Ocean Acidification on a Crossroad - Enhanced Respiration, Upwelling, Increasing Atmospheric CO2, and their interactions in the northwestern Gulf of Mexico

The human society has had significant influence on the global ocean carbonate chemistry (aka ocean acidification or OA) through fossil fuel combustion, deforestation, and cement production over the past 250 years. In the coastal ocean however, other forcings such as continental nutrient input and physical oceanographic changes can have stronger impacts on both the magnitude of short-term variation and long-term trend in carbonate parameters (pH, carbonate saturation states). Among the NOAA designated Large Marine Ecosystems, the Gulf of Mexico (GOM) remains poorly understood in terms its current OA conditions, despite its ecological and economic significance. In the northwestern GOM (nwGOM), a decadal acidification has been observed in the shelf-slope region with the anthropogenic CO2 contributing to a smaller fraction of CO2 accumulation than that from metabolic production. This acidification effect is significantly greater than that in other tropical and subtropical areas. Unfortunately, whether the observed OA in this region represents a short-term phenomenon or a long-term trend is unknown. Given the fact that nutrient pollution through continental runoff is predicted to worsen due to enhanced hydrological cycle and that future upwelling may become stronger, both as a result of climate change, the nwGOM will likely experience more serious acidification while atmospheric CO2 level keeps increasing. Collaborating with colleauges from NOAA Atlantic Oceanographic and Meteorological Laboratory, Texas A&M University, the Gulf of Mexico Coast Ocean Observing System, and Texas A&M University-Corpus Christi, we will investigate spatial and temporal changes in carbonate chemistry signals in the northwestern Gulf of Mexico for the optiminzation of ocean acidification monitoring effort in this region.

This effort is funded by the  National Oceanographic and Atmospheric Administration through the Ocean Acidification Program and the Intergrated Ocean Observing System.

Data Collection

A combination of ship-based survey, wave glider operation, and in-situ sensor deployment will be taken in this project to collect seawater physical and chemcial data for the next step modeling exercises. The ship-based survey will collect both underway data (at sea surface) and those at discrete depths from shelf to upper slope of the northwestern Gulf of Mexico. A Liquid Robotics wave glide   that carries sensors for CO2, pH, and fluorescence measurements will be used to survey sea surface conditions for prolonged periods of time.

(Source: Field photo by Steve DiMarco, 2021)

Two additional fixed mount sensors - a SeaFET pH sensor and a SAMICO2 sensor - will be deployed at a Flower Garden Bank site to obtain high temporal resolution data.

SeaFET pH sensor

SAMICO2 pCO2 sensor

Project Members

Advisory Committee

This project has seven independent experts on the advisory committee. They include experts in monitoring (Drs. Derek Manzello, Katie Shamberger, and Kimberly Yates), modeling (Drs. Katja Fennel and George Xue), natural resource management (Ms. Emma Hickerson), and infrastructure management (Dr. Barbara Kirkpatrick). These experts will guide the progress and direction of this field-intensive project and ensure that the outputs and outcomes of this project will meet the long-term goal of optimizing OA monitoring in the northwestern Gulf of Mexico and will provide documentation of methodology that can be used in similar efforts in the future.