Influence of light intensity, water volume and density in tadpoles raised in mesocosm experiments

Abstract

The ability of an organism to produce different phenotypes under different environmental conditions is a common adaptation in nature. Biotic factors like competition, community structure and predation can influence the survival and time to metamorphosis in amphibians. However, abiotic factors such as the hydroperiod and light intensity can be as important as biotic ones. We examine the influence of abiotic (light, hydroperiod) and biotic (density) factors on the morphology, growth and development of Argenteohyla siemersi pederseni tadpoles. Our main goal was to determine whether the morphology, growth and development vary in relation to changes in water volume, light intensity and number of conspecifics. The experiment was conducted under mesocosm conditions. We used a randomized block design with a factorial combination of two densities of tadpoles, two volumes of water and two light intensity conditions. The main findings were as follows: (1) Tadpole morphology was significantly affected by density and water volume but not by light intensity. Tadpoles maintained at low density increased their tail length and tail depth, tadpoles exposed to low volumes of water increased their tail length and tail muscle depth; (2) The growth rate and development rate of tadpoles were significantly affected by the effects of volume of water and density. Tadpoles maintained at low densities and low volume of water showed a significant increase in growth and development rate; (3) The growth and development rates of tadpoles were significantly affected by the effect of light intensity. Tadpoles exposed to lower light intensity showed an increase in their growth and development rates.