Optimizing Light Spectrum to Upscale Grow-Out of Coral Recruits for Restoration
Location
HCAS Guy Harvey Oceanographic Center, Nova Southeastern University
Start
2-14-2025 9:30 AM
End
2-14-2025 9:45 AM
Type of Presentation
Oral Presentation
Abstract
Coral populations globally have been declining due to numerous direct and indirect anthropogenic stressors, including rising sea temperatures, coral diseases, and pollution. To minimize this decline and preserve genetic diversity, land-based nurseries have been sexually propagating corals to repopulate reefs. While the methodologies to induce corals to spawn and rear their larvae are well established, the grow-out stage remains to be fully optimized. The quantity and time it takes corals to reach a size suitable for outplanting is affected by many factors, including light, as that is vital for supporting their symbionts. This study investigates the post-settlement survival and growth of the reef building corals Colpophyllia natans and Pseudodiploria strigosa under three light spectra: (1) radion aquarium lights with a blue-shifted spectrum peaking in 400-450nm, (2) radion aquarium lights to mimic light spectrum at a 10m (reef) depth; (3) natural sunlight spectrum at surface/shallow. All treatments had the same level of photosynthetic active radiation (PAR) with a gradual increase from 25 µmol photons.m-2s-1 at week 0 to 200 µmol photons.m-2s-1 at week 19. Through the course of seven months, the coral recruits were checked for survival, and had their growth measured monthly. The blue shifted spectrum was expected to perform best as coral symbionts have shown higher photosynthetic rates under blue-shifted light; however, Pseudodiploria strigosa showed greater sizes under the reef mimic treatment and Colpophyllia natans showed no significant size difference between treatments. Sunlight showed reduced growth for the first 15 weeks but reached comparable sizes to the artificial light treatments in the last 13 weeks.
Optimizing Light Spectrum to Upscale Grow-Out of Coral Recruits for Restoration
HCAS Guy Harvey Oceanographic Center, Nova Southeastern University
Coral populations globally have been declining due to numerous direct and indirect anthropogenic stressors, including rising sea temperatures, coral diseases, and pollution. To minimize this decline and preserve genetic diversity, land-based nurseries have been sexually propagating corals to repopulate reefs. While the methodologies to induce corals to spawn and rear their larvae are well established, the grow-out stage remains to be fully optimized. The quantity and time it takes corals to reach a size suitable for outplanting is affected by many factors, including light, as that is vital for supporting their symbionts. This study investigates the post-settlement survival and growth of the reef building corals Colpophyllia natans and Pseudodiploria strigosa under three light spectra: (1) radion aquarium lights with a blue-shifted spectrum peaking in 400-450nm, (2) radion aquarium lights to mimic light spectrum at a 10m (reef) depth; (3) natural sunlight spectrum at surface/shallow. All treatments had the same level of photosynthetic active radiation (PAR) with a gradual increase from 25 µmol photons.m-2s-1 at week 0 to 200 µmol photons.m-2s-1 at week 19. Through the course of seven months, the coral recruits were checked for survival, and had their growth measured monthly. The blue shifted spectrum was expected to perform best as coral symbionts have shown higher photosynthetic rates under blue-shifted light; however, Pseudodiploria strigosa showed greater sizes under the reef mimic treatment and Colpophyllia natans showed no significant size difference between treatments. Sunlight showed reduced growth for the first 15 weeks but reached comparable sizes to the artificial light treatments in the last 13 weeks.