Stream metabolism, in the form of gross primary production (GPP) and ecosystem respiration (ER), is an important metric of stream ecosystem function, given GPP and ER are integrative measurements of basal ecosystem activity that are highly sensitive to environmental change. In agricultural streams of temperate North America GPP can be mediated by water column turbidity associated with soil erosion during periods when the terrestrial landscape is bare (that is, typically late fall through spring; Oct–May in N America). We estimated a 10-year time series of stream metabolism using continuous dissolved oxygen measurements in an agricultural watershed (Shatto Ditch, IN), comparing metabolism metrics before and after vegetative cover was added to fields during normally fallow periods when they would otherwise be bare. Adding vegetative cover reduced water column turbidity by 54% during days with high precipitation (upper 25th percentile). We also found that GPP varied seasonally with light and temperature (range = 0.1–17.2 g m⁻² d⁻¹) and increased significantly in spring with landscape vegetative cover addition. Finally, we used a subset of storms to show that turbidity was lower and GPP was higher during storms after adding watershed vegetative cover, suggesting that increased GPP could be attributed to increased light availability with less turbid water. We found that ER also increased after adding vegetative cover, which we attribute, in part, to increased autotrophic respiration. These results suggest that water turbidity is a mediating driver of stream metabolism, particularly when other primary drivers are not limiting GPP. Likewise, stream turbidity can be mediated by land cover on the surrounding watershed, demonstrating a clear linkage between land use and stream metabolic signatures.

河流代谢，以总初级生产 (GPP) 和生态系统呼吸 (ER) 的形式，是河流生态系统功能的重要指标，因为 GPP 和 ER 是对环境变化高度敏感的基础生态系统活动的综合测量。在北美温带的农业河流中，在陆地景观裸露期间（即通常在深秋至春季；北美的 10 月至 5 月）期间，与土壤侵蚀相关的水柱浊度可以调节 GPP。我们使用农业流域（美国印第安纳州沙托沟）中的连续溶解氧测量估计了 10 年的河流代谢时间序列，比较了在通常休耕期间将植物覆盖添加到田地之前和之后的代谢指标，否则它们将是裸露的。在降水量高的日子（上 25 个百分位数），添加植被可将水体浊度降低 54%。我们还发现 GPP 随光照和温度的季节性变化（范围 = 0.1–17.2 g m^-2 d ^-1 ) 并在春季显着增加景观植被覆盖。最后，我们使用了暴风雨的一个子集来表明，在增加流域植被覆盖后，暴风雨期间的浊度较低，GPP 较高，这表明 GPP 的增加可归因于增加的光可用性和较少的浑浊水。我们发现添加植物覆盖后 ER 也增加，我们将其部分归因于自养呼吸增加。这些结果表明，水浊度是溪流代谢的中介驱动因素，特别是当其他主要驱动因素不限制 GPP 时。同样，河流浊度可以通过周围流域的土地覆盖来调节，表明土地利用和河流代谢特征之间存在明显的联系。