A Decadal Study of Ocean Acidification Conditions in Coastal Waters of the Gulf of Mexico

The Gulf of Mexico (GoM) is a low-latitude, semi-enclosed basin bounded by the US Gulf Coast, the eastern coasts of Mexico and northern Cuba. The region is strongly influenced by the loop current and riverine inputs including from the 10^th largest river in the world, the Mississippi River which contributes to eutrophication and hypoxia events. Since 2007, the NOAA Ocean Acidification Program supports synoptic coastal cruises in the GoM as part of its commitment to monitor ocean acidification conditions in coastal waters of the United States. Three Gulf of Mexico Ecosystems and Carbon Cycle (GOMECC) cruises have been conducted during the summer in the years 2007, 2012 and 2017. Four transects along US coastal waters of Florida, Louisiana and Texas have been re-occupied at least twice during that time frame. Additional lines in U.S. as well as Mexican and Cuban coastal waters were added for the first time in 2017. Here we look at decadal trends in dissolved inorganic carbon (DIC), partial pressure of CO₂ (pCO₂), and total alkalinity (TA) measurements. Aragonite saturation state and related parameters of relevance to OA processes are also estimated. The reasons for the differences observed between the different transects are discussed.