Seasonal Phytoplankton Production at the New England Shelf Break Front: Observations Using the Coastal Pioneer Array’s Submarine Gliders

Kyle Ehmann1, Samantha Ferguson1, Cassandra Este Alexander2 and Robert D Vaillancourt3, (1)Millersville University of Pennsylvania, Millersville, United States, (2)Millersville University of Pennsylvania, Millersville, PA, United States, (3)Millersville University, Millersville, PA, United States
The New England shelf break front is one the most biologically active regions of the world ocean. Known for its high abundances of commercially important fish, and the fishing economy that the zone creates is important to New England. Studying this area with in-situ sampling platforms for extended time scales has been difficult until recently. The Ocean Observatories Initiative’s Pioneer Array is a series of platforms and sensor systems located at the New England shelf break front and is used to measure changes in various ocean properties and processes extending from sea surface to sea floor. We used this new source of locally collected data to test our hypothesis that the enhanced biological production of the shelf break front occurs at certain times of the year when the density surfaces of the ocean water are oriented in such a way that upwelling can deliver phytoplankton nutrients into the euphotic zone. Autonomous underwater glider data was used to analyze sections of the shelf break front for temperature, salinity, backscatter, and chlorophyll-a, a proxy for primary production. Our preliminary results show enhancement of phytoplankton production occurs at the shelf break during spring months when the frontal boundaries slanted from the ocean surface to the ocean floor and the density surfaces, along which upwelling has been shown to be active, reach into the euphotic zone. We also found that sediment backscatter along the ocean floor is a possible tracer for upwelling of nutrients. Further research will be done into measuring the mixed layer depth to conduct a numerical analysis of chlorophyll-a concentration.