In order to understand the defenses of corals against warm waters, Meibom and his colleagues wanted to understand how much heat the corals and their complex networks (called holographic organisms) can withstand. He likened this to testing the strength of a rubber band: how far can you stretch before it breaks? How long does it take to return to normal shape?
Karine Kleinhaus, who studies corals at Stony Brook University, said that understanding how these corals work at the cellular level is crucial. “These amazing corals will be the last corals to survive” until the end of the 21st century, she said. “We need to figure out what they are doing, what happened, how they did it.”
In their experiments, the researchers grew pistil In a series of aquariums, they called it the “Red Sea Simulator”. Each aquarium can be customized to replicate specific water conditions and expose corals, algae and bacteria to different temperatures for different periods of time. Then, the researchers examined the genes that corals express under normal conditions, the changes that occur with increasing temperature, and the rate at which gene activity returns to normal when the temperature drops.
They found that when the water warms, all three organisms can change the genes they use.For example, corals have begun to use genes involved in unfolded protein responses, which are a type of Maintain homeostasis In the cell; in other studies, it is described as a coral First line of defense Heat resistant. At the same time, the algae inhibited the activation of genes related to photosynthesis. In general, Red Sea species can survive a temperature rise of more than 5 degrees Celsius. Once the scientist lowered the temperature in the water tank, the entire holographic creature returned to normal even after a week in hot conditions. Meibom likened their elasticity to a super healthy athlete who was able to recover quickly after a big workout. And prepare for the next challenge.
Andréa Grottoli, a professor at the Ohio State University School of Earth Sciences who studies corals and climate change, said: “This paper is excellent and reveals the early stages of the heat stress response of heat-resistant corals.” She noticed that this method has some limitations. Just because genes are activated does not mean that corals will eventually produce new proteins. This is an indicator of the coral’s response to its environment, but it is not all-you will also want to know exactly what biochemical changes it is making to adapt, and how these changes physically alter the coral.
Grottoli also pointed out that the longest exposure time in the study (up to 7 days) was shorter than many real-life heat waves. “Most natural bleaching events last two months,” she said.
Meibom agrees that his research does not explain how these newly activated genes help corals survive, but he said identifying them is a step towards figuring this out. “It provides clues to what is happening.”
It is unclear why these corals have such heat resistance, while other corals do not. Probably not because they evolved in the hot climate of the Red Sea, but because they came from hotter places. Meibom believes that this may be related to species that lived in the Red Sea during the last ice age about 20,000 years ago. The water around the equator evaporates and eventually freezes into large glaciers. All the water was blocked by ice, and the sea level dropped sharply, separating the Red Sea from the Arabian Sea and basically turning into a lake. The water level drops and salt accumulates, making it a desolate environment. But when the glacier melted and the connection to the rest of the ocean was repaired, new water and life forms poured in. These include corals that live in the Arabian Sea, which slowly rise from the warmer southern waters. Only these high-temperature-adapted species are healthy enough to migrate their larvae north to the Gulf of Aqaba. “They were selected. It’s like a filter,” Meibom said.