PDF(Pubmed)
Abstract：
Estuaries provide a suite of ecosystem services to people but are also under heavy stress from human development including excess nutrient loading and alterations in benthic habitat that affect nutrient cycling. Here we examine the interaction of two important and common ecosystem management priorities in estuaries: limiting eutrophication and restoration of submerged aquatic vegetation (SAV). Rates of benthic nitrogen processing can vary by habitat type and there is need for more complete data on the contribution of SAV to overall nitrogen cycling in estuaries, as well as a need to examine nitrogen cycling in situ to better characterize the role of SAV areal coverage in mediating estuarine eutrophication. We compare nitrogen cycling between two common and adjacent habitat types (SAV and adjacent bare sediment [BS]) in an index coastal estuary using an in situ chamber-based approach to better capture realized habitat differences. We also examined genomic community structure of sediment bacteria and archaea to identify biological indicators of nitrogen exchange. Both mean sediment-water exchange of dissolved N2 and microbial functional community structure differed between SAV and BS. Habitat differences were more consistent with lower variability at locations with low salinity and when sediment organic content was highest, which aligns with findings in other studies. Habitat types differed significantly in microbial composition, including functional groups and genes, like nifH, that may contribute to observed differences in nitrogen cycling. Overall, habitat type appeared most important to nitrogen cycling near the river mouth where sediment nitrogen was higher, and this information has implications for integrated management of habitat restoration/conservation and nutrient loading.
摘要：
河口为人们提供了一套生态系统服务，但也承受着人类发展的沉重压力，包括过多的营养负荷和影响营养循环的底栖栖息地的改变。在这里，我们研究了河口两个重要和共同的生态系统管理优先事项之间的相互作用：限制富营养化和恢复淹没的水生植被（SAV）。底栖氮处理率可能因栖息地类型而异，需要更完整的SAV对河口整体氮循环的贡献数据，以及需要原位检查氮循环以更好地表征SAV区域覆盖在介导河口富营养化中的作用。我们使用基于原位室的方法比较了索引沿海河口中两种常见和相邻栖息地类型（SAV和相邻的裸露沉积物[BS]）之间的氮循环，以更好地捕获已实现的栖息地差异。我们还检查了沉积物细菌和古细菌的基因组群落结构，以确定氮交换的生物学指标。SAV和BS之间溶解的N2的平均沉积物-水交换和微生物功能群落结构均不同。在低盐度和沉积物有机物含量最高的位置，生境差异与较低的变异性更为一致，这与其他研究的结果一致。生境类型在微生物组成上有显著差异，包括功能群和基因，就像nifH,这可能有助于观察到氮循环的差异。总的来说,生境类型对沉积物氮含量较高的河口附近的氮循环最为重要，这些信息对栖息地恢复/保护和养分负荷的综合管理具有重要意义。
