Survival of Alytes cisternasii tadpoles in stream pools: A capture-recapture study using photo-identification

Abstract

For amphibians with complex life cycles, the regulation of populations may occur in each life history stage and although available data stress the importance of studying amphibian population dynamics during the larval stage, most studies so far still focus only on the adult phase, due to the difficulty to estimate larval survival under field conditions. Through a two-months capture-recapture study of 646 photo-identified tadpoles of Alytes cisternasii we aimed to estimate tadpole survival in isolated temporary stream pools - their main habitat - as well as to evaluate how pool characteristics and intraspecific competition (tadpole density) affect this parameter. Photo-identification was performed with the help of the software I 3S. We used the POPAN formulation of the Jolly-Seber model to estimate survival rates and population size in 9 stream pools. Tadpole density varied from ∼1 to 40 tadpoles • m -2. Tadpole weekly survival was relatively high, varying from 75 to 99% • week -1. Among-pool differences in survival were best explained by pool depth, and not by tadpole density or other pool characteristics. The lower survival estimates were obtained for the deep pools. The very high survival estimates for some pools are an indication that this type of discrete habitat may play an important role for this species. To our knowledge, this is the first time that photo-identification is used to obtain estimates for survival and density of tadpoles. © 2011 Brill Academic Publishers.