Analysis of the zooplanktonic community in rice fields during a crop cycle in agroecological versus conventional management

This study investigated the zooplankton community in rice fields with different management practices: conventional crop (CC) and agroecological crop (AE). In both wetlands, physicochemical parameters and pesticide residues in water and sediment were measured, and the structure of zooplankton was analyzed. Environmental parameters did not show significant differences between the wetlands. In AE samples, no pesticide residues were recorded in water; only bentazone residues were found in sediment. In CC water samples, bentazone, glyphosate, and AMPA were found, while bentazone, AMPA, clomazone, imidacloprid, and tebuconazole were detected in sediment. AE rice field presented significantly (p < 0.01) higher richness of Cladocera taxa, which is considered the most sensitive group among zooplankters, as well as abundance of rotifers, diversity, and evenness of taxa (p < 0.05). In contrast, in CC, only the dominance was significantly (p < 0.05) higher than in AE, mainly explained by the dominance of smaller species and copepods, considered more tolerant. The percentage of dissimilarity between crops was high (79.9 %). Through different biological indicators and ecological indices, we conclude that the AE rice field showed better environmental quality than CC. This study contributes to understanding the effect of pesticides on zooplankton and alerts about the importance of diversifying crop management practices and diminishing the use of agrochemicals in rice production.