Manganelli Maura, Stefanelli Mara, Vichi Susanna, Andreani Paolo, Nascetti Giuseppe, Scialanca Fabrizio, Scardala Simona, Testai Emanuela, Funari Enzo
Department of the Environment and Primary Prevention - Istituto Superiore di Sanità, Viale Regina Elena 299, Rome, Italy.
Research, Certification and Control Division - INAIL, via Fontana candida 1, Monteporzio Catone, Rome, Italy.
Toxicon. 2016 Jun 1;115:28-40. doi: 10.1016/j.toxicon.2016.03.004. Epub 2016 Mar 4.
Vico Lake, a volcanic meso-eutrophic lake in Central Italy, whose water is used for drinking and recreational activities, experienced the presence of the microcystins (MC) producing cyanobacterium Planktothrix rubescens. In order to assess the human health risks and to provide the local health authorities with a scientific basis for planning tailored monitoring activities, we studied P. rubescens ecology and toxicity for two years. P. rubescens generally dominated the phytoplankton community, alternating with Limnothrix redekei, potentially toxic. P. rubescens was distributed throughout the water column during winter; in summer it produced intense blooms where drinking water is collected (-20 m); here MC were detected all year round (0.5-5 μg/L), with implications for drinking water quality. In surface waters, MC posed no risk for recreational activities in summer, while in winter surface blooms and foams (containing up to 56 μg MC/L) can represent a risk for people and children practicing water sports and for animals consuming raw water. Total phosphorus, phosphate and inorganic nitrogen were not relevant to predict densities nor toxicity; however, a strong correlation between P. rubescens density and aminopeptidase ectoenzymatic activity, an enzyme involved in protein degradation, suggested a role of organic nitrogen for this species. The fraction of potentially toxic population, determined both as mcyB(+)/16SrDNA (10-100%) and as the MC/mcyB(+) cells (0.03-0.79 pg MC/cell), was much more variable than usually observed for P. rubescens. Differently from other Italian and European lakes, the correlation between cell density or the mcyB(+) cells and MC explained only ∼50 and 30% of MC variability, respectively: for Vico Lake, monitoring only cell or the mcyB(+) cell density is not sufficient to predict MC concentrations, and consequently to protect population health. Finally, during a winter bloom one site has been sampled weekly, showing that monthly sampling during such a phase could greatly underestimate the 'hazard'. Our results highlight the need to adopt a stepwise monitoring activity, considering the lake and the cyanobacteria specific features. This activity should be complemented with communication to the public and involvement of stakeholders.
维科湖是意大利中部一个火山型中富营养湖泊，其湖水用于饮用和休闲活动，该湖出现了产微囊藻毒素（MC）的蓝藻——微红颤藻。为评估对人类健康的风险，并为当地卫生当局规划针对性监测活动提供科学依据，我们对微红颤藻的生态学和毒性进行了为期两年的研究。微红颤藻通常在浮游植物群落中占主导地位，与可能有毒的红褐林氏藻交替出现。微红颤藻在冬季分布于整个水柱中；夏季，在取水处（-20米）会形成密集水华；全年都能在此检测到微囊藻毒素（0.5 - 5微克/升），这对饮用水质量有影响。在地表水方面，微囊藻毒素在夏季对休闲活动没有风险，而在冬季，水面水华和浮沫（微囊藻毒素含量高达56微克/升）可能对进行水上运动的人和儿童以及饮用原水的动物构成风险。总磷、磷酸盐和无机氮与预测藻密度和毒性无关；然而，微红颤藻密度与氨肽酶胞外酶活性（一种参与蛋白质降解的酶）之间存在很强的相关性，这表明有机氮对该物种有作用。潜在有毒种群的比例，通过mcyB(+)/16SrDNA（10 - 100%）和MC/mcyB(+)细胞（0.03 - 0.79皮克微囊藻毒素/细胞）来确定，其变化比通常观察到的微红颤藻要大得多。与其他意大利和欧洲湖泊不同，细胞密度或mcyB(+)细胞与微囊藻毒素之间的相关性分别仅解释了微囊藻毒素变异性的约50%和30%：对于维科湖，仅监测细胞或mcyB(+)细胞密度不足以预测微囊藻毒素浓度，因此也不足以保护公众健康。最后，在一次冬季水华期间，对一个采样点每周进行采样，结果表明在此阶段每月采样可能会大大低估“危害”。我们的结果强调需要根据湖泊和蓝藻的具体特征采取逐步监测活动。这项活动应辅以与公众的沟通和利益相关者的参与。
