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As climate change and carbon dioxide (CO2) emissions continue to alter oceans, it is critical to understand how marine life will respond. Atmospheric CO2 dissolves into ocean water, beginning a series of chemical reactions that lower pH and deplete free carbonate ions—this phenomenon is called ocean acidification (OA). Marine phytoplankton impact ocean chemistry by performing photosynthesis and cycling carbon. They also form the base of marine food webs and are thus implicated in fishery productivity and human food security. As part of the National Oceanic and Atmospheric Administration's Ocean Acidification Program, this research aimed to document the progression of OA and its effects on marine life. The project combined data analysis, remote sensing, and laboratory experiments to understand phytoplankton community change. Data from scientific cruises in 2018 and 2022 were compared to investigate inter-annual variability in phytoplankton distribution, size, and efficiency. These cruises measured chemical and biological indicators, including pH, temperature, and pigments associated with particular plankton taxa. Water samples collected at various depths were imaged to gather phytoplankton cell counts. The findings demonstrate a clear pH gradient along the East Coast, with northern waters being significantly more acidic than southern waters. This difference is primarily driven by increased precipitation, land characteristics, and ocean current dynamics. Biological community structure and the photosynthetic efficiency of the phytoplankton sampled along the coast varied with latitude and time, demonstrating that continued climate change and intensifying acidification will affect phytoplankton distribution and consumption of CO2, with reverberations throughout the ocean and climate systems at large. 

Earth’s oceans serve as a large atmospheric reservoir where carbon dioxide is absorbed and stored. In modern years, fossil fuel emissions have caused a large influx of CO₂ into the atmosphere and thus it is being absorbed into the oceans causing ocean acidification. This phenomenon has vast negative impacts, especially on the most abundant organism in the ocean– phytoplankton. Using data from a cruise in 2018, a prominent pH gradient has been mapped along the East Coast of the U.S, with Northeastern waters being more acidic. It is the purpose of this research to investigate how certain phytoplankton species are responding to this pH gradient and changes in their nutrient supplies. Four different species of phytoplankton were chosen from the Long Island Sound, and are currently being tested in varying concentrations of CO₂ (280 ppm, 400 ppm, and 800 ppm) – to mimic the pre industrial, modern, and future CO₂ levels of the Atlantic ocean. With the preliminary results of this experiment, it’s evident that the Diatom taxa is performing best overall, and specifically well in the 280 ppm, because of their unique carbon concentrating mechanisms that allow them to outcompete other phytoplankton in low pCO₂ waters. Future research will include monitoring this ongoing CO₂ experiment as well as testing other species of phytoplankton. It’s imperative to understand how these phytoplankton will react to changes in their environments as harmful algal blooms are becoming more common with climate change. 

In 2018, a working group sponsored by the NASA Plankton, Aerosol, Cloud, and ocean Ecosystem (PACE) project, in conjunction with the International Ocean Colour Coordinating Group (IOCCG), European Organization for the Exploitation of Meteorological Satellites (EUMETSAT), and Japan Aerospace Exploration Agency (JAXA), was assembled with the aim to develop community consensus on multiple methods for measuring aquatic primary productivity used for satellite validation and model synthesis. A workshop to commence the working group efforts was held December 5–7, 2018, at the University Space Research Association headquarters in Columbia, MD, USA, bringing together 26 active researchers from 16 institutions. In this document, we discuss and develop the workshop findings as they pertain to primary productivity measurements, including the essential issues, nuances, definitions, scales, uncertainties, and ultimately best practices for data collection across multiple methodologies. doi: http://dx.doi.org/10.25607/OBP-1835 

Abstract CP24C-1147 

Abstract H43O-2277