The effect of sugarcane vinasse on the dormant forms of aquatic invertebrates

Abstract

Abstract: Aim To evaluate the impacts of vinasse on the hatching of dormant forms of aquatic invertebrates, through ex-situ experimental units. Methods Sediment samples were collected from three ponds in Parque Estadual Morro do Diabo, located in Teodoro Sampaio (SP), Brazil. Each experimental unit consisted of 100 g of sediment and vinasse solutions at concentrations of 10% and 50%, plus control groups without the byproduct addition. Three replicates were used for each treatment and pond. The experiment lasted 28 days, with filtrations performed every six days along with monitoring of pH and dissolved oxygen. Additionally, unexpected fungal growth was observed in the experimental units, which was removed weekly and subsequently identified. Results Vinasse induced significant reductions in dissolved oxygen (normoxic control: 5.62±0.95 mg/L; 10% hypoxic: 1.97±1.77 mg/L; 50% anoxic: 0.78±0.58 mg/L), pH variations with distinct patterns: in Pond 1, the 50% treatment reduced the pH; in Pond 2, it increased the pH; and in Pond 3, the 10% treatment showed a higher pH than the others; and an unexpected fungal proliferation was also recorded in the vinasse treatments, with a higher occurrence at the 50% concentration. All of these changes possibly contributed to the low abundance, richness, and diversity of hatched organisms. Conclusions The results demonstrate that vinasse addition reduced dissolved oxygen concentrations in all ponds, creating potentially unfavorable conditions for the hatching of organisms emerging from dormant egg banks, accompanied by intense fungal proliferation, particularly at the highest vinasse concentrations. The biological effects were most evident in Pond 3, where reductions in abundance, taxon richness, and diversity were observed, together with changes in the taxonomic composition of the emerging community. The contrasting responses observed among ponds also indicate that the effects of vinasse depend on local environmental characteristics, highlighting the importance of considering ecological context when assessing the impacts of this effluent on aquatic ecosystems.