Thesis Defense Seminar - Adewumi Andrew

ENVIRONMENTAL SCIENCE PROGRAM
DEPARTMENT OF PHYSICAL AND ENVIRONMENTAL SCIENCES
TEXAS A&M UNIVERSITY-CORPUS CHRISTI

TITLE: Influence of River Discharge on Chlorophyll Concentration Variability in the Northwestern Gulf of Mexico

GRADUATE COMMITTEE: Dr. Xinping Hu (Chair), Dr. Lei Jin, Dr. Paul Montagna

ABSTRACT
Climate change is a contributor in altering productivity in aquatic ecosystems, mostly through changes in hydrological and associated nutrient cycles. These changes have the potential to significantly affect the chlorophyll concentration in the surface coastal ocean, a proxy for phytoplankton abundance and marine primary productivity. Using publicly available surface ocean chlorophyll record derived from remote sensing, this study investigates the relationship between river discharge variability and chlorophyll concentration. Statistical analyses utilizing regression modeling and time-series analysis were conducted over a 15-year period (2007-2022) using discharge data from multiple rivers in the northern and northwestern Gulf of Mexico and surface chlorophyll concentration data at several outer continental shelf sites within Flower Garden Banks National Marine Sanctuary located in the northwestern Gulf of Mexico. Anticipated delayed parallel correlation in chlorophyll concentrations with fluctuations in river discharge was revealed through Partial Least Squares Regression modeling. The chlorophyll concentration at the selected sites showed a predictable correlation within the two major rivers in the study, the Mississippi and Lower Atchafalaya River, with no significant statistical correlations with the Brazos River, which has much smaller discharge. It is expected that these otherwise oligotrophic locations exhibit distinct seasonality and interannual variations, reflecting the cyclical nature of climate patterns and hydrological systems.