Field testing the influence of settlement recesses and nighttime feeding lights on coral recruitment

This is the authors' abstract. We don't add key points for this paper.

Previous studies show that two promising technologies can increase recruitment probability and survival: (i) helix recesses for entraining coral larvae and (ii) night-time feeding lights for improving subsequent survival. We evaluated whether these technologies can be combined to improve coral settlement and survival under in situ reef conditions on concrete restoration modules designed for a large-scale hybrid reef deployment in Hawaiʻi. During a 6-month experiment in Kāneʻohe Bay, recesses dramatically improved initial natural larval entrainment, but specific recess depths and light intensities had little effect on survival of settlers 2 months after settlement. After 6 months, survival was significantly higher in deeper recesses. Higher survival was likely associated with increased protection from algal competition and predation; although increased heterotrophic food availability in shaded microhabitats may contribute to recruit persistence, this mechanism could not be confirmed due to experimental limitations. Integration of these technologies is straightforward and can be incorporated into coastal engineering structures to accelerate coral growth in local, high-value coastal areas.