Name: Haoran Liu
Date: 11/17/2025
Time (EST/EDT): 10:30 am
Location: Carver Hall Conference Room, University of Maryland Eastern Shore
Remote Access: email: mees@umd.edu

Committee Chair: Meng Xia
Committee Members: Jeseph Pitula Johan Schijf O'Neil M. Judith Roman Jesien
Dean’s Representative: Harris LaKeisha

Title: Modeling Biogeochemical Interactions and Ecosystem Dynamics in the
Maryland Coastal Bays

Abstract: Coastal lagoons comprise approximately 13% of the world’s
coastlines and serve as critical breeding and nursery habitats for diverse
organisms. They are distinguished by their shallow waters and restricted ocean
exchange compared to river-dominated estuaries. The Maryland Coastal Bays
(MCBs), a representative restricted lagoon system in a rapidly urbanizing
watershed, have experienced more than four decades of eutrophication and
recurring algal blooms. A three-dimensional biophysical model was developed to
quantify the effects of nutrient and physical forcing on bloom dynamics and to
investigate the biogeochemical interactions between microalgae and benthos in
the bays. Simulation results reveal distinct horizontal gradients and seasonal
nutrient and phytoplankton variability. One main finding shows that wind
forcing exerts stronger control on phytoplankton spatial variability than
nutrient loading alone by altering the bay-ocean and inter-bay exchanges.
Persistent southwesterly winds, typical of summer conditions and along the long
axis of the bays, at high speeds can reduce phytoplankton biomass across the
bays, exceeding the effects of 75% nitrogen reduction or tidal influence. This
study emphasizes the complex interactions between nutrients and physical
processes and bay geomorphology, underscoring the integrated ecological
influences of nutrient and hydrodynamics in shallow coastal systems.