A new Bermudian-based study has challenged assumptions about how corals and algae in the island’s reefs generate energy for survival over the course of the day.

While past studies have estimated coral respiration rates — the rate at which food is converted into energy — based on their activity at night, a recently published study by Arizona State University and the Bermuda Institute of Ocean Sciences found that rates varied significantly over the course of a day and a year.

The research, led by Yvonne Sawall, a marine benthic ecologist and assistant scientist at ASU Bios, found that respiration rates of reef organisms peaked in the afternoon, several hours after the height of photosynthesis, and often fell to their lowest at about sunrise.

The results indicated that the past approach to measuring respiration and photosynthesis might have underestimated rates by up to 23 per cent and 18 per cent respectively.

Ms Sawall said in Bios’s Currents newsletter: “Scientists have known that respiration depends on light, but many discounted its variability, assuming it wouldn't significantly affect the math. Our results show otherwise.”

As part of the study, researchers used specimens of three coral and algae species collected from Hog Reef to the north of the island to conduct detailed measurements at Bios, simulating near-natural light and temperature conditions.

Over the course of the day, the researchers tracked oxygen changes to determine the patterns of respiration and photosynthesis.

Ms Sawall said: “This is the first study that systematically investigated respiration under natural, diurnal light conditions.

“We found that both corals and algae show increased respiration during the day, especially in the afternoon. This has a big impact on how we calculate energy use and production, which are key indicators of reef health.”

Ms Sawall said that more accurate information about how algae and coral produce and use energy are important to understand how they deal with environmental factors such as rising water temperatures, ocean acidification and pollution.

She said: “This research will help refine energy budgets and essentially determine how much energy corals and algae gain through photosynthesis and use through respiration.

“That matters because resilience to climate change is directly linked to energy availability and how that energy is allocated.”