Observing seasonal cycles, drivers, and potential biological impacts of ocean acidification in the Mid-Atlantic Bight
Creators: name: Wright-Fairbanks, Elizabeth Kelly
Publisher: name: No Publisher Supplied
Year: 2022

description: Ocean acidification due to oceanic uptake of atmospheric carbon dioxide is occurring at unprecedented rates globally. Acidification can be further exacerbated or mitigated due to highly variable physical, biological, and chemical processes in economically important coastal zones like the Mid-Atlantic Bight (MAB). In the MAB, the extent of acidification is altered by freshwater input, biological productivity and respiration, periodic upwelling, seasonal changes in temperature and water column structure, and interactions between coastal water masses. The various drivers of acidification change and interact on time scales from minutes to years, and those interactions have historically been missed due to low spatial or temporal resolution monitoring efforts. Organisms living in the coastal shelf zone that utilize carbonate structures, including economically vital shellfish, are especially susceptible to acidification. Therefore, it is necessary to understand how the carbonate system is changing at a scale that could affect biological processes.This dissertation is composed of three projects that depict cycles, drivers, and impacts of seasonal changes in the MAB carbonate system. Chapter 2 describes the first ever seasonal deployments of a deep-ISFET based pH sensor integrated into a Slocum glider autonomous observing platform. These deployments took place over the course of 2 years in the MAB, and illustrate the seasonal development and degradation of periods of acidification along the coastal shelf. Additionally, quality assurance, quality control, and data analysis techniques distinctive to this sensor are described for the first time.Chapter 3 further decomposes the seasonal pH glider deployments, employing a first-order Taylor Series Decomposition analysis of the seasonal data to quantify the drivers of carbonate chemistry in the MAB. Water mass mixing and biogeochemical activity are identified as the main drivers of the MAB carbonate system, with freshwater inputs, shelf-break current interactions, photosynthesis, and respiration interacting to exacerbate or mitigate acidification in the coastal zone.Chapter 4 addresses the biological implications of seasonal carbonate chemistry dynamics in the MAB. A literature review is conducted to develop a general relationship between larval bivalve growth and acidification. This relationship is then applied to a coupled Regional Ocean Modeling System – Individual Based Model using the ROMSPath program to simulate the impacts of seasonal hydrodynamic conditions on sea scallop larval dispersal in the MAB. Sea scallops that are sensitive to acidification see lower success rates and population connectivity than those that are not sensitive. However, sensitivity to acidification can make up for loss due to high temperatures in high-carbonate saturation state conditions.This dissertation exemplifies ways in which observing systems, modeling techniques, and laboratory research can be used together to understand the ecological impacts of climate change. The continued development of ocean acidification monitoring platforms, modeling, laboratory studies, and field research is paramount to predicting and preparing for the physical, societal, and economic effects of future change.