State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing 210098, China; The Key Laboratory of marine ecological monitoring and restoration technology of the Ministry of natural resources, Shanghai 201206, China; State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China.
State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China.
Water Res. 2022 Jul 15;220:118660. doi: 10.1016/j.watres.2022.118660. Epub 2022 May 26.
Estuarine mudflats are profoundly affected by increased coastal erosion and reduced sediment delivery from major rivers. Although managers are having difficulties to control the cause of increased coastal erosion, they can help to manage the resilience of mudflat ecosystems to erosion through river flow regulation. In this study, we associated the resilience of a mudflat ecosystem to erosion with various magnitudes of river flow using a mechanism-based eco-morphodynamic model. Ecosystem resilience was reported in terms of i) what range of erosion rate the system can withstand before function collapse (persistence), ii) at which point function can be recovered (recovery), and iii) the uncertainty of system response to disturbances (response uncertainty). Specifically, the function of intertidal mudflat was characterized by landscape heterogeneity, primary productivity, and sediment stabilization. In a case study of the Yellow River Estuary (YRE) of China, it is found that increased erosion induced a collapse of the functioning state. Once collapsed, the erosion rate at which mudflat could recovered was lower than the erosion rate at which mudflat collapsed. Increased river flow enhanced the resilience of the mudflat ecosystem to erosion by increasing sediment deposition rate, which was an important attribute in the interaction process driving ecosystem resilience. Furthermore, given the same river flow allocation, the system with dynamic grazer population was more resilient than the system with a constant grazer number, highlighting the importance of controlling mudflat aquaculture to optimize the performance of river flow regulation. Our modeling results are dependent on the environment with several assumptions, however, as a preliminary, we believe our work represents a fundamental shift to modeling ecosystem resilience based on the mechanism of bio-physical interactions rather than relying on just quantifying the vital rates of particular species to compare river flow scenarios.
河口滩涂深受海岸侵蚀加剧和主要河流输沙量减少的影响。尽管管理者难以控制海岸侵蚀加剧的原因，但他们可以通过河流流量调节来帮助管理滩涂生态系统对侵蚀的恢复力。在这项研究中，我们使用基于机制的生态形态动力学模型，将滩涂生态系统对侵蚀的恢复力与不同规模的河流流量联系起来。生态系统的恢复力以以下几个方面来报告：i）系统在功能崩溃（持久性）之前可以承受多大范围的侵蚀率，ii）在什么情况下可以恢复功能，以及 iii）系统对干扰的响应不确定性。具体来说，潮间带滩涂的功能由景观异质性、初级生产力和沉积物稳定化来表征。在对中国黄河口的案例研究中，发现增加的侵蚀导致了功能状态的崩溃。一旦崩溃，滩涂恢复的侵蚀率低于滩涂崩溃的侵蚀率。增加的河流流量通过增加沉积物沉积率来增强滩涂生态系统对侵蚀的恢复力，这是驱动生态系统恢复力的相互作用过程中的一个重要属性。此外，在相同的河流流量分配下，具有动态食草动物种群的系统比具有恒定食草动物数量的系统更具恢复力，这强调了控制滩涂水产养殖以优化河流流量调节性能的重要性。然而，我们的建模结果依赖于环境和几个假设，但是，作为初步研究，我们相信我们的工作代表了一种基于生物物理相互作用机制而不是仅仅量化特定物种的关键速率来比较河流流量情景的基本转变，从而对生态系统恢复力进行建模。
