Meeting Abstract
Nest sand temperature strongly influences development of sea turtle embryos and sex differentiation; however in nature eggs experience temperature along with other environmental factors. We tested the hypothesis that moisture affects sea turtle hatchling sex ratios. We studied the relationships among humidity, temperature, and loggerhead (Caretta caretta) sex ratios in an experimental study. Eggs were incubated in sterile nest sand in the laboratory under different moisture regimes to test the role of humidity at a constant incubation temperature. Incubator temperature was set at 29.4 degrees C, which is slightly above the temperature that should yield a 1:1 sex ratio. Nest moisture was maintained by daily DI water treatments and high relative humidity was maintained with the aid of a mist humidifier throughout incubation. All hatchlings were collected, raised for several months and sexed laparoscopically to establish sex ratios for each treatment. The experimental treatments tested the effects of (i) very high moisture, (ii) moisture with potential for evaporative cooling, and (iii) moisture added at average rain temperatures plus the potential for evaporative cooling. The nests were expected to produce a moderate female bias if moisture played no role. We found 87-93% males across all experimental treatments. The results support our hypothesis that moisture impacts hatchling sex ratios. High moisture conditions can produce shifts in developmental response from that expected based on temperature alone.
