Mangroves are critical marine habitats. High hydrogen sulphide (H2S) is a feature of these important ecosystems and its toxicity creates a challenge for mangrove inhabitants. The mangrove rivulus (Kryptolebias marmoratus) is a selfing, hermaphroditic, amphibious fish that can survive exposure to 1116 μM H2S in the wild. These fish rely on cutaneous respiration for gas and ion exchange when emerged. We hypothesized that the skin surface is fundamentally important in H2S tolerance in these mangrove fish by limiting H2S permeability. To test our hypothesis, we first disrupted the skin surface in one isogenic lineage and measured H2S tolerance and sensitivity. We increased water H2S concentration until emersion as a measure of the ability to sense and react to H2S, which we refer to as sensitivity. We then determined H2S tolerance by preventing emersion and increasing H2S until loss of equilibrium (LOE). The H2S concentration at emersion and LOE were significantly affected by disrupting the skin surface, providing support that the skin is involved in limiting H2S permeability. Capitalizing on their unique reproductive strategy, we used three distinct isogenic lineages to test the hypothesis that there would be genetic differences in H2S sensitivity and tolerance. We found significant differences in emersion concentration only among lineages, suggesting a genetic component to H2S sensitivity but not tolerance. Our study also demonstrated that external skin modifications and avoidance behaviours are two distinct strategies used to tolerate ecologically relevant H2S concentrations and likely facilitate survival in challenging mangrove habitats.

中文翻译：

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自交红树林鱼 (Kryptolebias marmoratus) 遗传不同谱系的硫化氢敏感性和耐受性

红树林是重要的海洋栖息地。高硫化氢 (H2S) 是这些重要生态系统的一个特征，其毒性给红树林居民带来了挑战。红树林河 (Kryptolebias marmoratus) 是一种自交、雌雄同体的两栖鱼类，可以在野外暴露于 1116 μM H2S 中存活下来。这些鱼在出现时依靠皮肤呼吸进行气体和离子交换。我们假设皮肤表面通过限制 H2S 渗透性对这些红树林鱼的 H2S 耐受性至关重要。为了验证我们的假设，我们首先破坏了一个同基因谱系的皮肤表面，并测量了 H2S 耐受性和敏感性。我们增加了水中 H2S 的浓度，直到出现为止，以此来衡量对 H2S 的感知和反应能力，我们将其称为灵敏度。然后我们通过防止出现和增加 H2S 直到失去平衡 (LOE) 来确定 H2S 耐受性。渗出时的 H2S 浓度和 LOE 受到破坏皮肤表面的显着影响，支持皮肤参与限制 H2S 渗透性。利用他们独特的繁殖策略，我们使用了三个不同的同基因谱系来检验 H2S 敏感性和耐受性存在遗传差异的假设。我们发现仅在谱系之间​​出现浓度的显着差异，表明 H2S 敏感性的遗传成分而不是耐受性。我们的研究还表明，外部皮肤修饰和回避行为是两种不同的策略，用于耐受与生态相关的 H2S 浓度，并可能促进在具有挑战性的红树林栖息地的生存。