Mediterranean coastal ecosystems experience many local and global stressors and require long-term monitoring to detect and follow trends in community structure. Between 2009 and 2017, we seasonally and annually monitored the spatiotemporal community dynamics at 11 sites on the rocky shores of the southeastern Mediterranean, focusing on the understudied intertidal vermetid reef ecosystem. Marked seasonal trends were found in biodiversity, with the highest diversity in winter and spring. Canopy-forming brown algae, dominating the northwestern Mediterranean intertidal reefs, were generally scarce on the reef platform and only found in tidepools. Interannual shifts in community structure were driven mostly by sharp fluctuations in a few dominant native and alien species and the regional mass mortality of an Indo-Pacific mussel in summer 2016. Compared to an older macroalgae dataset, dating back to 1973–1995, we found that some warm-affinity (summer) taxa became more dominant and cold-affinity (winter) species less dominant, while one conspicuous species, Halimeda tuna, completely disappeared. The observed community shifts are probably driven mostly by stressors related to climate change. We encourage forming a network of long-term, multi-site ecological monitoring programs in the Mediterranean to improve our understanding of ecosystem change and to enable making better predictions at the basin scale.

地中海沿岸的生态系统经历了许多本地和全球压力源，需要进行长期监测以发现并关注社区结构的趋势。在2009年至2017年之间，我们按季节和年度监测了东南地中海多岩石海岸上11个地点的时空群落动态，重点研究了潮间带的温带礁生态系统。在生物多样性中发现了明显的季节性趋势，冬季和春季的多样性最高。形成冠层的褐藻占地中海西北部潮间带礁的主导地位，通常在礁石平台上稀少，仅在潮汐池中发现。社区结构的年度变化主要是由一些主要的本地和外来物种的急剧波动以及2016年夏季印度太平洋太平洋贻贝的区域大规模死亡所致。Halimeda金枪鱼，完全消失了。观察到的社区转变可能主要是由与气候变化有关的压力因素驱动的。我们鼓励在地中海建立长期的，多站点的生态监测计划网络，以增进我们对生态系统变化的理解，并在流域范围内做出更好的预测。