Density-dependent injury in larval salamanders.

The effects of initial larval density, food level, and pond drying regime on intraspecific aggression of larval Ambystoma talpoideum were studied in an artificial pond experiment. Aggression was measured by the frequency of injury of feet, limbs, tail, and the extent of tail loss. Initial larval density had a significant effect on the frequency of foot, limb, and tail loss but not on the extent of tail loss. More larvae reared at medium and high densities sustained injuries than larvae reared at low densities but injuries were not more extensive. Food level had no effect on the four measures of injury. Pond drying regime had no effect on foot loss, limb loss, or extent of tail loss but more larvae reared in constant water level ponds had tail loss than in drying ponds. The frequency of limb and tail loss was negatively correlated to density-dependent survival which was the result of intraspecific predation or cannibalism. These results indicate that substantive levels of body injury, particularly tail loss, can occur at high natural larval densities and may result in a subsequent reduction of growth and survival.