A high degree of uncertainty exists for understanding and predicting coastal estuarine response to changing climate, land-use, and sea-level conditions, leaving geologic records as a best-proxy for constraining potential outcomes. With the majority of the world's population focused in coastal regions, understanding how local systems respond to global, regional, and even local pressures is key in developing mitigation, adaptation, and management plans. The geomorphology of Mobile Bay in southeast Alabama (USA) has evolved considerably (e.g., bayhead delta back-stepping) over the late Holocene in response to global and regional sea-level and climate change. Smaller-scale geomorphic changes (e.g., spit and beach ridge development) have also had a significant influence on the evolution of the estuary. Organic matter characteristics, inorganic sediment geochemistry, benthic microfossils, and pollen in a ~ 3500 cal yr BP sediment sequence recovered in a gravity core (20GC) from Bon Secour Bay, a small sub-bay in the southeast corner of Mobile Bay, record time-varying marine influence. Increases in marine influence during ~3500 to 2300 cal yr BP and 1930 to 1160 cal yr BP are defined as zones with high-density and pre-dominantly calcareous foraminiferal species, abundant sand (>10%) and more marine-like geochemical signatures, which contrast the low-density and pre-dominantly agglutinated foraminiferal and more terrestrially influenced estuarine muds observed in other intervals of the sedimentary record (2300–1930 and 1160–400 cal yr BP) and the modern bay. Hydrodynamic models constrained by geomorphic boundary conditions for the time ~ 3500 cal yr BP, consistent with the most prominent marine-influenced sediment, provide insight to potential coastal configuration that might have permitted such marine water intrusion into the bay. Of several scenarios evaluated, a breach in Morgan Peninsula produces tidal circulation within the basin supportive of persistent marine incursions in the bay between ~3500 to 2300 cal yr BP. The findings show that slight variations in coastal configuration can have broad-scale effects on bays and estuaries with consequences that may relate to water quality, vertebrate and invertebrate habitat, and coastal vulnerability to episodic events like (extra)tropical storms.

对于了解和预测沿海河口对气候变化，土地利用和海平面状况的反应，存在很大的不确定性，而地质记录则是限制潜在结果的最佳方法。由于世界上大多数人口都集中在沿海地区，因此了解本地系统如何应对全球，区域甚至本地压力是制定缓解，适应和管理计划的关键。响应全球和区域海平面以及气候变化，在新世晚期晚期，美国阿拉巴马州东南部的莫比尔湾地貌发生了很大的变化（例如，Bayhead delta后退）。较小规模的地貌变化（例如，沙坑和海滩山脊发育）也对河口的演变产生了重大影响。有机质特征 无机沉积物地球化学，底栖微化石和花粉在约3500 cal的BP沉积物序列中，从莫比尔湾东南角的一个小子湾Bon Secour湾的重力岩心（20GC）中回收，记录了随时间变化的海洋影响。在约3500至2300 cal BP和1930到1160 yr BP期间，海洋影响的增加被定义为高密度和钙质有孔虫物种，丰富的砂土（> 10％）和更多类似海洋的地球化学特征的区域，这与在沉积记录的其他时间段（2300–1930年和1160–400 cal yr BP）和现代湾中观察到的低密度，主要凝集的有孔虫和受陆地影响较大的河口泥形成对比。在约3500 cal yr BP的时间内受地貌边界条件约束的流体动力学模型，与最突出的受海洋影响的沉积物相吻合，提供对潜在沿海构造的洞察力，而这些潜在的沿海构造可能已允许这种海水侵入海湾。在评估的几种情况中，摩根半岛的破裂在盆地内产生了潮汐环流，从而支持了在约3500到2300 cal BP之间海湾中持续的海洋入侵。研究结果表明，沿海构造的细微变化可能会对海湾和河口产生广泛影响，其后果可能与水质，脊椎动物和无脊椎动物的栖息地以及沿海地区对（额外）热带风暴等突发事件的脆弱性有关。摩根半岛的裂隙在盆地内部产生了潮汐循环，从而支持了在3500到2300 cal BP年之间海湾的持续海侵。研究结果表明，沿海构造的微小变化可能会对海湾和河口产生广泛影响，其后果可能与水质，脊椎动物和无脊椎动物的栖息地以及沿海地区对（额外）热带风暴等突发事件的脆弱性有关。摩根半岛的裂隙在盆地内部产生了潮汐循环，从而支持了在3500到2300 cal BP年之间海湾的持续海侵。研究结果表明，沿海构造的细微变化可能会对海湾和河口产生广泛影响，其后果可能与水质，脊椎动物和无脊椎动物的栖息地以及沿海地区对（额外）热带风暴等突发事件的脆弱性有关。