Effects of chemical management for invasive plants on the performance of Lithobates pipiens tadpoles

Abstract

Invasive plants impact amphibians by altering habitat, altering species interactions, and releasing potentially toxic secondary chemicals. Despite being costly and having the potential to affect nontarget wildlife, chemical management is commonly used to control invasive plants. Prior research has indicated that individual effects of invasive plants or herbicides can be harmful to aquatic organisms; however, information is lacking on the combined effect of these factors on amphibians. A laboratory experiment was performed to assess the impact of leachates of the invasive plants Eurasian watermilfoil (Myriophyllum spicatum) and European buckthorn (Rhamnus cathartica), the herbicide Renovate 3 (triclopyr [3, 5, 6-trichloro-2-pyridinyloxyacetic acid]), and the combined effects of each plant leachate and the herbicide on the growth, morphology, and survival of northern leopard frog (Lithobates pipiens) tadpoles. No effects of treatment on survival were observed. Tadpole exposure to M. spicatum reduced body mass by 17%, exposure to R. cathartica increased body mass by 36%, and exposure to R. cathartica + low herbicide increased body mass by 38% (although only early in the experiment). Exposure to Renovate 3 induced a 16% and 29% decrease in tadpole size in lower (0.22 mg triclopyr active ingredient [a.i.]/L) and higher (0.92 mg triclopyr a.i./L) concentration treatments, respectively. Results from the present study highlight the importance of considering both individual and combined effects of invasive plants and herbicides because they may have different outcomes for tadpole growth and development. Environ Toxicol Chem 2017;36:2958-2964. © 2017 SETAC.

Determination of the Ecotoxicity of Herbicides Roundup® Classic Pro and Garlon New in Aquatic and Terrestrial Environments

“…The exposure of red-legged frogs (Rana aurora) to triclopyr did not lead to increased mortality, organ damage, or changes in post-exposure behavior; although, lethargy during exposure and a prolongation of the metamorphosis cycle by one day were observed [38]. No effects were observed on the survival of tadpoles of the northern leopard frog (Lithobates pipiens); although, they were physically smaller after the exposure to triclopyr [39]. Tests on embryos and tadpoles of the green frog (Rana clamitans), leopard frog (Rana pipiens), and bull frog (Rana catesbeiana) show that triclopyr has no effect on the hatching, behavior, or size of these amphibians, yet freshly-hatched individuals are very sensitive to the herbicide, and increased mortality or paralysis may occur [40].…”

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

“…For aquatic invasive plants, herbicides are directly applied to aquatic environments, which may increase exposure to nontarget organisms. Exposure to herbicides can result in mortality, reduced size, endocrine disruption, or little/no effect on amphibians (Bridges and Semlitsch 2000; Boone and James 2003; Hayes et al 2006; Relyea 2009; Curtis and Bidart 2017). Nonlethal but detrimental effects of herbicide exposure on amphibian behavior, metabolism, skin bacterial communities, and immunity have also been reported (Krynak et al 2017; McMahon et al 2017; Freitas et al 2019; Moreira et al 2019).…”

“…Management for R. cathartica often consists of a stump cut followed by a direct application of undiluted herbicide (e.g., glyphosate or triclopyr), and resprouting or persistent seed banks can require repeated herbicide treatments (Delanoy and Archibold 2007). Amphibian exposure to triclopyr appears to have mixed results, ranging from no significant effects to behavioral changes and mortality (Wojtaszek et al 2005; Curtis and Bidart 2017; Yahnke et al 2017). Berrill et al (1994) found that exposure to triclopyr concentrations at 1.2 mg/L altered tadpole avoidance behavior and resulted in complete mortality of green frog ( Lithobates clamitans ) and bullfrog ( Lithobates catesbeianus ) tadpoles at concentrations ≥2.4 mg/L.…”

“…Berrill et al (1994) found that exposure to triclopyr concentrations at 1.2 mg/L altered tadpole avoidance behavior and resulted in complete mortality of green frog ( Lithobates clamitans ) and bullfrog ( Lithobates catesbeianus ) tadpoles at concentrations ≥2.4 mg/L. Others have reported decreased tadpole growth at concentrations of triclopyr: 0.9 mg/L (Curtis and Bidart 2017) and 2.5 to 200 mg/L (Perkins et al 2009).…”

“…The individual effects of some invasive plants or the herbicides used to control these plants have been studied; however, the combined effects of these 2 factors on amphibians are largely unknown (but see Curtis and Bidart 2017). The present study sought to examine how chemical management of one invasive plant species ( R. cathartica ) coupled with projected increases in temperature could impact northern leopard frog ( Lithobates pipiens , Schreber) tadpoles.…”