NEW CHALLENGES. “Submergence also exposes organisms to the forces of wave action and tidal currents that effects reproductive functions and reduces the availability of carbon dioxide (CO2). Consequently, seagrasses have evolved to propagate via hydrophilous pollination and rely on carbonic acid and bicarbonate instead of CO2.”
http://bmcevolbiol.biomedcentral.com/articles/10.1186/1471-2148-11-8