Understanding the interactions between various stressors, and the resulting cumulative impacts they exert, is essential in order to predict the potential resilience of marine habitats to climate change. Crustose coralline algae (CCA) are a major calcifying component of marine habitats, from tropical to polar oceans, and play a central role as ecosystem engineers in many rocky reefs. These species are increasingly threatened by the stress of climate change. However, the effects of other stressors linked to global change, such as invasive species, have scarcely been addressed.

We have studied the interactive effects of invasive algae and global warming on CCA, combining observational and experimental approaches. CCA sensitivity to invasive algae is heightened when they are concurrently exposed to elevated seawater temperature, and the interaction between these two stressors triggers drastic synergistic effects on CCA. The reduction and eventual disappearance of these “ecosystem foundation species” may undermine ecological functioning, leading to the disappearance and/or fragmentation of the communities associated with them.

了解各种压力源之间的相互作用及其产生的累积影响，对于预测海洋栖息地对气候变化的潜在恢复能力至关重要。甲壳珊瑚藻 (CCA) 是从热带到极地海洋的海洋栖息地的主要钙化成分，在许多岩礁中作为生态系统工程师发挥着核心作用。这些物种正日益受到气候变化压力的威胁。然而，与全球变化相关的其他压力因素（例如入侵物种）的影响几乎没有得到解决。

我们结合观察和实验方法研究了入侵藻类和全球变暖对 CCA 的交互影响。当它们同时暴露于升高的海水温度时，CCA 对入侵藻类的敏感性会提高，并且这两种压力源之间的相互作用会触发对 CCA 的剧烈协同效应。这些“生态系统基础物种”的减少和最终消失可能会破坏生态功能，导致与之相关的社区消失和/或分裂。