Meeting Abstract

56-5   09:00 - 09:15  Breaking of embryonic arrest in turtle eggs and the link to protection from movement-induced mortality Williamson, SA*; Evans, RG; Reina, RD; Florida Atlantic University, Boca Raton and Monash University, Melbourne, Australia; Monash University, Melbourne, Australia; Monash University, Melbourne, Australia sean.alexander.williamson@gmail.com https://www.researchgate.net/profile/Sean-Williamson-2

Turtles embryos pause development due to a lack of oxygen in the mother’s hypoxic oviducts (~1% oxygen availability) and recommence development once eggs are oviposited into the normoxic nest (~21% oxygen availability). Following oviposition, embryonic mortality can occur if eggs are moved within 12 hours to 14 days post-oviposition in some species. We aimed to identify latency until recommencement of development post-oviposition and whether embryos can re-enter embryonic arrest by placing eggs back into hypoxia. We also aimed to identify whether extending arrest through hypoxic incubation protects embryos from movement-induced mortality (MIM). Green turtle (Chelonia mydas) eggs were randomly placed into hypoxia at 10 different intervals up until 72 hrs post oviposition. Each treatment group remained in hypoxia for three days. In a similar experiment with olive ridley turtles (Lepidochelys olivacea), a proportion of eggs were also inverted when removed from their respective treatment in order to test the validity of using hypoxia to prevent MIM. We identified that 12 to 16 h of exposure to normoxic conditions is required to recommence embryonic development after oviposition. Secondly, if eggs are placed back into hypoxia prior to that point, arrest can be artificially extended and embryos will be protected from MIM. The information gained from these experiment enables improved conservation outcomes by providing a better understanding of the ideal time to relocate eggs and how to reduce mortality during translocation. In addition, our experiments revealed that turtle embryos are unable to re-enter a state of arrest if incubated in hypoxia following the recommencement of development after pre-ovipositional embryonic arrest. These data further highlight that oxygen availability and susceptibility to MIM are a major constraint for the evolution of viviparity in turtles.