Independent and interactive effects of temperature, water level and density on the cannibalism of Levant Green Frog, Pelophylax bedriagae (Camerano, 1882) larvae

Cannibalism is an aggressive behavior in which the living organism eats whole or part of its body. In amphibians, cannibalism is done by feeding on its own eggs or larvae. The increase in temperature resulting from global warming, by affecting on the rate of intraspecific interaction and intensifying water level fluctuations and change in density, can alter the rate of cannibalism with a high coefficient in amphibian populations. In this study, independent and interactive effects of temperature (high and low), water level (hydroperiod) (high, low, and decreasing water levels), and density (low and high) factors on the cannibalism of Levant green frog Pelophylax bedriagae larvae was investigated in within 10 months. By considering the independent effect of the factors, the highest rate of cannibalism was observed in high temperature (56.6%), low water level (47.5%) and low density (53.33%). Due to the interactive effect, the highest percentage of cannibalism (including biting and whole body cannibalism) was recorded in the high temperature/low water level/low density treatment with 90%. In contrast, the lowest rate of cannibalism was recorded in two treatments: low temperature/low water level/low density, and low temperature/high water level/low density with 20%. The results of study showed that temperature and density had significant independent effects on the cannibalism but water level fluctuations are not significant. Also, interaction of three factors included temperature, water level and density had a significant effect on the rate of cannibalism.