Calcareous pink power: algal eco-economic potential

Calcareous red algae (CRA) are key ecosystem engineers in marine environments, shaping reef architecture and sustaining biodiversity. Through calcification, they produce approximately 1.6 × 10⁹ tonnes of CaCO₃ annually, driving long-term carbon storage and contributing to global carbon cycling at rates comparable to mangroves, salt marshes, and seagrass meadows. This review presents a comprehensive synthesis of current knowledge on calcareous red algae (CRA), including their evolving taxonomic classification based on the morphology, life cycles, reproduction and molecular phylogenetic markers. We also describe the algal habitat and ecosystem dynamics, including responses to abiotic factors, such as light intensity, temperature, and depth (> 270 m). This review elaborates on the cellular and biochemical mechanisms underlying the intricate CRA calcification process and discuss abiotic conditions affecting CRA growth to guide process-centered cultivation optimization. In addition, the impact of climate change on these organisms is explored, highlighting documented reductions in calcification under ocean acidification and warming, and the need for conservation and sustainable cultivation. Despite their ecological importance, exploratory economic potential of CRA remains underreported as compared to seaweed macroalgae. To that end, we provide an outlook on potential economic application in emerging fields, such as construction biotechnology and biomaterials production, linked to biogenic carbon sequestration. This review offers comprehensive and up–to–date information to researchers, industry experts, as well as policy makers, and outlines research priorities requiring interdisciplinary collaboration to fully realize the ecological and biotechnological value of CRA.