Elevated temperature alleviates benzophenone-3 toxicity in Daphnia magna

Abstract

Water temperature rises due to thermal discharge and global warming and the potential resulting impacts on the ecotoxicity of emerging chemicals are a growing concern. Benzophenone-3 (BP-3) is an ultraviolet filter added to personal care and plastic products, which is detected at highest concentrations during the hot summer season. This study aimed to investigate the effect of elevated temperature on acute (48 h) and chronic (21 d) BP-3 toxicity in Daphnia magna. Neonates (<24 h) acclimated at 28 degrees C showed much lower acute toxicity (EC50 = 3.91 and 2.69 mg L-1 at 20 and 28 degrees C, respectively) than those acclimated at 20 degrees C (EC50 = 2.96 and 2.04 mg L-1 at 20 and 28 degrees C, respectively). The body length, embryonic development, and the number of offspring in D. magna offspring exposed to BP-3 for 21 d were significantly decreased after exposure to 0.8 mg L-1 BP-3 at 20 degrees C. However, these adverse effects of BP-3 in D. magna were significantly ameliorated at 28 degrees C. Under these conditions, stress response genes such as Hb (hemoglobin), Hsp70 (heat shock protein), Cyp4 (cytochrome P450), and GST (glutathione-S-transferase) were significantly upregulated. These findings suggest that elevated temperature activated stress responses in D. magna, leading to enhanced protection against BP-3 toxicity. This study will contribute to a better understanding of the ecotoxicological impacts of toxic chemicals on aquatic organisms at elevated temperature.