Modeling the effects of climate change on eelgrass stability and resilience: future scenarios and leading indicators of collapse
Modeling the effects of climate change on eelgrass stability and resilience: future scenarios and leading indicators of collapse
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DOI：
10.3354/meps09556
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发表时间：
2012-01-01
影响因子：
2.5
通讯作者：
Wiberg, Patricia L.
中科院分区：
文献类型：
--
作者：
Carr, Joel A.;D'Odorico, Paolo;Wiberg, Patricia L.
海草草甸影响沿海海湾的局部水动力，导致作用于底层沉积物的剪切应力减少。减少的沉积物悬浮和水柱浊度为海草的进一步生长创造了更有利的光环境。这种正反馈是足够强大的，以诱导深度依赖的沉积动力学与2种可能的稳定状态，现存的草甸和裸露的沉积物表面。一个耦合的植被生长的水动力学模型被用来调查鳗鱼草的稳定性和领先的生态系统转变的指标下，海平面上升和水温增加与气候变化的影响。该模型被应用到猪岛湾，弗吉尼亚海岸保护区，美国，在那里的鳗草恢复工作正在进行中的一个浅的沿海海湾。研究结果表明，虽然现存的鳗草草甸可能耐受海平面上升，但夏季水温超过30摄氏度的天数频率增加将导致夏季更频繁的死亡。高温扰动事件数量的增加可能会推动最初位于水深范围（平均海平面1.6至1.8米）内的密集草甸走向并最终超过临界分叉点，从该点恢复是不可能的。我们确定了接近这个分叉点的草甸的2个主要指标，两者都与每枝叶子的数量有关：“闪烁”，反映了从一个吸引子到另一个吸引子的明显波动，以及“减速”，这是当系统接近阈值时，从扰动中恢复的减少。我们的模型表明，这些沿海海湾的鳗草对当前气候变化模型预测的水温升高的适应能力有限。
Seagrass meadows influence local hydrodynamics in coastal bays, resulting in a decrease in the shear stress acting on the underlying bed sediment. The reduced sediment suspension and water column turbidity creates a more favorable light environment for further seagrass growth. This positive feedback is strong enough to induce depth-dependent bistable dynamics with 2 possible stable states, an extant meadow and a bare sediment surface. A coupled vegetation-growth hydrodynamic model was used to investigate eelgrass stability and leading indicators of ecosystem shift under the effects of sea-level rise and increases in water temperature associated with climate change. The model was applied to Hog Island Bay, a shallow coastal bay within the Virginia Coast Reserve, USA, where eelgrass restoration efforts are ongoing. The results indicate that while extant eelgrass meadows are likely to tolerate sea-level rise, an increase in the frequency of days when summer water temperature exceeds 30 degrees C will cause more frequent summer die-offs. This increase in the number of higher temperature disturbance events is likely to push a dense meadow initially located within the bistable depth range (1.6 to 1.8 m mean sea level) toward and eventually past a critical bifurcation point, from which recovery is not possible. We identified 2 leading indicators of a meadow nearing this bifurcation point, both associated with the number of leaves per shoot: 'flickering,' which reflects conspicuous fluctuations from one attractor to the other across the threshold, and 'slowing down,' which is the decreased recovery from perturbations as a system gets close to a threshold. Our model indicates that the eelgrass in these coastal bays has limited resilience to increases in water temperatures predicted from current climate change models.