Predation of Ringed Salamander Larvae, Ambystoma Annulatum
Predation on larval Ambystoma annulatum was studied in 1991-1993. The following predators, which are normally present in the breeding ponds of A. annulatum during larval development, were studied : dragonfly nymphs (Anax and Tramea), waterbugs (Belostoma), backswimmers (Notonecta), and newts (Notopthalmus). In 1991-92, five larvae and one predator were placed into each of 30 containers and were checked every 24 hours for five days. On each day the number of larvae eaten was recorded, the number of larvae was restored to five per container, and the old predator was replaced with a new one. This procedure was initiated in October (larval SVL = 7-8mm) and repeated in November (SVL = 12-15mm), December (SVL = 20-23mm), and March (SVL = 28-30 mm). No predation occurred in the control and March groups. A three-way ANOVA on the predation rates showed highly significant main effects of predator (P < 0.0001), prey size (P < 0.0001), and day (P = 0.001), and a highly significant interaction between predator and prey size (P < 0.0001). In 1992-93, the experiments were repeated with the number of larvae eaten recorded during one twenty-four hour period instead of five. Ranatra (water scorpion) and larger A. annulatum larvae were added as predators. A two-way ANOVA showed significant main effects of predator, (P < 0.0001), and prey size (P < 0.0001), and a significant interaction (P < 0.0001). Tukey's multiple comparison tests showed significant differences among predators between experiments (1991), and within experiments (1992).
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