ABSTRACT
Food preference analyses of T. gratilla show that it is herbivorous on fringing reef flats of the Nosy Bé high island, located in a large coral reef/coastal complex off the NW coast of Madagascar. This edible urchin grazes mainly on seagrass leaves (including the periphyton) of the species: Thalassodendron ciliatum, Syringodim isoetifolium, and less frequently: Thalassia hemprichii, Halodule uninervis and other algae. Their food preference is a function of the avaibility, the accessibility, and the leaf characteristics (toughness and chemical composition). According to gut content analyses, food preference does not vary seasonally (no important variations between the dry and wet seasons), while the repletion index shows seasonal fluctuations that appear inversely correlated to the spawning periods (mainly in the austral winter, or dryer and cooler season).
