Trophic relations in a temporary pond: larval salamanders and their microinvertebrate prey

Abstract

Population densities and diets of larval salamanders and dynamics of their microinvertebrate prey were studied concurrently in 1984 in Rainbow Bay, a temporary pond in Barnwell County, South Carolina [USA]. The larvae of Eurycea quadridigitata, Ambystoma talpoideum, and Notophthalmus viridescens fed on a wide variety of small invertebrates, especially cladocerans, chironomid larvae, and ostracods. Electivity was measured using a nonparametric variant of Strauss'' linear index. Larvae of all three species showed statistically significant negative electivities toward copepods. Other electivities were less consistent. Smaller, younger larvae of all three species usually consumed higher proportions of cladocerans, and larger, older larvae consumed higher proportions of chironomids. The larvae strongly preferred larger individuals of the cladocerans Daphnia laevis, Pseudosida bidentata, and Simocephalus serrulatus. Production of cladocerans was insufficient to support production of the salamander larvae, and chironomids were probably their energetic mainstay during the latter part of their development. Because microinvertebrate prey remained abundant throughout the period of larval development, we infer that the larvae were not limited by food availability in 1984.