Water warming induced by human activities can impact fish larvae survival, notably because it influences larval development and prey abundances. Amphidromous gobies of the subfamily Sicydiinae are particularly sensitive to this threat as the newly hatched free embryos are poorly developed and the first feeding opportunity only occurs after they reach the ocean. Here, we studied how water temperature (21, 23, 25, 29 and 31°C) impacts early development stages of Sicyopterus lagocephalus in both freshwater and marine aquaria (salinity 35). We monitored survival time, larval condition and the occurrence of critical developmental events such as mouth opening, yolk sac and oil globule resorption. In freshwater, the survival exceeded 150 hours at 21°C, while it dropped below 50 hours at 31°C. In seawater, the larval development of unfed larvae was significantly affected by temperature, survival time being greatly reduced in warmer waters. Accounting for the observed duration between mouth opening and the resorption of the oil globule, we estimated that larvae need to find suitable prey in seawater within a short time: around 30 hours during the peak of reproduction in summer. Otherwise, their endogenous reserves become depleted and their condition degrades. This study emphasises the sensitivity of free embryos to stream flow alterations, which contributes to the increase in water temperature and to the slowing down of larvae drift to the ocean. We conclude that once in seawater the temperature and feeding conditions experienced by amphidromous larvae are critical for survival.

中文翻译：

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水温影响两栖虾虎鱼 Sicyopterus lagocephalus 的幼虫存活

人类活动引起的水温变暖会影响鱼类幼虫的存活，特别是因为它会影响幼虫的发育和猎物的丰度。Sicydiinae 亚科的两栖虾虎鱼对这种威胁特别敏感，因为新孵化的游离胚胎发育不良，只有在它们到达海洋后才会有第一次进食机会。在这里，我们研究了水温（21、23、25、29和 31°C）如何影响Sicyopterus lagocephalus 的早期发育阶段在淡水和海洋水族馆中（盐度 35）。我们监测了存活时间、幼虫状况和关键发育事件的发生，如张口、卵黄囊和油球吸收。在淡水中，存活时间在 21°C 时超过 150 小时，而在 31°C 时则低于 50 小时。在海水中，未饲喂幼虫的幼虫发育受温度影响显着，在较温暖的水域中存活时间大大缩短。考虑到观察到的张嘴和油球吸收之间的持续时间，我们估计幼虫需要在短时间内在海水中找到合适的猎物：夏季繁殖高峰期约 30 小时。否则，他们的内生储备就会枯竭，他们的状况就会恶化。这项研究强调了自由胚胎对溪流变化的敏感性，这有助于水温升高和幼虫漂流到海洋的速度减慢。我们得出的结论是，一旦在海水中，两栖类幼虫所经历的温度和摄食条件对生存至关重要。