SMAST Seminar - DEOS - September 24, 2025 - "Disentangling the biological and physical drivers of finescale oceanic plankton patchiness" by: Shailja Gangrade
Seminar Announcement
Department of Estuarine and Ocean Sciences
"Disentangling the biological and physical drivers of finescale oceanic plankton patchiness"
Shailja Gangrade
Postdoctoral Research Associate, Brown University
Wednesday, September 24, 2025
12:30pm-1:30pm
SMAST E 101-103 and via Zoom
Abstract:
Oceanic fronts, filaments, and eddies horizontally stir planktonic communities, generating heterogeneity in their spatial and temporal distributions, or “patchiness.” Planktonic biomass and community structure have also been found to be non-uniform within the flow features themselves, often in correlation with temperature, salinity, and nutrients. But due to high horizontal velocities (50–80 km d-1) along fronts and filaments, the transit times of waters within a flow feature (a few days) are shorter than the timescales required for significant biological community changes (several days to weeks). Given this strong lateral advection, mesoscale (10–100 km) flow features must contain distinct plankton patches that propagate along their jets, and these patches must be predominantly structured by processes occurring at their upstream origins. Furthermore, sub-mesoscale (<10 km) processes have been shown to structure plankton patches, but relatively few observations of submesoscale biological gradients exist. Ultimately, few studies have investigated the underlying dynamics and upstream controls that lead to plankton patchiness in these features; therefore, this hypothesis remains largely untested. In this talk, I will demonstrate that plankton patches are entrained into fronts, filaments, and eddies. In these features, patches can converge with other patches and advect along a jet. Distinct patches, with nonuniform community structure and biomass, are shaped by fluctuations in upstream wind-driven upwelling intensity and source-water nutrient concentrations, as well as biological processes—such as growth, grazing, and iron limitation—that occur along Lagrangian trajectories. These findings help us to identify the physical-biological processes that structure biological productivity and diversity, ecological hotspots, and carbon export.
Zoom Meeting
https://umassd.zoom.us/j/97440069270
Note: Zoom meeting ID and password required.
Please email Callie Rumbut for the zoom meeting ID and passcode.
SMAST East 101-103
: 836 S. Rodney French Boulevard, New Bedford MA 02744
Callie Rumbut
c.rumbut@umassd.edu
https://umassd.zoom.us/j/97440069270