Microphytobenthos (MPB) are a key primary producer of intertidal mudflats. MPB face strong variability in incident irradiance during low tides. Despite photoprotection and photoacclimation, such variations can translate into the photoinhibition of MPB cells. This study explores the effect of photoinhibition on MPB primary production (PP) over a large and productive temperate mudflat (Brouage mudflat, NW France). We used a regional and high-resolution tri-dimensional hydrodynamic model coupled to an MPB model with or without photoinhibition. Photoinhibition leads to a 20% (−0.79 × t C) decrease of the simulated MPB PP over the entire mudflat. As the upper shore is exposed to light more frequently and longer than the lower shore, the decrease of MPB PP is higher on the upper shore (−29%) than on the lower shore (−5%). With the highest photosynthetically active radiation cumulated over the mudflat, the decrease of MPB PP due to photoinhibition is the highest during spring and spring tides (−22% and −23%, respectively). The model suggests MPB photoinhibition is sensitive to the photoacclimation status of MPB cells through the light saturation parameter. This first modeling attempt to account for MPB photoinhibition is highly constrained by our current theoretical knowledge and limitations on the MPB growth physiology, but it suggests that this process can have a substantial impact on the MPB PP. As such, assessing the MPB photosynthetic response to the highly variable environmental conditions that prevail in large and productive intertidal mudflats is a real challenge for quantifying MPB PP from a synoptic to inter-annual time scale.

中文翻译：

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光抑制对大型潮间带泥滩微底栖植物初级生产的潜在影响

底栖微植物（MPB）是潮间带泥滩的主要初级生产者。MPB 面临低潮期间入射辐照度的强烈变化。尽管有光保护和光驯化，但这种变化可以转化为 MPB 细胞的光抑制。本研究探讨了光抑制对大型多产温带泥滩（Brouage 泥滩，法国西北部）上 MPB 初级生产 (PP) 的影响。我们使用了区域和高分辨率三维流体动力学模型，该模型与具有或不具有光抑制作用的 MPB 模型耦合。光抑制导致 20% (-0.79 ×t C) 在整个泥滩上模拟 MPB PP 的减少。由于上岸比下岸更频繁、更长时间地暴露在光线下，上岸 (-29%) 的 MPB PP 下降幅度高于下岸 (-5%)。随着在泥滩上累积的最高光合有效辐射，由于光抑制引起的 MPB PP 减少在春潮和大潮期间最高（分别为 -22% 和 -23%）。该模型表明 MPB 光抑制通过光饱和参数对 MPB 细胞的光驯化状态敏感。第一次解释 MPB 光抑制的建模尝试受到我们当前理论知识和 MPB 生长生理学限制的高度限制，但它表明该过程可能对 MPB PP 产生重大影响。像这样，