Award: OCE-1334848

Marine sediments cover approximately 70% of the Earth?s solid surface and they play a vital role in organic matter decomposition, and for shallow water areas exposed to light, also production. Oxygen exchange between the seafloor and the water column above is the most used proxy for these complex carbon transformation processes, and the exchange is one of the most frequently measured variables in marine science. The aquatic eddy covariance technique is a relatively new approach that for the first time allows us to measure this oxygen exchange at the seafloor under natural field conditions. This is of course a huge leap forward in our effort to describe these carbon cycling processes, but methodological challenges have prevented wider use of this powerful technique. These challenges are mainly associated with measuring oxygen concentrations at the seafloor accurately and at a fast rate, and the subsequent calculation of the oxygen exchange from the measured data. This project was designed to remove these barriers by developing new robust eddy covariance instrumentation based on optical oxygen detection and new interpretation software. Working with three oxygen sensor manufactures and the Max Planck Institute for Microbiology, Germany, several new sensor solutions were developed and tested in marine environments, all in parallel with our standard aquatic eddy covariance instrumentation. As a result, two new robust plug-and-play optical oxygen sensor solutions are now available on a commercial basis, and a third one is underway. Other sensors with multiple oxygen sensor heads were developed specifically for this research and these results were used to improve the existing software for the interpretation of aquatic eddy covariance data. Additionally, long-term test data measured over different substrates, including permeable sands and seagrass beds, were used to enhance our understanding of their ecological functioning with respect to oxygen dynamics and carbon cycling. Project results were presented at major international conferences, published in peer-reviewed journals, and presented in department seminars given in the US and abroad. Project outcomes will directly benefit old and new users of the aquatic eddy covariance technique, and on a longer term, aid researches working on understanding and quantifying oxygen dynamics and carbon cycling at the seafloor. Two PhD students we trained as part of the project. Last Modified: 06/22/2019 Submitted by: Peter Berg