AUTHOR=Ousley Sara , de Beer Dirk , Bejarano Sonia , Chennu Arjun 

TITLE=High-Resolution Dynamics of Hydrogen Peroxide on the Surface of Scleractinian Corals in Relation to Photosynthesis and Feeding

JOURNAL=Frontiers in Marine Science

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2022.812839

DOI=10.3389/fmars.2022.812839

ISSN=2296-7745

ABSTRACT=<p>We developed and used a microsensor to measure fast (&lt;1 s) dynamics of hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) on the polyp tissue of two scleractinian coral species (<italic>Stylophora pistillata</italic> and <italic>Pocillopora damicornis</italic>) under manipulations of illumination, photosynthesis, and feeding activity. Our real-time tracking of H<sub>2</sub>O<sub>2</sub> concentrations on the coral tissue revealed rapid changes with peaks of up to 60 μM. We observed bursts of H<sub>2</sub>O<sub>2</sub> release, lasting seconds to minutes, with rapid increase and decrease of surficial H<sub>2</sub>O<sub>2</sub> levels at rates up to 15 μM s<sup>–1</sup>. We found that the H<sub>2</sub>O<sub>2</sub> levels on the polyp surface are enhanced by oxygenic photosynthesis and feeding, whereas H<sub>2</sub>O<sub>2</sub> bursts occurred randomly, independently from photosynthesis. Feeding resulted in a threefold increase of baseline H<sub>2</sub>O<sub>2</sub> levels and was accompanied by H<sub>2</sub>O<sub>2</sub> bursts, suggesting that the coral host is the source of the bursts. Our study reveals that H<sub>2</sub>O<sub>2</sub> levels at the surface of coral polyps are much higher and more dynamic than previously reported, and that bursts are a regular feature of the H<sub>2</sub>O<sub>2</sub> dynamics in the coral holobiont.</p>