PHENOLIC-ACIDS IN SEAGRASSES

Six phenolic acids were found in leaves of over 50% of the seagrasses surveyed. p-Hydroxybenzoic acid was the most ubiquitous and was recorded in each of the 12 genera and in each of the 25 species that included both Gulf-Caribbean and Indo-Pacific seagrasses. p-Coumaric, caffeic, ferulic, vanillic and protocatechuic acids were also of frequent occurrence. The six phenolic acids were detected in rhizomes and roots as well as in leaves of four Texas seagrasses, Thalassia testudinum Banks ex König, Halodule wrightii Aschers., Syringodium filiforme Kütz., and Halophila engelmannii Aschers. The phenolic acids that predominate in the seagrasses also occur widely in land plants, but gallic acid was detected in a greater percentage of seagrasses than had been observed in a comparable number of land plants of Central Texas origin. Although trhe phenolic acids have been cited in the allelopathic literature of land plants as major water-borne inhibitors, their role in seagrass ecosystems is under investigation. © 1979.