Expected limits on the ocean acidification buffering potential of a temperate seagrass meadow
Expected limits on the ocean acidification buffering potential of a temperate seagrass meadow
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DOI：
10.1002/eap.1771
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发表时间：
2018-10-01
影响因子：
5
通讯作者：
Caldeira, Ken
中科院分区：
文献类型：
--
作者：
Koweek, David A.;Zimmerman, Richard C.;Caldeira, Ken
海洋酸化威胁着许多海洋生物，尤其是海洋钙化生物。解决海洋酸化的唯一全球性方案仍然是迅速减少二氧化碳排放。然而，由于认识到海洋酸化对自然群落（包括对人类重要的群落）构成的威胁，人们对局部缓解策略的兴趣迅速增长。由于海草床拥有大量的有机碳储量和高生产力，保护海草床被视为一种可能的局部缓解海洋酸化的方法。然而，要确定海草潜在缓冲效应的程度和时间尺度，仍有大量工作要做。我们开发了一个生物地球化学箱式模型，以更好地了解温带海草床在局部缓解海洋酸化影响方面的潜力。然后，我们使用来自美国加利福尼亚海岸的托马利斯湾（一个支持主要牡蛎养殖业的海湾）的数据对模型进行参数化。我们进行了一系列为期一个月的模型模拟，以描述夏季和冬季发生的过程。我们发现，海草床内的平均pH值通常在进入草床的主要源水pH值的0.04个单位范围内，尽管我们确实偶尔发现（几个小时）海草的新陈代谢可能会使pH值改变多达±0.2个单位。相对于昼夜循环的潮汐相位调节着海草床内的局部pH缓冲，使得在一年中中午出现低潮的时期缓冲作用最大。我们的模型结果表明，托马利斯湾的海草新陈代谢不会提供长期的海洋酸化缓解作用。然而，我们强调，如果关于海草床内深度平均净生产量和海水停留时间的假设与我们的模型假设不同，我们的模型结果可能不适用于其他草床。我们的建模方法提供了一个易于适用于其他海草床的框架，以便评估它们各自的缓冲能力程度。无论其缓冲海洋酸化的能力如何，海草床都维持着许多至关重要的生态系统产品和服务，随着人类对沿海生态系统的影响日益增大，这些产品和服务将变得越来越重要。
Ocean acidification threatens many marine organisms, especially marine calcifiers. The only global-scale solution to ocean acidification remains rapid reduction in CO2 emissions. Nevertheless, interest in localized mitigation strategies has grown rapidly because of the recognized threat ocean acidification imposes on natural communities, including ones important to humans. Protection of seagrass meadows has been considered as a possible approach for localized mitigation of ocean acidification due to their large standing stocks of organic carbon and high productivity. Yet much work remains to constrain the magnitudes and timescales of potential buffering effects from seagrasses. We developed a biogeochemical box model to better understand the potential for a temperate seagrass meadow to locally mitigate the effects of ocean acidification. Then we parameterized the model using data from Tomales Bay, an inlet on the coast of California, USA which supports a major oyster farming industry. We conducted a series of month-long model simulations to characterize processes that occur during summer and winter. We found that average pH in the seagrass meadows was typically within 0.04 units of the pH of the primary source waters into the meadow, although we did find occasional periods (hours) when seagrass metabolism may modify the pH by up to +/- 0.2 units. Tidal phasing relative to the diel cycle modulates localized pH buffering within the seagrass meadow such that maximum buffering occurs during periods of the year with midday low tides. Our model results suggest that seagrass metabolism in Tomales Bay would not provide long-term ocean acidification mitigation. However, we emphasize that our model results may not hold in meadows where assumptions about depth-averaged net production and seawater residence time within the seagrass meadow differ from our model assumptions. Our modeling approach provides a framework that is easily adaptable to other seagrass meadows in order to evaluate the extent of their individual buffering capacities. Regardless of their ability to buffer ocean acidification, seagrass meadows maintain many critically important ecosystem goods and services that will be increasingly important as humans increasingly affect coastal ecosystems.