Combined effects of landscape composition and agrochemicals on frog communities amid sugarcane‐dominated agroecosystems

Abstract

Global demand for crops will continue increasing over the next few decades to cover both food and biofuel needs. This demand will put further pressure to expand arable land and replace natural habitats. However, we are only beginning to understand the combined effects of agrochemicals and land‐use change on tropical freshwater biodiversity. In this study, we analyzed how pond‐dwelling anuran larvae responded to pond characteristics, landscape composition, and agrochemical contamination in a sugarcane‐dominated agroecosystem in Brazil. Then we used an information theoretical approach with generalized linear models to relate species richness and abundance to predictor variables. The variation in tadpole abundance was associated with both agrochemical concentration (e.g., ametryn, diuron, and malathion) and landscape variables (e.g., percentage of forest, percentage of agriculture, and distance to closest forest). The relationship between species abundance and agrochemicals was species‐specific. For example, the abundances of Scinax fuscovarius and Physalaemus nattereri were negatively associated with ametryn, and Dendropsophus nanus was negatively associated with tebuthiuron, whereas that of Leptodactylus fuscus was positively associated with malathion. Conversely, species richness was associated with distance to forest fragments and aquatic vegetation heterogeneity, but not agrochemicals. Although we were unable to assign a specific mechanism to the variation in tadpole abundance based on field observations, the lower abundance of three species in ponds with high concentrations of agrochemicals suggest they negatively impact some frog species inhabiting agroecosystems. We recommend conserving ponds near forest fragments, with abundant stratified vegetation, and far from agrochemical runoffs to safeguard more sensitive pond‐breeding species.

Leaf-Litter Anurans in An Agricultural Landscape in the araucaria Forest: A Case Study for Southern Brazil

“…Although we did not evaluate agrochemical usage in the plantation, it should be noted that these substances could represent a threat to the anurans in the agricultural landscape, given that these substances can promote cellular and genetic alterations leading to morphological abnormalities, thereby affecting population viability (Laurentino et al, 2016; Lenhardt et al, 2017; Assis et al, 2021). Many studies have described the negative effects of agrochemicals on anuran populations (Guerra and Aráoz, 2016; Ascoli-Morrete et al, 2019; Agostini et al, 2020; Ascoli-Morrete et al, 2022; Sánchez-Domene et al, 2022). In this sense, the occurrence of endangered species in plantations, such as Melanophryniscus devincenzii, which occurred almost exclusively in this environment, is concerning because the viability and maintenance of their populations can be threatened.…”