Climate change is expected to increase the magnitude, frequency, and intensity of extreme natural phenomena such as droughts and floods. These events can have devastating impacts on aquatic biota, thus there is a dire need to assess species' natural dynamics and to incorporate them into species' conservation actions and flood management decisions. In September 2023, an extreme meteorological event (Storm Daniel) occurred over the eastern Mediterranean, causing unprecedented high flooding events in many streams and rivers of central Greece. Almost 2 months after the event, we investigated the effects of the storm on Salmo farioides in a high-altitude stream (Kraniotiko stream, Acheloos river basin) by comparing pre-flood (June and August 2023) with post-flood (October 2023) data on fish population abundances and size structure. Our results provide direct evidence that the population of S. farioides was almost wipedout from the investigated stream, as post-flood fish densities were 9.3% of the pre-flood data (August) densities. Small-sized individuals (6–10 cm) were extirpated, indicating a 99% decrease during the post-flood period, totally reversing the increasing trend observed from June to August (pre-flood period). In conclusion, the profound and rapid decline observed in the population of S. farioides following the extreme flooding event highlights the urgent need for proactive conservation measures and adaptive management strategies to safeguard vulnerable aquatic species in the face of escalating climate-related challenges.

中文翻译：

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丹尼尔风暴对高梯度溪流中的鲑鱼 (Karaman, 1938) 的短期影响

气候变化预计将增加干旱和洪水等极端自然现象的规模、频率和强度。这些事件可能对水生生物群产生毁灭性影响，因此迫切需要评估物种的自然动态并将其纳入物种保护行动和洪水管理决策中。 2023年9月，地中海东部发生极端气象事件（风暴丹尼尔），导致希腊中部多条溪流和​​河流出现前所未有的高洪水事件。事件发生近两个月后，我们通过比较洪水前（2023 年 6 月和 8 月）与洪水后（2023 年 10 月），调查了风暴对高海拔溪流（Acheloos 河流域的 Kraniotiko 溪流）中的Salmo farioides的影响。有关鱼类种群丰度和大小结构的数据。我们的结果提供了直接证据，表明S. farioides的种群几乎从调查的河流中消失，因为洪水后的鱼类密度是洪水前数据（8 月）密度的 9.3%。小型个体（6-10厘米）已被消灭，表明洪水后时期减少了99％，完全扭转了6月至8月（洪水前时期）观察到的增加趋势。总之，在极端洪水事件后观察到的法里奥德鳅种群数量急剧下降，凸显了在面临不断升级的气候相关挑战时，迫切需要采取积极的保护措施和适应性管理策略，以保护脆弱的水生物种。