The organic pollutant bisphenol A (BPA) causes adverse effects on aquatic biota. The present study explored the toxicity mechanism of environmentally occurring BPA concentrations (0.03-3 μg L⁻¹) on the seagrass Cymodocea nodosa intermediate leaf photosynthetic machinery. A "mosaic" type BPA effect pattern was observed, with “unaffected” and “affected” leaf areas. In negatively affected leaf areas cells had a dark appearance and lost their chlorophyll auto-fluorescence, while hydrogen peroxide (H₂O₂) content increased time-dependently. In the “unaffected” leaf areas, cells exhibited increased phenolic compound production. At 1 μg L^-1 of BPA exposure, there was no effect on the fraction of open reaction centers (q_P) compared to control and also no significant effect on the quantum yield of non-regulated non-photochemical energy loss in PSII (Φ_ΝΟ). However, a 3 μg L⁻¹ BPA application resulted in a significant Φ_ΝΟ increase, even from the first exposure day. Ultrastructural observations revealed electronically dense damaged thylakoids in the plastids, while effects on Golgi dictyosomes and the endoplasmic reticulum were also observed at 3 μg L⁻¹ BPA. The up-regulated H₂O₂ BPA-derived production seems to be a key factor causing both oxidative damages but probably also triggering retrograde signalling, conferring tolerance to BPA in the “unaffected” leaf areas.

有机污染物双酚A（BPA）对水生生物造成不利影响。本研究探讨了环境中双酚A浓度（0.03-3μgL ^-1）对海草Cymodocea nodosa中间叶片光合作用机制的毒性机制。观察到“马赛克”型BPA效应模式，叶片区域“未受影响”和“受影响”。在受负面影响的叶区域中，细胞具有深色外观并失去其叶绿素自发荧光，而过氧化氢（H ₂ O ₂）含量则随时间增加。在“未受影响”的叶区域，细胞表现出增加的酚类化合物产量。在1μgL ^-1时BPA暴露的，有上的开放反应中心（Q分数没有影响_P与对照相比，并且在非限定非光化学能量损失在PSII的量子产率（也没有显著效果）Φ _ΝΟ）。然而，3微克大号^-1 BPA应用导致了显著Φ _ΝΟ增加，即使是从第一曝光天。超微结构观察显示，在质体中电子致密的类囊体受损，而在3μgL ^-1 BPA下也观察到对高尔基单核小体和内质网的影响。上调的H ₂ O ₂ BPA衍生的产生似乎是引起氧化损伤的关键因素，但也可能触发逆行信号，从而在“未受影响”的叶片区域赋予对BPA的耐受性。