Heat sensitivity differs between same-species-cells of coral microalgae symbionts
A recent study investigates temperature tolerance between coral symbiont cells across species. Researchers from Uppsala University, led by SciLifeLab Fellow Lars Behrendt, have revealed that even within the same species, cells differ in response to heat stress.
Coral species can tolerate temperature fluctuations to varying degrees. One factor that influences coral tolerance is the composition of their microalgae symbionts from the family Symbiodiniaceae, earlier known as Zooxanthellae.
While earlier research has focused mainly on the differences between species, the researchers took a step further and looked at the difference between individual cells of the same species.
“These differences among cells allowed us to predict the temperature tolerance of a cell before the stress actually occurred,” says first author Linhong Xiao in a press release, from Uppsala University.
Corals are marine invertebrates that utilize photosynthesis via a symbiotic relationship with a group of microalgae known as Symbiodiniaceae. These microscopic algae lives inside the external layer of corals and photosynthesize to create oxygen, glucose, glycerol and amino acids, which together sustain their coral hosts. In exchange, the coral provides the microalgae with inorganic matter and protection.
In the events of high water temperatures, however, the algae becomes stressed and may escape into the water column. As the symbionts flee their hosts, the corals will lose most of their coloration and become “bleached”.
“For one thing, our new method might be handy for coral reef monitoring because it enables us to recognize more heat-tolerant cells in a rapid, minimally-invasive assay. By providing the means to identify and select more temperature-tolerant coral symbionts, our method also holds potential to accelerate ongoing coral reef restoration efforts by ‘experimentally evolving’ temperature-tolerant coral symbionts which could, conceivably, be introduced back to coral host larvae in order to make corals more robust against climate change,” says Linhong Xiao.
In contrast with previous studies, Behrendts team used a one of a kind “miniaturized approach”. Using a microchip the size of a credit card, housing hundreds of coral symbiont cells, and a microscope, they could assess how individual single cells varied in temperature sensitivity.
Their results revealed that even though the sister cells originated from the same species, the behavior of individual cells in response to heat stress did indeed differ.
“We hope our new method can help to predict the thermal tolerance of corals in the field by extracting and measuring symbiont cells from live corals. While we still have a long way to go, our tools might help coral reef monitoring and also increase the speed at which we can create stocks of climate-resilient coral symbionts, a frontier research area,” says last author Lars Behrendt.
Read the entire study here, published in the Nature ISME journal.
