Propagation of corals from the Arabian Gulf in a land-based nursery: effects of fragment size and light color

Despite the Arabian Gulf hosting the most heat-tolerant corals in the world, coral restoration in the region remains constrained by the lack of species−specific husbandry guidelines. We fragmented donor colonies of seven common Gulf scleractinian species into five size classes and reared 1,540 ramets for 130 days in a land−based nursery under three controlled light-color treatments (blue, green, and white). Daily skeletal growth was quantified using buoyant−weight increments, and survivorship was monitored across treatments. Six species achieved 100% survival, whereas Porites harrisoni showed reduced survivorship across all treatments. Coral fragments consistently grew faster than whole colonies—up to eightfold in Dipsastraea pallida . Growth responses were strongly species−specific: Coscinaraea monile , Cyphastrea serailia , and Psammocora stellata grew fastest at medium fragment sizes, while Platygyra daedalea and D. pallida exhibited peak growth in smaller fragments. Light color significantly affected growth in only four species: blue light consistently enhanced growth in C. monile , C. serailia , and P. stellata , whereas P. daedalea generally grew fastest under green light. Responses to the same light spectrum varied markedly among species, underscoring the need for tailored nursery protocols. These findings provide the first species−level benchmarks for optimizing fragment size and lighting for ex situ propagation of Gulf corals, offering practical pathways to improve production efficiency and scalability of coral restoration in thermally extreme environments.