Calcification in the Coralline Algae: A Synthesis and Conceptual Model

A recent revival of interest in the red coralline algae and their ecophysiology has occurred across multiple scientific disciplines. Much of this focus has been applied, with coralline algal responses to global change tied to the fates of coastal marine ecosystems worldwide. Thus, it is imperative to understand the fates of coralline algae, with focus on the physiological mechanisms underlying their functional responses to environmental parameters. The models for coralline algal calcification that are most widely used are also generally agreed to be in urgent need of re-thinking, in light of many new developments in coralline algal physiology since their development in the 1970s and 1980s. While calcification mechanisms in this group remain poorly resolved, it is difficult to fully understand ecophysiological responses of coralline algae to climate stressors.

Multiple lines of evidence exist for a conceptual understanding of calcification processes in the coralline algae, however these types of evidence have not previously been synthesized into a full conceptual understanding of calcification in this group. Here, we present anatomical, geochemical, mineralogical, and physiological evidence for a unified conceptual model of calcification at the cellular and multi-cellular levels, robust to datasets across disciplines. We also describe the implications of coralline algal calcification mechanisms for global change scenarios.