Morphology and photosynthesis of Caulerpa (Chlorophyta) in relation to growth form

Morphological and photosynthetic performance were analyzed in species of th e genus Caulerpa from an exposed coral reef and a sheltered reef lagoon, Mo rphological characters, such as distance between modules, number of modules , stolen branches and rhizoid clusters per centimeter of stolen, indicated a uniformity among species within a specific habitat. "Guerilla," or diffus ive, growth forms were characteristic for lagoon species and "phalanx," or compact, growth forms for reef species. Differences in photosynthesis were found between Caulerpa species. Sun-tolerant species were found on the reef , and both sun- and shade-tolerant species were present in the lagoon, In t he lagoon, shade-tolerant species, such as C, lanuginosa J, Agardh, were fo und growing in the understory, and sun-tolerant species, such as C. paspalo ides (Bory) Greville, formed the canopy, C, cupressoides (West in Vahl) C, Agardh was the only species found in both environments; it showed higher ph otosynthetic rates and a compressed morphology when growing on the reef and lower photosynthetic rates and expanded morphology for lagoonal ramets, Th ese results suggest that C, cupressoides possesses a broad phenotypic abili ty to acclimate to lagoonal and reef settings in comparison to other Cauler pa species, enhancing its ecological success in this particular system.