Project: Carbonate System Chemistry in the Arabian Gulf

Project Summary

There is concern that coral reefs in the Arabian (Persian) Gulf are being severely impacted by ocean acidification yet little is known about the carbonate system geochemistry in this region. The tropical coral reefs of the world reach their northernmost limits in the Gulf. Reefs there may be relatively small but they represent the regions biological store house. Historically, the countries bordering the Gulf used pearl oyster beds and coral reefs as a large part of their economy and cultural heritage. It comes as a surprise to many that the Gulf is a repository of biodiversity. The carbonate system chemistry in the Gulf was first sampled in 1977 but has not been studied since. Surface water enters the Gulf with relatively high concentrations of DIC and alkalinity from the Arabian Sea. As the water flows northward, alkalinity and DIC increase but salinity normalized alkalinity and DIC decrease. The decrease in concentrations of DIC and alkalinity can be used to determine the relative importance of CO2 removal by CaCO3 formation versus primary production. Another factor to consider is that as the water flows north some CO2 is lost due to gas exchange. At the time of the study in 1977 the Arabian Gulf was degassing CO2 to the atmosphere. Now 40 years have passed and the gradients and fluxes may have changed.

Because data regarding the progress of ocean acidification in the Arabian Gulf is sparse, an international collaboration between Qatar University (QU) and the University of Washington (UW) has been organized to fill this deficiency. This study started in 2018 with institutional funding from Qatar University. At present there is no definite end date. The initial study will consist of seasonal cruises on the RV Janan in the Exclusive Economic Zone of Qatar. Our core data set will include hydrographic parameters, nutrients, dissolved inorganic carbon (DIC) and alkalinity. pH and pCO2 will be calculated from DIC and alkalinity. After establishing regional concentrations we plan a detailed study of a healthy coral reef system to measure net calcification.

The goal of this study is to assess the status of the ocean carbonate system in the Exclusive Economic Zone of Qatar in the Arabian Gulf with respect to present and future impacts by ocean acidification and use the distributions of DIC and alkalinity to determine the relative importance of organic matter production and CaCO3 formation for sinks and sources of CO2.