Coral Restoration in Palk Bay on the Southeast Coast of India

Abstract

Abstract Coral transplantation via asexual propagation of coral colonies has been used to restore the structure and function of degraded reefs in Palk Bay on the southeast coast of India. Successful restoration programs in India are rare. Therefore, this study aimed to implement a coral outplanting method at two different locations (Thonithurai and Munaikadu) in Palk Bay, India. Twenty metal frames and 800 cement slabs were used to make artificial substrates to install 800 small coral fragments, and the installation was performed in two sets to understand the variation in the growth and survivability of corals. The branching corals Acropora muricata, Acropora hyacinthus, Montipora digitata, and Pocillopora damicornis were used in this study. Eighteen months after coral transplantation, there was significant growth between the coral species (F = 8.0981; P = 0.0012), whereas, the growth difference between Thonithurai and Munaikadu was not significant (F = 0.0105; P = 0.91875). The average monthly growth rate of A. muricata (0.60cm/month) was the highest among all studied species, whereas A. hyacinthus, M. digitata, and P. damicornis had monthly growth rates of 0.44cm, 0.47cm, and 0.18cm, respectively. The survival rate for each species was calculated, and the survival rate for A. muricata (> 60%) and A. hyacinthus (> 50%) was the highest, whereas that for P. Damicornis was the lowest at both sites (< 35%). A large number of fish assemblages dominated by Terapon jarbua (grunter fish), Pomacentrus trilineatus (damsel fish), and Siganus javus (rabbitfish) were recorded from the sites after 9 months of transplantation. The results indicated that the coral out-planting method could be an effective tool for coral restoration in Palk Bay, and branching coral species can be considered promising contributors to artificial reef formation. Long-term restoration and multispecies out-planting can enrich the reef diversity in Palk Bay.