Effects of ashes from grassland burning in the Paraná River floodplain on aquatic microcrustaceans

The burning of grasslands is a widespread practice in many landscapes, yet it has complex and multifaceted effects on natural ecosystems. In regions such as the Middle Paraná River floodplain, the frequency and intensity of wildfires have increased, primarily due to livestock production and related land-use activities. However, there is limited information on the potential effects of ash on aquatic biota. This study aims to evaluate the impact of ash produced from the burning of two distinct grasslands (grassland A, dominated by Panicum sp., and grassland B, dominated by Cinnagrostis sp.) in the Middle Paraná River floodplain on the Cladocera species Ceriodaphnia reticulata. Our findings reveal negative effects of ash from both grasslands on survival. In turn, while reproduction decreased in treatments with ash from grassland A, it significantly increased in treatments with ash from grassland B. Furthermore, survival rates were primarily influenced by the total ash particles, whereas reproduction was affected by both total ash particles and the fine fraction. Additional research is needed to better understand which fire characteristics influence the toxicity of ash to biota. These insights are critical for improving and refining integrated fire management practices.