Release of dissolved organic matter by some marine macrophytes

The amount of photoassimilated carbon released as dissolved organic carbon was investigated for 5 species of benthic marine macrophytes (Thalassia testudinum, Diplanthera wrightii, Acanthophora spicifera, Chondria dasyphylla, and Dictyota dichotoma) and 1 species of pelagic marine macrophyte (Sargassum natans). Release rates ranged between 0.006 and 0.053 mg C g^-1 h^-1. Percent release values ranged from 1.1 to 3.8%. Spermatophytes had slightly lower percent release values than algae. Investigations performed on the ability of release products to be utilized by heterotrophic organisms showed that 20 to 30% of the released organic carbon was assimilated within a 2-h period.