Fisheries College, Guangdong Ocean University, Zhanjiang, China.
Pearl Research Institute, Guangdong Ocean University, Zhanjiang, China.
Mar Environ Res. 2023 Sep;190:106105. doi: 10.1016/j.marenvres.2023.106105. Epub 2023 Jul 20.
In the past decade, the frequency, intensity and duration of marine heatwaves (MHWs) in the South China Sea have been increasing strikingly, resulting in serious impacts on intertidal bivalves and their ecosystems. The Manila clam, Ruditapes philippinarum, is one of the most ecologically and economically important bivalve species in the South China Sea, yet very little is known about its fate under intensifying MHWs events. Here, we examined how R. philippinarum responded to two consecutive scenarios of MHWs, with each composed of 4 °C and 8 °C rises of seawater temperatures, respectively. Up to 87% of Manila clams survived recurrent MHWs events, and significant increases in standard metabolic rate occurred predominantly under extreme conditions (+8 °C), indicating that the clams could trigger compensatory mechanisms to mitigate MHWs-induced thermal stress. Following acute and repeated exposures to MHWs, Manila clams showed similar responses in enzymes underpinning energy metabolism (NKA, CMA, and T-ATP), antioxidant defence (SOD, CAT, and MDA), and biomineralization (AKP and ACP), most of which exhibited significantly increasing and then decreasing trends with the intensification of MHWs. Of eight genes associated with physiological tolerance and fitness, ATAD3A, PFK, SOD, and C3 were significantly down-regulated in response to recurrent MHWs events, demonstrating the certain resistance to MHWs. These findings provide a better understanding that marine bivalves hold the potential to acclimate simulated MHWs events from the physiological and molecular processes.
在过去的十年中，南海海洋热浪（MHWs）的频率、强度和持续时间显著增加，对潮间带双壳贝类及其生态系统造成了严重影响。菲律宾蛤仔（Ruditapes philippinarum）是南海生态和经济上最重要的双壳贝类之一，但对其在加剧的海洋热浪事件下的命运知之甚少。在这里，我们研究了菲律宾蛤仔如何应对连续两次海洋热浪事件，每次事件都由海水温度分别升高 4°C 和 8°C 组成。高达 87%的菲律宾蛤仔在反复发生的海洋热浪事件中存活下来，标准代谢率显著增加主要发生在极端条件下（+8°C），表明蛤仔可以触发补偿机制来减轻海洋热浪引起的热应激。在急性和反复暴露于海洋热浪后，菲律宾蛤仔在能量代谢（NKA、CMA 和 T-ATP）、抗氧化防御（SOD、CAT 和 MDA）和生物矿化（AKP 和 ACP）的支撑酶中表现出相似的反应，其中大多数酶随着海洋热浪的加剧呈现出先增加后减少的趋势。在与生理耐受和适应性相关的八个基因中，ATAD3A、PFK、SOD 和 C3 对反复发生的海洋热浪事件呈显著下调，表明其对海洋热浪有一定的抗性。这些发现为海洋双壳贝类在生理和分子过程中适应模拟海洋热浪事件提供了更好的理解。
