Poleward range extensions by warm-adapted sea urchins are switching temperate marine ecosystems from kelp-dominated to barren-dominated systems that favour the establishment of range-extending tropical fishes. Yet, such tropicalization may be buffered by ocean acidification, which reduces urchin grazing performance and the urchin barrens that tropical range-extending fishes prefer. Using ecosystems experiencing natural warming and acidification, we show that ocean acidification could buffer warming-facilitated tropicalization by reducing urchin populations (by 87%) and inhibiting the formation of barrens. This buffering effect of CO₂ enrichment was observed at natural CO₂ vents that are associated with a shift from a barren-dominated to a turf-dominated state, which we found is less favourable to tropical fishes. Together, these observations suggest that ocean acidification may buffer the tropicalization effect of ocean warming against urchin barren formation via multiple processes (fewer urchins and barrens) and consequently slow the increasing rate of tropicalization of temperate fish communities.

温暖适应的海胆向极地范围扩展正在将温带海洋生态系统从以海带为主的系统转变为有利于建立范围扩展的热带鱼的不育系统。然而，这种热带化可能会受到海洋酸化的缓冲，这会降低海胆的放牧性能和热带范围扩展鱼类喜欢的海胆贫瘠之地。利用经历自然变暖和酸化的生态系统，我们表明海洋酸化可以通过减少海胆数量（减少 87%）和抑制贫瘠之地的形成来缓冲变暖促进的热带化。_{在天然 CO 2}中观察到这种 CO ₂富集的缓冲作用与从以荒地为主的状态转变为以草皮为主的状态相关的通风口，我们发现这对热带鱼不太有利。总之，这些观察结果表明，海洋酸化可以通过多个过程（更少的海胆和贫瘠）缓冲海洋变暖对海胆贫瘠形成的热带化影响，从而减缓温带鱼类群落的热带化速度。