Pastorino Paolo, Colussi Silvia, Varello Katia, Meletiadis Arianna, Alberti Silvia, Di Blasio Alessia, Tedde Giovanni, Begovoeva Mattia, Peano Andrea, Rossi Luca, Renzi Monia, Acutis Pier Luigi, Barceló Damià, Prearo Marino
Istituto Zooprofilattico Sperimentale Del Piemonte, Liguria e Valle D'Aosta, Via Bologna 148, 10154, Torino, Italy.
Istituto Zooprofilattico Sperimentale Del Piemonte, Liguria e Valle D'Aosta, Via Bologna 148, 10154, Torino, Italy.
Environ Res. 2023 Apr 1;222:115411. doi: 10.1016/j.envres.2023.115411. Epub 2023 Feb 2.
The global decline in amphibian populations is a major environmental issue. Chytridiomycosis, Ranaviruses and the red-leg syndrome have been identified in unusual mortality events. However, these infections do not account for all causes of declining amphibian populations. Moreover, several cases of amphibian mortality are difficult to solve without resorting to an interdisciplinary approach. Two cases of unusual mortality in Rana temporaria occurred at two high-mountain ponds (northwest Italy) in April and May 2021. Water and frog samples were analysed to understand the possible causes responsible for the unusual mortalities. Results of the main physicochemical (pH, conductivity, dissolved oxygen, chemical and biochemical oxygen demand) and nutrient (ammonia/ammonium, nitrite, nitrate, total phosphorus) parameters revealed a good condition of the water quality, with the absence of the main cyanotoxins (microcystins/nodularins). However, unseasonably high spring water temperatures were recorded in both ponds (12.73 °C and 14.21 °C for Frog Pond and Selleries Pond, respectively). Frogs (n = 50; snout-vent length: 7.0-9.8 cm; body mass: 85-123 g) collected from Frog Pond mainly presented bumps on the ventral cavity and dermal ulceration associated with the isolation of Carnobacterium maltaromaticum. On the other hand, frogs (n = 5; snout-vent length: 8.0-9.1 cm; body mass: 87-92 g) from Selleries Pond presented petechiae and dermal ulcerations on the rear limbs associated with the isolation of Aeromonas salmonicida and A. sobria. In both mortality events, the interdisciplinary approach revealed an association between frog mortalities and the isolation of bacteria. Isolated bacteria are considered opportunistic pathogens, and the high values of the water temperature has certainly led a stress on the frogs, favouring the spread of bacteria and the death of the frogs. Further studies are needed to assess the pathophysiological effects of the opportunistic bacteria here isolated, clarifying the interactions between emerging pathogens and climate change.
全球两栖动物数量的减少是一个重大的环境问题。在异常死亡事件中已发现壶菌病、蛙病毒和红腿综合征。然而，这些感染并不能解释两栖动物数量下降的所有原因。此外，若不采用跨学科方法，几起两栖动物死亡案例很难得到解决。2021年4月和5月，在意大利西北部的两个高山池塘发生了两起欧洲林蛙异常死亡事件。对水和青蛙样本进行了分析，以了解导致异常死亡的可能原因。主要理化参数（pH值、电导率、溶解氧、化学需氧量和生化需氧量）和营养参数（氨/铵、亚硝酸盐、硝酸盐、总磷）的结果显示水质状况良好，且不存在主要的蓝藻毒素（微囊藻毒素/节球藻毒素）。然而，两个池塘都记录到了异常偏高的泉水温度（蛙池和芹池的水温分别为12.73℃和14.21℃）。从蛙池采集的青蛙（n = 50；吻肛长度：7.0 - 9.8厘米；体重：85 - 123克）主要表现为腹腔有肿块以及与麦芽香肉杆菌分离相关的皮肤溃疡。另一方面，来自芹池的青蛙（n = 5；吻肛长度：8.0 - 9.1厘米；体重：87 - 92克）后肢出现瘀点和皮肤溃疡，与杀鲑气单胞菌和温和气单胞菌的分离相关。在这两起死亡事件中，跨学科方法揭示了青蛙死亡与细菌分离之间的关联。分离出的细菌被认为是机会致病菌，水温过高肯定给青蛙带来了压力，有利于细菌传播和青蛙死亡。需要进一步研究来评估此处分离出的机会致病菌的病理生理效应，阐明新出现的病原体与气候变化之间的相互作用。
