High Frequency and Seasonal Controls on Calcium Carbonate Saturation States in Two Maine Estuaries

• Main Author: Liberti, Catherine
• Format: Text
• Language: unknown
• Published: DigitalCommons@UMaine 2024
• Subjects: carbonate chemistry; ocean acidification; estuarine productivity; aragonite saturation state; continuous data; coastal acidification; Damariscotta River; Casco Bay; Biogeochemistry; Inorganic Chemistry; Oceanography; Northwest Atlantic; Ocean acidification
• Online Access: https://digitalcommons.library.umaine.edu/etd/3949; https://digitalcommons.library.umaine.edu/context/etd/article/5025/viewcontent/D_Liberti__Kate_May24.pdf

The Gulf of Maine is a highly productive shelf sea in the Northwest Atlantic Ocean that supports many important commercial shellfish. The Gulf of Maine has naturally low calcium carbonate saturation states (ð›€) due to its relatively cold and fresh waters. 𛀠has been shown to be important predictors of larval and juvenile shellfish growth and mortality. Many of these shellfish species spend all or part of their life cycle within the estuaries that fringe the Gulf of Maine and shellfish aquaculture within the estuaries is increasing rapidly. The 𛀠of these estuaries are poorly understood, particularly on high frequency time scales such as days to months. 𛀠has been shown to be highly variable in estuaries due to the increased rates of physical and biogeochemical processes that impact it and alterations due to human activity. To better understand 𛀠variability in two Maine estuaries, I studied the relationship between 𛀠variability and physical, chemical, and biological processes that impacted ð›€, and identified why those processes were changing. In the upper Damariscotta River, I found that 𛀠varied both on a seasonal scale via changes in temperature and salinity, as well as on weekly time scales related to tidal cycles. These shorter timescale variations were correlated with changes in dissolved oxygen concentration, turbidity, and chlorophyll, indicating that ecosystem metabolism was likely the main driver of these changes. The upper Damariscotta River is also the largest oyster growing area in northern New England. I looked at the impact of oyster growth on 𛀠using 2018 industry size and oceanographic conditions and found that calcification and respiration rates could lower 𛀠by 2-3% over the course of the growing season. Increased industry size or continued ocean acidification further decreased 𛀠in the growing area. This is relevant to the industry because lower 𛀠could reduce the shell thickness of the oyster and lead to more breakage during processing or increased predation. Last, I ...