Carey J C, Raposa K B, Wigand C, Warren R S
The Ecosystems Center, Marine Biological Laboratory. Woods Hole, Massachusetts.
Narragansett Bay National Estuarine Research Reserve, Prudence Island, Rhode Island.
Estuaries Coast. 2017 May 1;40(3):651-661. doi: 10.1007/s12237-015-0059-8.
Northeastern US salt marshes face multiple co-stressors, including accelerating rates of relative sea level rise (RSLR), elevated nutrient inputs, and low sediment supplies. In order to evaluate how marsh surface elevations respond to such factors, we used surface elevation tables (SETs) and surface elevation pins to measure changes in marsh surface elevation in two eastern Long Island Sound salt marshes, Barn Island and Mamacoke Marsh. We compare marsh elevation change at these two systems with recent rates of RSLR and find evidence of differences between the two sites; Barn Island is maintaining its historic rate of elevation gain (2.3± 0.24 mm yr from 2003 to 2013) and is no longer keeping pace with RSLR, while Mamacoke shows evidence of a recent increase in rates (4.2 ± 0.52 mm yr from 1994 to 2014) to maintain its elevation relative to sea level. In addition to data on short-term elevation responses at these marshes, both sites have unusually long and detailed data on historic vegetation species composition extending back more than half a century. Over this study period, vegetation patterns track elevation change relative to sea levels, with the Barn Island plant community shifting towards those plants that are found at lower elevations and the Mamacoke vegetation patterns showing little change in plant composition. We hypothesize that the apparent contrasting trend in marsh elevation at the sites is due to differences in sediment availability, salinity, and elevation capital. Together these two systems provide critical insight into the relationships between marsh elevation, high marsh plant community, and changing hydroperiods. Our results highlight that not all marshes in southern New England may be responding to accelerated rates of RSLR in the same manner.
美国东北部的盐沼面临多种共同压力源，包括相对海平面上升（RSLR）加速、养分输入增加和沉积物供应不足。为了评估盐沼表面高程如何响应这些因素，我们使用表面高程表（SETs）和表面高程钉来测量长岛海峡东部两个盐沼（谷仓岛和马马科克盐沼）的盐沼表面高程变化。我们将这两个系统的盐沼高程变化与近期的RSLR速率进行比较，发现两个地点存在差异；谷仓岛保持其历史高程增加速率（2003年至2013年为2.3±0.24毫米/年），不再与RSLR同步，而马马科克则显示出近期速率增加的证据（1994年至2014年为4.2±0.52毫米/年），以维持其相对于海平面的高程。除了这些盐沼短期高程响应的数据外，两个地点都有关于历史植被物种组成的异常长期和详细的数据，可追溯到半个多世纪以前。在这个研究期间，植被模式跟踪相对于海平面的高程变化，谷仓岛的植物群落向低海拔地区发现的植物转变，而马马科克的植被模式在植物组成上几乎没有变化。我们假设，这些地点盐沼高程的明显对比趋势是由于沉积物可用性、盐度和高程资本的差异。这两个系统共同提供了对盐沼高程、高盐沼植物群落和变化的水文周期之间关系的关键见解。我们的结果突出表明，新英格兰南部并非所有盐沼都可能以相同方式响应RSLR的加速速率。
