Impact of Lagrangian Sea Surface Temperature Variability on Southern Ocean Phytoplankton Community Growth Rates
Impact of Lagrangian Sea Surface Temperature Variability on Southern Ocean Phytoplankton Community Growth Rates
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DOI：
10.1029/2020gb006880
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发表时间：
2020-11
影响因子：
5.2
通讯作者：
J. Zaiss;P. Boyd;S. Doney;J. Havenhand;N. Levine
中科院分区：
文献类型：
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作者：
J. Zaiss;P. Boyd;S. Doney;J. Havenhand;N. Levine
海洋浮游植物在全球碳循环中发挥着关键作用，贡献了全球光合作用的50%。作为浮游生物，浮游植物在整个海洋平流过程中会遇到显著的环境变化。这种可变性如何影响浮游植物的生长速率和种群动态尚不清楚。本文利用南大洋（bbb30°S）海面漂船观测数据和基于表型的生态系统模型，系统地研究了不同海表温度（SST）变化速率和幅度对浮游植物群落生长速率的影响。短期海温变率（<7天）对浮游植物群落生长速率的影响最小。7-45 d内3-4°C的中等海温变化导致温度变化与生物响应之间存在较大的时间差。海温变率对群落生长速率的影响是非线性的，是变化速率和幅度的函数。此外，在拉格朗日参照系（跟随地表水包的轨迹）中产生的变异性的性质比在欧拉参照系（定点）中产生的变异性的性质更大，这在两个参照系之间引发了不同的浮游植物响应。最后，我们发现全球生物地球化学模型中常用的Eppley生长模型没有捕捉到这些动态，导致高估了群落增长率，特别是在南大洋动态的强锋区。这项工作表明，环境选择（群落替代）的时间尺度是决定群落组成的关键因素，并向将变异性和生物反应时间的影响纳入生物地球化学模型迈出了第一步。
Ocean phytoplankton play a critical role in the global carbon cycle, contributing ∼50% of global photosynthesis. As planktonic organisms, phytoplankton encounter significant environmental variability as they are advected throughout the ocean. How this variability impacts phytoplankton growth rates and population dynamics remains unclear. Here, we systematically investigated the impact of different rates and magnitudes of sea surface temperature (SST) variability on phytoplankton community growth rates using surface drifter observations from the Southern Ocean (>30°S) and a phenotype‐based ecosystem model. Short‐term SST variability (<7 days) had a minimal impact on phytoplankton community growth rates. Moderate SST changes of 3–4°C over 7–45 days produced a large time lag between the temperature change and the biological response. The impact of SST variability on community growth rates was nonlinear and a function of the rate and magnitude of change. Additionally, the nature of variability generated in a Lagrangian reference frame (following trajectories of surface water parcels) was larger than that within an Eulerian reference frame (fixed point), which initiated different phytoplankton responses between the two reference frames. Finally, we found that these dynamics were not captured by the Eppley growth model commonly used in global biogeochemical models and resulted in an overestimation of community growth rates, particularly in dynamic, strong frontal regions of the Southern Ocean. This work demonstrates that the timescale for environmental selection (community replacement) is a critical factor in determining community composition and takes a first step towards including the impact of variability and biological response times into biogeochemical models.