Enzor L A, Hankins C, Hamilton-Frazier M, Moso E, Raimondo S, Barron M G
U.S. Environmental Protection Agency, Gulf Breeze, FL, USA 32561.
Mar Ecol Prog Ser. 2020 Feb 20;636:157-168. doi: 10.3354/meps13220.
Low dissolved oxygen and increased acidification are two environmental variables that concomitantly change in an estuarine environment, both of which are exacerbated by nutrient pollution and subsequent eutrophication. To better understand how estuarine residents compensate for daily fluctuations in these environmental variables, the interactive effects of acidification and hypoxia were assessed in developing sheepshead minnows () using a 2 by 2 factorial design over a 42-day exposure. Embryos were exposed to either acidic (partial pressure of CO, CO, ~2000 μatm), hypoxic (reduced dissolved oxygen, ~2 mg l), or combined acidic and hypoxic conditions and monitored for development, hatch rate, and survival. Changes in oxygen consumption, anaerobic metabolism, oxidative stress, and acid-base balance were evaluated at three life stages (embryo, larval, and juvenile fish) to discern if and how fish compensate for these stressors during development. The combination of acidification and hypoxia delayed hatching in embryos and significantly decreased oxygen consumption (p<0.001) in all three life-stages. Neither acidification, hypoxia, nor the combination of the stressors impacted the anaerobic metabolism or oxidative stress of juvenile fish, but acid-base equilibrium was disrupted by all three treatments in larval fish. Elevated carbonic anhydrase activity was observed in the multi-stress treatment in embryos and larval fish, but not in juvenile fish. These results show that developing sheepshead minnows can re-establish cellular homeostasis in compensating to acidified and hypoxic waters.
低溶解氧和酸化加剧是河口环境中同时变化的两个环境变量，营养物质污染和随后的富营养化会使这两个变量进一步恶化。为了更好地了解河口生物如何应对这些环境变量的日常波动，研究人员采用2×2析因设计，在42天的暴露实验中评估了酸化和缺氧对发育中的海湾鲱（）的交互作用。将胚胎暴露于酸性（二氧化碳分压，2000微大气压）、缺氧（溶解氧降低，2毫克/升）或酸性和缺氧组合条件下，并监测其发育、孵化率和存活率。在三个生命阶段（胚胎、幼体和成鱼）评估了耗氧量、无氧代谢、氧化应激和酸碱平衡的变化，以确定鱼类在发育过程中是否以及如何补偿这些应激源。酸化和缺氧的组合延迟了胚胎的孵化，并在所有三个生命阶段显著降低了耗氧量（p<0.001）。酸化、缺氧或应激源组合均未影响成鱼的无氧代谢或氧化应激，但幼体鱼的酸碱平衡在所有三种处理中均受到破坏。在胚胎和幼体鱼的多重应激处理中观察到碳酸酐酶活性升高，但在成鱼中未观察到。这些结果表明，发育中的海湾鲱能够在补偿酸化和缺氧水体影响的过程中重新建立细胞内稳态。
