Unravelling the effect of climate variability on species biology has been one of the main goals of ecological studies. Environmental factors such as river discharge and temperature have being proposed as triggers of reproductive cycle in fish. In temperate climates, fish reproduction is affected mainly by temperature, while is influenced by flood pulses in large tropical rivers. We evaluated the influence of temperature and river discharge as triggers of Iheringichthys labrosus’ reproduction. We studied the following reproductive variables: gonadosomatic index (GSI), hepatosomatic index (HSI) and condition factor (K). Females of I. labrosus were examined in a time series of ten years along three sites located in Lower Uruguay River at the beginning (last week of November‐first week of December, spring) and by the end of the reproductive period (middle‐end of April, autumn). Generalised linear models detected a positive effect of mean winter temperature and site on the spring mature female GSI. Site was significant in addition to the interaction between temperature and site. Moreover, the effect of winter temperature was stronger than water discharge in triggering reproductive timing of I. labrosus, contrary to the model proposed for other species in tropical systems. Additionally, a literature review suggested a latitudinal gradient on reproduction, occurring earlier and prolonged with decreasing latitude (and increasing temperature). In this study, we stated the effect of temperature on the life history in a Neotropical fish using a multifaceted approach, particularly important in the current context of global climate warming.

中文翻译：

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新热带鲶鱼 Iheringichthys labrosus (Lütken, 1874) 繁殖时间的长期研究：温度和河流流量的影响

阐明气候变异对物种生物学的影响一直是生态研究的主要目标之一。河流流量和温度等环境因素已被提议作为鱼类繁殖周期的触发因素。在温带气候下，鱼类繁殖主要受温度影响，同时受大型热带河流洪水脉冲的影响。我们评估了温度和河流流量作为 Iheringichthys labrosus 繁殖触发因素的影响。我们研究了以下生殖变量：性腺体指数 (GSI)、肝体指数 (HSI) 和条件因子 (K)。I. labrosus 的雌性在开始时（11 月的最后一周 - 12 月的第一周）在位于乌拉圭河下游的三个地点进行了为期十年的时间序列检查。春季）和生殖期结束（四月中下旬，秋季）。广义线性模型检测到冬季平均温度和地点对春季成熟雌性 GSI 的积极影响。除了温度和场地之间的相互作用外，场地也很重要。此外，与为热带系统中的其他物种提出的模型相反，冬季温度对触发 I. labrosus 繁殖时间的影响强于排水量。此外，一篇文献综述表明，繁殖的纬度梯度会随着纬度的降低（和温度的升高）发生得更早和延长。在这项研究中，我们使用多方面的方法阐述了温度对新热带鱼类生活史的影响，这在当前全球气候变暖的背景下尤为重要。