Non-target effects of a glyphosate-based herbicide on Common toad larvae (Bufo bufo, Amphibia) and associated algae are altered by temperature

Abstract

BackgroundGlyphosate-based herbicides are the most widely used pesticides in agriculture, horticulture, municipalities and private gardens that can potentially contaminate nearby water bodies inhabited by amphibians and algae. Moreover, the development and diversity of these aquatic organisms could also be affected by human-induced climate change that might lead to more periods with extreme temperatures. However, to what extent non-target effects of these herbicides on amphibians or algae are altered by varying temperature is not well known.MethodsWe studied effects of five concentrations of the glyphosate-based herbicide formulation Roundup PowerFlex (0, 1.5, 3, 4 mg acid equivalent glyphosate L−1 as a one time addition and a pulse treatment of totally 4 mg a.e. glyphosate L−1) on larval development of Common toads (Bufo bufo, L.; Amphibia: Anura) and associated algae communities under two temperature regimes (15 vs. 20 °C).ResultsHerbicide contamination reduced tail growth (−8%), induced the occurrence of tail deformations (i.e. lacerated or crooked tails) and reduced algae diversity (−6%). Higher water temperature increased tadpole growth (tail and body length (tl/bl) +66%, length-to-width ratio +4%) and decreased algae diversity (−21%). No clear relation between herbicide concentrations and tadpole growth or algae density or diversity was observed. Interactive effects of herbicides and temperature affected growth parameters, tail deformation and tadpole mortality indicating that the herbicide effects are temperature-dependent. Remarkably, herbicide-temperature interactions resulted in deformed tails in 34% of all herbicide treated tadpoles at 15 °C whereas no tail deformations were observed for the herbicide-free control at 15 °C or any tadpole at 20 °C; herbicide-induced mortality was higher at 15 °C but lower at 20 °C.DiscussionThese herbicide- and temperature-induced changes may have decided effects on ecological interactions in freshwater ecosystems. Although no clear dose-response effect was seen, the presence of glyphosate was decisive for an effect, suggesting that the lowest observed effect concentration (LOEC) in our study was 1.5 mg a.e. glyphosate L−1 water. Overall, our findings also question the relevance of pesticide risk assessments conducted at standard temperatures.

Effects of glyphosate and its commercial formulation, Roundup® Ultramax, on liver histology of tadpoles of the neotropical frog, Leptodactylus latrans (amphibia: Anura)

“…Specifically, lethal effects were shown in anuran larvae after the exposure to several glyphosatebased formulations (Annett et al, 2014;Bach et al, 2016;Bernal et al, 2009;Fuentes et al, 2011;Güng€ ordü, 2013;Howe et al, 2004;Mann and Bidwell, 1999;Moore et al, 2012;Relyea and Jones, 2009;Wagner et al, 2017a;Yadav et al, 2013). Also, different sub-lethal effects were observed in anuran larvae such as: growth, swimming activity, behavior, morphological abnormalities, DNA damage, alterations in enzyme activities, cardiac and respiratory functions, sex ratio, and histology of the respiratory tract (Bach et al, 2016;Baier et al, 2016;Clements et al, 1997;Costa et al, 2008;Edginton et al, 2004;Howe et al, 2004;Lajmanovich et al, 2003Lajmanovich et al, , 2011Lanctôt et al, 2013Lanctôt et al, , 2014Relyea, 2004Relyea, , 2012Rissoli et al, 2016;Wagner et al, 2017a;.…”

Biodiversity Decline as a Consequence of an Inappropriate Environmental Risk Assessment of Pesticides

“…Jänsch et al, 2006;Desneux et al, 2007;Stahlschmidt and Brühl, 2012;Brühl et al, 2013). The consideration of interactions of pesticide effects with additional stressors such as nutrients or climate change was also pointed out (Köhler and Triebskorn, 2013;Baier et al, 2016).…”

Herbicide Roundup shows toxic effects in nontarget organism Drosophila

“…Exposure of pregnant female rats to glyphosate‐based herbicides delays fetal growth and induces structural congenital anomalies (Milesi et al, 2018). Slower growth and development of the aquatic larval stages were demonstrated in common toads under treatment by glyphosate‐based herbicides (Baier et al, 2016).…”