Brückner Muriel Z M, Schwarz Christian, Coco Giovanni, Baar Anne, Boechat Albernaz Márcio, Kleinhans Maarten G
Faculty of Geosciences Utrecht University PObox 80115 3508 TC Utrecht The Netherlands.
College of Earth, Ocean, and Environment University of Delaware Lewes DE USA.
Earth Surf Process Landf. 2021 May;46(6):1128-1144. doi: 10.1002/esp.5080. Epub 2021 Mar 24.
Sediment-stabilizing and -destabilizing organisms, i.e. microphytobenthos (biofilms) and macrozoobenthos (bioturbators), affect the erodibility of muddy sediments, potentially altering large-scale estuarine morphology. Using a novel eco-morphodynamic model of an idealized estuary, we investigate eco-engineering effects of microphytobenthos and two macrozoobenthic bioturbators. Local mud erodibility is based on species pattern predicted through hydrodynamics, soil mud content, competition and grazing. Mud resuspension and export is enhanced under bioturbation and prevented under biostabilization through respective exposure and protection of the supra- and intertidal. Bioturbation decreases mud thickness and bed elevations, which increases net mud fluxes. Microphytobenthos reduces erosion, leading to a local mud increase of intertidal sediments. In multi-species scenarios, an effective mud-prone bioturbator strongly alters morphology, exceeding that of a more abundant sand-prone moderate species, showing that morphological change depends on species traits as opposed to abundance. Altering their habitat, the effective mud-prone bioturbator facilitates expansion of the sand-prone moderate bioturbator. Grazing and species competition favor species distributions of dominant bioturbators. Consequently, eco-engineering affects habitat conditions while species interactions determine species dominance. Our results show that eco-engineering species determine the mud content of the estuary, which suggests large effects on the morphology of estuaries with aggravating habitat degradation.
沉积物稳定和不稳定生物，即微型底栖植物（生物膜）和大型底栖动物（生物扰动者），会影响泥泞沉积物的可侵蚀性，有可能改变大规模河口形态。我们使用一个理想化河口的新型生态形态动力学模型，研究微型底栖植物和两种大型底栖生物扰动者的生态工程效应。局部泥浆可侵蚀性基于通过水动力、土壤泥浆含量、竞争和啃食预测的物种模式。在生物扰动作用下，泥浆再悬浮和输出会增强，而通过对潮上带和潮间带的相应暴露和保护，在生物稳定作用下则会阻止这种情况发生。生物扰动会降低泥浆厚度和河床高程，从而增加泥浆净通量。微型底栖植物减少侵蚀，导致潮间带沉积物局部泥浆增加。在多物种情景中，一种有效的易形成泥浆的生物扰动者会强烈改变形态，超过一种更丰富的易形成沙子的中等物种，这表明形态变化取决于物种特征而非丰度。改变其栖息地，有效的易形成泥浆的生物扰动者会促进易形成沙子的中等生物扰动者的扩张。啃食和物种竞争有利于优势生物扰动者的物种分布。因此，生态工程影响栖息地条件，而物种相互作用决定物种优势。我们的结果表明，生态工程物种决定河口的泥浆含量，这表明对栖息地退化加剧的河口形态有很大影响。
