The Effects of Raw and Phytoremediated Ethanol Vinasse on the Survival and Swimming Behaviour of the Amphipod Gammarus pulex

Considering the promising use of ethanol as an alternative energy source, it is important to understand how by-products such as vinasse can affect the environment, especially when they are applied directly to the environment as a fertilizer. Although treatments have been proposed for this wastewater, the focus has mainly been on the physical and chemical characteristics of vinasse. Therefore, ecotoxicology studies are necessary to confirm the efficiency of these treatments. Several studies have highlighted the acute toxicity potential of vinasse however very little is known about chronic exposure and ecologically relevant endpoints such as behaviour. In order to evaluate the toxicity of raw and phytoremediated vinasse, we exposed individuals of Gammarus pulex to raw, 7-day, and 15-day phytoremediated vinasses for 96 hours, recording mortality and behavioural endpoints. The animals exposed to the different vinasses showed alterations in the swimming pattern. Also, the mortality was higher in animals exposed to raw vinasse. Mortality and effects on swimming speed were related to differences in Biological and Chemical Oxygen Demand (BOD and COD), as well as low pH and zinc concentration. Our results suggest that, even after treatment, the toxic potential of vinasse remains, affecting animals' fitness. In this way, despite the ecological benefits of ethanol energy, its by-products' discharge must be evaluated to minimize effects on the biota.