Hypoxia Tolerance and Metabolic Suppression in Oxygen Minimum Zone Euphausiids: Implications for Ocean Deoxygenation and Biogeochemical Cycles
Hypoxia Tolerance and Metabolic Suppression in Oxygen Minimum Zone Euphausiids: Implications for Ocean Deoxygenation and Biogeochemical Cycles
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氧最低区磷虾的缺氧耐受性和代谢抑制：对海洋脱氧和生物地球化学循环的影响
DOI：
10.1093/icb/icw091
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发表时间：
2016
影响因子：
2.6
通讯作者：
Daly, K.L.
中科院分区：
文献类型：
--
作者：
Seibel, B.A.;Schneider, J.L.;Kaartvedt, S.;Wishner, K.F.;Daly, K.L.
氧和温度水平随深度的区域变化对优势种的新陈代谢和耐低氧能力的影响进行了评估。这些物种所采用的生理策略有助于预测随着氧气最小区域的扩大而变化的垂直分布，并有助于估计垂直迁移的物种对生物地球化学循环的贡献。来自东热带太平洋的迁徙物种Euphausia eximia和Nematoscelis gracilis在10℃下耐受0.8kPaPO2(∼15µMO2)至少12h没有死亡，而加州当前物种艰难线虫在该温度下即使是2.4kPaPO2(∼32µMO2)也不能存活超过3h。来自红海的Euphausia diomedeae迁徙到中等氧气最小区，但深度温度保持在22℃附近1.6kPPaO2(∼22µM O2)，持续6小时的呼吸实验。对每个物种的临界氧分压进行了估算，并对结果进行了分析。Eximia，通过耗氧量(2.1kPa10°C，n=2)和乳酸累积(1.1kPa10°C)测量。促进低氧耐受的一个主要机制是在白天进入低氧水域时大幅减少能量消耗的能力。在低氧条件下，ETP和红海物种的有氧代谢减少了50%以上。无氧糖酵解能量的产生，如整个动物乳酸积累所表明的，对能量赤字的贡献很小。因此，总代谢率受到∼49-%的抑制。在向深海迁移的过程中，代谢抑制将这些物种对垂直碳和氮通量(即生物泵)的代谢贡献减少了等量。越来越多的证据表明，新陈代谢抑制是在氧气最少区域迁徙的浮游动物中的一种普遍策略，可能对海洋的经济和生态产生重要影响。氧和温度对海洋物种新陈代谢的相互作用有助于预测垂直分布随气候变化的变化。
The effects of regional variations in oxygen and temperature levels with depth were assessed for the metabolism and hypoxia tolerance of dominant euphausiid species. The physiological strategies employed by these species facilitate prediction of changing vertical distributions with expanding oxygen minimum zones and inform estimates of the contribution of vertically migrating species to biogeochemical cycles. The migrating species from the Eastern Tropical Pacific (ETP),Euphausia eximiaandNematoscelis gracilis, tolerate a Partial Pressure (PO2) of 0.8 kPa at 10 °C (∼15 µM O2) for at least 12 h without mortality, while the California Current species,Nematoscelis difficilis, is incapable of surviving even 2.4 kPa PO2(∼32 µM O2) for more than 3 h at that temperature.Euphausia diomedeaefrom the Red Sea migrates into an intermediate oxygen minimum zone, but one in which the temperature at depth remains near 22 °C.Euphausia diomedeaesurvived 1.6 kPa PO2(∼22 µM O2) at 22 °C for the duration of six hour respiration experiments. Critical oxygen partial pressures were estimated for each species, and, forE. eximia, measured via oxygen consumption (2.1 kPa, 10 °C,n= 2) and lactate accumulation (1.1 kPa, 10 °C). A primary mechanism facilitating low oxygen tolerance is an ability to dramatically reduce energy expenditure during daytime forays into low oxygen waters. The ETP and Red Sea species reduced aerobic metabolism by more than 50% during exposure to hypoxia. Anaerobic glycolytic energy production, as indicated by whole-animal lactate accumulation, contributed only modestly to the energy deficit. Thus, the total metabolic rate was suppressed by ∼49–64%. Metabolic suppression during diel migrations to depth reduces the metabolic contribution of these species to vertical carbon and nitrogen flux (i.e., the biological pump) by an equivalent amount. Growing evidence suggests that metabolic suppression is a widespread strategy among migrating zooplankton in oxygen minimum zones and may have important implications for the economy and ecology of the oceans. The interacting effects of oxygen and temperature on the metabolism of oceanic species facilitate predictions of changing vertical distribution with climate change.