Export of dissolved organic matter from a mangrove swamp ecosystem: evidence from natural fluorescence, dissolved lignir phenols, and bacterial secondary production

Export of dissolved organic matter (DOM) from a n island mangrove swamp was traced and quantified by analysis of dissolved lignin-derived humic substances and naturally fluorescing compounds.Concentrations of both lignin phenols and fluorescent compounds indcated the tidallymediated movement of DOM offshore from the swamp to distances at least 1 km seaward.Laboratory studies documented the formation of significant amounts of DOM from degrading mangrove leaves, about 20°/0 of which was highly-fluorescent humic substances.At the 1 km station, vascular plantderived material was calculated to account for about 10 % of the total DOM, based on slmple mixing models.A correlation between apparent concentrations of vascular plant-derived DOM and rates of bacterial secondary production suggests that some components of exported DOM are available for bactenoplankton growth in offshore environments.