Macrofaunal species inhabiting intertidal mudflats and performing intense bioturbation are considered as ecosystem engineers, since they profoundly influence their physical, chemical, and biological environments. Nowadays, to complete our knowledge on the effect of bioturbation processes on the surrounding environment, interdisciplinary approach is essential to unravel their complex intertwined effects on intertidal mudflats. In this study, the effects of bioturbators on sediment properties, biogeochemical variables, and microbial dynamics (microphytobenthos, bacteria and archaea) were investigated. To this end, manipulation experiments were carried out in an intertidal mudflat of the Seine Estuary (France) by revamped the abundance of the two dominant bioturbators, and , in winter and late summer. Results showed that the presence of in winter had a significant effect, with a significant increase in bed level accretion and microbial nitrate reduction rates. In contrast, the presence of showed no significant impact on sediment properties, most likely due to a reduced bioturbating activity at low temperature. In summer, both ecosystem engineers strongly influenced their surrounding environment but with opposite effects. The intense reworking of the sediment surface by limited microbial growth and enhanced erosion processes. Conversely, the presence of favoured sediment accretion and enhanced microbial growth. Overall, this interdisciplinary study confirms the importance of these two ecosystem engineers in temperate estuarine mudflats by highlighting their simultaneous and intertwined effects on the sedimentary, physicochemical, and biological features. This confirms the importance of actively considering ecosystem engineers when restoring the natural habitats of tidal flats to cope with the different vulnerability risks related to global warming (sandification of estuarine sediments, disappearance of productive mudflats, sea level rise, vulnerability to storms and erosion).

中文翻译：

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底栖生物扰动物种的拮抗影响：对沉积特性、生物地球化学变量和微生物动力学的相互关联的影响

栖息于潮间带泥滩并进行强烈生物扰动的大型动物物种被认为是生态系统工程师，因为它们深刻地影响着其物理、化学和生物环境。如今，为了完善我们对生物扰动过程对周围环境影响的了解，跨学科方法对于阐明其对潮间带泥滩复杂、交织的影响至关重要。在这项研究中，研究了生物扰动器对沉积物性质、生物地球化学变量和微生物动力学（微型底栖植物、细菌和古细菌）的影响。为此，在塞纳河口（法国）的潮间带泥滩上进行了操纵实​​验，修改了冬季和夏末两个主要生物扰动因子 和 的丰度。结果表明，冬季的存在具有显着影响，床位沉积率和微生物硝酸盐还原率显着增加。相比之下， 的存在对沉积物性质没有显着影响，很可能是由于低温下生物扰动活动的减少。在夏天，两位生态系统工程师都强烈影响了周围的环境，但效果却相反。限制微生物生长和增强侵蚀过程对沉积物表面进行强烈改造。相反，有利于沉积物堆积并促进微生物生长。总体而言，这项跨学科研究通过强调这两位生态系统工程师对沉积、物理化学和生物特征的同时且相互交织的影响，证实了这两位生态系统工程师在温带河口泥滩中的重要性。这证实了在恢复滩涂自然栖息地以应对与全球变暖相关的不同脆弱性风险（河口沉积物沙化、生产性泥滩消失、海平面上升、风暴和侵蚀脆弱性）时积极考虑生态系统工程师的重要性。