Wetlands, especially marshes, support many services such as carbon catchment control or water purification led by primary producers such as phytoplankton and microphytobenthos (PB). The impact of the sedimentary compartment, as source and sink of essential nutrients for the water column, is often neglected in the study of their dynamics and water purification capacity of the systems. This work compared monthly (between February 2020 and April 2021) the benthic and pelagic primary producers’ dynamics in two anthropised freshwater marshes (Marans and Genouillé), with the simultaneous follow-up of physico-chemical parameters of the water column and nutrient fluxes at the sediment-water (SWI) interface. It was suggested a strong contribution of phytoplankton (pumping) and the benthic compartment (denitrification) to the water purification of these two nitrates (NO₃⁻)-rich marshes. Total phytoplankton production fluctuated between ∼5 (winter) and 1500 mg C m⁻³ d⁻¹ (fall) at Marans and between 40 (winter) and ∼750 mg C m⁻³ d⁻¹ (spring) at Genouillé. At Marans, soluble reactive phosphorus (SRP) benthic effluxes (-2.10¹ to -6.10² µmol m⁻² d⁻¹ in fall and summer, respectively) coincided with phytoplankton bloom periods. These effluxes were inhibited by NO₃⁻ penetration in the sediment (0 to 5.10⁴ µmol m⁻² d⁻¹), by inhibiting iron respiration. At Genouillé, inhibition of SRP effluxes depended on denitrification rate and on P stocks in the sediment, where slight SRP effluxes (-10¹ µmol m⁻² d⁻¹) could have co-occurred with slight NO₃⁻ influxes (5.10² µmol m⁻² d⁻¹) in spring. The presence of PB (between 10–60 and 40–120 mg g_sed⁻¹ at Marans and Genouillé, respectively), suggested a strong contribution of the benthic compartment to the total primary production (benthic and pelagic through resuspension processes) in these environments. This work encourages to consider the benthos and the pelagos as a unicum to provide better sustainable management of such systems and limit eutrophication risks in coastal areas.

湿地，尤其是沼泽地，支持许多服务，例如由浮游植物和微型底栖植物 (PB) 等初级生产者主导的碳汇控制或水净化。沉积隔室作为水柱必需养分的来源和汇的影响，在研究其动力学和系统的水净化能力时常常被忽视。这项工作每月（2020 年 2 月至 2021 年 4 月）比较两个人为淡水沼泽（Marans 和 Genouillé）的底栖和远洋初级生产者的动态，同时跟踪水柱的物理化学参数和营养通量沉积物-水（SWI）界面。₃ ^- ) 丰富的沼泽。Marans 的浮游植物总产量在 ∼5（冬季）和 1500 mg C m ^-3 d ^-1（秋季）之间波动，而 Genouillé 的总浮游植物产量在 40（冬季）和 ∼750 mg C m ^-3 d ^-1（春季）之间波动。在 Marans，可溶性活性磷 (SRP) 底栖流出物（秋季和夏季分别为 -2.10 ¹至 -6.10 ² µmol m ^-2 d ^-1）与浮游植物开花期相吻合。这些流出物被沉积物中的 NO ₃ ^-渗透抑制（0 至 5.10 ⁴  µmol m ^-2 d ^-1)，通过抑制铁的呼吸作用。在 Genouillé，SRP 流出的抑制取决于反硝化速率和沉积物中的 P 储量，其中轻微的 SRP 流出（-10 ¹  µmol m ^-2 d ^-1）可能与轻微的 NO ₃ ^-流入（5.10 ²  µmol ）同时发生m ^-2 d ^-1 ) 在春天。PB 的存在（10–60 和 40–120 mg g _sed ^-1分别在 Marans 和 Genouillé）表明，在这些环境中，底栖隔间对总初级生产（底栖和远洋通过再悬浮过程）的贡献很大。这项工作鼓励将底栖生物和中上层海洋视为一个统一体，以更好地对此类系统进行可持续管理，并限制沿海地区的富营养化风险。