| Title | Variability of microcystin cell quota in metapopulations of Planktothrix rubescens: Causes and implications for water management |
| Abstract | In this study, we investigated the relationships between microcystin (MCs) concentrations and the biovolumes of Planktothrix rubescens (B-Pr.) in 2 natural lakes (Pusiano and Garda) and 2 artificially dammed reservoirs (Occhito and Ledro) in Italy. In all the considered water bodies, P. rubescens was the dominant cyanobacterium. All the lakes were characterized by significant relationships between MCs and B-Pr, with limited variability in the MC quota (the content of MCs per unit of biovolume) within each water body compared with the variability between sites. The results were consistent with the development of specific MC-genotypes, with moderate seasonal and spatial changes in the proportion between toxic and non-toxic strains. The MC cell quota obtained in our work (ECQ Environmental Cell Quota) were in the same range of values computed on the basis of analyses made on environmental samples dominated by P. rubescens or Planktothrix agardhii, and on isolates of the same two species (<1 to over 10 mu g mm(-3)). Besides the usual ordinary least square regressions, models have been evaluated by using quantile regression, a method that allows estimating the conditional median or other quantiles of the response variable. We showed that the use of quantile regressions has different advantages, which included the computation of MC quota based on the whole range of available data, the robustness against outliers, and the ability to estimate models also in cases where there is no or only weak relationships. The highest ECQ values estimated from 95% quantile regressions in specific water bodies might be used to estimate the worst-case MC concentrations from algal abundances. Nevertheless, it was stressed that a realistic assessment of toxicity and potential adverse health effects necessarily should take into account the toxicity potential of the more abundant MC-congeners produced by specific cyanobacteria populations. (C) 2014 Elsevier Ltd. All rights reserved. |
| Source | Toxicon (Oxf.) 90, pp. 82–96 |
| Keywords | CyanobacteriaPlanktothrixMicrocystinsCell quotaQuantile regressionsRisk assessment |
| Journal | Toxicon (Oxf.) |
| Editor | Pergamon,, Oxford, Regno Unito |
| Year | 2014 |
| Type | Articolo in rivista |
| DOI | 10.1016/j.toxicon.2014.07.022 |
| Authors | Salmaso, Nico; Copetti, Diego; Cerasino, Leonardo; Shams, Shiva; Capelli, Camilla; Boscaini, Adriano; Valsecchi, Lucia; Pozzoni, Fiorenzo; Guzzella, Licia |
| Text | 296559 2014 10.1016/j.toxicon.2014.07.022 ISI Web of Science WOS 000345817200009 Cyanobacteria Planktothrix Microcystins Cell quota Quantile regressions Risk assessment Variability of microcystin cell quota in metapopulations of Planktothrix rubescens Causes and implications for water management Salmaso, Nico; Copetti, Diego; Cerasino, Leonardo; Shams, Shiva; Capelli, Camilla; Boscaini, Adriano; Valsecchi, Lucia; Pozzoni, Fiorenzo; Guzzella, Licia Fondazione Edmund Mach; UOS Brugherio; University of Konstanz; University of Florence In this study, we investigated the relationships between microcystin MCs concentrations and the biovolumes of Planktothrix rubescens B Pr. in 2 natural lakes Pusiano and Garda and 2 artificially dammed reservoirs Occhito and Ledro in Italy. In all the considered water bodies, P. rubescens was the dominant cyanobacterium. All the lakes were characterized by significant relationships between MCs and B Pr, with limited variability in the MC quota the content of MCs per unit of biovolume within each water body compared with the variability between sites. The results were consistent with the development of specific MC genotypes, with moderate seasonal and spatial changes in the proportion between toxic and non toxic strains. The MC cell quota obtained in our work ECQ Environmental Cell Quota were in the same range of values computed on the basis of analyses made on environmental samples dominated by P. rubescens or Planktothrix agardhii, and on isolates of the same two species <1 to over 10 mu g mm 3 . Besides the usual ordinary least square regressions, models have been evaluated by using quantile regression, a method that allows estimating the conditional median or other quantiles of the response variable. We showed that the use of quantile regressions has different advantages, which included the computation of MC quota based on the whole range of available data, the robustness against outliers, and the ability to estimate models also in cases where there is no or only weak relationships. The highest ECQ values estimated from 95% quantile regressions in specific water bodies might be used to estimate the worst case MC concentrations from algal abundances. Nevertheless, it was stressed that a realistic assessment of toxicity and potential adverse health effects necessarily should take into account the toxicity potential of the more abundant MC congeners produced by specific cyanobacteria populations. C 2014 Elsevier Ltd. All rights reserved. 90 Variability of microcystin cell quota in metapopulations of Planktothrix rubescens Causes and implications for water management Salmaso_et_2014_Toxicon.pdf Articolo in rivista Pergamon, 0041 0101 Toxicon Oxf. Toxicon Oxf. Toxicon Oxf. Toxicon. Oxf. liciamaria.guzzella GUZZELLA LICIA MARIA diego.copetti COPETTI DIEGO TA.P04.021.009 Trasporto degli inquinanti a scala di bacino e impatto sulle comunita biologiche |
