底栖生物影响下的潮滩微地貌演化数值模拟

潮滩是海岸带湿地的主要类型之一，其中分布的底栖生物对生态环境具有重要的调节作用。潮滩底栖微藻、泥沙与水动力之间存在相互作用，影响潮滩微地貌形态，明晰底栖生物对潮滩微地貌的演化机制至关重要。以黄河三角洲潮滩湿地为研究区，通过构建潮滩微地貌动力模型，探究底栖生物对微地貌格局演化的作用机制，分析底栖生物对微地貌系统稳定性的影响。结果表明(1)底栖微藻生长与泥沙扩散、水流再分配过程交互作用驱动下，潮滩上可形成底栖微藻覆盖的高丘与积水洼地交替分布的规则性微地貌斑图；(2)微地貌斑图的形成提高了潮滩生态系统初级生产力和泥沙淤积高度；(3)底栖微藻与泥沙、水流的交互作用使得潮滩微地貌系统对侵蚀扰动呈现非线性响应行为，系统存在临界点，且在一定侵蚀率范围内存在双稳态；(4)黄河口泥螺入侵使得微地貌系统抵抗侵蚀扰动能力减小，且系统稳定性随泥螺生物量的增加而降低。

Numerical simulation of micro-geomorphic evolution under the influence of benthic organisms in a tidal flat

Tidal flats are one of the main types of coastal wetlands in the world. Benthic organisms, which accommodate in tidal flats, playing an important role in regulating the ecological environment. Benthic microalgae can interacts with sediment and hydrodynamic process, driving the development of micro-geomorphic patterns in tidal flats. It is very important to clarify the effect of benthic organisms on the evolution of micro-geomorphic patterns in tidal flats. In this paper, taking the tidal flat in the Yellow River Delta wetland as a study area, by constructing a micro-geomorphic dynamic model, we explored the effect of benthic organisms on the evolution of the micro-geo micro-geomorphic microtopographic system. The results show that (1) under the interaction of the benthic microalgae growth, sediment diffusion and water flow redistribution, a regular micro-geomorphic pattern of microalgae-covered hummocks alternating with water-filled hollows is formed. (2) The formation of micro-geomorphic pattern improves the primary productivity and sediment elevation in the flat tidal ecosystem. (3) Microalgal biomass and sediment elevation in the micro-geomorphic system respond nonlinearly to erosion disturbance, the system has tipping points and bistable states within a certain range of erosion rate. (4) The invasion of mud snails in the Yellow River estuary reduces the stability of the micro-geomorphic system to erosion disturbance, and the stability of system decreases with the increase of mud snail biomass.