Study investigate alterations in coral microbiome caused by hypoxia
California, US: A recent study was the first to characterise the coral microbiome in the presence of hypoxia, or low oxygen levels in the water.
The findings were published in the journal Applied and Environmental Microbiology by the American Society for Microbiology.
The research is a first step towards identifying possibly beneficial microbes for corals exposed to this environmental stressor.
The study was conducted because there is an increasing understanding of the impact of the microbiome on host health. For example, a healthy human gut microbiome is vital for digestion, immune system response, and even mental health. Like the human microbiome, the coral microbiome benefits its host, the coral animal.
Among these include disease prevention, nutrient uptake, and adaptability to environmental stressors like as rising temperatures and acidity.
Despite this, scientists know very little about the role of the microbiome in coral hypoxia. The researchers wanted to know how microorganisms on the coral's surface respond to hypoxia. They hoped that the research would provide light on how symbiotic bacteria adapt to host and environmental stress.
The studies were carried out in Bahia Almirante, Bocas del Toro, Panama.
"We picked this site because we have seen hypoxic events here associated with human activity, including agriculture and coastal development," said lead study author Rachel Howard, PhD candidate, Department of Soil, Water and Ecosystem Sciences, University of Florida.
"We established experimental chambers which lowered dissolved oxygen on patches of coral reef. We then sampled the microorganisms living on corals in those chambers and corals outside the chambers after 2 days to see how the community of microbes differed with and without the stress of low oxygen."
The researchers found that when oxygen levels dropped, the overall coral microbiome changed after only 48 hours, and the number of some specific types of bacteria increased.
The bacteria that increase are those that can survive without oxygen and are ready to take advantage of a change in resources. When there is not enough oxygen in the water, it throws the community of microorganisms on the coral out of balance, and some of the suspected harmful bacteria, such as Desulfovibrionaceae or Clostridia, become more active.
"Because corals vary in their sensitivity to deoxygenation and given the crucial role of microorganisms in coral health, we suggest that changes in the microbiome may influence coral resilience to oxygen-conditions">oxygen-conditions">low oxygen conditions. Episodes of low oxygen, along with other impacts of climate change, pose a threat to coral and other marine organisms," Howard said.
