A recent study in Science Advances reveals that coral reefs play a key role in regulating daily rhythms of nearby marine microbes, beyond providing habitat. Researchers from the Hebrew University of Jerusalem monitored microbial populations above a coral reef in the northern Gulf of Aqaba in the Red Sea, comparing them to populations in adjacent open waters during both winter and summer.
The study found that reef waters consistently hosted fewer bacteria and microalgae than surrounding waters, suggesting that reef organisms actively remove and consume these microbes, effectively “cleaning” the water. Daily cycles influenced by sunlight and coral metabolism were clearly observed, with Symbiodiniaceae, a family of coral symbionts, peaking around midday.
Importantly, the research showed that these daily microbial rhythms often exceeded seasonal variations, highlighting the significance of time-of-day in reef studies. Samples collected at different hours could show drastically different microbial compositions, regardless of the season. These findings suggest that tracking daily microbial cycles could become a valuable tool for scientists to monitor reef health in a changing ocean environment.
