Department of Global Ecology, Carnegie Insitution for Science, 260 Panama Street, Stanford, California, 94305, USA.
Department of Ocean, Earth, and Atmospheric Sciences, Old Dominion University, 4600 Elkhorn Avenue, Norfolk, Virginia, 23529, USA.
Ecol Appl. 2018 Oct;28(7):1694-1714. doi: 10.1002/eap.1771. Epub 2018 Jul 31.
Ocean acidification threatens many marine organisms, especially marine calcifiers. The only global-scale solution to ocean acidification remains rapid reduction in CO 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.
海洋酸化威胁着许多海洋生物，尤其是海洋钙化生物。应对海洋酸化的唯一全球性解决方案仍然是迅速减少 CO 排放。尽管如此，由于海洋酸化对自然群落（包括对人类重要的自然群落）构成的公认威胁，人们对局部缓解策略的兴趣迅速增长。保护海草草甸已被认为是局部缓解海洋酸化的一种可能方法，因为它们具有大量的有机碳储量和高生产力。然而，要限制海草可能产生的缓冲作用的幅度和时间尺度，仍有许多工作要做。我们开发了一个生物地球化学箱模型，以更好地了解温带海草草甸局部缓解海洋酸化影响的潜力。然后，我们使用来自美国加利福尼亚州海岸的托马莱斯湾的数据对模型进行了参数化，该湾支持着一个主要的牡蛎养殖产业。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，海草草甸中的平均 pH 值通常与进入草甸的主要水源的 pH 值相差 0.04 个单位，尽管我们确实发现了几个小时的时间，在此期间，海草的新陈代谢可能会使 pH 值发生±0.2 个单位的变化。潮汐相位与昼夜周期的关系调节了海草草甸内的局部 pH 缓冲作用，使得最大缓冲作用发生在一年中中午低潮的时期。我们的模型结果表明，托马莱斯湾的海草代谢不会提供长期的海洋酸化缓解。然而，我们强调，我们的模型结果可能不适用于那些关于海草草甸中平均净产量和海水停留时间的假设与我们的模型假设不同的草甸。我们的建模方法提供了一个易于适应其他海草草甸的框架，以便评估它们各自缓冲能力的程度。无论它们是否具有缓冲海洋酸化的能力，海草草甸都维持着许多至关重要的生态系统服务和商品，随着人类对沿海生态系统的影响越来越大，这些服务和商品将变得越来越重要。
