Abstract
<jats:p>We conducted a reciprocal transplant experiment between Kāneʻohe Bay and Ulupaʻu, Oʻahu, Hawaiʻi using fragments of Montipora capitata and Porites compressa to assess the retention of thermotolerance thresholds in differing environmental regimes. Survivorship differed strongly between transplant destinations, with substantially higher survival at the Kāneʻohe Bay site. Thermal tolerance was measured using experimental heat stress assays conducted before transplantation and nine months later after transplantation. Across surviving colonies, thermal tolerance declined slightly by ~1 eDHW after transplantation but remained above the ~4 DHW bleaching threshold commonly associated with widespread bleaching. Patterns of conservation differed among origin bay, with partial conservation in Kāneʻohe-origin corals but reorganization in Ulupaʻu-origin corals. After transplantation, there were no longer significant differences in ED30 values across populations, and variance in ED30 decreased among surviving colonies, suggesting convergence following exposure to shared environmental conditions. These findings highlight the importance of environmental context in shaping coral performance following transplantation and have implications for restoration planning and outplant site selection.</jats:p>