Yang Qingwei, Yang Yanhui, Xia Jun, Fukuda Hideki, Okazaki Yusuke, Nagata Toshi, Ogata Hiroyuki, Endo Hisashi
Bioinformatics Center, Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, 611-0011, Japan.
Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa, Chiba 277-8561, Japan.
ISME Commun. 2024 Nov 4;4(1):ycae136. doi: 10.1093/ismeco/ycae136. eCollection 2024 Jan.
Microeukaryotes are critical components of sinking particles contributing to carbon export from the surface to deep oceans. However, the knowledge of the sinking microeukaryotic communities and their dynamics is currently limited. In this study, we applied 18S rRNA gene metabarcoding to investigate the microeukaryotic communities in sinking and suspended particles distinguished by marine snow catchers during spring in the Oyashio region. Sinking particles displayed distinct communities and lower diversity than suspended particles. The community compositions of the sinking particles varied with depth, suggesting that microeukaryotes were selectively disaggregated or decomposed during settling. Prymnesiophyceae and diatoms were effectively removed, as indicated by their decreased abundance in sinking particles at increasing depths. Conversely, Dinophyceae maintained a higher abundance in sinking particles across depths, indicating resistance to disaggregation and decomposition. Spirotrichea and heterotrophic Dinophyceae were enriched in sinking particles, while marine stramenopiles groups were enriched in suspended particles. The heterotrophs in the deeper layers were mainly transported from the surface layers by increasing their relative abundance towards deep layers, indicating that they contributed to the transformation processes of sinking particles. Overall, our results demonstrate the functional differences among microeukaryotes in the biological carbon pump.
微型真核生物是沉降颗粒的关键组成部分，有助于碳从海洋表层向深层输出。然而，目前对于沉降微型真核生物群落及其动态的了解仍然有限。在本研究中，我们应用18S rRNA基因 metabarcoding技术，调查了在亲潮区域春季由海洋雪收集器区分的沉降颗粒和悬浮颗粒中的微型真核生物群落。沉降颗粒显示出与悬浮颗粒不同的群落结构，且多样性较低。沉降颗粒的群落组成随深度而变化，这表明微型真核生物在沉降过程中被选择性地分解或解体。定鞭藻纲和硅藻被有效地去除，这可以从它们在沉降颗粒中随深度增加而减少的丰度中看出。相反，甲藻在整个深度的沉降颗粒中保持较高的丰度，表明其对分解和解体具有抗性。旋毛纲和异养甲藻在沉降颗粒中富集，而海洋不等鞭毛藻群在悬浮颗粒中富集。深层的异养生物主要通过向深层增加其相对丰度而从表层运输而来，这表明它们对沉降颗粒的转化过程有贡献。总体而言，我们的结果证明了微型真核生物在生物碳泵中的功能差异。
