Mangroves rank among the most productive ecosystems on Earth, yet they are increasingly threatened by climate change and the expansion of agricultural land use. Among agricultural pollutants reaching coastal environments, glyphosate-based herbicide formulations (GBHFs) are of particular concern owing to their widespread application and environmental persistence. This study evaluated the phytotoxic effects of a GBHF (commercial product Velfosato, 48% active ingredient) on Rhizophora mangle L. seedlings under controlled experimental conditions simulating the intertidal regime of the collection site. Propagules were collected from the Los Petenes Biosphere Reserve (Campeche, Mexico), established in experimental tanks containing mangrove soil, and grown until uniform seedling development was achieved. Once seedlings reached uniform development, they were exposed to nominal concentrations of 0.003, 0.03, 0.3, 3.0, and 10 mg L−1 of the formulation dissolved in interstitial water. The experiment followed a completely randomized design (three replicate tanks per treatment plus a triplicate control; n = 1170 seedlings total). All inferential tests used the tank as the experimental unit (n = 3 per treatment). Total chlorophyll concentration was significantly lower in treated seedlings than in the control across all tested concentrations (ANOVA F5,12 = 4.55, p = 0.015). Height growth rates were significantly reduced at concentrations ≥ 3 mg L−1 (F5,12 = 6.84, p = 0.003). Lenticel number increased significantly at the two highest concentrations (F5,24 = 3.63, p = 0.014). Mangrove soil exhibited significant increases in pH and decreases in redox potential across the concentration gradient (p < 0.001 and p = 0.001, respectively). These findings indicate that sublethal exposure to a GBHF is associated with alterations in key ecophysiological processes and soil physicochemical conditions in R. mangle seedlings under controlled conditions, highlighting the sensitivity of early developmental stages to GBHF exposure.
Memije et al. (Mon,) studied this question.