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

NSF Award Abstract:
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