Functional group-specific traits drive phytoplankton dynamics in the oligotrophic ocean
Functional group-specific traits drive phytoplankton dynamics in the oligotrophic ocean
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DOI：
10.1073/pnas.1518165112
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发表时间：
2015-11-03
影响因子：
11.1
通讯作者：
Dyhrman, Sonya T.
中科院分区：
文献类型：
--
作者：
Alexander, Harriet;Rouco, Monica;Dyhrman, Sonya T.
海洋中多样化的微生物组合负责全球初级生产的近一半。假设和实验证明，营养负荷可以刺激寡营养系统中大型真核浮游植物的繁殖。尽管对于平衡生物地球化学模型至关重要，但对控制这些形成水华的浮游植物动态的代谢特征的了解仍然有限。我们使用真核宏转录组技术来确定功能组特异性特征的代谢基础，这些特征可能驱动寡营养海洋中净异养和自养之间的转变。通过添加深海水（DSW）来模拟北太平洋副热带环流中的营养负荷，模拟重复的水华，并分析了浮游植物功能群的转录反应。模拟水华中硅藻、附着植物和甲藻功能群的响应是独特的，硅藻和附着植物显着（95% 置信度）将其定量代谢指纹从原位条件转移，而甲藻几乎没有表现出响应。显着差异丰富的基因确定了营养物、金属和维生素在该系统中真核浮游植物代谢和水华形成中的共限制的重要性。用于量化 DSW 修正后的转录本重新分配的可变转录本分配比对于硅藻和附着藻来说是不同的，反映了浮游植物 r 型和 K 型生长策略的长期范例。尽管大型真核浮游植物的潜在代谢潜力始终存在，但在研究期间缺乏水华表明对物理和生物地球化学强迫的关键依赖，这些强迫很容易随着气候变化而改变。
A diverse microbial assemblage in the ocean is responsible for nearly half of global primary production. It has been hypothesized and experimentally demonstrated that nutrient loading can stimulate blooms of large eukaryotic phytoplankton in oligotrophic systems. Although central to balancing biogeochemical models, knowledge of the metabolic traits that govern the dynamics of these bloom-forming phytoplankton is limited. We used eukaryotic metatranscriptomic techniques to identify the metabolic basis of functional group-specific traits that may drive the shift between net heterotrophy and autotrophy in the oligotrophic ocean. Replicated blooms were simulated by deep seawater (DSW) addition to mimic nutrient loading in the North Pacific Subtropical Gyre, and the transcriptional responses of phytoplankton functional groups were assayed. Responses of the diatom, haptophyte, and dinoflagellate functional groups in simulated blooms were unique, with diatoms and haptophytes significantly (95% confidence) shifting their quantitative metabolic fingerprint from the in situ condition, whereas dinoflagellates showed little response. Significantly differentially abundant genes identified the importance of colimitation by nutrients, metals, and vitamins in eukaryotic phytoplankton metabolism and bloom formation in this system. The variable transcript allocation ratio, used to quantify transcript reallocation following DSW amendment, differed for diatoms and haptophytes, reflecting the longstanding paradigm of phytoplankton r- and K-type growth strategies. Although the underlying metabolic potential of the large eukaryotic phytoplankton was consistently present, the lack of a bloom during the study period suggests a crucial dependence on physical and biogeochemical forcing, which are susceptible to alteration with changing climate.