Temporal variation of light availability in coastal benthic habitats: Effects of clouds, turbidity, and tides
Temporal variation of light availability in coastal benthic habitats: Effects of clouds, turbidity, and tides
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DOI：
10.4319/lo.2004.49.6.2201
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发表时间：
2004-11-01
影响因子：
4.5
通讯作者：
Lough, J
中科院分区：
文献类型：
--
作者：
Anthony, KRN;Ridd, PV;Lough, J
我们分析了云，浊度和潮汐的贡献，在辐照度的变化和预测的海底初级生产力的沿海珊瑚礁在2年（2001-2002年）。在最低天文潮（潮差3.8米）以下1.5米处，悬浮固体（浊度）的衰减占辐照度年总变化的74-79%，云占14- 17%，潮汐占7- 10%。随着深度的增加，从浊度到辐照度变化的贡献逐渐增加到95%。傅立叶（光谱）分析表明，海底辐照度制度遵循强的8周周期和较弱的2-4周周期。8周的周期主要是由混浊度和其次是由云驱动，并匹配的季节内马登-朱利安大气振荡的周期性。较弱的3-4周的辐照度周期是由浊度驱动的; 2周的周期是由潮汐驱动的，在较小程度上，云。海底辐照度模式与Turbinaria mesenterina珊瑚生理最佳辐照度水平（参数E-k）预测的比较表明，该地点的珊瑚在潜在光限制和光应力状态之间交替，主要由浊度变化引起的2-8周周期性。外部光源的光减少，如偶发径流事件，对底栖初级生产者的能量的影响可能会随着这些事件的时间发生重大变化。
We analyzed the contributions of clouds, turbidity, and tides to variations in irradiance and predicted benthic primary productivity on a coastal coral reef over a period of 2 yr (2001-2002). At 1.5 m below lowest astronomical tide (3.8-m tidal range), attenuation by suspended solids (turbidity) accounted for 74-79% of the total annual variation in irradiance, clouds for 14-17%, and tides for 7-10%. With increasing depth, the contribution from turbidity to irradiance variation increased asymptotically toward 95%. Fourier (spectral) analyses indicated that the benthic irradiance regime followed strong 8-week periodicities and weaker 2-4-week periodicities. The 8-week cycle was driven primarily by turbidity and secondarily by clouds and matches the periodicity of the intraseasonal Madden-Julian atmospheric oscillation. The weaker 3-4-week irradiance cycle was driven by turbidity; the 2-week cycle was driven by tides and, to a lesser extent, clouds. Comparisons of the benthic irradiance pattern with predictions of physiologically optimal irradiance levels (parameter E-k) for the coral Turbinaria mesenterina suggested that corals at the site alternate between states of potential light limitation and light stress, with a 2-8-week periodicity caused mainly by variations in turbidity. The effect of external sources of light reduction, such as episodic runoff events, on the energetics of benthic primary producers is likely to vary critically with the timing of such events.