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Application of the coastal generalized ecosystem model (CGEM) to assess the impacts of a potential future climate scenario on northern Gulf of Mexico hypoxia
Lehrter, J., D. Ko, L. Lowe, B. Jarvis, AND C. Le. Application of the coastal generalized ecosystem model (CGEM) to assess the impacts of a potential future climate scenario on northern Gulf of Mexico hypoxia. 2015 Aquatic Sciences Meeting, Grenada, SPAIN, February 22 - 27, 2015.
The purpose is to investigate via numerical modeling the potential impacts on hypoxia by a future climate change scenario. The future scenario is developed from the IPCC (2014) report and other published literature.
Mechanistic hypoxia models for the northern Gulf of Mexico are being used to guide policy goals for Mississippi River nutrient loading reductions. However, to date, these models have not examined the effects of both nutrient loads and future climate. Here, we simulate a future climate scenario of + 3°C air temperature and + 10% river discharge using the Navy Coastal Ocean Model (NCOM) coupled to the Coastal General Ecosystem Model (CGEM). CGEM represents phytoplankton community dynamics and the biogeochemistry leading to hypoxia. Results suggest the primary response to the climate scenario was an increase in water temperature (mean = 1.1 ºC in the hypoxic area) that changed the pycnocline strength and ecosystem emergent properties like primary production, respiration, and the phytoplankton community. In sum, these changes resulted in a future hypoxic area that was less sensitive to nutrient load reductions than in the present and potentially having more significant aquatic life impacts due to shoreward migration of hypoxia. We discuss current opportunities and challenges for implementing complex models like CGEM and their role in assessing future nutrient and climate scenarios.