Canopy-forming macroalgae are engineer species of the Mediterranean, creating complex underwater forests that provide food and shelter for countless marine species. As ocean acidification threatens marine life, submarine CO₂ vents in the Aeolian Islands offer a glimpse into the future, acting as natural laboratories to study how these vital habitats respond to environmental stress. Our research explores the metabolic health of Ericaria brachycarpa marine forests along natural acidification gradients. We found that macroalgae living near CO₂ vents show a significant boost in photosynthetic performance, likely fueled by the extra carbon. Interestingly, their respiration rates remained stable, suggesting a metabolic "surplus" that allows them to thrive despite lower pH levels. This metabolic resilience could be a crucial aspect in the maintenance of the associated biodiversity. By maintaining high productivity, canopy-formers could act as a biological buffer, regulating oxygen and pH levels within their dense fronds. This creates a localized "refuge" for the associated fauna, such as invertebrates and juvenile fish, that might otherwise struggle in acidified waters. However, our findings also show that local environmental factors play a major role in these responses. Our ongoing work aims to understand how this individual algal "boost" scales up to protect entire communities. Protecting these carbon-rich marine forests is essential, as their ability to adapt will determine the survival of the diverse ecosystems they support in a changing ocean.