Abstract
The spread of invasive exotic vegetation is a serious threat to native habitats in South Florida. The exotic Australian pine proliferates in coastal areas forming monocultures. They fall over easily during strong winds, making nesting habitat inaccessible to sea turtles. The objective of this study was to determine if removing the standing pines would alter hatchling sex ratios of sea turtles because nest temperatures could increase in the absence of shade provided by the exotic pine species. A total of 274 Hobo temperature data loggers were deployed in sea turtle nests on Keewaydin Island, Collier County, Florida, during the 2001, 2002, 2004, 2005, and 2006 nesting seasons to monitor the effect of Australian pine removal on incubation temperatures. The results indicated that shading from the pines did not affect incubation temperatures differently than native vegetation. Therefore, removing the pines did not alter hatchling sex ratios. During the study, southwest Florida was affected by several storm events and hurricanes washing out 57 data loggers and causing an additional 15 data loggers to malfunction. Nest temperatures during the thermosensitive period ranged from 23.24°C to 34.85°C with mean temperatures ranging from 26.61°C to 31.51°C. Hatchling sex ratios were predicted based on mean incubation temperatures during the thermosensitive period. The predictions indicated that nests on Keewaydin Island were producing predominately mixed ratio and male-biased clutches. Dead hatchlings were collected for histological examination to substantiate sex ratio predictions. Histology samples were female-biased in 2002 and male-biased in 2001 and 2004.
