Abigail Gross, Pitzer College

Class Year:

2024

Mentor:

Greg Silsbe, Ph.D.

Abstract:

Phytoplankton are pivotal in aquatic ecosystems, influencing trophic dynamics and global biogeochemical cycles. In the Chesapeake Bay, shifts in phytoplankton community composition have occurred over centuries due to effects of anthropogenic activities, particularly eutrophication. While past studies tend to monitor phytoplankton by general biomass, this study attempts to look at phytoplankton changes on a population level, assessing changes within floral composition in response to nutrient inputs. This work can be done via automated plankton imaging tools, and this project looked at the Imaging Flow CytoBot (IFCB) and the Planktoscope. A nutrient bioassay was conducted on samples taken from the main stem of the Bay and run through these instruments to determine nutrient limitation across taxonomic groups. Diatoms, dinoflagellates, and zooplankton counts were recorded for each nutrient-treated sample and control. Results indicate that diatom abundance increases significantly with nitrogen additions, underscoring nitrogen as a key limiting nutrient in this region. These findings align with previous studies, which also observed heightened diatom proliferation during wet years with elevated nutrient runoff. The study highlights the potential for increased diatom blooms under ongoing eutrophication. Automated imaging technologies, such as the Planktoscope and Imaging FlowCytobot (IFCB), demonstrate their utility in advancing phytoplankton monitoring. This research ultimately contributes to a growing image database, aiding in the development of taxonomic classifiers and providing critical insights into the future impacts of nutrient management and climate change on the Bay's phytoplankton communities.

Location:

Horn Point Laboratory