Eleven seagrass species were found in South Sulawesi, Indonesia. Seagrasses occurred in five different habitats, i.e. intertidal terrigenous mudflats, shallow terrigenous sandy bays, coastal reef flats, reef flats of patch reefs, and sandy reef bases, from the intertidal to a maximum depth of 35 m. Thalassia hemprichii and Enhalus acoroides were the dominant constant species of stable environments (permanently present in climax vegetations). Cymodocea rotundata, Halodule uninervis and Halophila ovalis were the dominant pioneering species in the area. A considerable number (117) of macroalgal taxa were found associated with seagrass vegetation, but only 13 of these were found exclusively in association with seagrasses. Macroalgal biomass in the seagrass beds was usually low (< 5 g AFDW m-2). However, in stressed habitats macroalgae may contribute up to 50% to the total biomass, notably during periods of occasional blooming. Species diversity of seagrasses and associated macroalgae was much lower in stressed habitats, which are characterized by heavy sedimentation, physical instability of the substratum, or high turbidity.