Ocean Acidification Monitoring in the Aransas Ship Channel

Ocean acidification is reflected by the decrease in pH caused by the uptake of atmospheric carbon dioxide (CO2). As CO2 dissolves into the ocean, carbonic acid is formed and leads to increase of hydrogen ion concentration (or a decline in pH). Changing the chemistry of the ocean has many adverse effects on multiple marine organisms. The decline of these organisms would have many cascading effects, such as changing marine food web structure, decreasing shellfish fishery production, and decreasing coral reef production.

Prior research revealed an overall decline in both pH and alkalinity (i.e., acidification) in almost all estuaries (including estuaries and coastal bays) in the State of Texas (northwestern Gulf of Mexico). This study is based on a long-term dataset that has been collected by the Texas Commission on Environmental Quality. Among these estuaries, the ones in the southern Texas that is subject to semi-arid conditions experiences the most decline in alkalinity and pH, including the Mission-Aransas Estuary (comprised of Copano, Aransas and Mesquite Bays).

To further study the acidification phenomenon in estuarine settings, especially under the current ocean acidification conditions (due to uptake of atmospheric CO2 by the open ocean), which could add to the already acidifying estuarine water, this project will resume monitoring high temporal resolution pH and partial pressure of carbon dioxide (pCO2) using two in situ sensors.

These high-resolution data will allow us to examine both the short-term (daily to monthly) variations and long-term (interannual) changes in water carbonate system in the Aransas Ship Channel, which connects estuarine water with the northwestern Gulf of Mexico coast, under the influence of freshwater inflow variation and ocean acidification effect.

This project will generate a high temporal resolution (hourly) pH and pCO2 dataset along with auxiliary data including water temperature and salinity. The data will be deposited to the GRIIDC Gulf data repository server upon the completion of the project for public access.