Salinity conditions experienced by organisms in coastal regions may shape their life histories. Here, salinity’s impact on reproduction and survival of the hydrozoan Eleutheria dichotoma was investigated using laboratory-cultured individuals originating from Banyuls-sur-Mer (southern France) collected several decades ago. During the experiment (October 2014–July 2015), hydroid colonies and medusae were exposed to three salinities (25, 35, 45). Asexually budded medusae were collected from colonies and reared for three generations obtained by asexual budding of medusae. Salinities experienced by hydroid colonies had only minor effects on initial size, time to maturity, medusa budding, sexual production of planulae by medusae, and survival. In contrast, salinities experienced by medusae influenced their life histories. Compared with medium salinity (35), low-salinity medusae (25) had an earlier onset and higher rates of asexual budding, a later onset and slower rates of sexual reproduction, and higher mortality, which could result from allocation tradeoffs. The increased production of planulae by medusae in low salinity indicated that they were transitioning to a benthic polyp life form more resistant to environmental stress. High salinity (45) delayed asexual maturity, prevented sexual maturity in medusae, and led to lower survival and asexual reproduction rates. Budding rates decreased across the generations; however, planula production rates decreased in medium salinity but increased in low salinity. This might be explained by the accumulation of damage with each generation, and/or by internal rhythms. The flexible responses of this tractable model organism, Eleutheria dichotoma, to salinity change may be useful in future studies on changing estuarine conditions.

中文翻译：

---

盐度对水生Eleutheria dichotoma存活和繁殖的影响

沿海地区生物体所经历的盐度条件可能会影响其生活史。在这里，盐度对水生Eleutheria dichotoma繁殖和存活的影响使用几十年前收集的来自法国南部的Banyuls-sur-Mer的实验室培养人员进行了调查。在实验期间（2014年10月至2015年7月），水状菌落和水母暴露于三种盐度下（25、35、45）。从菌落中收集无性芽的美杜鹃，并通过无性芽的美杜鹃进行饲养三代。液状菌落所经历的盐度对初始大小，成熟时间，水母出芽，水母有性扁平藻的有性繁殖以及存活率只有很小的影响。相反，美杜莎所经历的盐度影响了他们的生活史。与中度盐度（35）相比，低盐度水母（25）的发病较早，无性芽的发生率较高，性繁殖的发生较晚，发生率较慢，死亡率较高，这可能是分配权衡造成的。美杜莎在低盐度条件下增加的扁平藻产量表明它们正在向底栖息肉生活过渡，对环境压力的抵抗力更大。高盐度（45）延迟了无性成熟，阻止了美杜莎的性成熟，并导致存活率和无性繁殖率降低。几代人的出芽率均下降；然而，中盐度的平plan生产率下降，而盐度低的则上升。这可能是由于每一代的伤害积累和/或内部节奏所造成的。这种易处理的模式生物的灵活反应，高盐度（45）延迟了无性成熟，阻止了美杜莎的性成熟，并导致存活率和无性繁殖率降低。几代人的出芽率均下降；然而，中盐度的平plan生产率下降，而盐度低的则上升。这可能是由于每一代的伤害积累和/或内部节奏所造成的。这种易处理的模式生物的灵活反应，高盐度（45）延迟了无性成熟，阻止了美杜莎的性成熟，并导致存活率和无性繁殖率降低。几代人的出芽率均下降；然而，中盐度的平plan生产率下降，而盐度低的则上升。这可能是由于每一代的伤害积累和/或内部节奏所造成的。这种易处理的模式生物的灵活反应，盐度变化的Eleutheria dichotoma在将来关于河口条件变化的研究中可能有用。