Multiple stress effects of Vision® herbicide, pH, and food on zooplankton and larval amphibian species from forest wetlands

Abstract

As part of a multiple-tier research program, interactions of the herbicide Vision (glyphosate) with two stressors, pH and food level, were examined. Effects of the formulated product Vision were tested at two test concentrations (0.75 and 1.50 mg acid equivalent/L), two pH levels (pH 5.5 and 7.5), and under high and low food concentrations. Effects of each stressor alone and in combination were examined using two common wetland taxa: Zooplankton, Simocephalus vetulus, and tadpoles (Gosner stage 25) of Rana pipiens. For S. vetulus, survival, reproduction, and development time were measured; survival was measured for R. pipiens. For both species, significant effects of the herbicide were measured at concentrations lower than the calculated worst-case value for the expected environmental concentration ([EEC], 1.40 mg acid equivalent/L). Moreover, high pH (7.5) increased the toxic effects of the herbicide on all response variables for both species even though it improved reproductive rate of S. vetulus over pH 5.5 in the absence of herbicide. Stress due to low food alone also interacted with pH 5.5 to diminish S. vetulus survival. These results support the general postulate that multiple stress interactions may exacerbate chemical effects on aquatic biota in natural systems.

Effects of Herbicide Glyphosate and Glyphosate-Based Formulations on Aquatic Ecosystems

“…We considered a EEC of 2.6 mg a.i./L, (following Relyea, 2005). Similar values were estimated by other authors: 1.87 mg a.i./L (Chen et al, 2004) and 3.73 mg a.i./L (Perkins et al, 2000); though higher values were also evaluated (e.g. 10.…”

“…Values of LC 50 obtained in Roundup ® treatments ranged from 1.5 mg a.e./L for the amphipod Hyalella azteca (Tsui & Chu, 2004) to 62.0 mg a.i./L for other amphipod Gammarus pseudolimnaeu (Folmar et al, 1979) (Table 3). In addition, 0.7 mg a.e./L of Vision ® (a commercial formulation containing POEA) elicited a 100 % of mortality and more than 50 % reduction in total neonates per female in the cladoceran Simocephalus vetulus at values of pH = 7.5 (Chen et al, 2004). Sublethal effects were observed at much lower concentration of Roundup (1.1 μg/L) in the Clam, Ruditapes decussates, showing histological alterations (Abdel-Nabi, et al, 2007;ElShenawy, et al, 2009).…”

“…However, lower concentrations have shown significant effects in mortality and growth. For instance, Chen et al (2004) reported 100 % of mortality in tadpoles of Rana pipiens treated with 0.75 mg a.e./L of Vision ® at pH of 7.5. Cauble & Wagner (2005) observed 50% of mortality for tadpoles of Rana cascadae treated with 1.94 mg a.i./L of Roundup ® and an earlier metamorphosis time with 1 mg a.i.…”

Actue Toxic Effects of Round-Up Herbicide on Wood Frog Tadpoles (Rana sylvatica)

“…Previous studies on the toxicity of glyphosate and commercial formulations of glyphosate to amphibians have found that while glyphosate itself is not very toxic (Perkins et al 2000, Howe et al 2004, the formulations that are actually applied by users can be very toxic (Mann and Bidwell 1999, Smith 2001, Lajinanovich et al 2003, Chen et al 2004, Howe et al 2004, Cauble and Wagner 2005, Relyea 2004,2005a. 2005b.…”

Evaluación De La Toxicidad De Dos Agroquimicos, Roundup® Activo Y Cosmo-Flux®411f, en Renacuajos De Anuros Colombianos

“…También, que su interacción con otros factores como el pH (Edginton et al, 2004) y la disponibilidad del alimento (Chen et al, 2004) potencian su efecto. Sin embargo, cuando los experimentos se han realizado bajo condiciones de microcosmos se ha observado una reducción significativa en la toxicidad del glifosato (Wojtaszek et al, 2004;Bernal et al, 2009b), la cual es atribuida a la materia orgánica y macrófitas acuáticas presentes en este tipo de experimentos que favorecen la degradación del glifosato a su principal metabolito, ácido aminometil fosfórico (AMPA) (Plötner y Matschke, 2012).…”