44-10 Behavioral response of Ammonia confertitestsa (foraminifera) of the Long Island Sound to minerals proposed for Ocean Alkalinity Enhancement

Abstract:

Ocean alkalinity enhancement (OAE) is a marine carbon dioxide removal (mCDR) approach by which alkaline materials are added to the ocean to encourage production of bicarbonate. Olivine sand has been deployed at a small scale in the Long Island Sound (LIS), east of New York City, USA. It is important to consider both the direct and indirect effects of OAE on marine calcifiers, as their response has the potential to change the efficacy of the OAE. Foraminifera (forams), unicellular, calcareous-shelled eukaryotes, are a critical marine calcifier in the LIS, and in recent decades, the invasive Ammonia confertitesta has become the dominant taxa in the region. Previous work has suggested that coastal benthic foraminifera morphology is strongly affected by sediment grain size. Little is known about how A. confertitesta (1) would respond to the addition of olivine grains to their natural environment, (2) interacts with any sediment particles, or (3) possibly differentiates between particle size and type. This study aims to fill that gap by culturing and observing A. confertitesta in experiments with varying sizes of  olivine, kaolinite, calcium carbonate, and glass beads. Results have indicated that smaller grained particles of any kind strongly inhibited A. confertitesta’s metabolic processes. A. confertitesta has also shown a strong affinity for kaolinite, suggesting a potential ability to differentiate between particle types. Further work on how A. confertitetsa shell morphology changes during growth in the presence of different particle types and seawater chemistry through scanning electron microscopy will allow us to investigate the influence of particle type on their longer-term calcification response. 

© Copyright 2026 The Geological Society of America (GSA), all rights reserved.