Climate change is forcing amphibians to change their diet – but they can only adapt so far

Published in Scientific Reports, the international study found that tadpoles actively alter their diet as temperatures increase, consuming more plant material and eating more overall in an attempt to offset the effects of warming. However, researchers discovered that these dietary adjustments become progressively less effective as temperatures continue to rise.

The findings provide the first experimental evidence in a vertebrate species that the ability to compensate for climate change through diet is constrained by physiological limits.

Researchers from the University of Lisbon worked with colleagues at Queen Mary University of London, Centre for Ecology, Evolution and Environmental Changes, and the Faculty of Sciences of the University of Lisbon to investigate how warming affects the development of the Iberian spined toad (Bufo spinosus), a common amphibian species found across Portugal.

Like fish, reptiles and other cold-blooded animals, amphibians rely on environmental temperatures to regulate their body functions. Rising temperatures can therefore have profound effects on their growth, development and survival.

To explore whether diet could help offset these impacts, the team reared tadpoles collected from the Sintra Mountains under different temperatures and feeding conditions.

The results revealed that tadpoles actively respond to warming by changing their feeding behaviour.

Lead author Dr Sara Bento from the University of Lisbon said:

"This is the first study of its kind conducted in vertebrates and it shows that tadpoles can adjust their diet in response to temperature. At lower temperatures, tadpoles incorporate a higher proportion of animal-derived food into their diet, whereas at higher temperatures they increase their consumption of plant material as well as their overall feeding rate. However, we found that this strategy becomes progressively less effective as temperatures rise."

Warmer temperatures dramatically accelerated development. Tadpoles raised at 20°C completed their larval stage in around 30 days, compared with approximately 177 days at 12°C.

However, the faster growth came at a cost.

Animals that developed under warmer conditions emerged smaller and in poorer physical condition than those raised at cooler temperatures, suggesting that accelerated development may reduce fitness later in life.

The study also uncovered evidence that warming alters the elemental composition of amphibian tissues, indicating that climate change may affect not only how animals grow but also how they process and store nutrients.

Dr Pavel Kratina, Senior Lecturer in Aquatic Ecology at Queen Mary University of London and corresponding author of the study, said:

“The implications of these findings extend beyond amphibians. Our findings help explain how global warming may alter feeding preferences, interactions among cold-blooded organisms, and systematically alter entire food webs. By modifying tissue composition, increasing temperatures may also affect the energetic value of these animals as prey, potentially altering the function of aquatic ecosystems.”

The researchers say the findings have important implications for biodiversity conservation, particularly in Mediterranean regions, where temperatures are projected to rise significantly in the coming decades.

Protecting cooler areas within wetlands and freshwater habitats could help provide vital thermal refuges for amphibians and other aquatic species facing increasing climate pressures.

Read the full paper in Scientific Reports.