Multiannual variations in Microcystis bloom episodes – Temperature drives shift in species composition

Ninio, Shira; Lupu, Achsa; Viner-Mozzini, Yehudit; Zohary, Tamar; Sukenik, Assaf

doi:10.1016/j.hal.2019.101710

Cited by 28 publications

(20 citation statements)

References 50 publications

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“…Cultures from different growth phases were used for the extraction of microcystins. In addition, Microcystis colonies were collected from Lake Kinneret (Sea of Galilee, Israel) during a Microcystis bloom event (February-March 2018) [13], using a silk plankton net of 63-µm mesh size, to select predominantly Microcystis colonies. Immediately after transport to the laboratory, samples were first filtered through a 200-µm sieve to remove large particles and then through a 63-µm sieve.…”

Section: Methodsmentioning

confidence: 99%

Removal of Cyanotoxins–Microcystins from Water by Filtration through Granulated Composites of Bentonite with Micelles of the Cation Octadecyltrimethyl Ammonium (ODTMA)

et al. 2021

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Cyanobacteria and their toxins present potential hazards to consumers of water from lakes, reservoirs and rivers; thus, their removal via water treatment is essential. Previously, we demonstrated that nanocomposites of octadecyltrimethyl ammonium (ODTMA) complexed with clay could efficiently remove cyanobacteria and their toxins from laboratory cultures and lake water. In this study, we determined the capacity of ODTMA nanocomposites to remove cyanotoxins, namely microcystins (MCs), from water to below 1 µg/L via filtration. This capacity was 1500 mg MC-LR per Kg of nanocomposite. Similar capacities were estimated for the removal of other MC congeners (MC-WR, MC-3aspWR and MC-YR), whereas substantially lower capacities were recorded for more positively charged MC congeners, such as MC-RR and MC-3aspRR. Filtration results were simulated with a filtration model, which considers convection and adsorption/desorption of one to several toxins. Model calculations for the removal of MC-LR, under a variety of situations, fitted well with all the experimentally measured values and also estimated the co-removal of several MC congeners. In agreement with model predictions, results demonstrated that in the presence of MC-WR, the emerging concentrations of MC-RR congeners eventually exceed their solution values. In conclusion, granulated nanocomposites of ODTMA–bentonite can be applied for the removal of microcystins from drinking water.

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Section: Methodsmentioning

confidence: 99%

Removal of Cyanotoxins–Microcystins from Water by Filtration through Granulated Composites of Bentonite with Micelles of the Cation Octadecyltrimethyl Ammonium (ODTMA)

et al. 2021

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“…Lei et al [22] discuss respective publications (see also Section 4.1), while for the results of their own co-culture experiments they do not consider microcystin production the key mechanism leading to dominance. Ninio et al [23] show that in laboratory experiments the Microcystis strain with a low MC content outcompetes the one with a high MC content particularly at high temperatures (20 and 25 • C), and this is in line with their field observation of the non-toxic strain increasingly dominating in Lake Kinneret in the wake of warming. These authors propose slight changes in temperature to be decisive for the outcome of competition between strains and suggest that there is no per se advantage of MC-producing over non-producing genotypes at elevated temperature; rather, this may vary between strains.…”

Section: Impact Of Warming On Cyanobacteria and Microcystin Concentrationsmentioning

confidence: 63%

“…These authors propose slight changes in temperature to be decisive for the outcome of competition between strains and suggest that there is no per se advantage of MC-producing over non-producing genotypes at elevated temperature; rather, this may vary between strains. Ninio et al [23] conclude that "this widely accepted model for the expansion and persistence of Microcystis blooms should be re-evaluated as higher temperatures may affect not just the intensity of the bloom, but also the composition of the Microcystis population, species, strains and genotypes". As of now, a general claim of elevated temperatures favouring microcystin-producing cyanobacteria does not appear to be well evidenced by data.…”

Section: Impact Of Warming On Cyanobacteria and Microcystin Concentrationsmentioning

confidence: 99%

Cyanobacteria and Cyanotoxins in a Changing Environment: Concepts, Controversies, Challenges

