Author Type

Graduate Student

Date of Award

Summer 7-25-2026

Document Type

Dissertation

Publication Status

Version of Record

Submission Date

August 2026

Department

Biological Sciences

College Granting Degree

Charles E. Schmidt College of Science

Department Granting Degree

Biological Sciences

Degree Name

Doctor of Philosophy (PhD)

Thesis/Dissertation Advisor [Chair]

Joshua D. Voss

Abstract

Coral reefs are increasingly threatened by marine heatwaves, disease outbreaks, and other anthropogenic stressors, leading to widespread declines in coral cover worldwide. As a result, efforts are increasingly focused on identifying thermally tolerant corals for reef restoration. However, it remains unclear whether thermal tolerance is maintained following transplantation and whether thermally tolerant corals perform differently in novel environments. This dissertation examined thermal tolerance, survivorship, symbiont communities, and growth in two dominant Hawaiian reef-building corals, Montipora capitata and Porites compressa, using a reciprocal transplant experiment between Kāneʻohe Bay and Ulupaʻu, Oʻahu. Initial heat-stress assays showed high thermal tolerance in both species. Porites compressa from Ulupaʻu exhibited higher thermal tolerance than conspecifics from Kāneʻohe Bay, while M. capitata showed little variation among sites. Following transplantation, survivorship was substantially higher in Kāneʻohe Bay than at Ulupaʻu. Because mortality at Ulupaʻu was severe, particularly among transplanted colonies, assessments of thermal tolerance conservation were largely limited to colonies surviving in Kāneʻohe Bay. Thermal tolerance declined by approximately 1 eDHW over nine months but remained above commonly reported bleaching thresholds. Patterns of conservation differed among populations, with partial conservation observed in Kāneʻohe-origin corals but not Ulupaʻu-origin colonies. Symbiont communities differed between species and origin bays at the start of the experiment and changed through time. However, dominant symbiont types remained largely unchanged. Growth responses were driven primarily by transplant destination. Corals maintained in Kāneʻohe Bay exhibited higher calcification and structural growth than those transplanted to Ulupaʻu. No relationship was detected between initial thermal tolerance and growth, suggesting that thermally tolerant corals do not necessarily experience reduced reef-building performance. Together, these findings indicate that coral responses to transplantation are shaped by both environmental history and local environmental conditions and provide information relevant to restoration efforts that utilize thermally tolerant corals.

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