The metabolic response of R. odorabile to suspended sediments of different mineralogical compositions was quantified in July 2007. Respiration rates of 15 paired R. odorabile explants were measured for a 7 h period whilst exposed to both clay and carbonate suspended sediments (n=5) of similar size (see below) and a controlled treatment (1 μm filtered seawater, n=5 per treatment). A kaolinite clay standard (KGA-1B, Source Clays Repository Purdue University, Indiana) with a mean grain size of 3.1±0.1 μm was used for the clay sediment treatment, while the carbonate sediment treatment consisted of crushed dead coral and Halimeda spp. skeletons collected from Rib Reef with a mean grain size of 8.2±0.7 μm. The slight differences in mean grain size of the two sediment types may influence the results; however, it was not possible to crush the coral and Halimeda spp. carbonate skeletons to exactly the same size as clay sediments.