Chorus

Fastner

Welker³

2021

Water

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Concern is widely being published that the occurrence of toxic cyanobacteria is increasing in consequence of climate change and eutrophication, substantially threatening human health. Here, we review evidence and pertinent publications to explore in which types of waterbodies climate change is likely to exacerbate cyanobacterial blooms; whether controlling blooms and toxin concentrations requires a balanced approach of reducing not only the concentrations of phosphorus (P) but also those of nitrogen (N); how trophic and climatic changes affect health risks caused by toxic cyanobacteria. We propose the following for further discussion: (i) Climate change is likely to promote blooms in some waterbodies—not in those with low concentrations of P or N stringently limiting biomass, and more so in shallow than in stratified waterbodies. Particularly in the latter, it can work both ways—rendering conditions for cyanobacterial proliferation more favourable or less favourable. (ii) While N emissions to the environment need to be reduced for a number of reasons, controlling blooms can definitely be successful by reducing only P, provided concentrations of P can be brought down to levels sufficiently low to stringently limit biomass. Not the N:P ratio, but the absolute concentration of the limiting nutrient determines the maximum possible biomass of phytoplankton and thus of cyanobacteria. The absolute concentrations of N or P show which of the two nutrients is currently limiting biomass. N can be the nutrient of choice to reduce if achieving sufficiently low concentrations has chances of success. (iii) Where trophic and climate change cause longer, stronger and more frequent blooms, they increase risks of exposure, and health risks depend on the amount by which concentrations exceed those of current WHO cyanotoxin guideline values for the respective exposure situation. Where trophic change reduces phytoplankton biomass in the epilimnion, thus increasing transparency, cyanobacterial species composition may shift to those that reside on benthic surfaces or in the metalimnion, changing risks of exposure. We conclude that studying how environmental changes affect the genotype composition of cyanobacterial populations is a relatively new and exciting research field, holding promises for understanding the biological function of the wide range of metabolites found in cyanobacteria, of which only a small fraction is toxic to humans. Overall, management needs case-by-case assessments focusing on the impacts of environmental change on the respective waterbody, rather than generalisations.

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“…Sequencing was performed at MR DNA (http://www.mrdnalab.com, Shallowater, TX, USA) on a MiSeq following the manufacturer's guidelines. Raw sequence data were analysed essentially as previously described (Ninio et al., 2020). The sequence reads were first processed using MacQIIME 1.9.1(Caporaso et al., 2010) to achieve correct read orientation and then using QIIME 2 2018.11(Bolyen et al., 2018) for the remainder of the analysis.…”

Section: Methodsmentioning

confidence: 99%

Metalimnetic chlorophyll maxima in Lake Kinneret ‐ Chlorobium revisited

et al. 2020

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A deep chlorophyll maximum (DCM) is often seen in stratified freshwater bodies at the interface between an anaerobic layer and an oxic layer. A DCM of the green sulfur bacterium Chlorobium phaeobacteroides was previously reported as a dense population in the oxygen devoid layer of a monomictic stratified lake, Lake Kinneret, Israel. In this multidisciplinary study, we examined the vertical distribution and diversity of the DCM photosynthetic community and characterised it spectrally and genetically, over two consecutive years. Pigment composition, together with 16S rDNA sequencing data unveil the presence of more than a single Chlorobium species as dominant members of the DCM community. Altogether, five different Chlorobia genotypes were identified, four of which occurred in both of the studied years. Phylogenetic analysis suggests that the dominant genotype is closely related to C. phaeobacteroides, implying that it contributes the majority of the bacteriochlorophyll‐e found in the DCM of the lake. Hierarchical clustering analysis demonstrates that dissolved oxygen concentration is a strong predictor for the distribution of all Chlorobia genotypes found in Lake Kinneret. Furthermore, this analysis suggests that competition probably exists between the various Chlorobia genotypes and proposes that a C. phaeobacteroides‐related amplicon sequence variant is better equipped to cope with the conditions prevailing in Lake Kinneret metalimnion. Chlorobia genotypes composing the DCM appear at a similar relative abundance in two consecutive years, even though timing and intensity of the DCM were different. This stable structure of the Chlorobia community observed here may represent a general theme in other stratified freshwater bodies harbouring Chlorobia.

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Multiannual variations in Microcystis bloom episodes – Temperature drives shift in species composition

Cited by 28 publications

References 50 publications

Removal of Cyanotoxins–Microcystins from Water by Filtration through Granulated Composites of Bentonite with Micelles of the Cation Octadecyltrimethyl Ammonium (ODTMA)

Removal of Cyanotoxins–Microcystins from Water by Filtration through Granulated Composites of Bentonite with Micelles of the Cation Octadecyltrimethyl Ammonium (ODTMA)

Cyanobacteria and Cyanotoxins in a Changing Environment: Concepts, Controversies, Challenges

Metalimnetic chlorophyll maxima in Lake Kinneret ‐ Chlorobium revisited

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