How thermal priming of coral gametes shapes fertilization success

Abstract: Seawater temperature rise is damaging coral reef ecosystems. There is growing evidence for the negative impact of rising temperatures on the survival of adult corals and their reproductive success. However, the effect of elevated temperatures on gametes remains scarcely studied. Here we tested the effect of the thermal priming of gametes on the fertilization success in experimentally tested populations of Acropora cytherea corals in French Polynesia. As expected, a temperature of 30 {\textdegree}C (ambient +3 {\textdegree}C) reduces coral fertilization success. However, the thermal exposure of gametes to 30 {\textdegree}C after their release in seawater prior to fertilization limited fertilization failure, with a greater impact of oocytes in comparison to sperm. This temperature is similar to temperatures observed in nature under the changing climate. Our findings imply that the thermal priming of early life stages, such as gametes may play a role in maintaining the coral fertilization success in spite of increasing seawater temperature.