Visual environment of rearing sites affects larval response to perceived risk.

Turbidity challenges the visual performance of aquatic animals. Here, we use the natural diversity of ephemeral rearing sites occupied by tadpoles of two poison frog species to explore the relationship between environments with limited visibility and individual response to perceived risk. We sampled wild tadpoles of Dendrobates tinctorius, a rearing-site generalist with facultatively cannibalistic tadpoles, and Oophaga pumilio, a small-pool specialist dependent on maternal food-provisioning, to compare how species with diverse natural histories respond to risk having developed in a range of photic environments. Using experimental arenas, we measured tadpole activity and space use first on a black and white background, and then on either black or white backgrounds where tadpoles were exposed to potentially predatory visual stimuli. The effects of rearing environment on D. tinctorius tadpoles were clear: tadpoles from darker pools were less active than tadpoles from brighter pools, and did not respond to either visual stimuli, whereas tadpoles from brighter pools swam more when paired with conspecifics versus odonate larvae, suggesting that tadpoles can visually discriminate between predators. For O. pumilio, tadpoles were more active on experimental backgrounds that more closely matched the luminosity of their rearing sites, but their responses to the two visual stimuli did not differ. Larval specialisation associated with species-specific microhabitat use may underlie the observed responses to visual stimuli. Our findings demonstrate that light availability of wild larval rearing conditions influences the perception of risk in novel contexts, and provides insight into how visually guided animals may respond to sudden environmental disturbances.