Elevated temperature affects development, survivorship, and settlement of the elkhorn coral, Acropora palmata...

Elevated seawater temperatures during the late summer have the potential to negatively affect the development and survivorship of the larvae of reef corals that are reproductive during that time of year. Acropora palmata, a major Caribbean hermatype, reproduces annually during August and September. A. palmata populations have severely declined over the past three decades, and recovery will require high recruitment rates. Such recruitment will be limited if larval supply is reduced by elevated temperatures. The effects of elevated temperatures on development, survival, and larval settlement of A. palmata were investigated by culturing newly fertilized eggs at temperatures ranging from 27.5 to 31.5 degrees C. Development was accelerated and the percentage of developmental abnormalities increased at higher temperatures. Embryo mortality peaked during gastrulation, indicating that this complex developmental process is particularly sensitive to elevated temperatures. Larvae cultured at 30 and 31.5 degrees C experienced as much as an 8-fold decrease in survivorship compared to those at 28 degrees C. Additionally, settlement was 62% at 28 degrees C compared to 37% at 31.5 degrees C. These results indicate that embryos and larvae of A. palmata will be negatively affected as sea surface temperatures continue to warm, likely reducing recruitment and the recovery potential of A. palmata on Caribbean reefs.