Influence of Habitat Complexity on Predator–Prey Interactions between the Fish (Gambusia holbrooki) and Tadpoles of Hyla squirella and Gastrophryne carolinensis

Abstract

We examined the role of habitat complexity in influencing predator–prey interactions between fish and tadpoles. Tadpoles of the Squirrel Treefrog (Hyla squirella) and the Eastern Narrow-Mouth Toad (Gastrophryne carolinensis) were exposed to Eastern Mosquitofish (Gambusia holbrooki) under different degrees of habitat complexity (no cover, low cover, and high cover) in a randomized block, replicated, controlled experiment using wading pools. This study indicates that Gambusia can quickly and dramatically impact tadpole populations even at low predator densities and can forage effectively in vegetated areas that might normally serve as prey refugia from larger predatory fish (e.g., Lepomis spp.). Moreover, the influence of habitat complexity on predator-prey interactions may be species-specific. The number of H. squirella tadpoles consumed was not affected significantly by the degree of habitat complexity; however, consumption of G. carolinensis by Gambusia decreased with increasing habitat complexity. We attribute this finding to the observation that G. carolinensis are less active than H. squirella and, therefore, more difficult for Gambusia to detect with increasing habitat complexity.