The Flower Garden Banks National Marine Sanctuary (FGBNMS) includes 17 banks, topped by tropical and mesophotic corals, located ~200 km offshore on the edge of the continental shelf in the northern Gulf of Mexico. This area serves as a valuable habitat for fisheries and threatened/endangered species of manta rays, sea turtles, and corals. Because ocean acidification slows coral reef growth and enhances erosion and dissolution, this study investigates local and global drivers of acidification at the FGBNMS, which occur in a region with enhanced acidification rates relative to the open ocean. Acidification in the FGBNMS can be influenced by upwelling from deeper waters, freshwater runoff from land, Loop Current Eddies, hurricanes, and subsurface hypoxia. Data were collected within the FGBNMS from 2015 to 2019, which includes two major hurricanes, several freshwater discharge events, and possible upwelling of deep water onto the reefs. In the subsurface, from ~25-125m, acidification was enhanced in 2016 compared to 2015 and 2017. 2015-2017 had comparable total alkalinity (TA) at these depths, but subsurface dissolved inorganic carbon (DIC) and partial pressure of carbon dioxide were higher, and aragonite saturation state (Ω_ar) and pH were lower in 2016. The 2016 enhanced subsurface acidification is likely due to an upwelling event that led to colder, more acidic waters reaching the depth of the coral reefs (~16-46 m). Data from 2018 & 2019 are being analyzed and the potential impacts of loop current eddies and hurricanes will also be investigated across the 5-year dataset.

Primary Presenter: Allison Savoie, Texas A&M University (allison.m.savoie@tamu.edu)

Authors:

Allison Savoie, Texas A&M University  (ams5420@gmail.com)

Kathryn Shamberger, Texas A&M University  (katie.shamberger@tamu.edu)

Adrienne Correa, Rice University  (adrienne.correa@rice.edu)

Sarah Davies, Boston University  (daviessw@bu.edu)

Steven DiMarco, Texas A&M University  (sdimarco@tamu.edu)

Shawn Doyle, Texas A&M University  (shawndoyle@tamu.edu)

Robert Hetland, Texas A&M University  (hetland@tamu.edu)

Andrea Kealoha, University of Hawai'i Maui College  (andreake@hawaii.edu)

Henry Potter, Texas A&M University  (hpotter@tamu.edu)

Lory Santiago-Vasquez, University of Houston Clear Lake  (santiago@uhcl.edu)

Jason Sylvan, Texas A&M University  (jasonsylvan@tamu.edu)