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首页> 外文期刊>Marine ecology progress series >Effects of seagrass beds (Zostera noltii and Z. marina) on near-bed hydrodynamics and sediment resuspension
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Effects of seagrass beds (Zostera noltii and Z. marina) on near-bed hydrodynamics and sediment resuspension

机译：海草床（Zostera noltii和滨海鲈）对近床水动力和沉积物重悬的影响

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摘要

The main objectives of this flume study were to (1) quantify density dependent effects of the short-leaf seagrass Zostera nolti on hydrodynamics and sediment resuspension from a sandy bed, and (2) measure the erodability of 2 contrasting sediments (sandy and muddy) and the extent to which this is modified by the presence of 2 seagrass species, Z. noltii (sandy) and Z. marina (muddy). Field measurements of near-bed tidal currents, turbulence and suspended particulate matter at 2 different Z. noltii locations (low energy [sheltered] and higher energy [exposed] environments) were interpreted in the context of the flume results. Skimming flow above the high density bed of Z. noltii was accompanied by a 40 % reduction in near-bed flow, but this was offset by a 2-fold increase in turbulent kinetic energy (TKE) and bed shear stress (τ_0). Despite this increase in τ_0 there was an increase in sediment stabilisation with increasing seagrass density (10-fold increase in critical bed shear stress for erosion [τ_e] from 0.1 [bare sediment] to 1.0 Pa at the highest shoot density). This was largely explained by the increased microphytobenthos abundance (reflected in the higher chlorophyll a and carbohydrate contents) and a lower density of the grazer and bio-destabiliser Hydrobia ulvae. In contrast, the muddy site was more easily eroded (10-fold higher), with Z. marina having little effect on sediment erodability (bare:τ_e = 0.05 Pa; Z. marina:τ_e = 0.07 Pa). This higher erodability was due to differences in hydrodynamics and the physical/biological properties of the sediment.
机译：这项水槽研究的主要目的是（1）量化短叶海草Zostera nolti对水动力和沙质悬浮物的密度依赖性影响，以及（2）测量2种对比沉积物（砂质和泥质）的易蚀性以及由于存在两种海草物种，即诺氏梭菌（桑迪）和滨海梭菌（泥泞）而改变的程度。在水槽结果的背景下，解释了在2个不同的Z. noltii位置（低能量[避开]和高能量[暴露]的环境）附近床潮流，湍流和悬浮颗粒物的现场测量。 Z. noltii高密度床上方的撇油流量使近床流量减少40％，但这被湍动能（TKE）和床剪切应力（τ_0）的2倍增加所抵消。尽管τ_0有所增加，但随着海草密度的增加，沉积物的稳定性也有所提高（在最高芽密度下，侵蚀的临界床剪应力[τ_e]从0.1 [裸露的沉积物]增加到10 Pa的10倍）。这在很大程度上是由于微植物底栖动物的丰度增加（反映在较高的叶绿素a和碳水化合物含量中）以及较低的放牧者和破坏生物的Hydro虫Hydrobia ulvae密度造成的。相比之下，浑浊的部位更容易被侵蚀（高10倍），而滨海梭菌对沉积物的侵蚀性几乎没有影响（裸露：τ_e= 0.05 Pa；滨海梭菌：τ_e= 0.07 Pa）。这种较高的可蚀性是由于流体动力学和沉积物的物理/生物学特性的差异。

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