Heterogeneous dissolved organic nitrogen supply over a coral reef: First evidence from nitrogen stable isotope ratios
Heterogeneous dissolved organic nitrogen supply over a coral reef: First evidence from nitrogen stable isotope ratios
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珊瑚礁上空的异质溶解有机氮供应：来自氮稳定同位素比率的第一个证据
DOI：
10.1007/s00338-013-1070-9
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发表时间：
2013
期刊：
影响因子：
3.5
通讯作者：
Nagata T
中科院分区：
文献类型：
--
作者：
Thibodeau B;Miyajima T;Tayasu I;Wyatt A;Watanabe A;Morimoto N;Yoshimizu C;Nagata T
溶解有机氮（DON）在维持珊瑚礁的高生产力和生物多样性方面可能起着重要作用。然而，关于DON的源和汇的数据很少。本研究首次测定了珊瑚礁水体中反映DON同位素特征的总溶解氮（δ15NTDN）的15N同位素组成。涨潮时δ 15 NTDN的均一性（3.2 ± 0.3 ‰）表明DON主要来源于近海沃茨。低潮期δ15NTDN（3.1 ± 0.9 ‰）和DON浓度的空间异质性较高，表明生物礁上存在局部DON源。低δ 15 NTDN值位于礁中部，表明生物通过固氮获得氮，而高δ 15 NTDN值则反映生物暴露于溶解无机氮（如陆地和近海输入的15 N）时DON的局部释放。总的来说，这些结果突出了珊瑚礁N循环中珊瑚礁群落DON释放的空间格局的重要性。
Dissolved organic nitrogen (DON) potentially plays a major role in sustaining the high productivity and biological diversity of coral reefs. However, data are scarce regarding sources and sinks of DON. This study, for the first time, determined the15N isotopic composition of total dissolved nitrogen (δ15NTDN), reflecting the isotopic signature of DON, in the water column over a coral reef. The uniformity in δ15NTDNduring high tide (3.2 ± 0.3 ‰) indicated that the DON was mainly derived from offshore waters. In contrast, higher spatial heterogeneity of δ15NTDN(3.1 ± 0.9 ‰) and DON concentrations during low tide indicated the existence of local DON sources patchily distributed over the reef. Low δ15NTDNvalues located mid-reef were indicative of DON release from organisms that obtained their N via N2fixation, whereas high δ15NTDNappeared to reflect localized release of DON by organisms exposed to dissolved inorganic nitrogen with elevated15N, such as from terrestrial and offshore inputs. Collectively, the results highlight the importance of spatial patterns in DON release from reef communities in the N cycling of coral reefs.