To evaluate the modification of carbon flow in estuarine systems by a dike construction, we compared the trophic structures of the macrobenthic food webs in two contrasting estuaries, one with and one without a dike, on the western and southern coasts of Korea, by measuring the δ¹³C and δ¹⁵N values of subtidal macrobenthic consumers. The isotopic values of most organic matter sources were similar between the two estuaries, but there was a different pattern in the isotopic spatial variability between them. For the consumer δ¹³C values in the diked estuary, there were no significant spatial differences among sites and the isotopic niche widths were much narrower than those in the dike-free estuary. Moreover, the indices of community-wide metrics were smaller in the diked estuary than in the dike-free estuary. These results suggest a lower trophic diversity of macrobenthic consumers with their increased trophic redundancy in the diked estuary. These differences between the dike and dike-free estuaries might be explained by the decrease of benthic producers and then their lower food availabilities for consumers resulting from the presence of the dike. Our findings provide evidence that dike construction and subsequent alteration of hydrologic and circulation processes may lead to modification of the trophic structure of estuarine macrobenthic communities.

中文翻译：

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稳定同位素确定的韩国温带海岸两个不同河口生态系统的营养结构

为了评估堤坝构造对河口系统中碳流量的调节作用，我们通过测量韩国西部和南部海岸两个不同河口（一个带堤坝和一个不带堤坝）的对比，比较了大型底栖食物网的营养结构。 δ ¹³ C和δ ^15个潮下底栖消费者的N个值。两个河口之间大多数有机质源的同位素值相似，但是它们之间的同位素空间变异性存在不同的模式。对于消费者δ ¹³堤防河口的C值，站点之间没有显着的空间差异，同位素壁n宽度比堤防无河口的狭窄。此外，堤防河口的社区范围指标指数小于堤防河口。这些结果表明，堤底河口大型底栖动物的营养多样性较低，其营养冗余增加。堤防和无堤河口之间的这些差异可以通过减少底栖生产者来解释，然后通过堤坝的存在降低消费者对食物的获取。我们的发现提供了证据，堤防建设以及随后的水文和循环过程改变可能导致河口大型底栖动物的营养结构发生变化。