Like many animals, the northern star coral (Astrangia cupulata) spends its winter in hibernation.
Don’t let the downtime fool you, though. There is a lot of house cleaning going on around those breathing polyps.
According to a new study led by researchers from the University of California, Davis, the communities of microorganisms that live on coral are disturbed during the annual break, preparing for the next season.
This finding may give us a better idea of how corals may affect climate change. As our oceans warm, protecting coral microbes will be important – and the findings could give scientists important information on how to keep corals healthy.
“Dormancy, to begin with, is a response to environmental stress — in this case, cold stress,” he says University of California, Davis, ecologist Anya Brownhe was previously a researcher with the Woods Hole Oceanographic Institution.
“If we understand more about this recovery time, it will help us understand what pathogens can reactivate corals in tropical climates.”
The northern star lives in the Atlantic Ocean, which stretches from the Gulf of Mexico to Massachusetts. When the water temperature drops, the coral goes into deep sleep: it retracts its walls, stops eating, and ignores physical contact.
Between October 2020 and May 2021, Brown and his colleagues collected 10 known localities of A. poculata coral from a depth of 60 feet (around 18 meters) off the coast of Massachusetts. These were divided into three groups representing samples taken before, during, and after sleep.
Genetic analysis of the microbiomes of the samples showed that during dormancy, Microorganisms associated with pathogens are released, as well pathogens that absorb nutrients.
Microorganisms that can provide nitrogen to corals, on the other hand, increase in abundance, indicating that corals effectively manage their microbial community while maintaining diversity.
This is in line with the team’s thinking – that there is a “renewal and regeneration” process going on, which protects the microbial community and meets the needs of the corals when they are both ‘awake’ and ‘sleeping’.
“This research shows that these organisms react to stress and recover as much as possible,” says marine biologist Amy Apprill, of the Woods Hole Oceanographic Institution in Massachusetts. “It’s basic information that can help us develop probiotics or other micro-medicines for stressed corals.”
This is the first time that a continuous movement of a group of microbes has been documented in aquatic animals during hibernation, although it has been noted in other wild animals: there is a change in the microbiome of ground squirrels, for example, which increases nitrogen recycling rates. during hibernation.
The next step is to better identify the pathogens that help corals to protect and recover from disturbances. Furthermore, they can be built or designed for better health.
Further research is needed to determine whether corals are producing and recruiting these microorganisms or whether they are leaving and arriving at will – long-term sampling and a larger area should reveal more.
“This work opens up a lot of questions,” says Brown. “The big question is: why does coral wake up at the beginning of spring? This study shows that large groups of microbes may play an important role in triggering the initiation or exit of coral dormancy and the regulation of its microbiome.”
Research has been published in Applied and Environmental Microbiology.
