Mapping the Dynamics of Particulate Organic Carbon: Satellite Observations of Coastal to Shelf Variability in the Northeastern Gulf of Mexico: Mapping the Dynamics of Particulate Organic Carbon.

Understanding the distribution and dynamics of particulate organic carbon (POC) is essential for assessing marine ecosystem health and carbon cycling. This study analyzed the spatial and temporal variability of POC in the northeastern coastal waters to the continental shelf of the Gulf of Mexico using satellite remote sensing data within the United States. Over 19 years, surface water POC averaged 155.57 ± 13.56 mg/m³, with values ranging from 127.17 to 188.81 mg/m³, and an insignificant annual increase of 0.78 mg/m³. Spatial analysis across five transects (T1–T5) revealed significant variability, with mean POC values ranging from 125.19 mg/m³ (T5) to 169.23 mg/m³ (T1) and standard deviations from 136.76 mg/m³ (T5) to 193.64 mg/m³ (T3). Transects near the estuaries of the Mississippi and Atchafalaya Rivers (T1–T4) exhibited elevated POC due to terrestrial organic matter and nutrient inputs, while the west Florida shelf (T5) had lower concentrations. Seasonal variations were influenced by wind-driven currents, sea surface temperature (SST), and mesoscale eddies. Analysis of Variance showed a significant seasonal effect on POC concentrations (F-value: 96.51, p < 0.001). A strong negative correlation between SST and POC during winter and fall suggests cooler temperatures enhance vertical mixing and nutrient upwelling, increasing POC. In contrast, warmer SSTs in summer were positively correlated with POC due to stratification and increased biological activity. Chlorophyll-a showed a strong positive correlation with POC, highlighting the role of primary productivity. These results emphasize the importance of satellite-based POC monitoring for a comprehensive understanding of carbon cycling and its biological impacts on marine ecosystems. [ABSTRACT FROM AUTHOR]