Thermal Thresholds of Phytoplankton Growth in Polar Waters and Their Consequences for a Warming Polar Ocean
Thermal Thresholds of Phytoplankton Growth in Polar Waters and Their Consequences for a Warming Polar Ocean
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DOI：
10.3389/fmars.2017.00168
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发表时间：
2017-01-01
影响因子：
3.7
通讯作者：
Agusti, Susana
中科院分区：
文献类型：
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作者：
Coello-Camba, Alexandra;Agusti, Susana
极地地区正在经历地球上最快的变暖速度，预计这一趋势将在未来继续下去。在这些生境中，浮游植物群落构成了食物网的基础，它们的耐热性可能决定了变暖如何影响这些脆弱的环境。在这里，我们汇编了有关极地沃茨浮游植物生长的热响应的可用数据。我们收集了53条生长与温度曲线（25条来自北极，28条来自南大洋），表明这些生态系统的可用信息有限。北极浮游植物的数据有一半来自自然群落，在那里，低环境浓度可能会限制生长速度。浮游植物从极地沃茨增长速度小的温度增加，直到达到最佳（（OPT）），并放缓时，温度增加超过这个值。这左偏曲线的特点是较高的活化能（Ea）的浮游植物生长以上比以下的T-OPT。结合这些热响应，我们得到了一个社区T-OPT为6.5摄氏度（+/- 0.2）和5.2摄氏度（+/- 0.1）的北极和南大洋浮游植物群落，分别。2013年8月上半月，这些阈值温度已经超过了70度N，这一点得到了海面温度的证明（SST，卫星数据，http://www.ncdc.noaa.gov）。我们通过假设整体上升3摄氏度，相当于低排放情景，预测了21世纪末的SST。我们的预测显示，到2100年夏季，北纬70度的海表温度预计将超过T-OPT，8月上半月的海表温度将超过北纬75度。虽然最近北极春季平均气温分别为0.5摄氏度和0.7摄氏度，但随着我们接近2100年，它们可能会增加到2.8摄氏度和2.2摄氏度。这种温度上升可能导致浮游植物大量繁殖，并因营养物质的快速消耗而缩短。随着海表温度的增加，浮游植物生长的温度阈值最终会超过水华的发展。这可能导致浮游植物群落的变化，威胁北极的生产高峰和周期。我们预测的浮游植物的反应，受到有限的数据集，除了在最合理的未来北极温度的情况下的不确定性。为了改善对极地海洋的预测，我们需要增加研究的数量，特别是对于快速变化的北极。
Polar areas are experiencing the steepest warming rates on Earth, a trend expected to continue in the future. In these habitats, phytoplankton communities constitute the basis of the food web and their thermal tolerance may dictate how warming affects these delicate environments. Here, we compiled available data on thermal responses of phytoplankton growth in polar waters. We assembled 53 growth-vs. -temperature curves (25 from the Arctic, 28 from the Southern oceans), indicating the limited information available for these ecosystems. Half of the data from Arctic phytoplankton came from natural communities where low ambient concentrations could limit growth rates. Phytoplankton from polar waters grew faster under small temperature increases until reaching an optimum ((OPT)), and slowed when temperatures increased beyond this value. This left-skewed curves were characterized by higher activation energies (Ea) for phytoplankton growth above than below the T-OPT. Combining these thermal responses we obtained a community T-OPT of 6.5 degrees C (+/- 0.2) and 5.2 degrees C (+/- 0.1) for Arctic and Southern Ocean phytoplankton communities, respectively. These threshold temperatures were already exceeded at 70 degrees N during the first half of August 2013, evidenced by sea surface temperatures (SSTs, satellite data, http://www.ncdc.noaa.gov). We forecasted SSTs for the end of the twenty-first century by assuming an overall 3 degrees C increase, equivalent to a low emission scenario. Our forecasts show that SSTs at 70 degrees N are expected to exceed T-OPT during summer by 2100, and during the first half of August at 75 degrees N. While recent Arctic spring temperatures average 0.5 degrees C and 0.7 degrees C at 70 degrees N and 75 degrees N, respectively, they could increase to 2.8 degrees C at 70 degrees N and 2.2 degrees C at 75 degrees N as we approach 2100. Such temperature increases could lead to intense phytoplankton blooms, shortened by fast nutrient consumption. As SSTs increase, thermal thresholds for phytoplankton growth would be eventually exceeded during bloom development. This could lead to changes in the blooming phytoplankton community, threatening the production peak and cycles in the Arctic. Our forecasted phytoplankton responses, are constrained by the limited data set, besides uncertainties in the most plausible future Arctic temperature scenarios. To improve predictions in polar oceans, we need to increase the number of studies, in particular for a fast-changing Arctic.