The Swire Institute of Marine Science and School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China.
School of Medical Sciences, The University of Sydney, NSW 2006, Australia; School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia.
Sci Total Environ. 2021 Sep 1;785:147281. doi: 10.1016/j.scitotenv.2021.147281. Epub 2021 Apr 23.
Heatwaves are increasing in frequency and intensity, with substantial impacts on ecosystems and species which maintain their function. Whether or not species are harmed by heatwave conditions by being pushed beyond their physiological bounds can depend on whether energy replacement is sufficient to enable recovery from acute stress. We exposed an ecologically important sea urchin, Heliocidaris erythrogramma, to experimental marine heatwave scenarios in context with recent summer heat anomalies in moderate (25 °C), and strong heatwave (26 °C) conditions for 10 days, followed by a 10-day recovery period at normal summer temperature (23 °C). Greater heatwave intensity drove higher metabolic rates which were not matched with a concurrent increase in food consumption or faecal production. However, food consumption increased during the post-heatwave recovery period, likely to replenish an energy deficit. Despite this, mortality increased into the recovery period and seemed to be caused by latent effects, manifesting as a decline in health index as individuals progressed from spine and pedicellariae loss, through to loss of tube foot rigor, bald patch disease, culminating in mortality. We show for the first time that the acute thermal stress of heatwaves can have latent physiological effects that cause mortality even when conditions return to normal. Our results show that the negative effects of heatwaves can manifest after relief from stressful conditions and highlight the importance of understanding the latent effects on physiology and health. This understanding will offer insights into the long-term potential for stress recovery following seemingly sublethal effects and whether the restoration of ambient conditions post-heatwave is sufficient to ensure population stability.
热浪的发生频率和强度正在增加，对维持其功能的生态系统和物种产生了重大影响。物种是否会因超出生理极限而受到热浪条件的伤害，这取决于是否有足够的能量补充来使其从急性压力中恢复。我们将一种生态上重要的海胆，即赤星太阳海胆，暴露在实验性海洋热浪情景中，这些情景与最近夏季的中度（25°C）和强烈热浪（26°C）异常条件下的 10 天，以及随后在正常夏季温度（23°C）下的 10 天恢复期有关。更强的热浪强度导致更高的代谢率，但没有与食物消耗或粪便产生的同步增加相匹配。然而，在热浪后恢复期食物消耗增加，可能是为了补充能量不足。尽管如此，死亡率在恢复期增加，似乎是由潜伏效应引起的，表现为随着个体从脊柱和小刺脱落，到足部刺的强直丧失、秃头疾病，最终导致死亡，健康指数下降。我们首次表明，热浪的急性热应激即使在条件恢复正常后，也会产生潜在的生理影响，导致死亡。我们的研究结果表明，热浪的负面影响可能在缓解压力条件后显现出来，并强调了了解对生理学和健康的潜在影响的重要性。这种理解将为了解在看似亚致死效应后应激恢复的长期潜力，以及热浪后恢复环境条件是否足以确保种群稳定提供深入的认识。
