As winter approaches, many species of animals – from bears and squirrels to parasitic wasps and a few lucky humans – crouch down for some needed rest. The Northern Star Coral (Astrangia poculata) also enters a sleep or hibernation state during this time. But what happens to its microbiome while it sleeps?
A study led by University of California, Davis, Assistant Professor Anya Brown found that microbial communities shift as this coral goes into hibernation, giving it an important seasonal reset. The work may impact corals in warmer waters, which are struggling with climate change and other environmental issues.
“Basically, hibernation is a response to an environmental stressor — in this case, cold stress,” said Brown, who is part of the UC Davis Bodega Marine Laboratory in the Department of Evolution and Ecology. “Understanding more about this recovery phase could help us understand which microbes might be responsible for coral recovery in warmer tropical systems.”
The study, published in the journal Applied and Environmental Microbiology with scientists from Woods Hole Oceanographic Institution (WHOI) and Roger Williams University, is the first to show sustained change in the quiescent microbial community in a marine animal.
“This study shows that microbes respond to stress and recover in a predictable pattern,” said co-author Amy Apprill, Associate Scientist at WHOI. “It’s fundamental knowledge that can help us develop probiotics or other microbial treatments for stressed tropical corals.”
while you were sleeping
From October 2020 to March 2021, researchers dove 60 feet deep in cold, nearly 40 degrees Fahrenheit water to collect 10 different colonies of the coral A.poculata from a dock in Woods Hole, Massachusetts. This coral is found in Atlantic waters stretching from the Gulf of Mexico to Massachusetts. When the water temperature cools, the coral retracts its tentacles, stops feeding or responding to touch, and goes dormant.
The scientists characterized the microbiomes of the wild coral before, during and after the dormant phase. They found that while the coral “sleeps,” its microbiome sheds nutrient-loving and pathogen-associated microbes, while it proliferates microbes that can contribute nitrogen while the coral stops eating. The scientists found that this restructuring helps the corals maintain their microbial community structure.
“We suspected that for a long time Astrangias The seasonal dormancy allows the coral microbiome to reset and restructure,” said co-author Koty Sharp, associate professor at Roger Williams University of Health and Disorder Recovery.”
Why is coral waking up?
With this study a marine species – the coral A. poculata — now joins bears, squirrels, crickets and others on the list of animals where microbiomes have been found to shift while they are resting. For example, the ground squirrel’s gut microbiome plays an important role in nitrogen recycling, while the squirrel fasts during hibernation.
“This work raises a lot of questions,” Brown said. “A big question is: why does the coral wake up in early spring? This study suggests that key microbial groups may play an important role in triggering the onset or emergence of this coral’s dormancy and the regulation of its microbiome.”
The study was funded by a WHOI Postdoctoral Scholar Award to Brown, as well as by the National Oceanic and Atmospheric Administration, the National Science Foundation, and the National Institutes of Health.
Materials provided by University of California – Davis. Originally written by Kat Kerlin. Note: Content can be edited for style and length.