Cyanobacteria biennal dynamic in a volcanic mesotrophic lake in central Italy: Strategies to prevent dangerous human exposures to cyanotoxins

Manganelli, Maura; Stefanelli, Mara; Vichi, Susanna; Andreani, Paolo; Nascetti, Giuseppe; Scialanca, Fabrizio; Scardala, Simona; Testai, Emanuela; Funari, Enzo

doi:10.1016/j.toxicon.2016.03.004

Cited by 15 publications

(12 citation statements)

References 78 publications

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“…The quantification of mcy genes of P. rubescens has been indicated as a better predictor of MC concentrations (Ostermaier and Kurmayer, 2010;Hautala et al, 2013). However, in this study the application of the linear regression to the mcyB + cells and MC reduced the percentage of MC variation explained, from >80% to ~50%, i.e., a value very close to what was observed by Briand et al (2008) in a population of P. agardhii and consistent with what we previously described in Lake Vico (Manganelli et al, 2016). There are several possible explanations for this outcome, as summarized in Kurmayer et al (2016), such as other coexisting non identified toxic species, problems in the amplification of mcy genes or mutation inactivating mcy genes.…”

Section: Discussionsupporting

confidence: 91%

“…These results allowed to associate the potential producing species with the different MC variants and furthermore to obtain a model which explained more than 80% of the variation in MC concentration in this system. The association between P. rubescens and MC-dem-RR and -dem-LR was also confirmed by the 10 monoclonal isolated strains producing only the two variants, and is in line with data from other Italian lakes (Messineo et al, 2006;Manganelli et al, 2010Manganelli et al, , 2016.…”

Section: Discussionsupporting

confidence: 88%

“…P. rubescens was always present and generally dominant until summer 2012, with the typical trend of depth blooms in summer and more homogeneous distribution along the water column during the other seasons (Kurmayer et al, 2016). These results confirmed the need to sample the metalimnetic layers, especially when they are the source of drinking water supply (Manganelli et al, 2010(Manganelli et al, , 2016. The dominating species alternating with P. rubescens was W. naegeliana, previously described in the lake only in (Meregalli et al, 2002.…”

Section: Discussionsupporting

confidence: 73%

“…But this is not always the case: in Lake Vico (Central Italy), where P. rubescens was dominant, the fraction of the mcyB + cells was highly variable over time, especially during the blooms. In those conditions, the correlation between cell density and MC could explain only about 50% of MC variation (Manganelli et al, 2016). The quantification of mcy genes of P. rubescens has been indicated as a better predictor of MC concentrations (Ostermaier and Kurmayer, 2010;Hautala et al, 2013).…”

Section: Discussionmentioning

confidence: 99%

“…After Oct 2012, the site 3 was no longer sampled, since the values of the studied parameters were not different from the other sites. Since in some periods some CB species density was very low, two different strategies of sampling were used to monitor their temporal dynamics: i) discrete samples were collected monthly in the whole sampling period (18 months) in the three stations at the surface (S1, S2, S3) and in the stations 1 and 2 at 20 m depths (P1, P2; depth of the water offtake site, which is important to check when P. rubescens occurs) (Manganelli et al, 2016) using a Van Dorn bottle; ii) periodically, integrated samples were collected with a 20 µm phytoplankton net on a water column of 30 m (R1), 25 m (R2) and 7 m (R3). Samples were collected and stored in acid clean polycarbonate bottles, in cold and dark conditions until the arrival in the laboratory where they were aliquoted for the different analysis.…”

Section: Description Of the Site And Sampling Strategymentioning

confidence: 99%

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Cyanobacterial dynamics and toxins concentrations in Lake Alto Flumendosa, Sardinia, Italy

