response of Cyanobacteria and Other Bacterioplankton during Different Stages of a Harmful Cyanobacterial Bloom

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