13.06.2023: Low light and cloudy water are bad for vision. But how do such environmental conditions affect the behaviour of aquatic animals? A recently published study by the University of Veterinary Medicine in Vienna investigated this question using tadpoles. According to this, changing environmental conditions influence the behaviour of frog larvae - an important finding, especially because of the disturbance of many natural habitats by humans.
In their study, the international research team examined the behaviour of tadpoles of two poison dart frog species. The aim was to investigate the connection between environments with restricted vision and the individual reaction to perceived risks.
The poison dart frog species Dendrobates tinctorius - a frog with facultatively cannibalistic tadpoles - and Oophaga pumilio - whose tadpoles depend on their mother's food supply - were tested in different experimental settings. First, the general activity and space utilization of the tadpoles was measured on a black and white background, and then on either a black or white background where the tadpoles were exposed to visual cues from potential predators.
Clear and less clear effects
The effects of the original environment on the tadpoles of Dendrobates tinctorius were clear, according to study co-author Bibiana Rojas from the Konrad Lorenz Institute of Ethology at Vetmeduni: "Tadpoles that grew up in a darker original habitat were less active than tadpoles from lighter original habitats and did not respond to either of the two visual predators with increased activity. In contrast, tadpoles from a brighter source environment swam more when in the presence of potentially hostile conspecifics.” According to Rojas, this suggests that tadpoles can visually distinguish between predators. This hypothesis is also supported by the results with Oophaga pumilio: Their reactions to the two visual stimuli did not differ.
Clear proof of the influence of environmental disturbances on growing animals
A key finding of the study is that risk perception in animals is situation-dependent. In addition, the quality of light during adolescence has a significant impact on how animals respond to risk in novel contexts."As animals are increasingly exposed to disturbed habitats, our results underscore how sensitively animals that rely on their vision respond to sudden environmental disturbances," Bibiana Rojas stresses.
The article „Visual environment of rearing sites affects larval response to perceived risk“ by Chloe A. Fouilloux, Jennifer L. Stynoski, Carola A. M. Yovanovich and Bibiana Rojas was published in „Journal of Experimental Biology“.