Ciprofloxacin (CFX) and ofloxacin (OFX) are two of the most often used fluoroquinolone antibiotics, and their residues are found in large amounts in various aquatic settings. However, the toxicity tests of CFX using eukaryotic organisms such as Daphnia magna are inadequate, and the test result of OFX is currently unknown. Therefore, the chronic toxicity test for D. magna was performed during 42 days under exposure to CFX and OFX concentrations of 50, 500, and 5000 μg L⁻¹. All exposure conditions did not cause mortality for D. magna. CFX exposure at 500 μg L⁻¹ resulted in an earlier oogenesis date and increased brood size in the second birth. The Poisson-based generalized linear mixed-effects model revealed that the reduction of fertility was statistically significant for the CFX and OFX exposures at 5000 μg L⁻¹. On the other hand, the production of dead eggs as offspring degradation was also found significantly as maternal D. magna exposed to antibiotics at 5000 μg L⁻¹. In addition, following long-term exposure to antibiotics, maternal adaptation to antibiotics was established for offspring deterioration and fertility. However, the OFX exposure showed that the fertility-suppressed effects continued for a longer period than the CFX exposure. Although no rational explanation has yet been given for the more substantial effect of OFX on reducing fertility than CFX, molecular cell biology and symbiotic microbial flora derived from previous studies could explain our ecotoxicological results. This study is the first report for the OFX chronic toxicities on D. magna by comparing it to the toxicity of CFX. Our study contributes to guiding the future impact assessment of fluoroquinolone antibiotic pollution on ecosystems, including the need for new statistical methods in ecotoxicological studies.

环丙沙星 (CFX) 和氧氟沙星 (OFX) 是两种最常用的氟喹诺酮类抗生素，它们在各种水生环境中大量残留。然而，CFX使用大水蚤等真核生物的毒性试验不充分，目前OFX的试验结果未知。因此，在暴露于 50、500 和 5000 μg L ^{-1 的}CFX 和 OFX 浓度下的 42 天内，对D. magna进行了慢性毒性试验。所有暴露条件均不会导致大麦角藻死亡。CFX 暴露于 500 μg L ^-1导致较早的卵子发生日期和第二胎中的育雏尺寸增加。基于泊松的广义线性混合效应模型显示，对于 5000 μg L ^-1的 CFX 和 OFX 暴露，生育力的降低在统计上是显着的。另一方面，当母体D. magna暴露于 5000 μg L ^{-1 的}抗生素时，也发现了作为后代降解产生的死卵。. 此外，在长期接触抗生素后，母体对抗生素的适应建立了后代退化和生育能力。然而，OFX 暴露表明生育抑制效应比 CFX 暴露持续更长的时间。尽管尚未对 OFX 对降低生育能力的影响比 CFX 更显着，但从先前研究中得出的分子细胞生物学和共生微生物群落可以解释我们的生态毒理学结果。本研究是首次报告 OFX 对D. magna 的慢性毒性通过将其与 CFX 的毒性进行比较。我们的研究有助于指导未来氟喹诺酮类抗生素污染对生态系统的影响评估，包括在生态毒理学研究中需要新的统计方法。