**5. Conclusions**

This study has identified four Chlorophyta species: *Caulerpa sertularioides*, *Halimeda tuna*, *Valonia aegagropila* and *Valoniopsis pachynema,* exclusive to the backreef zone I of Bet Shankhodhar Reef. *H. tuna* generally occurs in the sub-littoral zone and the infra-littoral fringe while rest of the Chlorophyta species occurs in the mid-littoral zone. Two of the species, *C. sertularioides* and *V. aegagropila,* prefer shallow tidal pools as their microhabitat within the backreef zone. All the four species grow on intertidal rocks having a calcareous or coralline origin. However, *C. sertularioides* prefers a thin veneer of fine sediments on the intertidal rocks as a suitable substrate to settle and grow. Thus, *C. sertularioides* prefers soft sediment substratum as compared to other three species. Since *Halimeda* and *Caulerpa* genera are well-known primary producers in backreef habitats, presence of these four species indicates backreef zone or environment for the Bet Shankhodhar Reef. Presence of chlorophyll *a* and chlorophyll *b* as the main accessory pigment in these species restricts the distribution of these sub- and mid-littoral species to relatively shallow depths of the reef with strong sunlight as compared to other reef algae belonging to other pigment groups.
