Carry-over effects of opioid exposure in European common frogs (Rana temporaria)

Early-life exposure to stress can haunt you later if individuals delay their response to those experiences. Many species carry over stress or information gained in early life history stages regarding predators, climate conditions, and contaminants, which influences adult behavior and development. We found that European Common frog tadpoles exposed to tramadol, an opioid contaminant in freshwater systems, metamorphosed into juveniles with slower reaction speeds. However, this effect was only found in combination with high levels of competition. Carry-over effects of tramadol in a multiple stressor framework highlights the need for ecology-based contaminant studies over an individual’s lifetime.