Bacterial protection offers hope against coral degradation
28 Feb 2017 by Evoluted New Media
Coral reefs may be protected from bleaching by bacteria in certain microbiomes, according to researchers in Saudi Arabia.
Coral reefs may be protected from bleaching by bacteria in certain microbiomes, according to researchers in Saudi Arabia.
The scientists also believe bacteria helps the coral adapt to higher water temperatures, making this relationship vital to help corals survive rising ocean temperatures.
Associate Professor Christian Voolstra, from the King Abdullah University of Science and Technology (KAUST) and project leader, said: “We designed an experiment that allowed us to monitor coral-bacterial interactions over time and assess their responses to changes in water temperature.”
To survive coral often relies on algal and bacterial symbionts – a close and usually long-term interaction between two different biological species – to survive. Researchers believe that these relationships are a means to offer coral protection against rising sea temperatures.
Using reef pools based in the South Pacific, the research team chose areas very close in proximity to one another which hosted the same coral species, Acropora Hyacinthus. However, the temperatures of the two pools were very different – one fluctuated between 25 - 35°C and the other rarely exceeded 32°C. Coral fragments were transplanted from one pool to the other and closely observed for 17 months.
Dr Voolstra said: “17 months after transplantation, we conducted a short-term heat stress experiment and found that the corals transplanted to the warmer environment had changed their associated bacteria and were more heat resistant.”
Corals native to the cooler pool bleached significantly over the course of 17 months, but corals that were moved to the warmer pool 17 months earlier bleached less, due to their newly acquired microbiome. Analysis of the microbial communities from the pools showed that higher temperature microbiomes had a higher carbohydrate metabolism and more functional sugar-transport system.
The researchers’ next step is to prove that specific bacteria directly contribute to thermal tolerance. This will be attempted through showing that bacterial absence makes the coral host heat sensitive and vice versa. Dr Voolstra admitted this will be “challenging, as finding the right bacteria is like finding a needle in a haystack.”
The research was published in Nature Communications.
