Effects of the herbicide bentazone on the structure of plankton and benthic communities representative of Mediterranean coastal wetlands: a mesocosm experiment
摘要
Pesticide pollution poses one of the most important threats for the ecological status of coastal wetland ecosystems. In this study, we evaluated the effects of the herbicide bentazone on aquatic communities characteristic of Mediterranean coastal wetlands using outdoor mesocosms. The herbicide was applied weekly for four weeks at concentrations of 0 (control), 25, 250, and 2500 µg/L in mesocosms representing two different ecological conditions: one with submerged macrophytes and one without macrophytes. The impact of bentazone on diverse taxonomic groups, including benthic diatoms, phytoplankton, submerged macrophytes, zooplankton, and aquatic macroinvertebrates, was examined before the first bentazone application, after the last application and sixty days after the last application. The results show that benthic diatoms were the most affected group in terms of community structure. Zooplankton was the second most affected group, mainly driven by indirect effects that resulted in the replacement of large filter feeders by small filter feeders. This suggests strong bottom-up effects caused by the herbicide, altering the structure of the primary producers’ community which, in turn, indirectly affected key zooplankton taxa. Our study shows that the exposure levels of bentazone measured in Mediterranean coastal wetlands could result in long-term direct and indirect impacts on the structure of aquatic communities.