MCR LTER: Coral Reef: Water Column fDOM in lagoons of Moorea, French Polynesia

Dissolved organic matter (DOM) is a mixture of organic materials that are dissolved in water. DOM represents a significant fraction of carbon and nutrient stocks in seawater. To quantify the distribution and dynamics of organic matter in nearshore marine environments, fluorescent dissolved organic matter (fDOM; a subset of DOM that fluoresces under ultraviolet light) was quantified from water column samples collected in lagoons around Moorea, French Polynesia during May 2021, April 2022, and April 2023. fDOM components, such as humic-like compounds, as well as fDOM indices, such as the humification index, were measured using fluorometry (for more details refer to methods). Humification Index was higher in bays and fringing reef habitats, whereas Fluorescence Index and M:C ratio were higher further offshore at back reef sites.