Ruđer Bošković Institute, Center for Marine Research, G. Paliaga 5, 52210 Rovinj, Croatia.
Ann Bot. 2024 Aug 22;134(3):415-426. doi: 10.1093/aob/mcae038.
Globally, rising seawater temperatures contribute to the regression of marine macroalgal forests. Along the Istrian coastline (northern Adriatic), an isolated population of Gongolaria barbata persists in a coastal lagoon, representing one of the last marine macroalgal forests in the region. Our objective was to examine the impact of extreme temperatures on the morphology and physiology of G. barbata and test its potential for recovery after simulating marine heatwave (MHW) conditions.
We explored the occurrence of marine heatwaves in southern Istria, adjacent to the study area, in addition to extreme temperatures inside the area itself. Subsequently, we performed a thermotolerance experiment, consisting of a stress and recovery phase, in which we exposed G. barbata thalli to four extreme (28, 30, 32 and 34 °C) and one favourable (18 °C) temperature. We monitored morphological and physiological responses.
Our findings indicate a significant rise in frequency, duration and intensity of MHWs over decades on the southern Istrian coast. Experimental results show that G. barbata demonstrates potential for both morphological and physiological recovery after exposure to temperatures as high as 32 °C. However, exposure to 34 °C led to thallus decay, with limited ability to regenerate.
Our results show that G. barbata has a remarkable resilience to long-term exposure to extreme temperatures ≤32 °C and suggest that short-term exposure to temperatures beyond this, as currently recorded inside the lagoon, do not notably affect the physiology or morphology of local G. barbata. With more MHWs expected in the future, such an adapted population might represent an important donor suitable for future restoration activities along the Istrian coast. These results emphasize the resilience of this unique population, but also warn of the vulnerability of marine macroalgal forests to rising seawater temperatures in rapidly changing climatic conditions.
全球范围内，海水温度升高导致海洋大型藻类森林退化。在伊斯特拉海岸（亚得里亚海北部），一个孤立的巴巴多斯藻种群在沿海泻湖中存活，是该地区最后几个海洋大型藻类森林之一。我们的目标是研究极端温度对巴巴多斯藻形态和生理的影响，并在模拟海洋热浪（MHW）条件后测试其恢复潜力。
我们探讨了伊斯特拉南部（与研究区域相邻）海洋热浪的发生情况，以及该区域内极端温度的发生情况。随后，我们进行了耐热性实验，包括应激和恢复两个阶段，在这两个阶段中，我们将巴巴多斯藻暴露在四个极端温度（28、30、32 和 34°C）和一个适宜温度（18°C）下。我们监测了形态和生理反应。
我们的研究结果表明，在过去几十年里，伊斯特拉南部海岸的海洋热浪发生频率、持续时间和强度都显著增加。实验结果表明，巴巴多斯藻在暴露于 32°C 高温后具有形态和生理恢复的潜力。然而，暴露于 34°C 会导致藻体腐烂，再生能力有限。
我们的研究结果表明，巴巴多斯藻对长期暴露于≤32°C 的极端温度具有显著的恢复能力，并表明在泻湖内目前记录的短期暴露于超出此范围的温度下，不会显著影响当地巴巴多斯藻的生理或形态。随着未来预计会有更多的海洋热浪，这样一个适应环境的种群可能代表着一个重要的供体，适合未来在伊斯特拉海岸进行恢复活动。这些结果强调了这一独特种群的恢复力，但也警告说，在快速变化的气候条件下，海洋大型藻类森林容易受到海水温度升高的影响。
