Often considered detrimental to the environment and human activities, jellyfish blooms are increasing in several coastal regions worldwide. Yet, the overall effect of these outbreaks on ecosystem productivity and structure are not fully understood. Here we provide evidence for a so far unanticipated role of jellyfish in marine nitrogen cycling. Pelagic jellyfish release nitrogen as a metabolic waste product in form of ammonium. Yet, we observed high rates of nitrification (NH₄⁺ → NO₃⁻, 5.7–40.8 nM gWW⁻¹ [wet weight] h⁻¹) associated with the scyphomedusae Aurelia aurita, Chrysaora hysoscella, and Chrysaora pacifica and low rates of incomplete nitrification (NH₄⁺ → NO₂⁻, 1.0–2.8 nM gWW⁻¹ h⁻¹) associated with Chrysaora fulgida, C. hysoscella, and C. pacifica. These observations indicate that microbes living in association with these jellyfish thrive by oxidizing the readily available ammonia to nitrite and nitrate. The four studied species have a large geographic distribution and exhibit frequent population outbreaks. We show that, during such outbreaks, jellyfish-associated release of nitrogen can provide more than 100% of the nitrogen required for primary production. These findings reveal a so far overlooked pathway when assessing pelagic nitrification rates that might be of particular relevance in nitrogen depleted surface waters and at high jellyfish population densities.

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与全球分布的远洋水母有关的硝化作用的证据

通常被认为对环境和人类活动有害的水母在全球多个沿海地区大量繁殖。然而，尚未完全了解这些爆发对生态系统生产力和结构的总体影响。在这里，我们提供了迄今为止水母在海洋氮循环中出乎意料的作用的证据。远洋水母以铵的形式释放氮作为代谢废物。然而，我们观察到与 scyphomedusae Aurelia aurita、Chrysaora hysoscella和Chrysaora pacifica相关的高硝化速率（NH ₄ ⁺  → NO ₃ ^-，5.7–40.8 nM gWW ^-1 [湿重] h ^-1）和不完全硝化的低速率（NH ₄ ⁺  →NO ₂ ^-，1.0-2.8纳米GWW ^-1  ħ ^-1）相关联Chrysaora fulgida，Ç。hysoscella，和Ç。太平洋. 这些观察表明，与这些水母一起生活的微生物通过将容易获得的氨氧化成亚硝酸盐和硝酸盐而茁壮成长。研究的四个物种具有广泛的地理分布，并表现出频繁的种群爆发。我们表明，在此类爆发期间，与水母相关的氮释放可以提供初级生产所需的 100% 以上的氮。这些发现揭示了迄今为止在评估远洋硝化率时被忽视的途径，这可能与贫氮地表水和高水母种群密度特别相关。