et al. 2017

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Seasonal blooms of cyanobacteria (CB) are a typical feature of Lake Alto Flumendosa (Sardinia, Italy). The waters of this lake are used for drinking water supply, for agricultural and industrial uses, and fish farming activities. Since cyanotoxins are not monitored in edible organisms, diet could be a relevant route of human exposure. CB also represent a threat for the health of wild and domestic animals that use lake water for beverage. Therefore, to characterize the CB community and assess the risk for human and animal population, CB dynamic, mcyB+ fraction, and microcystins (MCs) concentration have been followed monthly for 18 months, in three stations. Results confirmed the presence of several toxigenic species. Planktothrix rubescens dominated between August 2011 and April 2012 (3.5×106 cells L-1), alternating with Woronichinia naegeliana (8×106 cells L-1) and Microcystis botrys (9×105 cells L-1). Dolichospermum planctonicum was always present at low densities (104 cells L-1). MCs were detected, at values well below the 1 µg L-1 threshold of WHO for drinking water. The molecular analysis of mcyB gene for P. rubescens indicated the presence of a persistent toxic population (average 0.45 mcyB/16S rDNA). Highly significant linear regressions were found between P. rubescens and the sum of the demethylated MC variants, and between M. botrys and the sum of MC-LR and MC-LA, also when co-occurring, suggesting that these two species were responsible for different MC patterns production. The regression lines indicated a quite stable MC cell quota. However, in some spotted samples very different values were obtained for both MC concentrations and cell quota (from 10-fold lower to 30-40-fold higher than the ‘average’) showing an unexpected significant variability in the rate of toxin production. The relatively low cell densities during the monitoring period is consistent with the low-to absent MC contamination level found in trout muscle; however, the analytical method was affected by low recovery, probably due to MC-protein binding. Our results show that, during the study period, no risk of exposure for the human and animal population occurred. However, the persistence of a complex CB community characterised by a significant toxic fraction suggests the need for periodic monitoring activity. Particularly, the hidden deep summer P. rubescens blooms, located where water is taken for drinking water supply, and M. botrys, able to produce the most toxic MC variants with high cell quota, should be kept under control. The documentation and interpretation of sudden changes in toxins concentrations deserve special attention. This is particularly relevant in proximity of fish farming plants and water catchment sites.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionsupporting

confidence: 88%

Section: Discussionsupporting

confidence: 73%

Section: Discussionmentioning

confidence: 99%

Section: Description Of the Site And Sampling Strategymentioning

confidence: 99%

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Cyanobacterial dynamics and toxins concentrations in Lake Alto Flumendosa, Sardinia, Italy

et al. 2017

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Patterns and impacts of cyanobacteria in a deep, thermally stratified, oligotrophic lake

et al. 2023

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Cyanobacterial blooms are a concern in oligotrophic lakes because these systems are often used for multiple purposes (i.e., recreation and public water supplies). Monitoring cyanobacteria impacts is challenging in such cases because of low and heterogeneous concentrations over time, space, and depth. Canandaigua Lake (New York State) is oligotrophic, but has been impacted by blooms since at least the early 2000s, with limited quantification. This study integrated data from established shoreline surveillance and inter-agency monitoring programs to connect lake processes and evaluate use impacts. Surveys

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Microcystins in planktonic and benthic food web components from Greenlandic lakes

Trout‐Haney

Cottingham

2021

Ecosphere

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There is increasing global concern regarding the social, economic, human health, and environmental health implications of cyanotoxins. However, much of what we know about cyanotoxins comes from studies of temperate or tropical systems with conspicuous surface blooms of cyanobacteria. We measured the concentrations of microcystins (MCs), potent cyanotoxins produced by many cyanobacterial taxa, within lake food webs in southwestern Greenland. We detected MCs in six taxonomic groups of organisms and found that median MC concentrations in large (>50 µm) phytoplankton were an order of magnitude higher than benthic cyanobacteria (genus Nostoc) and two orders of magnitude higher than benthic grazers and consumers (snails, dytiscid larvae, and chironomid larvae). Microcystin concentrations generally decreased with increasing trophic position, suggesting that biomagnification does not occur in these lakes. We conclude that MCs are prevalent in multiple components of these Arctic aquatic food webs and that both benthic and pelagic taxa may be sources of MCs.

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Cyanobacteria biennal dynamic in a volcanic mesotrophic lake in central Italy: Strategies to prevent dangerous human exposures to cyanotoxins

Cited by 15 publications

References 78 publications

Cyanobacterial dynamics and toxins concentrations in Lake Alto Flumendosa, Sardinia, Italy

Cyanobacterial dynamics and toxins concentrations in Lake Alto Flumendosa, Sardinia, Italy

Patterns and impacts of cyanobacteria in a deep, thermally stratified, oligotrophic lake

Microcystins in planktonic and benthic food web components from Greenlandic lakes

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