Dietary tannins alter growth, development, behavior, and the gut microbiome of larval amphibians

In this study, green frog tadpoles Lithobates clamitans were fed a diets with or without 2 percent tannic acid to test how their growth, development, behavior, and gut microbiome respond to dietary tannins. At the end of the trial, we conducted a behavioral assay to measure tadpole activity and boldness. We then measured tadpole body length and mass before dissecting to remove the whole gut for microbiome analysis. Overall, we predicted that tadpoles that consumed tannic acid would be less developed and have a smaller body mass. We also predicted that tadpoles would exhibit differential behavior due to tannic acid. Tadpoles may increase exploration, boldness, or activity with the goal of searching for new food resources, or these aspects may decrease if animals energy budgets are compromised by the presence of tannic acid. Last, we predicted that the gut microbiomes of the tadpoles would differ significantly as a result of tannic acid, as has been seen in mammalian herbivores.