Drivers of ocean acidification in a temperate urbanized estuary undergoing nutrient loading reductions

大约三分之一的人类产生的二氧化碳（CO2）已经溶解在海洋中，显著减缓了气候变化和全球变暖。然而，随着更多的二氧化碳溶解在海洋中，海水变得酸化，因为二氧化碳是一种弱酸。我们称这种变化为海洋酸化（OA）。OA对海洋生物有重大而持久的影响，因为酸化的水会导致许多海洋物种的壳溶解。美国社会已经在努力应对OA的负面影响。据预测，到2100年，OA将给美国贝类产业造成每年4亿美元的经济损失。因此，迫切需要了解OA是如何变化的，以及在沿海水域管理OA的潜在方法。目前，我们对大型或小型的OA变化都没有很好的了解，因为有太多的竞争过程影响OA。影响海洋酸化（OA）的最显著的过程之一是由于人类输入而从河流中增加的额外营养负荷。虽然适度的营养水平对维持海洋生物是必要的，但营养水平过高会导致海洋浮游生物大量繁殖。随着浮游生物的死亡，它们下沉到海底，在那里被细菌分解，加速了贝类生活的OA。近几十年来，管理机构一直致力于通过减少对沿海水域的营养投入来改善水质，这有可能减少OA，尽管OA不是最初的动机。据我们所知，目前还没有针对性的研究来了解OA如何应对积极的营养减少。纳拉甘西特湾是美国变暖最快的河口之一，由于有意减少营养物，近几十年来，纳拉甘西特湾的平均营养物输入减少了三分之一以上。因此，纳拉甘西特湾可以被认为是一个自然实验室，可以帮助我们更好地理解其他沿海地区可能很快就会经历的环境管理行动和气候变化带来的OA变化。该项目将利用现有的水质监测网络，收集新的数据，并利用沿海生物地球化学模型来量化纳拉甘西特湾的OA变化及其驱动其变化的机制。通过与公众和当地贝类养殖者的接触，我们将提高他们对OA的认识，并在近期和长期内提高他们开展正在进行的或新的水产养殖业务的能力。随着美国越来越多的州减少营养物投入以改善沿海水质，该项目将使全国的管理机构能够在气候变化的情况下，对可持续渔业和野生动物的OA进行最佳限制。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

About one-third of human-produced carbon dioxide (CO2) has dissolved in the ocean, significantly slowing down climate change and global warming. However, as more CO2 dissolves in the sea, the ocean water becomes acidified because CO2 is a weak acid. We call this change ocean acidification (OA). OA has a significant and lasting impact on marine life, as acidified water causes shell dissolution for numerous marine species. US society is already grappling with the adverse effects of OA. OA is predicted to lead to economic losses of $400 million annually by 2100 for the US shellfish industry. Therefore, it is urgent to understand how OA is changing and the potential approaches to managing it in coastal waters. Presently, we do not have a good understanding of OA change at either the large or the small scale because so many competing processes impact OA. One of the most dramatic processes that affect ocean acidification (OA) is the extra nutrient loading from rivers due to human inputs. While moderate nutrient levels are necessary to support marine life, nutrient levels that are too high can cause oceanic plankton blooms. As plankton die, they sink to the seafloor, where they are decomposed by bacteria and speed up OA where shellfish live. In recent decades, management agencies have been working on improving water quality by reducing the nutrient input to coastal waters, which has the potential to reduce the OA even though OA is not the initial motivation. To our knowledge, there has yet to be targeted research to understand how OA responds to aggressive nutrient reduction. The average nutrient input to Narragansett Bay– one of the most rapidly warming estuaries in the US–has been reduced over one-third in recent decades because of intentional nutrient reduction. Therefore, Narragansett Bay can be considered a natural laboratory that can help in better understanding the OA change that other coastal areas may soon experience resulting from environmental management actions and climate change. This project will leverage the existing water quality monitoring network, collect new data, and utilize a coastal biogeochemical model to quantify OA change and the mechanisms driving its change in Narragansett Bay, RI. Through engagement with the public and local shellfish growers, we will increase their awareness of OA and enhance their ability to carry out ongoing or new aquaculture operations in the near and long term. As more US states reduce nutrient input to improve coastal water quality, this project will allow management agencies nationwide to make next-generation refinements to best limit OA for sustainable fisheries and wildlife in the face of climate change.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.