As global climates shift, coastal systems experience changes that alter function within the tidal zone. However, it remains uncertain how changes in tidal extent and magnitude will alter coastal biogeochemical cycling. We present high‐frequency data collected in situ along two transects across a tidal creek and floodplain to capture how vertical and lateral connectivity changes act as biogeochemical control points. Using wavelet coherence analysis, we identified short periods of vertical tide–floodplain connectivity during spring tides followed by extended periods of floodplain isolation from tides. During a drier period, neap tides were linked to lateral creek–floodplain connectivity, detected by discharge of saline, oxygen‐depleted groundwater to the creek on ebb tides. We estimate that up to half of creek water throughout the tidal cycle was associated with floodplain drainage. From point measurements of carbon, nitrogen, and greenhouse gases along the creek–floodplain transect, we infer that lateral connectivity functions as a biogeochemically significant control point.

中文翻译：

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潮汐小溪与其洪泛区之间连通性的生物地球化学控制点

随着全球气候变化，沿海系统会经历改变潮汐区功能的变化。但是，尚不确定潮汐范围和大小的变化将如何改变沿海生物地球化学循环。我们介绍了沿潮汐小溪和洪泛区沿两个样点就地收集的高频数据，以捕获垂直和横向连通性变化如何充当生物地球化学控制点。使用小波相干分析，我们确定了春季潮汐期间潮汐与洪泛区之间的连通性很短，随后洪泛区与潮汐隔离的时间延长了。在较干燥的时期，潮汐与小溪与洪泛平原的横向连通性相关联，这是通过在退潮时向小溪排放盐水，贫氧的地下水来检测的。我们估计在整个潮汐周期中，多达一半的小溪水与洪泛区排水有关。从沿小溪—洪泛平原横断面的碳，氮和温室气体的点测量值，我们可以推断出横向连通性是生物地球化学上重要的控制点。