Demographics of Sympatric Musk Turtles: The Loggerhead Musk Turtle (Sternotherus minor) and Eastern Musk Turtle (Sternotherus odoratus) in a Florida Spring Ecosystem

摘要

The loggerhead musk turtle (Sternotherus minor) and eastern musk turtle (Sternotherus odoratus) are widespread species considered common throughout much of their respective ranges. Florida populations of S. minor and S. odoratus inhabit a variety of habitats, including freshwater springs and spring runs. We sampled populations of S. minor and S. odoratus from May 2000 through July 2015 as part of a long-term freshwater turtle assemblage study in a state-protected spring-run complex in central Florida. For each species, we 1) generated population estimates, 2) quantified survivorship and recruitment, and 3) calculated sex ratios, biomass, and density. Population estimates were 3417 for S. minor and 1977 for S. odoratus. Sex ratios were approximately 1:1 for both species, and density and biomass estimates were higher than most previous studies. Annual apparent survivorship was higher in male S. minor than in females, but the opposite was true for S. odoratus. Lambda values (lambda) suggest stable to slowly increasing populations for both species. Population growth rates for S. odoratus were equally influenced by both adult female mortality and mortality of first-year turtles, while those for S. minor were influenced by only adult female mortality. The lower fecundity values for S. odoratus may increase the importance of younger age classes in maintaining populations. Healthy populations of common species are important in maintaining overall community functions, as they often provide the base for many ecosystems. Therefore, it is prudent to promote conservation of common species to protect ecosystem structures and services.