Abstract: This study investigated the acute toxicity and transgenerational effects of p-xylene（PX）on Moina mongolica. The experiments were conducted under the following conditions: salinity of seawater 30±0.5, pH 8.1, temperature set at 28 ℃, and a light-dark cycle of 12L-12D with light intensity ranging from 2 000 to 3 000 lx. The results showed that the 24 h LC₅₀ and 48 h LC₅₀ values of PX on Moina mongolica were 9.82 mg/L and 7.16 mg/L, respectively, with a safety concentration of 1.14 mg/L. Under the influence of PX at concentrations ranging from 0.20 to 1.00 mg/L, significant decreases（P<0.05）were observed in total reproductive output and first brood reproductive output in the parental generation（P generation）compared to the control group. However, these parameters returned to normal levels in the F2 generation, with significant transgenerational effects appearing in the F3 or F4 generations. This study demonstrates that the toxic effects of PX on Moina mongolica can be transmitted to subsequent generations, providing theoretical support for the detection of marine organic pollutants and the screening of new test organisms.

Key words: p-xylene, Moina mongolica, acute toxicity, transgenerational toxicity