Metamorphosis and Effects of Enrichment on the Survival of Polypedates leucomystax and Duttaphrynus melanostictus Tadpoles in Captivity

Abstract

Amphibian populations, particularly those of the order Anura, are experiencing global declines due to habitat destruction, climate change, and emerging pathogens, such as Batrachochytrium dendrobatidis fungus. Captive rearing and enrichment activities have been proposed as conservation tools, however the specific effects of enrichment on anuran development and post-metamorphosis survival remain underexplored. This study investigated the metamorphosis, physiological development, and survival rates of Polypedates leucomystax (Four-lined Tree Frog) and Duttaphrynus melanostictus (Common Toad) tadpoles in captivity, with and without enrichment activities. Sixty tadpoles (30 per species) were collected from Sabah, Malaysia, and reared in controlled tanks. Half of the specimens were then subjected to environmental and feeding enrichment following metamorphosis, while the other half were maintained without enrichment. Results shows that D. melanostictus completed metamorphosis faster, while P. leucomystax exhibited higher post-metamorphosis survival rates. Enrichment activities initially led to slightly lower survival in captivity, likely due to environmental disturbance, but significantly improved performance during environmental stress trials. Enriched individuals hunted prey more efficiently and showed higher resilience to food deprivation. These findings suggest that early enrichment enhances behavioural adaptability and survival in variable environments. This study highlights the importance of incorporating enrichment strategies in captive rearing programs to improve anuran survivability during and after reintroduction.

Kewords: captive rearing, Duttaphrynus melanostictus, enrichment, metamorphosis, Polypedates leucomystax, survival rate