M.S. Biological Sciences
Ocean warming causes stress to corals and records reveal that periods of thermal stress are increasing in frequency and severity. Previous studies show that thermal stress negatively impacts the reproductive output of corals. However, the transgenerational impacts of coral bleaching have never been quantified. As a consequence, it is unclear how ocean warming may alter population dynamics due to effects on reproduction and recruitment. This study quantified the transgenerational impacts of thermal stress in Montastraea cavernosa. To assess transgenerational effects of temperature stress during gametogenesis, colonies were exposed to elevated temperature for two weeks four months prior to spawning, and then returned to the reef. At spawning, eggs were collected to measure egg diameter and eggs from stressed females were significantly smaller than those from unstressed females. Then gametes from temperature stressed and unstressed corals were combined to create four fertilization crosses: unstressed female and male, unstressed female with stressed male, stressed female with unstressed male, and stressed female and male. Larvae and juveniles from each cross were kept at ambient (29°C) and elevated (31°C) temperatures. Larvae originating from stressed gametes overall had lower survival, but the separate effects of the male and female revealed paternal transgenerational acclimation and negative maternal effects. There were no transgenerational effects on initial size of juveniles, but elevated temperature in the larval stage decreased initial size. The transgenerational effects on juvenile survival were negative parental effects. Juvenile growth rate was only affected by adult male exposure to thermal stress. Juveniles originating from a thermally stressed male had higher growth rates. The timing of the thermal stress, which was during oogenesis and before spermatogenesis, most likely explains why negative effects were observed from the female and positive effects from the male. These results demonstrate that temperature stress has varying transgenerational effects.
Alyson Kuba. 2016. Transgenerational Effects of Thermal Stress: Impacts On and Beyond Coral Reproduction. Master's thesis. Nova Southeastern University. Retrieved from NSUWorks, . (429)
Available for download on Saturday, December 16, 2017