COMMUNITY ECOLOGY IN STREAMS - EFFECTS OF 2 SPECIES OF PREDATORY SALAMANDERS ON A PREY SPECIES OF SALAMANDER

I investigated how density affected the growth and survival of two pre datory species (Gyrinophilus porphyriticus, Desmognathus quadramaculat us) and one prey species (Eurycea wilderae) of larval salamanders by m anipulating the density of each species in stream enclosures. Survival and-growth of E. wilderae was independent of density, suggesting a la ck of competition. Growth also was not affected by the presence of pre dator species. However, survival of E. wilderae was significantly redu ced when exposed to one or both predators. Larvae of G. porphyriticus were more effective predators than larval D. quadramaculatus, and larv ae of G. porphyriticus exposed to high prey density grew more than tho se exposed to low prey density. Prey density had no effect on prey sur vival. Predator effects on prey survival were additive, indicating nei ther a mutualistic nor a competitive interaction between the two preda tors.