Juvenile Recruitment of Oak Toads (Anaxyrus quercicus) Varies with Time-Since-Fire in Seasonal Ponds

Abstract

The direct and indirect effects of fire on different life stages of amphibians are poorly understood and difficult to predict given interspecific variation in physiology and life history. We investigated how time-since-fire (TSF) of seasonal ponds embedded within Florida scrub habitat affected growth, development, and survival of larval Oak Toads (Anaxyrus quercicus). We selected 12 ponds at Archbold Biological Station on the southern Lake Wales Ridge, Florida: four burned within the last 4 mo, four burned 3–4 yr ago, and four burned 11 yr ago. We hatched and reared three clutches of Oak Toads in the laboratory for 2 wk and then sorted larvae into groups of 24 having equal representation from each clutch. We randomly assigned groups of larvae to 0.22-m3 mesh field enclosures in each pond (n = 2–3 enclosures per pond) and measured environmental variables that might contribute to observed amphibian responses including pH, temperature, and periphyton growth. After 15 d, when larvae began metamorphosing, mean survival was significantly higher in the most-recently burned ponds. The TSF did not have a significant effect on developmental stage or tadpole size, although Oak Toad larvae tended to develop faster in the most-recently burned ponds. Although all ponds were acidic (pH < 4.3), there was a trend toward higher pH in the more-recently burned ponds, and survival was significantly positively correlated with pH. Overall our results suggest that performance and recruitment of larval Oak Toads are higher in recently burned ponds.