科学家提出，淡水沼泽比咸水湿地相对较弱可能有助于解释卡特琳娜飓风和丽塔飓风过后海岸侵蚀的模式。为了比较淡水和咸水湿地对飓风驱动的海浪的抵抗力，Nick Howes及其同事测试了美国的墨西哥湾沿海高盐度和低盐度沼泽的土壤剪切强度。这组科学家发现了淡水湿地土壤的一个薄弱区与植物根系的基础重合。来自高盐度湿地的土壤没有这种弱区，而且含有更深的根系。
这组作者说，在这个弱区的土壤强度低于计算出的卡特琳娜飓风产生的海浪的剪切力，这可能解释了在这场飓风期间低盐度沼泽比咸水沼泽的破坏率更高。海岸湿地因为它们保护内陆地区不受剧烈的风暴冲击的能力而具有价值。这组作者提出，目前向墨西哥湾沿海地区附近的内陆沼泽引入淡水的计划可能削弱保护性的海岸屏障，让内陆区域更容易遭受飓风破坏。(生物谷Bioon.com)
生物谷推荐原文出处：
PNAS doi: 10.1073/pnas.0914582107
Hurricane-induced failure of low salinity wetlands
Nick C. Howesa,1, Duncan M. FitzGeralda, Zoe J. Hughesa, Ioannis Y. Georgioub, Mark A. Kulpb, Michael D. Minerb, Jane M. Smithc, and John A. Barras d
aDepartment of Earth Sciences, Boston University, 675 Commonwealth Avenue, Boston, MA 02215;
bPontchartrain Institute for Environmental Sciences, University of New Orleans, New Orleans, LA 70148;
cUnited States Army Engineer Research and Development Center, 3909 Halls Ferry Road, Vicksburg, MS 39180-6199; and
dUnited States Army Engineer Research and Development Center, Environmental Laboratory, Wetlands Environmental Technology Research Facility, Baton Rouge, LA 70803
During the 2005 hurricane season, the storm surge and wave field associated with Hurricanes Katrina and Rita eroded 527 km2 of wetlands within the Louisiana coastal plain. Low salinity wetlands were preferentially eroded, while higher salinity wetlands remained robust and largely unchanged. Here we highlight geotechnical differences between the soil profiles of high and low salinity regimes, which are controlled by vegetation and result in differential erosion. In low salinity wetlands, a weak zone (shear strength 500–1450 Pa) was observed ～30 cm below the marsh surface, coinciding with the base of rooting. High salinity wetlands had no such zone (shear strengths > 4500 Pa) and contained deeper rooting. Storm waves during Hurricane Katrina produced shear stresses between 425–3600 Pa, sufficient to cause widespread erosion of the low salinity wetlands. Vegetation in low salinity marshes is subject to shallower rooting and is susceptible to erosion during large magnitude storms; these conditions may be exacerbated by low inorganic sediment content and high nutrient inputs. The dramatic difference in resiliency of fresh versus more saline marshes suggests that the introduction of freshwater to marshes as part of restoration efforts may therefore weaken existing wetlands rendering them vulnerable to hurricanes.
