Ocean warming and increasing incidence of marine heatwaves (MHW) challenge the survival of marine organisms. While the impacts of climate scenario-based ocean warming are well investigated, the response of organisms to extreme events such as MHW is less understood. In this study, the thermal tolerance of the amphipod Hyale niger, an ecologically important amphipod in southeast Australia, and its algal host Sargassum linearifolium, were determined. For H. niger, a broad temperature range (2–33 °C) was tested in 6-day exposures in three seasons (summer, autumn and winter) and extended to 11 days in summer. Despite the 7 °C difference in mean habitat temperature across seasons, H. niger had a similar broad thermal optimum (Topt) range with ≥ 90% survival across a 17–20 degree temperature range. The upper lethal temperature with 50% mortality in the 6-day tests was also similar across seasons (LT50 29–30 °C). In 11-day tests in summer, the LT50 was reduced to 26 °C. Cold tolerance of H. niger indicated potential for poleward migration. Sargassum linearifolium had a similar broad thermal tolerance with a 50% reduction in the photosynthetic capacity at 33 °C. Temperature significantly affected survival of H. niger depending on the size and sex. The decrease in the Topt range over time pointed to the deleterious influence of prolonged heatwaves. The broad thermal tolerance of H. niger and S. linearifolium suggests that this important amphipod–host system may be resilient to habitat warming.

中文翻译：

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端足类动物 Hyale niger 及其藻类宿主 Sargassum linearifolium 对热浪条件的恢复能力

海洋变暖和海洋热浪 (MHW) 发生率的增加对海洋生物的生存构成了挑战。虽然对基于气候情景的海洋变暖的影响进行了深入研究，但人们对生物对 MHW 等极端事件的反应知之甚少。在这项研究中，确定了澳大利亚东南部具有重要生态意义的片脚类动物 Hyale niger 及其藻类宿主 Sargassum linearifolium 的耐热性。对于 H. niger，在三个季节（夏季、秋季和冬季）的 6 天暴露中测试了较宽的温度范围（2–33 °C），并在夏季延长至 11 天。尽管不同季节的平均栖息地温度存在 7 °C 的差异，但黑猩猩在 17-20 度的温度范围内具有相似的广泛热最佳 (Topt) 范围，其存活率 ≥ 90%。在为期 6 天的测试中，死亡率为 50% 的最高致死温度在不同季节也相似（LT50 29–30 °C）。在夏季的 11 天测试中，LT50 降至 26 °C。H. niger 的耐寒性表明向极地迁移的潜力。Sargassum linearifolium 具有类似的广泛耐热性，在 33 °C 时光合能力降低 50%。温度显着影响 H. niger 的存活取决于大小和性别。随着时间的推移，Topt 范围的下降表明了长期热浪的有害影响。H. niger 和 S. linearifolium 的广泛耐热性表明，这种重要的片脚类动物 - 宿主系统可能对栖息地变暖具有弹性。尼日尔表示有向极地迁移的潜力。Sargassum linearifolium 具有类似的广泛耐热性，在 33 °C 时光合能力降低 50%。温度显着影响 H. niger 的存活取决于大小和性别。随着时间的推移，Topt 范围的下降表明了长期热浪的有害影响。H. niger 和 S. linearifolium 的广泛耐热性表明，这种重要的片脚类动物 - 宿主系统可能对栖息地变暖具有弹性。尼日尔表示有向极地迁移的潜力。Sargassum linearifolium 具有类似的广泛耐热性，在 33 °C 时光合能力降低 50%。温度显着影响 H. niger 的存活取决于大小和性别。随着时间的推移，Topt 范围的下降表明了长期热浪的有害影响。H. niger 和 S. linearifolium 的广泛耐热性表明，这种重要的片脚类动物 - 宿主系统可能对栖息地变暖具有弹性。