Direct measurements of air‐sea CO 2 exchange over a coral reef

Quantification of CO 2 exchange with the atmosphere over coral reefs has relied on microscale measurements of p CO 2 gradients across the air‐sea interfacial boundary; shipboard measurements of air‐sea CO 2 exchange over adjacent ocean inferred to represent over reef processes or ecosystem productivity modeling. Here we present by way of case study the first direct measurements of air‐sea CO 2 exchange over a coral reef made using the eddy covariance method. Research was conducted during the summer monsoon over a lagoonal platform reef in the southern Great Barrier Reef, Australia. Results show the reef flat to be a net source of CO 2 to the atmosphere of similar magnitude as coastal lakes, while adjacent shallow and deep lagoons were net sinks as was the surrounding ocean. This heterogeneity in CO 2 exchange with the atmosphere confirms need for spatially representative direct measurements of CO 2 over coral reefs to accurately quantify their role in atmospheric carbon budgets.