The freshwater jellyfish Craspedacusta sowerbii (Lankester, 1880) is a global invader of lakes. Empirical and experimental evidence indicate that the environmental factors that govern the global expansion of Craspedacusta and the development of jellyfish blooms are temperature, meso-eutrophic character and food availability in lakes. In newly colonised lakes, the medusa stage of C. sowerbii feeds preferentially on medium-sized (0.2–2.0 mm in diameter) microcrustaceans, for example Daphnids and copepods. Clonal populations of this invader have recently been recorded in several Andean lakes of northern Patagonia (40°S). Here, we report for the first-time synchronous blooms of clonal populations of C. sowerbii in two nordpatagonian lakes with similar habitat and water quality but with different types of zooplankton as food supply for jellyfish. Jellyfish populations in these lakes showed notable differences in body size, as well as in the colour of the gonads. We speculate that the observed differences of the medusa populations reflect phenotypic plasticity and could be mediated by the quality of the diet, which was the main environmental factor that differed between the studied lakes. Both lakes are inhabited by microcrustaceans, but in one lake, the highly coloured symbiotic ciliate Stentor amethystinus was also present, amounting to almost 52% of total zooplankton biomass. This type of food source for jellyfish blooms of C. sowerbii is for the first time reported in the world. The invasion process of clonal jellyfish in north Patagonian lakes represents a unique opportunity to study the potential role of diet quality in inducing plasticity responses to environmental stress derived from climate change.

中文翻译：

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南半球湖泊（智利）淡水水母 Craspedacusta sowerbii（Lankester，1880 年）克隆种群的表型可塑性和浮游动物饮食的潜在作用

淡水水母Craspedacusta sowerbii (Lankester, 1880) 是全球湖泊入侵者。经验和实验证据表明，控制Craspedacusta全球扩张和水母大量繁殖的环境因素是温度、中型富营养化特征和湖泊中的食物供应。在新殖民的湖泊中，C. sowerbii的水母阶段优先以中等大小（直径 0.2-2.0 毫米）的微型甲壳动物为食，例如水蚤和桡足类。最近在巴塔哥尼亚北部（40°S）的几个安第斯湖泊中记录了这种入侵者的克隆种群。在这里，我们报告了C. sowerbii克隆种群的首次同步开花在两个栖息地和水质相似但有不同类型的浮游动物作为水母食物供应的北巴塔哥尼亚湖泊中。这些湖泊中的水母种群在体型和性腺颜色方面表现出显着差异。我们推测，观察到的美杜莎种群的差异反映了表型可塑性，并且可能由饮食质量介导，这是研究湖泊之间不同的主要环境因素。两个湖泊都居住着微型甲壳类动物，但在一个湖泊中，还存在高度着色的共生纤毛虫Stentor amethystinus，几乎占浮游动物总生物量的 52%。这种类型的C. sowerbii水母开花的食物来源是世界上首次报道。无性系水母在北巴塔哥尼亚湖泊的入侵过程代表了一个独特的机会来研究饮食质量在诱导对气候变化引起的环境压力的可塑性反应方面的潜在作用。