INCREASED LEVELS. “One of the questions that has to remain open is how exactly do seagrasses deal with the high salinity of the ocean. Seagrasses have been found to harbor increased intracellular levels of Na+ and K+ as compared to terrestrial angiosperm species as well as to other aquatic angiosperms.”
http://bmcevolbiol.biomedcentral.com/articles/10.1186/1471-2148-11-8