Predator–prey relationships within natural, restored, and created vernal pools

Abstract

We performed a multiyear monitoring study to compare amphibian habitat quality among four natural, four restored, and six created pools. We used successful reproduction and metamorphosis of two vernal pool indicator species, the wood frog and spotted salamander, to represent desired outcomes. Ordination techniques were used to identify the aspects of habitat quality that were most correlated with desired outcomes. Previously published results indicated that pool depth, volume, and hydroperiod were among the best predictors of success, regardless of pool type. Observations in the first few years of monitoring also suggested that pools with longer hydroperiods had a greater abundance of aquatic predators of eggs and larvae of indicator species. This follow‐up study further explores and compares predator–prey relationships among pool types. We quantified within‐pool predator and prey abundance and diversity and collected another year of data on the reproductive success of indicator species. Our results confirmed that mean predator abundance was eight times higher in pools with longer hydroperiods. We documented a 96% decrease in wood frog survival rates in a semi‐permanent, natural pool following a 41% decrease in overhead canopy cover and an increase in green frog abundance. At the same time, wood frog reproductive success increased in nearby restored pools with lower predator abundance. Pools with the highest mean survival rates for the two indicator species combined were short‐ or long‐cycle pools (i.e. hydroperiod of 12–35 weeks) with low predator abundance (i.e. <1 organism L−1) and greater proportions of arthropod prey relative to other food items.