EFFECTS OF LARVAL DENSITY IN AMBYSTOMA-OPACUM - AN EXPERIMENT IN LARGE-SCALE FIELD ENCLOSURES

Larvae at high density grew more slowly, exhibited longer larval periods, were smaller at metamorphosis, and had reduced survival compared with those raised at low density. Where experiments were conducted during 3 yr, larval quality and quantity were enhanced in the year of longest hydroperiod. When ponds dried early, larvae metamorphosed sooner, were smaller, and exhibited lower survival. Slower growth at high densities probably increased mortality through an increased probability of desiccation in the early-drying years, and increased susceptibility to predation in all years. Larval survival in the enclosures was not elevated compared to natural ponds, as may occur in predator-free small enclosures and artificial ponds. In natural ponds, the importance of intraspecific competition is dependent upon hydroperiod, and the intensity of competition influences predation risk. Thus, both density-dependent and density-independent factors affect body size and recruitment of larval A. opacum into the adult population. -from Author