2018–2023 Monitoring of Repositioned Coral Bommies at Manta Ray Bay, Hook Island, Whitsunday Island Group

Abstract

Following a major cyclone in 2017, 400 tonnes of Porites coral bommies stranded in the intertidal zone were relocated sub tidally in Manta Ray Bay off Hook Island (Whitsunday Islands). Earthmoving machinery was used to restore coral habitat, improve aesthetics and access to the beach, and test novel marine park management techniques. Over the next five years 22 bommies were monitored for remnant live coral tissue, recruitment and growth of new corals and other benthic organisms. Fish species density and diversity was also recorded using a single line transect. While little of the original Porites tissue survived due to extended exposure (about 84 days), the relocation achieved all other objectives. Coral recruits to the bommies increased from 17 in 2018 to 457 in 2023, with 16 coral genera recorded. Other benthic fauna also increased. Fish diversity and density increased significantly, from 20 fish species and 894 fish/1,000 m² in 2018 to 57 species and 1,442 fish/1,000 m² in 2023. This project provided valuable insights on habitat change and recovery on artificially placed structures, contributing to the growing field of reef restoration. Continued monitoring and additional restoration efforts may be considered by management agencies.