AN EXPERIMENTAL-STUDY ON THE EFFECTS OF SALAMANDER LARVAE ON ISOPODS IN STREAM POOLS

1. We used a combination of field surveys and field and laboratory experiments to examine the effects of predatory small-mouthed salamander larvae, Ambystoma barbouri (Kraus and Petranka), on the density and microhabitat use of benthic isopods, Lirceus fontinalis (Rafinesque). 2. A survey of four field stations yielded a significant negative relationship between the densities of salamander larvae and isopods. 3. A field experimental manipulation of salamander density confirmed that salamanders reduce isopod density and isopod use of open microhabitat. Salamanders did not significantly affect the mean or coefficient of variation in isopod size. 4. A laboratory experiment showed that in the absence of refuges for isopods, salamanders were capable of eating large numbers of isopods; small isopods were particularly vulnerable to salamander predation.