Dissolved organic nitrogen: A relevant, complementary source of nitrogen for the seagrass Zostera marina
Dissolved organic nitrogen: A relevant, complementary source of nitrogen for the seagrass Zostera marina
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DOI：
10.1002/lno.10084
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发表时间：
2015-09-01
影响因子：
4.5
通讯作者：
Santos, Rui
中科院分区：
文献类型：
--
作者：
Alexandre, Ana;Hill, Paul W.;Santos, Rui
溶解有机氮（DON）形成了一个重要的池中的水柱（62%）和沉积物中的Ria福尔摩沙泻湖（53%）的生物可利用氮。我们评估了无机和有机氮的吸收速率及其相互作用的海草大叶藻marina，并进一步探讨了海草使用复杂的有机底物（肽）的可能性。叶片和根的吸收率进行了量化的选择吸收实验中，植物暴露于混合N溶液中含有15 N无机（铵+硝酸盐）和13 C 15 N有机（丙氨酸+三丙氨酸）氮在现场相关的浓度，并与单一的无机或有机N形式的吸收率进行比较。氨是首选的N源，但植物更喜欢DON硝酸盐。DON吸收显着高于通过根比叶，符合一个数量级的DON浓度在沉积物中比在水中高。不仅氨基酸，如其他地方报道的其他海草，而且肽构成相关的N源Z。滨海（占总N吸收量的10%和4%）。因此，海草可能在氮循环中蛋白质降解的早期阶段与微生物竞争有机底物。由于无机氮和有机氮之间没有交互作用，因此，Z.当两种来源都存在时，marina较高，表明有机氮是氮的补充而不是替代来源。在未来的研究中，应包括有机氮的吸收评估海草草甸的总氮预算。
Dissolved organic nitrogen (DON) forms a significant pool of bioavailable N in the water column (62%) and in sediments of Ria Formosa lagoon (53%). We assessed the uptake rates of inorganic and organic nitrogen and its interactions in the seagrass Zostera marina, and further explored the possibility of seagrasses to use complex organic substrates (peptides). Uptake rates by leaves and roots were quantified in choice-uptake experiments where plants were exposed to mixed N solutions containing both 15 N inorganic (ammonium + nitrate) and 13 C 15 N organic (alanine + trialanine) nitrogen at field-relevant concentrations, and compared with uptake rates of single inorganic or organic N forms. Ammonia was the preferred N source, but plants preferred DON to nitrate. DON uptake was significantly higher through roots than leaves, coinciding with the one-order of magnitude higher concentration of DON in the sediment than in the water. Not only amino acids, as reported elsewhere for other seagrasses, but also peptides constitute relevant N sources for Z. marina (10% and 4% of the total N uptake). Seagrasses may thus compete with microbes for organic substrates at an earlier stage of protein degradation in the N cycle than previously thought. Because no interactions occurred between inorganic and organic N sources, the total N uptake by Z. marina was higher when both sources were present, showing that organic nitrogen is a complementary rather than alternative source of nitrogen. The uptake of organic nitrogen should be included in future studies assessing the total N budgets of seagrass meadows.