[A-OS19] Marine ecosystems and biogeochemical cycles: theory, observation and modeling

[AOS19-17] Drivers and dynamics of change in Altamaha, Doboy, and Sapelo Sounds along the Georgia coast

*Kimberly K Takagi¹, Kimberley S Hunter², James B Deemy¹, Wei-Jun Cai³, Samantha B Joye² (1.College of Coastal Georgia, 2.University of Georgia, 3.University of Delaware)

Keywords:Estuarine, Biogeochemistry, Nutrients

Changes in climate, weather, and population alter the biogeochemical dynamics of coastal environments. The Altamaha River Estuarine System provides a unique opportunity to assess how these dynamics are altered across three sounds (Altamaha, Doboy, and Sapelo) with unique freshwater inputs, hydrologic circulation, and physics. The dominant freshwater source to the system is the Altamaha River. The Altamaha watershed is the largest in Georgia and is comprised of five sub-watersheds covering roughly 35,500 km². Nutrient loads to the system were dominated by organic forms of nitrogen and phosphorous. Nutrient loading was strongly impacted by population, land and water use, and livestock, whereas retention within the system was affected by changes in climate and weather. The aim of this study was to elucidate the factors that impact biogeochemical dynamics in the Altamaha River Estuarine System. This was accomplished through integration of long-term chemical, climatological, and hydrological data collected through the Georgia Coastal Ecosystems – Long Term Ecological Research project (2000-2019), US Geological Survey discharge database, and the South Eastern Regional Climate Center. We project that the biogeochemical dynamics of the Altamaha River Estuarine System mirror the changes seen in the Altamaha River Watershed over this time period. These changes are likely exacerbated by changes in climate patterns.