Proposed biotic controls of CCA surface pH and Ca<sup>2+</sup>-H<sup>+</sup> exchange processes based on dynamic studies (D) and profiles (P) at the thallus surface of a tropical CCA.

<p>Proposed biotic controls of CCA surface pH and Ca<sup>2+</sup>-H<sup>+</sup> exchange processes based on dynamic studies (D) and profiles (P) at the thallus surface of a tropical CCA.</p>