in this study, we aimed to evaluate the effect of temperature and irradiance on the growth and photosynthetic activity of the three recently validated species of Caulerpa, C. prolifera (Forsskål) J.V. Lamouroux, C. mexicana Sonder ex Kützing, and C. scalpelliformis (R. Brown ex Turner) C. Agardh. Based on the reported phenotypic plasticity of the genus (Verlaque et al., 2003; Einav and Israel, 2007; Guiry and Guiry, 2011), we hypothesizedthattherewouldbedistinctresponsesofphotosynthesisand growthamongspeciesthatwilllikelyreflectthegrowthconditions in nature.