Increased Temperature Influenced Growth and Development of Lithobates pipiens Tadpoles Exposed to Leachates of the Invasive Plant European Buckthorn (Rhamnus cathartica) and a Triclopyr Herbicide

Multiple factors including habitat loss, pollutants, invasive species, and disease have contributed to the global decline of amphibians, and further declines can be expected as a result of climate change. Warming temperatures may allow for range expansion of invasive plants, and because herbicides are the primary method to control invasive plants, chemical use may increase. A laboratory experiment was performed to examine the individual and combined effects of leachates from the invasive plant European buckthorn (Rhamnus cathartica, L.) and a triclopyr herbicide (Renovate (R) 3; 0.21 mg/L), which is commonly used to manage R. cathartica, on northern leopard frog (Lithobates pipiens, Schreber) tadpoles at 2 temperature regimes (20 and 25 degrees C). We measured tadpole growth weekly and body and intestine morphology at the conclusion of the experiment after 8 wk. In the presence of R. cathartica leachates, tadpole growth increased at 25 degrees C, but only during the first 3 to 4 wk of the experiment. From week 5 until the end of the experiment, tadpoles were significantly smaller at 25 degrees C compared with 20 degrees C, but had more developed limb buds at the end of the experiment (except in the triclopyr treatment). Triclopyr had minimal effects on tadpole growth at the low dose used in this study. These results encourage further examination of potential effects of global climate changes in combination with other environmental factors that may impact amphibian populations. Environ Toxicol Chem 2021;00:1-12. (c) 2021 SETAC

Automated summary

Multiple factors contribute to the global decline of amphibians, including habitat loss, pollutants, invasive species, and disease, with further declines expected due to climate change. A laboratory experiment showed that tadpole growth increased under the influence of European buckthorn leachates at 25 degrees C, but tadpoles were significantly smaller than those at 20 degrees C from week 5 until the end of the experiment.