Large solitary ascidians, like Herdmania grandis (Heller), can dominate the benthic substrates of subtropical and temperate reefs; however, their influence on nitrogen cycling, particularly nitrous oxide (N₂O) production, is unknown. Here, we incubated individual H. grandis and compared fluxes of dissolved inorganic and gaseous nitrogen species to fluxes from reef sediments. Nitrous oxide production rates per individual ascidian (21 ± 8 nmol ind h⁻¹) are the highest reported for any marine invertebrate. An individual ascidian produced more N₂O than 1 m² of inter-reef sediment (1.7 ± 1.7 nmol m⁻² h⁻¹). Ascidian mediated N₂O production was found to occur under nutrient depleted conditions. The addition of ¹⁵N labeled organic material showed that the microbiota associated with H. grandis is capable of both nitrification and denitrification, but the contribution of these pathways to N₂O production could not be ascertained. As the ecology of temperate reefs change, any range expansion of H. grandis will increase coastal N₂O production.

中文翻译：

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隐藏在视线中：孤零零的海鞘 Herdmania grandis 对温带珊瑚礁产生一氧化二氮的秘密贡献

大型孤立海鞘，如Herdmania grandis (Heller)，可以支配亚热带和温带珊瑚礁的底栖基质；然而，它们对氮循环，尤其是一氧化二氮 (N ₂ O) 产生的影响尚不清楚。在这里，我们孵化了个体H. grandis，并将溶解的无机和气态氮物种的通量与来自珊瑚礁沉积物的通量进行了比较。每只海鞘的一氧化二氮产生率 (21 ± 8 nmol ind h ^-1 ) 是所有海洋无脊椎动物中最高的。单个海鞘产生的 N ₂ O 比 1 m ²的珊瑚礁间沉积物多（1.7 ± 1.7 nmol m ^-2  h ^-1）。海鞘介导的N发现₂ O 产生发生在营养物耗尽的条件下。添加¹⁵ N 标记的有机材料表明与H. grandis相关的微生物群能够硝化和反硝化，但无法确定这些途径对 N ₂ O 生产的贡献。随着温带珊瑚礁生态的变化，H. grandis 的任何范围扩大都会增加沿海N ₂ O 的产量。