Inter‐patch connectivity and intra‐patch structure differentially alter prey consumption by multiple predators. Issue 11 (22nd November 2016) - Pitcher, Kristopher A.
Abstract: Structural habitat complexity (SHC) and functional habitat connectivity (FHC) have important effects on predator–prey interactions and exert a strong influence on community structure/dynamics in terrestrial and aquatic ecosystems. Although these factors vary simultaneously in most systems, their interactive effects are poorly understood. Using artificial pond mesocosms and multiple prey types, we manipulated plant density (SHC: low, high) and inter‐patch distance (FHC: short, long) in a full factorial design to test for potential interactive effects of these factors on competition and predation by a dragonfly larva ( Anax junius ) and fish predator ( Lepomis cyanallus ). When inter‐patch distances (FHC) were short, A. junius consumed more amphipods (36% ± 4.6%) compared with long treatments (19% ± 4.8%). We detected no significant effects of plant density (SHC) on prey consumption by A. junius . There were significant interactive effects of FHC and SHC on Lepomis cyanellus consumption of amphipods and damselflies. The most counterintuitive of these effects was that sunfish consumed more larval damselflies at high plant density (64% ± 6.0%) than at low plant density (38% ± 8.6%) but only in short connection treatments. This interactive effect of SHC and FHC on damselfly predation by L. cyanellus was likely because damselflies exhibited riskier behavior at higher SHC. Prey consumption with both predators present was additive, but no significant effect of either SHC or FHC on interspecific predation was detected, suggesting compensatory foraging responses. Structural habitat complexity and FHC interactively influence predator foraging behavior in complex, non‐intuitive ways that are highly dependent on the predator/prey combination in question. Structural habitat complexity and FHC are currently being influenced by anthropogenic factors in multiple ways (e.g., habitat loss, global climate change), and being able to predict the responses of biotic communities to these changes should be an important consideration in restoration and conservation efforts.