Results of a field transplant experiment using newly-settled Porites corals in Palau in 2023

We aimed to investigate whether coral larvae spawned in semi-enclosed lagoons in Palau have the potential to disperse out of the lagoons, settle, and survive on outer reefs. We focused on massive Porites, which is a common mounding coral on both classic and extreme reefs in Palau. We conducted an experiment to determine whether post-settlement survival differs between corals settling on their natal (home) extreme reef or at a classic (away) reef. Adult massive Porites corals were collected from six sites in Palau immediately prior to their spawning season in April 2023. Porites gametes from 3 males and 2 females were used in a bulk cross. Two dpf, larvae were settled on limestone tiles (15 x 15 cm) with crushed CCA used as a cue. Tiles were maintained in individual plastic containers in flow-through ASW tanks at PICRC. Nine days post fertilization, tiles were deployed to their home reef and an away site (n=10 tiles per site). Sixteen days after deployment (25 days post fertilization), tiles were recovered and examined under a dissecting microscope to identify and count surviving individuals. The number of corals was counted on all tiles post transplantation. Light and temperature were quantified at transplant locations at each site using Hobo Pendants (Onset, Wareham, USA).