How corals react to climate change
“There are species of corals that are more robust and species that are more sensitive to drastic changes in their habitat,” he sums up. Fabian Gösser, a PhD student from the department of Animal Ecology, Evolution and Biodiversity at the Ruhr University of Bochum in Germany, who has been studying how corals react to changing environmental conditions and how their response to stress could contribute to reef survival.
The research, recently published in the specialized journal Ecology and Evolutionunder the title The history, biological relevance, and potential applications for polyp bailout in corals, focuses on the phenomenon known by the English term of polip bailout, or polyps rescue.
Throughout their evolution, corals have developed a wide variety of stress responses to changing conditions. Among them, polyps rescue is a drastic response to acute stress in which coral colonies break down, either in polyps -small individual bud-shaped corals- or patches of these, which detach from the colony and its calcareous skeleton. These individual polyps can settle elsewhere and form new coral colonies, greatly increasing their chances of survival, however, despite the great potential of this response for good reef health, the phenomenon has not been investigated until now. Slowly.
To understand in detail the reactions of corals to climate change, the research team led by Gösser has been conducting various experiments in research tanks modifying variables such as temperature, partial pressure of CO2 and salinity up to limit levels. “We put the corals through a stress test, simulating even more dramatic environmental conditions,” describes the researcher, whose team has already determined that different coral species react with different degrees of intensity to stressors, such as increased salinity. .
As we said a few lines back, the investigation focused on the polyps rescue response that it observed in stony corals. “Individual polyps, for example, shed from the coral colony in response to a 4 ° C rise in temperature above their tolerance, at which point they would abandon the sinking ship, so to speak,” explains the author. .
But something even more surprising in his opinion is that These polyps may have started to grow in a different location. “Even if only a small proportion survive the shedding process, it could have a major impact on the preservation of the coral population, genetic diversity and reef survival,” adds Gosser, offering testimony to the importance of this strategy.
A genetic response to stress
To understand the reaction in more detail, Gösser is currently studying the polyp salvage process at the molecular level, looking at what happens to polyps when they shed and which genes are turned on during this process.
To do this, the biologist first extracts DNA and RNA from stony coral tissue samples that were taken at different times during the rescue process. It then sequences the complete messenger RNA, which transmits the information of the active genes, and compares the base sequence with previously decoded genomes. “We see that the genes that are activated during the rescue process are the genes responsible for immune responses in humans, for example”, Describes the biologist.
These immune system responses during polyps rescue seem to indicate that the microbial partners of corals – for example zooxanthellae – are involved in the response. Gösser’s analyzes also suggest that the polyp rescue process is a general response of corals to acute stress, regardless of the type of stressor. An extreme answer, to be sure, but behind which could be the secret to the future survival of coral reefs.
- You enjoy history? Are you a photography lover? Do you want to keep up to date with the latest scientific advances? Do you love to travel? ¡Apúntate gratis a nuestras newsletter National Geographic!